New Phytologist Foundation

‘Sam Gamgee planted saplings in all the places where specially beautiful or beloved trees had been destroyed, and he put a grain of the precious dust from Galadriel in the soil at the root of each. The little silver nut he planted in the Party Field where the tree had once been; and he wondered what would come of it. All through the winter he remained as patient as he could, and tried to restrain himself from going round constantly to see if anything was happening. Spring surpassed his wildest hopes. His trees began to sprout and grow, as if time was in a hurry and wished to make one year do for twenty. In the Party Field a beautiful young sapling leaped up: it had silver bark and long leaves and burst into golden flowers in April. It was indeed a mallorn, and it was the wonder of the neighbourhood. In after years, as it grew in grace and beauty, it was known far and wide and people would come long journeys to see it: the only mallorn west of the Mountains and east of the Sea, and one of the finest in the world.’ (J. R. R. Tolkien, The Return of the King, Book Six, Chapter IX, The Grey Havens) Next time you walk in the misty woods captivated by the sheer beauty and majesty of trees, thank the cast of a million species of soil organisms living in the endless foam of tiny niches of weathered rock, mineral particles and decomposing soil organic matter. As a tree forms, it interacts with guilds of beneficial microorganisms promoting its growth and development. The box of dust given by the Elven queen of Lothlorien, Galadriel, contained the needed mycorrhizal inoculum for promoting the growth of mallorn trees, but infortunately this ancestral knowledge was lost for millenia. It is now very strange to realize that before Professor Jack Harley began his research on the mycorrhiza of beech (Fagus sylvatica) in the middle of last century, botanists and foresters regarded mycorrhizas as being obscure and of little importance. Harley's series of outstanding, now classical, experiments on ectomycorrhizas elucidated the mechanisms by which tree mycorrhizas take up essential nutrients such as phosphate from the soil (Harley, 1953). He clarified the nature of what is undoubtedly the commonest and most important symbiosis in the world. Simply stated, nearly all families of plants form root symbiotic organs, termed mycorrhizas, with soil fungi belonging to all the main phyla; namely Glomeromycota, Ascomycotina and Basidiomycotina. Within days of their emergence in the upper soil profiles, up to 95% of short roots of trees are colonized by mycorrhizal fungi. The importance of this symbiosis in controlling plant nutrient status and growth is now well established (Read & Perez-Moreno, 2003). New Phytologist hosted Harley's seminal papers on ectomycorrhizal physiology, and from this a strong association between the journal and the mycorrhizal community has developed. Indeed, from ISI citation analysis, it is clear that mycorrhizal research still contributes greatly to the success of the journal; the most widely cited and influential article in recent years being the Tansley review by Read & Perez-Moreno (2003) discussing the key ecological role of the different types of mycorrhizal symbioses in plant nutrition. Today, with the advent of new tools and techniques, the possibility of integration across a wide range of disciplines from genomics to molecular ecology and field ecology is becoming a reality that is much encouraged by New Phytologist. In this Editorial we will highlight some of the recent innovative mycorrhizal research published in the journal and look to future challenges that lie ahead. This theme is continued throughout the Forum of this issue, including Commentaries on selected papers and a series of Letters stimulated by discussions and the ideas exchanged at the last International Conference on Mycorrhiza (ICOM5: July 2006, Granada, Spain). Primary research papers in the last few years have broken the ground for new lines of research from regulation of gene expression to the ecological relevance of mycorrhizal symbioses. To cite a few, these studies have provided a new perspective on how the mycorrhizal symbionts play a critical role in biogeochemical cycles. The main stumbling block has been that a large proportion of mycorrhizal fungi do not produce conspicuous fruit bodies or cannot be grown in laboratory cultures, but most importantly there were no techniques available to assess the extensive and highly active webs of extraradical hyphae permeating the soil. The techniques and approaches of above-ground ecology do not translate well to the soil environment. However, during the past decade, PCR-based molecular methods and DNA sequencing have been routinely used to identify mycorrhizal fungi, and the application of these molecular methods has provided detailed insights into the complexity of mycorrhizal fungal communities and populations, and offers exciting prospects for elucidation of the processes that structure ectomycorrhizal fungal communities (Horton & Bruns, 2001). These tools have managed to reveal the tremendous diversity of mycorrhizal fungi interacting with their host in space (Genney et al., 2006) and time (Koide et al., in press), but also how different environmental factors and forest land usage could alter the composition of these soil fungal communities (Richard et al., 2005; Toljander et al., 2006). These molecular ecology studies will spur work on dynamics and functions of mycorrhizal communities and populations, but also generate hypotheses about their role in the changing forest ecosystems. For example, it appears that the formidable webs of extramatrical hyphae of mycorrhizal fungi not only permeate the mineral soil horizons, but are also very abundant in litter and decaying wood debris (Rosling et al., 2003; Tedersoo et al., 2003). With improvements in molecular techniques and appropriate DNA databases (Kõljalg et al., 2005), identification of taxa in fungal ecology has expanded from fruit bodies to mycorrhizal roots to extraradical hyphae (Anderson & Cairney, 2004). Combined with isotopic tools, these techniques provide novel insights into soil fungal ecology. In an elegant study, Lindahl et al. (2007) reported on the spatial patterns of ectomycorrhizal and saprotrophic fungi from soil profiles in a Pinus sylvestris forest in Sweden, and compared those patterns with profiles of bulk carbon:nitrogen (C:N) ratios, and 15N and 14C contents (as a proxy for age). Saprotrophic fungi were found to primarily colonize relatively recently shed litter components on the surface of the forest floor, where organic C was mineralized while N was retained. Mycorrhizal fungi were prominent in the underlying, more decayed litter and humus, where they apparently mobilized N and made it available to their host plants. Mycorrhizas not only shape the plant communities, they also affect the functional diversity of rhizospheric bacteria (Frey-Klett et al., 2005). In their seminal paper, Schrey et al. (2005) have shown that a molecular cross-talk is taking place between the members of these multitrophic associations. But beyond a gross understanding of their demography, the specific spatiotemporal dynamics of mycorrhizal species and communities in the underground remain elusive. The physical, chemical and biological complexity of the soil makes this kind of investigation a daunting prospect. The current situation could be eased by the development of high-throughput molecular diagnostic tools, such as DNA oligoarrays, for cataloging soil microbes on the larger scale imposed by field studies of a very heterogeneous subterranean world. The use of molecular approaches to inform the ecology and evolution of mycorrhizal symbioses has been a hallmark of Marc-André Selosse's research programs, and we are pleased to announce his appointment to the Editorial Board. His group at the University of Montpellier (France) has contributed much to the understanding of the ecology and evolution of mycorrhizal symbioses (Richard et al., 2005; Selosse et al., 2006). In a fascinating example of how molecular tools have provided new cues to understand plant ecology, he showed that the endomycorrhizal symbionts of forest achlorophyllous orchids, such as Neottia nidus-avis, belong to the genus Sebacina, a common ectomycorrhizal taxon associated with temperate trees (Selosse et al., 2002). This study of myco-heterotrophic plants has profoundly modified our view of the specificity of mycorrhizal fungi toward their host plants and the carbon fluxes between the different inhabitants of forest soils (Bidartondo, 2004). Marc-André's interests and expertise in the ecology and evolution of symbioses mesh well with the mycorrhizal expertise of the journal board which includes Iver Jakobsen, Alastair Fitter, Francis Martin, and Ian Alexander, whose perspectives range from genomics to field ecology. The next challenge on the agenda is to identify the functions played by the assemblages of mycorrhizal fungi in situ (Read & Perez-Moreno, 2003). As a prerequisite of such large-scale functional ecology studies, we now need to discover genes controlling the functioning of the mycorrhizal symbioses. Critical in this endeavor will be the use of genomic information on the recently sequenced Populus trichocarpa (Tuskan et al., 2006) and its mycorrhizal mutualists. The completion or impending completion of the genome sequences of the ectomycorrhizal Laccaria bicolor and endomycorrhizal Glomus intraradices (Martin et al., 2004; http://genome.jgi-psf.org/Lacbi1/Lacbi1.home.html) provides an unprecedented opportunity to identify the key components of interspecific and organism–environment interactions (Whitham et al., 2006). By examining, modeling and manipulating patterns of gene expression, we can identify the genetic control points regulating the mycorrhizal response to changing host physiology, and better understand how these interactions control ecosystem function. Complex biological systems such as symbiosis are thought to be caused by the interaction of many genes and the environment, and the genetic components can be determined by association with genetic variation. Association mapping and ecotilling (Gilchrist et al., 2006) compare genomes in wide-ranging natural populations of individuals with different phenotypes to allow ‘associations’ between genetic markers and phenotypic traits, such as nutrient acquisition or symbiosis efficiency. This approach is sparking the development of higher density genotyping arrays with greater power to detect common genetic variations, such as single nucleotide polymorphisms (SNPs) and copy number variants (CNVs); the latter being likely involved in ectomycorrhiza development (Le Quéréet al., 2006). Mycorrhiza-regulated genes involved in N and phosphate absorption and organic matter decay have now been identified (Tuskan et al., 2006; Couturier et al., in press). Analysis of their sequence polymorphisms in wild populations will set the stage for understanding the adaptation of the subsurface symbiotic duet to changes in the environment. In addition, novel DNA sequencers based on massively parallel sequencing of millions of fragments will provide a cost-effective, efficient tool for conducting these candidate-gene based association genetic studies on a large scale in situ. The development of highly parallel genomic assays is still a relatively young field and has not yet been applied to soil microbial ecology. Sequencing of PCR-amplified ribosomal DNA will be substituted by genome sequencing of hundreds of environmental mycorrhizal samples and selected soil metagenomes in the near future. There is no doubt that massive sequencing of soil entities will be fertile ground for novel hypotheses about how mycorrhizal symbioses drive ecosystems. Future efforts in this area will advance our general perspective on mycorrhizal ecology and evolution and elucidate the biological dynamics that mediate the flux of matter and energy in terrestrial ecosystems. New Phytologist is pleased to continue to host and to support these innovative studies. FM would like to thank David and Nicolas Martin for sharing their in-depth expertise on Middle-Earth. Research conducted in Martin's laboratory on the molecular ecology and genomics of mycorrhizal symbioses is funded by INRA, the Région Lorraine and the European Network of Excellence EVOLTREE.

Over the last 25 yr New Phytologist has roughly doubled in size. Over the same period the world population has increased by c. two billion people, a 40% rise. The rise in world population poses some exceptionally difficult challenges for the planet and for our species; the parallel increase in scientific knowledge, exemplified by this journal’s output, is one of the key levers that we have to help us meet those challenges. Currently c. one billion people subsist on < $1 a day. Over the next 30 yr population growth will probably double that number unless serious action is taken to improve their living standards. The likely growth in population in the least developed countries is equivalent to creating a new city of one million people every 5 d. If these people are to have acceptable standards of living, then their rate of consumption, particularly of food and energy, needs to increase. This achievement, which has so far proved elusive, needs to occur at a time when a range of indicators, such as planetary boundaries being crossed (Rockström et al., 2009), ecological footprints being exceeded (Ewing et al., 2010) and ecosystem services being degraded (Millennium Ecosystem Assessment, 2005), all point to the fact that global levels of consumption are excessive and unsustainable. The single biggest problem we face is how to feed the 9–10 billion people who will live on the planet in 30–50 yr time (Beddington, 2010). Historically we have achieved large increases in food production both by intensification and by bringing new land into cultivation. Expansion of the farmed area will not work as a strategy for the next phase both because the amount of suitable unfarmed land is small and because we now understand the consequences for biodiversity and planetary systems of converting much more of it into cropland (Midgley & Thuiller, 2005; Brussaard et al., 2010; Phalan et al., 2011). The problem is exacerbated both by the inevitable loss of productive farmland to urbanization and the high current rate of degradation of soils in many parts of the world (Lal, 2007). There are currently seven billion people living off 1.5 billion hectares of farmland, which means that each of us should have access to just over 2100 m2, or c. 45 m × 45 m – in reality, of course, some of us use the products of a much larger area. If population grows to 9.3 billion by 2050 [the United Nations (UN) medium projection] and we continue to lose c. 0.4% of that land each year to urbanization, salinization and other forms of land loss or degradation, the area available will then be under 1400 m2 per person (c. 37 m × 37 m): your personal square of land is shrinking by c. 20 cm yr−1. In consequence, productivity will have to rise by c. 50% just to keep pace with the current availability of food and the consequences of inequity in distribution will be even more stark. How can we do this? Some improvement in productivity is achievable by using known science and simple technology, notably in large parts of Africa where yields are often low and farmers cannot afford even basic inputs to boost them. New science will play its part too: exciting developments in the understanding of how the devastating parasitic weed Striga attaches to and damages its host have opened new avenues for its control (Cissoko et al., 2011; Jamil et al., 2011). Raising agricultural yields in Africa above their current low levels is therefore wholly achievable. However, the massive yields delivered by intensive agriculture are probably not sustainable, because of the energy costs of nitrogen (N) fertilizers and the decreasing supplies of phosphate (Cordell et al., 2009), and certainly not deliverable globally by that route. Nevertheless, big improvements are possible. Where the key limitation is soil fertility, N-fixing symbioses can be effective, perhaps by bringing new crop species into play. However, using mycorrhizal fungi to enhance crop phosphorus (P) acquisition is more challenging, though probably essential, and will be best achieved by effective agronomic practices (Verbruggen et al., 2010) and there is building evidence that these symbionts may play an important role in the N cycle too (Leigh et al., 2009; Hodge & Fitter, 2010). If fertilizer is available then it needs to be used cleverly, as in precision agriculture (Gebbers & Adamchuk, 2010). On many soils, however, making nutrients more available will do little because the problems are drought or toxicity, including salinity. Drought is an especially challenging problem because of the absolute scarcity of water in many parts of the world and because humans currently intercept c. 60% of all run-off following precipitation and use 80% of that for agriculture. There is real concern that one of the biggest impacts of climate change will be to increase the frequency, severity and global scale of drought (Romm, 2011). Using drought resistant plants as novel crops will help – for example, Crassulacean Acid Metabolism (CAM) species such as Agave have some potential (Borland et al., 2011) – and that will require a better understanding of the variety of ways that plants have evolved to cope with drought (McDowell et al., 2008), but attention has also been given to the possibility of engineering drought resistance. There has been great hope that genome knowledge can be used to improve crops and the plethora of new technologies (next generation sequencing, transcriptomics, phenomics) gives grounds for enhanced expectations (Jackson et al., 2011). One GE Shangri-la has been the creation of a N-fixing cereal, either by transferring the genetic pathways for symbiotic fixation from legumes (Oldroyd et al., 2009) or by direct transfer of the nitrogenase enzyme system to chloroplasts or mitochondria (Beatty & Good, 2011). The effort being put into this programme is large and it seems likely that progress will eventually be made, but it is not a risk-free approach: an N-fixing cereal could potentially become a major weed in other crops or invasive in unmanaged ecosystems, and if N-fixation were to be transferred to a crop with wild relatives, the ability might become more widespread with wholly unpredictable consequences for natural ecosystems and the global N cycle. Relying too heavily on genetic manipulations is always going to be a dangerous strategy. To date the technology has largely been used to counter weeds and pests, despite abundant evidence that plant pathogens and competitors can evolve rapidly to counter any clever defences we erect. Intelligent combinations of approaches can help to make bred or engineered resistance more durable, as shown by Brun et al. (2010), but a proper long-term solution may require a very different approach: ‘One idea is to re-engineer the agroecosystem to increase overall host diversity, at the species level as well as at the gene level, to reduce directional selection and present an evolutionary dilemma to the pathogen’ (MacDonald, 2010; pp. 3–5). In other words, we need to re-think the way we organize production systems. A more sustainable agriculture will use both the technological innovations of plant science and the ecosystem thinking that derives from ecology. The ecosystem is a relatively young concept (Currie, 2011) and is only now beginning to have an impact outside its core discipline, especially with the adoption of the concept of ecosystem services, the free services that we get from the natural world and on which we depend (Millennium Ecosystem Assessment, 2005; EASAC, 2009). The problem with intensive agriculture is that it uses land for a single purpose – food production; all other services that land might deliver are minimized, including soil formation, carbon storage (for climate control), water storage (for flood control) and water purification. Since we need to preserve and promote all these services, we are going to have to develop cleverer ways of managing land, whether in agriculture or elsewhere, that ensure that we get both sufficient food and a habitable planet. What is needed to attain that goal is better collaboration between plant scientists, ecologists, agronomists, social scientists and others to develop integrated and sustainable agricultural systems. New Phytologist will remain a forum for publication of the innovative fundamental plant science (Grierson et al., 2011) and ecology that underpins that development.

New Phytologist instituted the annual Tansley Medal competition for young scientists in 2009, with full information about the competition found in Woodward & Hetherington (2010). The broad spectrum of plant science that is published in New Phytologist means that the applications cover a very wide range of topics and this year was no different. Two editors from New Phytologist sifted through the initial applications that led to a final shortlist of six manuscripts, all of which are published in this issue of New Phytologist. This year, the winner was Frederic Lens from the Netherlands Centre for Biodiversity Naturalis at Leiden University in the Netherlands. The title of the paper is Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer. This nicely inclusive piece of work was carried out by Lens and his co-authors (this issue, pp. 709–723), while on a funded research visit to the laboratory of John Sperry at the University of Utah, in the USA. The research addresses the long-standing debates and theories about the relationships between wood structure and hydraulic transfer in tree xylem. High hydraulic conductivity is correlated with plant productivity but may be vulnerable to cavitation during high rates of water movement. The structure of the pits between individual xylem vessels is a major resistance in the hydraulic pathway to the formation of air bubbles in the xylem that cause cavitation. Lens et al. addressed the range of hypotheses linking pit structure and cavitation resistance using a wide range of techniques, including electron microscopy of pit structure. Many previous studies have been carried out on a wide range of genera, where phylogenetic differences may lead to different plant controls on cavitation resistance. This study reduced this problem by investigating seven taxa, all within the genus Acer. The very clear result that emerged was that cavitation resistance was strongly correlated with the membrane thickness, porosity and chamber depth of the intervessel pits, features best realized using electron microscopy. This response also carried a significant tradeoff in that greater cavitation resistance was strongly associated with lower xylem conductivity. The authors note that these trends in Acer may be different from observations in other tree species and genera, suggesting that evolution may follow different pathways in solving the conflict between cavitation resistance and conductivity. Congratulations are due also to the following five candidates whose manuscripts are published in this issue of New Phytologist: Francesco Licausi, Regulation of the molecular response to oxygen limitations in plants (pp. 550–555) Younousse Saidi, Heat perception and signalling in plants: a tortuous path to thermotolerance (pp. 556–565) Wei Ma, Ca2+conduction by plant cyclic nucleotide gated channels and associated signaling components in pathogen defense signal transduction cascades (pp. 566–572) Eleanor Gilroy, CMPG1-dependent cell death follows perception of diverse pathogen elicitors at the host plasma membrane and is suppressed by Phytophthorainfestans RXLR effector AVR3a (pp. 653–666) Nicole Hughes, Winter leaf reddening in ‘evergreen’ species (pp. 573–581) Thank you to the many applicants who submitted extended abstracts and to editors and referees for their work in allowing a successful fruition of this year’s competition.

The New Phytologist Tansley Medal was established in 2009 for the recognition of outstanding contributions made by scientists early in their independent career (Woodward & Hetherington, 2010, 2011). The 2011 Tansley Medal has been awarded to Neil Dalchau from Microsoft Research, Cambridge (UK; Box 1). Neil has made important discoveries that provide invaluable insights into the regulation of the circadian clock in Arabidopsis thaliana using a combination of mathematical modeling and experimental intervention. Most revealing among these has been the demonstration that components of the circadian clock are sensitive to sucrose and that the GIGANTIA gene is essential for its perception (Dalchau et al., 2011). Neil was selected from a final short-list of outstanding young scientists. These finalists included Ive De Smet (University of Nottingham, UK) who has made important contributions understanding the role of receptor kinases in plant development; Charles Price (University of Western Australia, Australia) has provided seminal insights to our understanding of the ecology of organism size; Shiv Kale (Virigina Tech, USA) discovered a novel mechanism of signaling in the interaction between oomycete pathogens and their hosts; Simon Conn (EMBO Laboratories, France) is harnessing the strength of natural genetic variation to identify nutrient transport mechanisms in A. thaliana. Each presents their breakthroughs to the general readership of the journal in Minireviews that are published in this issue of New Phytologist: Neil Dalchau, Understanding biological timing using mechanistic and black-box models (pp. 852–858) Simon Conn et al., Exploiting natural variation to uncover candidate genes that control element accumulation in Arabidopsis thaliana (pp. 859–866) Ive De Smet, Lateral root initiation: one step at a time (pp. 867–873) Shiv Kale, Oomycete and fungal effector entry, a microbial Trojan horse (pp. 874–881) Charles Price and J. S. Weitz, Allometric covariation: a hallmark behavior of plants and leaves (pp. 882–889) One thing that is striking as you read through the list of Tansley Medal finalists is that these young scientists cover a broad spectrum of research areas in plant biology. This diversity is a snapshot of the research areas that are published in New Phytologist and demonstrates the genuinely multidisciplinary nature of the journal – it spans everything from small molecules to global system science. It is likely that addressing the ecological and food security challenges of the twenty-first century (e.g. Grierson et al., 2011) will require combination of multidisciplinary and single disciplinary approaches. The journal is well situated to play an important role. With young scientists like Dalchau et al. there is every reason to be optimistic. Neil Dalchau is a scientist at Microsoft Research Cambridge (UK), where he was previously a post-doc, since 2009. His current research is aimed at understanding how biological systems perform computation using biochemistry to ensure their survival in the presence of pathogens and uncertain environmental conditions. This involves applying rigorous computational methods to the understanding of complex biological mechanisms, such as the adaptive immune system in vertebrates. The work covered in the winning review article (pp. 852–858, this issue) was conducted during his PhD studies in Alex Webb’s laboratory at the Department of Plant Sciences, University of Cambridge, in collaboration with Jorge Gonçalves at the Department of Engineering, University of Cambridge. The project was funded by a BBSRC strategic studentship aimed at bridging the divide between experimental and theoretical biology in plants. The success of the work can be attributed, in part, to the multidisciplinary nature of the Webb laboratory, where modeling and experimentation go hand-in-hand. Computationally-savvy researchers do experiments, and experimentally-savvy researchers engage in model construction and testing. This facilitates rapid cycles of model refinement and prediction, which is critical for uncovering novel insights into biological organization. Neil receives a £2000 prize in association with the Tansley Medal award (http://www.newphytologist.org/tansleymedal.htm). For more information about Neil visit http://research.microsoft.com/en-us/people/ndalchau/ or contact him at [email protected]

The ‘black diamond’, the ‘mysterious product of the earth’, the ‘ultimate fungus’ and ‘la grande mystique’ are some of the common names describing the delectable Périgord black truffle (Tuber melanosporum Vitt.). The culture, harvesting and marketing of this highly prized ectomycorrhizal fungus is a world that retains some of the secrets and intrigue of the past (Hall et al., 2007). Truffle cultivation is notoriously difficult, in part because of its cryptic life cycle as an underground symbiont, in which the fungus trades nutrients with oak-tree roots. By the end of the 1960s, there had been some success in devising new methods for producing truffle-infected seedlings under controlled conditions in glasshouses by inoculating plants with truffle cultures and spores. After successful plantation in orchards, reliable information on truffle yields and production is very difficult to obtain as a result of under-reporting of harvests, under-the-table marketing practices and a lack of administration records. It appears, however, that the production of truffles, as with other mushrooms, is erratic from year to year (depending on the weather conditions) and tends to decline as a result of global climate change. Decreasing supply and rising market prices have provided a strong incentive for research on truffle cultivation. This includes a better understanding of the fungus life cycle and the ecology of truffle grounds. Scientists investigating both plant–microbe interactions and the molecular ecology of the mycorrhizal symbiosis will benefit from the description of the T. melanosporum genome (Martin et al., 2010) and equally so from the companion papers compiled in this issue of New Phytologist (Ceccaroli et al., 2011; Montanini et al., 2011; Rubini et al., 2011a,b; Splivallo et al., 2011; Tisserant et al., 2011) and in Fungal Genetics and Biology (Bolchi et al., 2011; Murat et al., 2011; Zampieri et al., 2011). The authors of these papers have used the freshly minted truffle genome to begin to probe some of the most intriguing questions in both the biology and ecology of this iconic fungus. What has the initial analysis of the truffle genome sequence revealed? The Tuber genome, of 125 megabases, is one of the largest fungal genomes sequenced so far, but it contains fewer than 7500 protein-coding genes – a very compact gene space (Martin et al., 2010). It would appear, based on the different gene repertoires and symbiosis transcriptomes of T. melanosporum and the ectomycorrhizal basidiomycete Laccaria bicolor (Martin et al., 2008), that the evolution of the symbiotic lifestyle is quite divergent (Plett & Martin, 2011). The two symbionts use very different molecular ‘toolboxes’ to interact with their respective hosts. The Tuber genome comprises > 55% retrotransposons and DNA transposons (Martin et al., 2010). Born in bursts, retrotransposons mainly dispersed in the genome of Tuber during the last 5 million yr. Whether these retrotransposons are generating new genes through rearranging gene fragments in T. melanosporum remains to be investigated. Simple sequence repeats (SSR) are also highly abundant in the genome and have been used to generate multilocus SSR fingerprints of several geographic accessions (Murat et al., 2011). This survey showed that T. melanosporum is a species with a high genetic diversity, which is in agreement with its recently uncovered heterothallic mating system (Rubini et al., 2011b, pp. 710–722). While looking at the gene repertoire of T. melanosporum and classifying the function of its genes can tell us what it is capable of, it does not tell us whether that species ever takes advantage of this capability. Transcriptomics gives us a snapshot of which genes are expressed, and by comparing the transcriptomic profile of T. melanosporum as it experiences different environments, we can start to understand how the truffle will respond to changes within its host plant and ecosystem environment. To complement the genomic sequencing effort, Tisserant et al. (pp. 883–891) used Illumina-based RNA ultrasequencing to generate a picture of the repertoire of genes expressed during symbiosis and fruiting body formation. Having this picture proved to be very valuable to the community in the annotation process. Genome analysis and transcriptomics is only one power tool in the toolbox. To fully understand the biology of the truffle symbiosis, we need to perform multi -’omic observations using genomics, proteomics and metabolomics to determine changes in the genomic potential, protein inventory or metabolite profile. Montanini et al. (pp. 736–750) used functional analysis in yeast to identify and catalogue T. melanosporum transcriptional factors (TFs). They identified several strikingly upregulated TFs in the mycelium colonizing the root, suggesting that they are controlling both the development and functioning of the symbiosis. Comprehensive annotation and transcript profiling of genes involved in carbohydrate metabolism (Ceccaroli et al., pp. 751–764) and metal homeostasis (Bolchi et al., 2011) are providing novel insights on the functioning of T. melanosporum during truffle formation and symbiosis. One point to always consider is that without information about the environment from which these -’omic observations are made, we can reach no meaningful conclusions regarding the relationship of these observations to the ecosystem. Contextual information, such as temperature, rainfall and pH, may help us to build up a picture of the conditions which have acted to create the transcriptome in the first place. Thus, the identification of cold-responsive genes (Zampieri et al., 2011) is providing new markers to study the truffle biology in situ. Understanding how T. melanosporum functions and interacts in an ecosystem is vital. That issue is addressed directly in a breakthrough study of mating-type gene distribution and dynamics in a truffle ground by Rubini et al. (2011a, pp. 723–735). The observed biased distribution of mating types in a truffle ground is a factor that may severely limit truffle fructification and production, and a thorough understanding of this mechanism will probably benefit truffle ground management. Moreover, the availability of collections of several geographic accessions should allow for next-generation DNA and RNA sequencing to characterize the functional impact of genome variability. This will allow unique questions about genome organization and plasticity and gene expression, including sex-related genes. Truffle gourmands describe the scent of the Périgord truffle as sensual, seductive and unique. As pinpointed by Splivallo et al. (pp. 688–699), these aromatic volatile organic compounds (VOCs) are not synthesized for the mere pleasure of humans. Truffle volatiles act as odorant cues for mammals and insects, which are thus able to locate the precious fungi underground and spread their spores. VOCs also play a role in the ecology of the symbiont in controlling the interactions with the plants and rhizospheric microorganisms. Simultaneous analysis of VOCs and transcript profiles in environmental samples is currently underway and will become increasingly meaningful for understanding the synthesis of the complex cocktail of truffle aromatic volatiles. Clearly, the analysis of the first genome sequence from an ectomycorrhizal fungus, L. bicolor (Martin et al., 2008), and the present truffle genome have brought us to a point where we are faced with opportunities to develop an understanding of the evolution of the mycorrhizal symbiosis in ways never anticipated. The sequencing of the Périgord black truffle moves us a further step away from the past towards a future where we will be following multidimensional changes in gene networks and relating them to the ecology of the truffle ground. Genomics of T. melanosporum is also offering clues that could help a truffle industry that is fraught with unpredictable yields and a counterfeit market. The genome paper and its raft of companion papers are providing us with novel insight into the biology of this ‘ultimate’ fungus, yet this still leaves sufficient mystery in the area so that you can enjoy your truffled risotto. Bon appétit!

This article is a Commentary on Buchholzer &amp; Frommer (2023); 237 : 12–15.

Link to the Virtual Special Issue

Each year the New Phytologist Trust is proud to award the New Phytologist Tansley Medal to an individual in the early stages of his or her career who has made an outstanding contribution to plant science. We are delighted to announce that the recipient of the 2016 Tansley Medal is Dr Etienne Laliberté of the University of Montreal, Canada. Etienne's research focusses on the impact of ecological interactions among plants, microbes and soils on communities and ecosystems. To find out more about Etienne and his contributions to understanding community effects of plant–soil–microbe interactions, please see his Profile in this issue of the journal (Laliberté, 2017a, pp. 1580–1581), or listen to an interview with him, available at: https://soundcloud.com/new-phytologist/interview-with-etienne-laliberte-winner-tansley-medal-2016/s-t0hib. Etienne Laliberté's Tansley insight is titled ‘Below-ground frontiers in trait-based plant ecology’ (Laliberté, 2017b, pp. 1597–1603). In his Tansley insight Etienne notes that despite advances in plant biology using trait-based approaches, below-ground approaches have been overlooked. Etienne proposes to redress this by highlighting six ‘below-ground frontiers’ in trait-based plant ecology, with particular emphasis on traits that govern soil nutrient acquisition. These six frontiers are intended to help focus research efforts to maximize the potential of trait-based ecology, and to ultimately enhance predictive capacity across ecological scales. We offer our warmest congratulations to Etienne and his fellow finalists, and we wish them continued success. We look forward to following their future careers. The judging panel for the 2016 Tansley Medal was comprised of the following New Phytologist Editors: Prof. Amy Austin, Prof. Liam Dolan, Prof. Alistair Hetherington, Prof. Elena Kramer and Prof. Natalia Requena.

Link to the Virtual Special Issue

In the first issue of New Phytologist, in 1902, the founding editor, Sir Arthur Tansley told his readers that ‘Topics are constantly arising on which … discussion would be valuable not only to the one or two people immediately interested, but to the rest of their colleagues’. Accordingly, his vision from the outset was that the content of the journal would continue to evolve as the interest of its authors and readers evolved. To this day, we strive to ensure that the work we publish has broad appeal to our community and regularly review our content, asking ourselves whether any subject areas are missing from our pages. It is as a result of recently conducting this exercise that we are delighted to announce the formation of a new section of the journal to be headed by Professor Claire Halpin (University of Dundee, UK) called Transformative Plant Biotechnology. Our intention in establishing this new section is to reflect the growing interest in plant biotechnology. We recognize that plant biotechnology is a very wide discipline, so rather than attempting to capture its breadth we have decided to specialize. After much deliberation, we are pleased to announce that we wish to publish innovative studies that describe how results from the fields of plant bioengineering, plant synthetic biology, plant biodesign and other examples of exciting emerging technologies could provide solutions to major societal needs or could help to mitigate the effects of environment and climate change. The emphasis on research that contributes to societal needs and helps to mitigate the effects of climate change is deliberate. This is because we feel that it is particularly important that the efforts of plant scientists the world over in this area are recognized and celebrated. It is 40 yr since the first production of genetically modified plants and nearly 30 yr since the first commercial releases. These biotech crops have contributed to agricultural economics, global food security, sustainability and reduced carbon dioxide emissions by increasing crop productivity, conserving biodiversity, reducing pesticide use and alleviating poverty and hunger for many farmer's families. Yet, four crucial and disruptive advances accelerate the opportunities for plant biotechnology to have greater and more rapid ‘transformational’ value in the coming decades. Advances in our fundamental understanding of plant genes, mechanisms, biosynthetic pathways, regulatory circuits and signalling cascades allow us unprecedented insights with which to manipulate plant growth, environmental/ecological interactions and plant product biosynthesis. Advances in several technologies enable us to manipulate these processes for outcomes more ambitious, more versatile, more precise and more predictable than was previously possible. Advances in the regulatory landscape for precision breeding technologies in some countries will soon stimulate and expedite crucial early field testing, underpinning further translation towards societal benefit of promising projects. And, unfortunately, advances in the threats facing our expanding global population increase the urgency of deploying plant biotechnology towards transformational impacts on food security, climate change, biodiversity, long-term sustainability and improvements in human health. Of course, as with all submissions to the journal, manuscripts should offer novel insights into the field or should present advances that will be of significant interest to the community. In order to provide some guidance concerning the type of content that is likely to interest us, we have put together the following, nonexhaustive, list of the sort of topics that we would welcome. Over the past few years, we have commissioned several well-received Tansley reviews and insights on topics directly relevant to Transformative Plant Biotechnology, for example, on plant synthetic biology (Patron, 2020), optogenetics (Christie & Zurbriggen, 2021), forisomes (Noll et al., 2022) and genetic modification to improve disease resistance (Van Esse et al., 2020) or plant productivity (Raines, 2022). The growing interest in this area among our readers is illustrated by the number of relevant full research papers published within the past few months alone. While the focus of these works was usually on improving our understanding of fundamental plant processes rather than directly on exploiting the biotechnological applications that they exemplify, collectively they reveal the breadth of work that the new Transformative Plant Biotechnology section hopes to attract. Several describe very novel routes to engineering pathogen resistance, for example, to barley stripe mosaic virus (Wu et al., 2022), Fusarium wilt in cucumber (Bartholomew et al.,2022) or broad-spectrum resistance to multiple pathogens in rice (Feng et al., 2022). Others describe interventions that can improve seed size in soya bean, or seed vigour and longevity in rice (Hazra et al., 2022; Zhu et al., 2022). Biotechnological approaches to conferring tolerance to abiotic stresses likely to increase over the next decades are illustrated by work on salinity tolerance in rice (Lu et al., 2022) or drought tolerance in wheat (Du et al., 2022). And De Meester et al. (2022) remind us of the crucial role of field trials in evaluating all biotech crops by revealing that lignin-modified poplars that grew normally in the glasshouse and with processing benefits useful to a future bioeconomy show adverse phenotypes when grown in the field. In the current issue, we publish very topical correspondence on crop gene editing regulations in different countries from Buchholzer & Frommer (2022, in this issue), together with a commentary on the same topic from our Forum Editor, David Salt (2022, in this issue). We hope that you will share our excitement in developing this new section in the journal. In 2023, we will organize a scientific meeting devoted to research in the area of Transformative Plant Biotechnology. Please do look out for announcements. We hope to see you there.

The diverse assemblage of ecosystems in tropical regions of the Earth holds a large fraction of the terrestrial biosphere’s carbon (C) stock (Bonan, 2008), and the annual exchange between tropical ecosystems (plants and soils) and the atmosphere is a critical controller of the CO2 concentration of the atmosphere, and hence of climate. Large-scale changes in the structure and function of tropical ecosystems, whether from the pressures of development or the impacts of drought (Meir & Woodward, 2010), can alter the balance in the annual exchange of carbon with far-reaching implications for the pace of climate change. Global models that couple the Earth’s climate system to the C cycle must, therefore, characterize well the biogeochemical and ecophysiological processes of tropical ecosystems and their sensitivity to atmospheric and climatic change. However, major uncertainties about fundamental C cycle processes in tropical ecosystems continue to hinder our progress (Dolman et al., 2010). Diverse aspects of C cycling in tropical ecosystems – from plant physiology and plant–soil interactions to human interactions and regional and global analyses – were discussed at the 23rd New Phytologist Symposium, ‘Carbon cycling in tropical ecosystems’, convened in Guangzhou, China, in November 2009, and summarized by Douglas Schaefer and Matthew Warren (http://www.newphytologist.org/carbon/23rdreport.pdf). In this issue of New Phytologist, we present four papers that emerged from that symposium. They cover the full range of topics discussed – plant physiology, soil processes, human interactions and global analysis – and, from their different perspectives, they all present analyses of C uptake, storage and release in tropical ecosystems. Hättenschwiler et al. (this issue, pp. 950–965) review the literature on leaf litter chemistry in a nutrient-poor Amazonian rainforest. They start with the recognition that, although several large-scale decomposition experiments have been invaluable for parameterizing biogeochemical and global C models, they generally do not include consideration of the influence of soil meso- and macrofauna, which may be particularly important in wet tropical ecosystems, and they often do not incorporate local variation in leaf traits, which are especially important in highly diverse tropical rainforests. Their analysis challenges the commonly held view that litter decomposition in the tropics is fast – decomposition of native litter at their site in French Guiana, and elsewhere in the tropics as shown in a literature survey, was comparatively slow. The authors speculate that natural selection favoured a leaf litter trait syndrome that leads to starvation and inhibition of decomposers, thereby altering competitive dynamics for limiting nutrients, particularly phosphorus. Salinas et al. (this issue, pp. 967–977) carried out an ambitious and comprehensive litter translocation experiment to evaluate the influence of environmental factors on decay rates of multiple species. They conducted their experiment over an elevational gradient from the tropical Andes in Peru to the adjacent Amazon lowlands in what was probably the largest-scale tropical leaf decomposition study to date. Despite the logistical challenges, this gradient had the advantages of the consistently high annual rainfall and the absence of substantial seasonality in temperature and a dormant season that would confound interpretation. They found that soil temperature explained most of the variation in decomposition of a variety of species, and concluded that recent warming in the region may have increased decomposition and nutrient mineralization by c. 10%. This increase in litter mineralization, coupled with rising atmospheric CO2, may partially explain accelerated growth and increased biomass in lowland Amazon forests. Ruiz-Jaen & Potvin (this issue, pp. 978–987) explored whether functional trait diversity or species diversity inform analyses of tree C storage in a mixed-species plantation and a natural forest in Panama. They were motivated by the potential value of using information on functional traits from different natural forests to design tree plantations for C sequestration. They concluded that the C storage capacity of natural forests could not be predicted using data from experimental plantations and, conversely, that forest managers need to be cautious when applying functional traits measured in natural populations when they design plantations for C management. Prentice et al. (this issue, pp. 988–998) approached C cycling questions from a very different temporal and spatial perspective. They assessed the realism of models of the changes in vegetation distribution and C cycling between the last glacial maximum (LGM, c. 21 000 yr ago) to the pre-industrial Holocene (PIH) using stable isotope and pollen data. They concluded that tropical forests accounted for a greater proportion of land C storage at LGM than PIH. Both model results and palaeodata supported the hypothesis that ecophysiological effects of atmospheric CO2 concentration influence tree–grass competition and plant productivity – effects that are assumed still to be in play today.

The New Phytologist Tansley Medal is awarded to outstanding scientists in the early stages of their careers in recognition of their contribution to the field (Woodward & Hetherington, 2010, 2011; Dolan, 2012, 2013, 2014; Lennon & Dolan, 2015, 2016, 2017, 2018). We are delighted to announce that the latest Tansley Medal is to be awarded jointly to Dr Liana Burghardt and Dr Jana Sperschneider. Liana Burghardt is an Assistant Professor in the Department of Plant Science at Pennsylvania State University (USA). She works primarily on the nitrogen-fixing symbiosis between rhizobial bacteria and leguminous plants (specifically Medicago–Ensifer), and her work uses evolutionary and ecological approaches and advances in sequencing technology to understand mutualistic interactions in natural and agricultural systems in a changing climate. This is the focus of her Tansley insight ‘Evolving together, evolving apart: measuring the fitness of rhizobial bacteria in and out of symbiosis with leguminous plants’ in this issue of New Phytologist (Burghardt, 2020, pp. 28–34). Jana Sperschneider is an ARC DECRA (Discovery Early Career Researcher Award) fellow at the Australian National University in Canberra, Australia. Jana is a bioinformatician interested in the interactions between plants and their pathogens. Her work involves using computational techniques to gain new insights into plant–pathogen relationships, and her contribution includes widely used software tools for fungal effector prediction using machine learning. Jana's Tansley insight ‘Machine learning in plant–pathogen interactions: empowering biological predictions from field scale to genome scale’ (Sperschneider, 2020; pp. 35–41 in this issue of New Phytologist), focuses on machine learning (ML) applications in areas in plant–pathogen interactions and highlights benefits and challenges in using ML approaches. For more information on Liana and Jana, and their research, please see the Profile articles in this issue of the journal (pp. 24–26), and visit the Tansley Medal pages of the New Phytologist Foundation website, https://www.newphytologist.org/awards/tansleymedal. Charlotte Grossiord and James Schnable are recipients of honourable mentions. Charlotte is Professor and group leader at the Swiss Federal Institute for Forest, Snow and Landscape Research and she is recognised for her Tansley insight ‘Having the right neighbors: how tree species diversity modulates drought impacts on forests’ (in this issue of New Phytologist, pp. 42–49). James Schnable is Charles O. Gardner Professor of Maize Quantitative Genetics at the University of Nebraska-Lincoln (USA) and he is honoured for his Tansley insight ‘Genes and gene models, an important distinction’ (in this issue of New Phytologist, pp. 50–55). We are delighted to offer our congratulations to Liana, Jana, Charlotte and James. We wish them well in their future careers and look forward to their continued success. The judging panel was comprised of the following New Phytologist Editors: Prof. Amy Austin, Prof. Liam Dolan, Prof. Elena Kramer and Prof. Natalia Requena.

New Phytologist will be 110 years old in 2012, and the journal continues to go from strength to strength. I am sure that our authors and readers will have noted that our ISI impact factor for 2010, announced in June 2011, was 6.516, continuing the impressive upward trend of recent years and placing New Phytologist third in the list of primary research journals in the plant sciences (Thomson Reuters, 2011). This success is attributable to a number of things. First, there is the willingness of our authors to submit to us their best work, and a willingness of our community of advisors and reviewers to provide high-quality reports. Second, there is the quality of our Editors, who make the judgements that allow us to publish novel, rigorous and timely science, to recognize and promote emerging areas, and to encourage progress and innovation. Third, there is the commitment of our Central Office team, who provide an excellent service to authors, reviewers and readers at all stages of publication – something that a not-for-profit journal such as New Phytologist is particularly well placed to do. And finally, there is the willingness of the Editors of New Phytologist and the not-for-profit New Phytologist Trust, which owns the journal, to embrace change to ensure that the journal is a leader in innovative plant science publishing. With this in mind, 2012 will see another important change designed to enhance the standing of the journal and further improve the quality of our provision to authors and readers. From January 2012, New Phytologist will cease to exist in print form, and will only be available in electronic form online. Several interacting factors have prompted this decision. First, and most importantly, is our recognition that it is the online version of the journal that is increasingly used by the overwhelming majority of our readers. There is clear evidence for this in the 1 million article downloads from New Phytologist in 2010. Almost 90% of our subscribers now choose the online-only version of the journal (an increase from 50% in 2007). We therefore wish to concentrate our attention and resources on enhancing the reach and functionality of the online journal. Second, we recognize the problems for subscribers of storing and accessing the print copy of the journal, particularly as it has almost doubled in size over the past 10 years. Of course, there are concerns about the mutability and archiving of the ‘version of record’ of the articles that we publish when they no longer exist in print form, but fortunately our publishers, Wiley-Blackwell, are at the forefront of initiatives in this area. For example, all of our online content is preserved in long-term digital archives such as CLOCKKS (http://www.clockss.org/clockss/Home) and Portico (http://www.portico.org/digital-preservation/) and Wiley-Blackwell are working closely with CrossRef to introduce a new initiative that certifies the online version of record; ‘CrossMark’ (http://www.crossref.org/crossmark.html). Third, the printing, binding and distribution costs of the journal have risen significantly in recent years. By going online-only, thereby avoiding these costs, we will be able both to minimize increases in the cost of New Phytologist to subscribers and to free up some revenue to maintain the quality of the service we offer and further invest in the promotion of plant science (see http://www.newphytologist.org for details of how the New Phytologist Trust promotes plant science). Fourthly, but not least importantly, moving to online-only reduces the carbon footprint of the journal. In preparation for the move to online-only we have been looking at the best ways to improve the functionality of the online journal. For example, we recently completed an online survey of authors, reviewers and readers and we are currently engaged in a number of focus group discussions. If you want to get involved in this dialogue, and have any suggestions or feedback about New Phytologist online, please contact Holly Slater, the Managing Editor ([email protected]). Some enhancements to the online journal (at http://www.newphytologist.com) are standard across all journals hosted on our publisher’s platform, Wiley Online Library (WOL), launched in August 2010. The primary objective in designing WOL has been to provide a ‘clean and simple’ journal platform that allows the reader to navigate easily to, and around, content. So, for example, you can jump between different sections of an article, export citations into a reference managing system, or link directly to Supporting Information and cited references (Fig. 1). The ‘Article Tools’ box (top right-hand corner of each article page) allows you to perform a number of tasks including saving the article to your personal profile on WOL and article-sharing/bookmarking via social networks, such as Mendeley (http://www.mendeley.com) and CiteUlike (http://www.citeulike.org). These sites combine free reference managing with academic social networking to help you organize and discover scholarly articles. You can also ‘find more content like this’ and download figures in PowerPoint format for teaching and lecturing. Looking across to the left-hand side of the WOL webpages you will see a ‘Journal Menu’ that is specific to New Phytologist. Here you can go direct to some of the more frequently used information, such as the Author Guidelines, Current Issue and Editorial Board information, or jump to the New Phytologist‘Journal Home’ page (http://www.newphytologist.com). An example journal article from New Phytologist online hosted by Wiley Online Library. Highlighted features show how a reader can navigate easily to, and around, content, make use of article tools and link to journal information and special features specific to New Phytologist. This homepage provides access to a range of journal content (Fig. 2). Here you have a live feed to the latest articles on Early View as well as the highlights of the current issue. Although, in principle, an online-only journal can dispense with issues, our market research has shown that readers value issue-based publication and we have therefore decided to retain this format. The composition of issues will be determined in the traditional way as papers come through, but we are committed to increase value and interest at this stage through commissioning Reviews and Forum articles, which complement the original research. Our aim is to highlight particularly exciting papers, and also to stimulate interest across subject areas, making the work as widely accessible as possible. We will also be retaining the typeset PDF, which our feedback confirms as the most popular format for reading journal articles both on screen and in hard copy. The New Phytologist journal homepage http://www.newphytologist.com. The homepage is a launch pad for discovering the full breadth of New Phytologist content and the associated work of the New Phytologist Trust (e.g. New Phytologist Symposia and the Tansley Medal for Excellence in Plant Science). Log on to http://www.newphytologist.com to discover the full potential of New Phytologist online. New Phytologist has regularly produced themed issues that focus on areas of current importance and from the homepage you can navigate to all current and past collections of Special and Virtual Issues (http://bit.ly/NewPhytVirtualIssue). Special Issues contain new original research papers in a particular well-defined subject area along with a Forum section, in-depth Tansley reviews and/or concise Research reviews in the same area. These issues support the research community by bringing together timely, high-quality research and opinion in a given field. Virtual Special Issues (VSIs), by contrast, contain a collection of related articles sourced from previous issues of New Phytologist. By pulling these papers together with an up-to-date Editorial we can make them more visible and conveniently accessible to our readers and, hopefully, encourage further research in areas that we think are important. The latest VSIs are packaged in ‘flippable PDFs’ that allow the reader to flip through the Table of Contents and abstracts, as if reading a book, and link out to the full text articles – see, for example, the VSI on ‘Pathogenic plant–fungus interactions’ (Panstruga, 2010). Within our regular issues we also publish sets of Featured articles, which are also highlighted and can be reached directly from the homepage (http://bit.ly/NewPhytSpecialFeature). Recent examples include ‘Pollinator-mediated selection and floral evolution’ (Sapir & Armbruster, 2010) and ‘Carbon cycling in tropical ecosystems’ (Norby, 2011). The News and Highlights section of the homepage gives the latest journal-related information such as most accessed articles, current processing times, press releases, news on the most recent Special Issue, updates on the Tansley Medal for Excellence in Plant Science (see Woodward & Hetherington, 2010, 2011) or Symposia and Workshops that the Trust is supporting. Although there will no longer be a print version of New Phytologist, and therefore no ‘cover’, we will maintain an online cover gallery so that we can continue to showcase the spectacular images that our authors provide in association with their research. We hope you continue to use and enjoy this long-established, but successful and forward-looking, journal in its latest manifestation, and look forward to developing New Phytologist in collaboration with you, and in response to the evolving needs of the plant science community.

In the high valley of the Arc river in Haute Maurienne, France, glacier rivers and threatening seracs make loud roaring sounds, the snow is slowly retreating from the alpine meadows and hundreds of plants are rushing to generate their seeds in these highlands where winter lasts for 8 months of the year. In walking through this colorful cornocupia of flowering plants, enchanting forests of dwarf willows and rock lichens competing for light and nutrients – a peaceful struggle for life – it is hard to believe that a war is taking place in the entangled vegetal crowd. Necrotic spots, blisters and yellow pustules are the visible testimony of the invasion of plant leaves and stems by deadly bacterial and fungal parasites. Pathogenic microbes interact with their host cells to create unique niches for replication and dissemination. The invasion of plant tissues by these pathogenic microbes relies on a battery of secreted molecules, including exotoxins, phytohormone-related metabolites and hydrolytic enzymes (e.g. cellulases, pectinases and proteases) acting on the host tissues. Mutualist symbionts also use secreted metabolites to modify the host expression (Felten et al., 2009). Studies developed over the last five years have demonstrated that secreted proteins also act as powerful effectors. These secreted protein effectors are emerging as the prime weapons and decoys of plant parasites and also as targets for host recognition and immunity (McCann & Guttman, 2009; Panstruga & Dodds, 2009). Effectors are defined as molecules that manipulate host-cell structure and function, thereby facilitating infection (virulence factors or toxins) and/or triggering defense responses (avirulence factors or elicitors) (Kamoun, 2007). This dual (and conflicting) activity of effectors has been broadly reported in many plant–microbial pathosystems. The research topic is currently investigated by employing a variety of approaches (biochemical, physiological and developmental), together with cellular biology, bioinformatics, functional genomics and proteomics, rapidly moving towards genome-wide and evolutionary analyses (Kamoun, 2007; Schornack et al., 2008; McCann & Guttman, 2009; Panstruga & Dodds, 2009; Kebdani et al., 2010; Khang et al., 2010). However, despite tremendous progress in recent years many questions still remain unanswered. Very little is known about the genes that determine whether effectors can or cannot suppress the basal defence (Niks & Marcel, 2009). To understand how molecular information is exchanged among species, and how this information is related to the functional character of the plant and microbial interface, the 22nd New Phytologist Symposium ‘Effectors in plant–microbe interactions’ brought together scientists working on plant–microbe interactions across a range of organisms (viruses, bacteria, fungi and nematodes) (Lebrun & Kamoun, 2010). In addition to topical review papers (Ciuffetti et al., pp. 911–919; Genin, pp. 920–928; Terauchi and Yoshida, pp. 929–939), this issue of New Phytologist contains a feature that presents some of the most exciting results discussed at the symposium. The papers herein discuss the evolution (Chen et al., pp. 941–956; Genin, pp. 920–928; Khrunyk et al., pp. 957–968; Nguyen et al., pp. 969–982), secretion (Szczesny et al., 2010b; pp. 983–1002), trafficking (Wang et al., pp. 1003–1017) and the target (Macho et al., pp. 1018–1033; Manning et al., pp. 1034–1047; Römer et al., pp. 1048–1057; Szczesny et al., 2010a, pp. 1058–1074) of effectors. It appears that bacteria and eukaryotic microbes share a common small protein-coded ‘language’ to interact with plants that is distinct from general nutrient exchange. Effectors of bacteria and filamentous micro-organisms (fungi and Oomycetes) act on a wide range of plant cellular processes (Kamoun, 2007; Genin, 2010; Manning et al., 2010; Römer et al., 2010). However, to alter the host cell, effectors must reach a host target. Apoplastic effectors reside in the plant extracellular space, but most effectors investigated enter the host cell. The ability of microbial proteins to gain access to the host-cell cytoplasm, and subsequently to organelles and the nucleus, is therefore a crucial step in pathogenesis and probably in mutualistic symbiosis. There are several cellular mechanisms by which this protein secretion and subsequent host-cell entry can take place. Bacterial proteins can be auto-transported, they can pass through the general secretory pathway, or most importantly from the standpoint of virulence, they can be secreted by one of several specialized mechanisms found in pathogenic bacteria (McCann & Guttman, 2009; Genin, 2010). Many Gram-negative bacterial pathogens encode type III secretion systems (T3S), syringe-like macromolecular complexes, to directly deliver a cocktail of effector proteins into the host cell (Cornelis & Van Gijsegem, 2000; McCann & Guttman, 2009; Genin, 2010). Type II secretion (T2S) systems could also promote disease and contribute to the translocation of effector proteins that are delivered into the plant cell by the T3S system (Szczesny et al., 2010b). As plant-invading fungi have a common phylogenetic origin and a long history of co-evolution with plants, they probably share ancestral functions involved in interactions with host plants. Studies on genes/functions involved in pathogenicity and symbiosis have highlighted a particular class of effectors corresponding to secreted small proteins (SSP). Genome-wide surveys and transcript profilings have shown that several SSPs belong to protein families in Magnaporthe grisea (a fungal rice leaf pathogen) (Terauchi and Yoshida, 2010), Ustilago maydis (corn smut) (Khrunyk et al., 2010), Leptospheria maculans (a fungal rapeseed leaf/stem pathogen), Melampsora lini (flax rust), Laccaria bicolor (a mycorrhizal symbiont) (Martin et al., 2008; Martin & Selosse, 2008) and Oomycete Phythophtora spp. (Kamoun, 2007; Kebdani et al., 2010). Genome-wide transcriptomics experiments showed that M. grisea, U. maydis and L. bicolor genes, specifically expressed during infection, mainly encode SPPs. Together, these recent studies strongly suggested that SSPs play a role in the interactions between plant-invading fungi and their host. The main hypothesis is that symbiotic and pathogenic fungi mobilize a rich assortment of effector SSPs that interact with, or manipulate, host plants during infection or symbiosis. This research topic is currently investigated by a wide range of approaches combining bioinformatics, functional genomics (transcriptomics, reverse genetics, biochemical/biological assays) and proteomics. As hundreds of species of fungi undergo genome sequencing and annotation, we are moving rapidly toward genome-wide analyses of fungal effectors (Kamoun, 2007; Terauchi and Yoshida, 2010). In contrast to bacterial effectors, eukaryotic effector proteins are internalized into the plant cell in the absence of the fungus or oomycete, suggesting that they do not require a microbe-encoded transport mechanism. Several effectors of eukaryotic microbes, including biotrophic and hemibiotrophic fungi and oomycetes, appear to fuse to the host membranes via binding of an N-terminal motif, RXLR (arginine, any amino acid, leucine, arginine), to phosphoinositol-3-phosphate (PI3P) (Kale et al., 2010). One of the most pressing questions in the study of effectors is to characterize their biochemical activities to understand how they alter plant processes and increase the reproductive success of the pathogen. Recent findings illustrate a diversity of effector structures and activities (Kamoun, 2007; Genin). Many of them act as suppressors of specific plant defense through enzyme activities, such as proteases and/or acetyltransferases (Macho et al.; Szczesny et al., 2010a). Some effectors, such as the soybean cyst nematode (Heterodera glycines) CLE effector proteins, can also alter host gene expression and development in mimicking morphogenetic plant peptides (Wang et al.). The high number and diversity of SSPs lead to the proposal that they interfere with many aspects of the plant metabolism to allow the efficiency of the pathogenic or mutualistic process to be optimized. Recent data suggest that host plants also use this protein-based language to control invading mutualistic microbes. It has been suggested that correct symbiosome development in Medicago truncatula requires the orderly secretion of nodule-specific cysteine-rich (NCR) peptides that are targeted to the bacteria and enter the bacterial membrane and cytosol through the coordinated up-regulation of a nodule-specific pathway (Van de Velde et al., 2010; Wang et al., 2010). As several thousands of novel plant SSPs have been found in Arabidopsis and Poplar by RNA-Seq and protein profiling (X. Yang, G. Hurst, G. Tuskan, pers. comm.), I hypothesize that plants hosting eukaryotic microbes are not a silent partner in the pathogenic or mutualistic symbiotic equation. Rather, they too – through the use of SSPs – might manipulate the growth and development of invading bacterial and fungi within their tissues for their own protection or benefit. The scientific rewards from comprehensive research programs on microbial effectors include a greater fundamental understanding of the interactions between organisms at the community level and benefit for sustainable agriculture. A deeper understanding of the complex array of factors affecting host–pathogen interactions and co-evolution could indeed ensure efficient targeting of parasite-control methods in forest and agricultural ecosystems. I thank Jonathan Plett and Jerry Tuskan for inspiring discussions on the small secreted protein effectors. This review was drafted when hiking in the High Valley of Maurienne in the French Alps. Research in my laboratory is supported by the European Commission within the Project ENERGYPOPLAR (FP7-211917) and the Network of Excellence EVOLTREE (FP6-016322), and the US Department of Energy – Oak Ridge National Laboratory Scientific Focus Area for Genomics Foundational Sciences (Project Plant–Microbe Interfaces).

The United Nations declared 2010 to be the International Year of Biodiversity in which everyone should play some part in safeguarding the Earth’s diversity of living organisms. Individuals will have different visions of what constitutes the conservation of biodiversity, ranging from saving iconic species or small patches of species-rich habitat, to saving spatial scales of sufficient size from which the combined activities of the component species derive important ecosystem functions. All of these scales provide targets for conservation, and all can aim for the dual benefit of conserving species and at least some ecosystem characteristics. At large spatial scales there is often an interest in conserving virgin vegetation that has escaped human influences. Rackham (2008) points out, for woodlands at least, and even extending to the Amazon, that such virgin types probably do not exist in climates suitable for human habitation. The human footprint is ubiquitous and has many forms, from direct destruction to global-scale fumigation by oxides of nitrogen and CO2 from industrial activities. These large-scale phenomena can drive changes in biodiversity (Xia & Wan, 2008) and, potentially, in situ evolution (Onoda et al., 2009). The question of exactly what biodiversity should be conserved is difficult to answer, particularly when the biodiversity has rarely been quantified – anywhere. The diversity of flowering plants is easy to see but this can only hint at a much higher belowground diversity. The application of molecular techniques for investigating fungal diversity has been a major boon to those working in soil. Recent work shows that under a temperate forest including oak and beech, as little as 4 g of soil may contain > 2000 species of fungi (Buée et al., 2009; F. Martin pers. comm.), while just the leaves of bur oak may host one-third of this number of species (Jumpponen & Jones, 2009). Perhaps only 1% of this high species diversity dominates numerically, but the cut-off point for identifying important or useful species has no theoretical basis. Global-scale travel of people and plants affects biodiversity by enhancing the geographical spread of many species, which become identified as alien species. Even buried species of ectomycorrhizal fungi highjack rides on plant roots to new locations (Vellinga et al., 2009). These invasive plant species can exert large impacts on major ecosystem functions, such as the carbon and nitrogen cycles (Liao et al., 2008). Deliberate human intervention to replace natural vegetation with crops can be seen as the visible face of biodiversity destruction. Even here there is substantial diversity in the fungal communities of the crops and soil, and this inter-relationship experiences human impacts through different varieties of crops, which differ in their associated fungal diversity (Pan et al., 2008; Saunders & Kohn, 2009). However, the fungal diversity in the crop soil is probably less than one-tenth of that observed under either a mixed temperate forest (Buée et al., 2009), or a wet sclerophyll forest (Tedersoo et al., 2008). The aerial environment (Jumpponen & Jones, 2009), the chemical environment of the soil (Ehinger et al., 2009; Morris et al., 2009) and year-to-year variations in climate (Sthultz et al., 2009), all exert strong influences on the fungal diversity associated with plants, indicating a much faster species turnover and greater variation in diversity than their host plants. Molecular techniques have provided evidence of the large diversity of fungi associated with their host plants and which are largely hidden from general view. Molecular techniques have also been used to uncover the hidden histories of flowering plants, including their genetic responses to changes in geographical ranges, in particular since the last glacial maximum. It is generally considered that genetic diversity of a species declines towards its range limits. This is seen to be the case for the Mediterranean Aleppo pine (Grivet et al., 2009), which is a glacial relict in Greece and the source of less genetically diverse populations that have spread during the Holocene. Conservation of this species should clearly concentrate on populations in Greece. However, Aleppo pine also showed genetic change in response to the new environments encountered during its post-glacial spread, a response also observed for the shorter-lived bladder campion (Keller et al., 2009), inviting the question of which populations, if any, can afford not to be conserved? Generalizing about plant species seems always to lead to the get-out statement that species differ. This is nicely shown by the deerberry (Yakimowski & Eckert, 2008), which showed no decline in genetic diversity towards its range margins, over a large latitudinal range of 37 to 45°N in eastern North America. The responses of plant species and diversity to climatic change have perforce to base future responses on current geographical distributions. The climatic envelope of the currently realized distributions can then be moved geographically in step with a simulated and changing climate. This simple approach misses many key ecological features, such as the dynamics of geographical change and the influences of changing CO2 concentrations, but a key assumption is that the potential range of a species is little different from its realized range. In a phylogeographical study of myrtle beech, Worth et al. (2009) showed that the species withstood extreme aridity during the last glaciation, in climates beyond its currently realized physiologically determined range. In this case at least, the potential and realized distributions and climatic envelopes do not match, casting some doubt on current approaches used to predict future plant distributions. Larger-scale vegetation-based changes in distribution may provide more realistic future projections. The treeless tundra was warmer than the present during the last interglacial (Francis et al., 2006), with a greater extension of the boreal forests and a smaller area for tundra species (Hoffmann & Röser, 2009). This reduction is predicted for a future, warmer world (Woodward & Lomas, 2004), but a simulated increase in biodiversity (Woodward & Kelly, 2008) of boreal species and weeds could seriously change the characteristic biodiversity of the tundra. Tundra species have evolved in parallel from many nonarctic ancestors (Hoffmann & Röser, 2009), suggesting that the necessary functional adaptation is relatively easy but this evolutionary timescale greatly exceeds the timescales considered for future climatic change. The application of molecular approaches to diversity has identified, quantified and qualified long-held hypotheses in a variety of species and geographical locations. The results may help to focus the conservation of biodiversity, although the approaches have not yet reached the stage of identifying which species should be conserved, beyond the inevitable feeling that this should be all species. A genomic comparison of black cottonwood and thale cress (Quesada et al., 2008) provides a further take on this conclusion. It was demonstrated that the marked phenological differences between the two species were caused primarily by differences in the expression of orthologous genes, with the two species sharing > 90% of genes, even after a genetic separation of over 100 million yr. Biodiversity appears to be less about the differences in genes and much more about the regulation of gene expression.

Link to the Virtual Special Issue

Conversations with experimentalists about theory are often very short, with no real engagement about what is quite central to the scientific method. An objective approach for detecting the presence of theory in published papers can be achieved by searching academic databases. The term ‘theory’ was used to search all publications in New Phytologist for 2009 and 2010, using Thomson ISI Web of Knowledge, SciVerse Scopus, Google Scholar and the Wiley Online Library. The search engines produced markedly different quantitative information; ISI detected 12 papers, SciVerse Scopus 102, Google Scholar 193 and Wiley Online Library 362. The citations were then normalized and allocated to the New Phytologist sections: Physiology and Development, Environment, Interaction and Evolution (Fig. 1). Normalized citation frequency of ‘theory’ in New Phytologist between 2009 and 2010, using four search engines and allocated to the New Phytologist sections: Physiology and Development (Phys/Dev), Environment, Interaction and Evolution. In spite of widely differing total citations from the different search engines, the overall conclusion is that theory figures strongly in papers in the Evolution and Environment sections of New Phytologist and less so in Physiology and Development and in Interaction. The development of plant science is based on observations, the development of theories to explain these observations and the testing of these theories. ISI will count 664 papers between 2009 and 2010 in the calculation of the 2011 Impact Factor. Does this mean that only 2% of papers, according to ISI, or a maximum of 55%, according to Wiley, report on science that has been pursued in the accepted approach? This seems highly unlikely and is clearly a measure of the wide differences in search routines of the search engines. In fact science develops by two different approaches (Fig. 2). Development of science by induction and deduction. Deductive scientific development in plant science can be illustrated by the theory of evolution by natural selection, derived by Darwin. This is an all encompassing theory and needs to be reduced in scope to hypotheses but enhanced in detail to be operational. A sub-component of evolution by natural selection is hybrid zone theory, or in terms of Fig. 2 the hybrid zone hypothesis (Brennan et al., 2009). This addresses the mechanisms that maintain the zone. Observations in these zones can be used to quantify how they are maintained in a situation of selection and gene flow. New observations may lead to changes in the hypothesis but are unlikely to change the overall theory of natural selection. Darwin developed his theory of evolution inductively, based on large collections of observations, moving through smaller scale hypotheses to the overall large picture theory. This theory has since been a continual source of hypotheses for testing the validity and consequences of the theory. The breadth of papers published in New Phytologist provides a source of information to determine whether deductive or inductive approaches dominate overall and in the different sections of the journal. Overall, papers can be classified in both approaches and in all sections. Papers classified as deductive are those that have an overall banner of theory that drives, in general, the development of more specific hypotheses to be investigated. Papers classified as inductive are those that collect and use data sets to derive hypotheses about how a process or mechanism operates. The deductive approach dominates in the Evolution section. Although these papers can all consider natural selection as the overall theory, particular hypotheses need to be developed for testing and are quite distinct, from the importance of pollen grain selection (Hasegawa et al., 2009) and floral polymorphism (Dormont et al., 2009) in seed production, through quantification of crop transgene persistence (Snow et al., 2010), to identifying major problems in estimating the dating of polyploid events (Doyle & Egan, 2010). Papers in the Environment section are predominantly inductive, although Price et al. (2010) provide an unusual example of trying to establish a new theory. More typical are approaches to accumulate data sets of observations, to provide hypotheses of environmental controls, such as the impacts of precipitation events on desert productivity (Robertson et al., 2009) and comparing differences in species characteristics, such as recovery from stem damage in tree species (Romero et al., 2009) and variations in root traits (Comas & Eissenstat, 2009). The application of molecular approaches in ecology is increasing and provides a powerful approach to explain the current distribution of vegetation types in terms of past geological events (Qiu et al., 2009). Molecular approaches are central to many papers in the Physiology and Development section and Rowan et al. (2009) use the approach inductively in exploring the environmental regulation of anthocyanin biosynthesis. Deductive approaches investigate proposed mechanisms, such as the role of NAD metabolism in seed dormancy (Hunt & Gray, 2009) and the role of phytochrome in a non-photosynthetic plant parasite (Takagi et al., 2009). One of the purest examples of rejecting a theory is by Duckett et al. (2009), who clearly demonstrate that capsule dehiscence in Sphagnum is not due to the build up of air pressure as the capsule dries out, a theory of significant longevity, but is in fact due to differential shrinkage of the capsule walls. The Interaction section has papers with both deductive and inductive approaches to research. The interactions between fungal partners and their host plants are typical avenues of deductive enquiry, such as the mycorrhizal uptake of nitrogen from organic material (Leigh et al., 2009), the impact of plant defence compounds on non-mycorrhizal fungal endophytes (Saunders & Kohn, 2009) and the cryptic nature of the orchid mutualism (Cameron et al., 2009). However, the episodic nature of larch bud moth outbreaks (Büntgen et al., 2009) requires long-term data sets and an inductive approach to investigate the nature of this pseudo-cyclic interaction. New Phytologist author guidelines state clearly that submissions should be original research that addresses clear hypotheses and offers new insights. In Fig. 2 hypotheses are central to both deductive and inductive approaches to science. Neither approach has an ascendancy over the other in plant science – but perhaps après moi le déluge !

‘The discussion of new views as well as the reporting of new facts will … continue to be a main pre-occupation of the journal’ ( Clapham et al., 1932 ) The year 2012 is another milestone in the 110 yr history of New Phytologist, as it marks the retirement of Ian Woodward, Editor-in-Chief, and Ian Alexander, Chair of the New Phytologist Trust. It seems appropriate under the circumstances for the new incumbents in these roles to pause and reflect on where the journal is now and where it is headed in the future. Indeed, this is exactly the same exercise that A. R. Clapham, H. Godwin and W. O. James conducted when they took over the reins from the founding editor, Sir Arthur Tansley, 30 yr after the publication of the first volume of what was then known as The New Phytologist. The definite article in our title may have disappeared, but the quotation at the beginning of this article, from an editorial written to mark the start of their 30 yr tenure as editors, is as appropriate today as it was in 1932. Not surprisingly, we have continued to reflect upon the aims and objectives of the journal and, in the relatively recent past, these have been codified. Before thinking about the future, it is worth reminding ourselves what the journal is aiming to achieve. Foremost amongst these aims is the publication of excellent, novel, rigorous and timely research and scholarship in plant science, and to provide a high-quality service to authors, readers and reviewers. A second key aim is to recognize and promote emerging areas of plant science and to encourage continued progress and innovation in the field, achieved principally through support for symposia and workshops (e.g. Atkin et al., 2010; Herr, 2011; Spanu & Panstruga, 2012) and through the New Phytologist Tansley Medal, which recognizes excellence in plant science by those in the early stages of their careers (Woodward & Hetherington, 2010, 2011; Dolan, 2012). In terms of achieving these objectives, New Phytologist is in a fortunate position, in that it is neither owned by a publisher, and therefore subject to the vagaries of market forces, nor in thrall to one of the scientific societies. In fact, because it is owned by a not-for-profit charitable trust, known as the New Phytologist Trust (http://www.newphytologist.org/), it is totally independent and can steer a course decided by its editors and trustees. Over the years, successive editors and chairs of the trust have striven to ensure that New Phytologist publishes the best contemporary plant science as original research papers, reviews and opinion pieces. This will continue and, in keeping with our editorial forefathers’ vision to promote the exchange of ideas and debate, we are pleased to be able to offer free publication of articles (there are no publication charges) and to maintain free access to the Forum and the prestigious Tansley reviews series. Tansley reviews cover all research areas within the plant sciences, from intracellular processes through to global environmental change, and also serve as excellent teaching tools. Recent example topics include cell signalling networks (Dietz et al., 2010), ecosystem science (Currie, 2011), mycorrhizal fungal ecology (Kennedy, 2010) and evo-devo (Mathews & Kramer, 2012). A complete database of all Tansley reviews published can be searched at http://www.newphytologist.org/tansleysearch.asp. We also recognize that the success of New Phytologist comes from the reputation it has earned for publishing high-quality, rigorously peer-reviewed science and for providing our authors and readers with an excellent service in terms of production values and the journal–author interface. Indeed, our current time from submission to first decision is less than 25 days and, on average, the majority of authors will receive three referee reports per paper. Maintaining and striving to improve on this will continue to be a priority. However, we face a number of challenges and, indeed, opportunities: the world of scientific publishing is in flux. Readers will be aware that New Phytologist has recently moved to online-only publication (Alexander & Slater, 2011). The debate concerning different publishing models, especially open access, is lively and provoking much interest. However, what is really exciting are the technological developments that promise, in the short rather than in the medium term, significant changes in how we read scientific papers. What the publishers refer to as ‘content enrichment’ is set to make a major impact on scientific publishing. Our publishing partner, Wiley-Blackwell, is at the forefront of such innovations and we, our authors and readers will be benefiting from these in the near future. Maintaining the success of New Phytologist will involve exploiting the best of these new technologies and this means that the journal will have to be light on its feet and not afraid of experiment or change. These challenges and opportunities were recognized by our immediate predecessors, Ian Woodward and Ian Alexander, and it is our intention, without any sense of complacency, to carry on their good work.

It is our great pleasure to announce that the 2020 New Phytologist Tansley Medal for Excellence in Plant Science has been awarded to Tommaso Jucker. The Tansley Medal is awarded annually in recognition of an outstanding contribution to research in plant science by an individual in the early stages of their career (Woodward & Hetherington, 2010, 2011; Dolan, 2012, 2013, 2014; Lennon & Dolan, 2015, 2016, 2017, 2018, 2020a,b). Tommaso is a NERC Independent Research Fellow and Lecturer in the School of Biological Sciences at the University of Bristol, UK. His research focusses on understanding the processes that shape the structure and function of the world’s forests, in an effort to predict how these will respond to rapid environmental change. Tommaso uses a range of approaches from manipulative experiments, long-term field observations and remote sensing to unravel forest productivity and dynamics and this is brought together in his Tansley insight ‘Deciphering the fingerprint of disturbance on the three-dimensional structure of the world’s forests’ (in this issue; Jucker, 2022a, pp. 612–617). In this Tansley insight, Tommaso considers and outlines a roadmap for integrating remote sensing with field data and individual-based models to build a comprehensive picture of how environmental constraints and disturbance regimes shape the three-dimensional structure of the world’s forests. More information on Tommaso and his research can be found in the accompanying Profile article in this issue of the journal (Jucker, 2022b, pp. 610–611). As with many things in the last two years, the completion of the 2020 Tansley Medal competition is later than we would have liked due to the COVID-19 pandemic. Nevertheless, we are pleased to be moving forwards now and want to highlight that the New Phytologist Tansley Medal is a global competition open to all plant scientists in the early stages of their career (including students and any researcher with up to five years’ experience since gaining/defending their PhD). Selection is a two-stage process. In the first round, applicants are invited to submit their curriculum vitae and a personal statement describing their scientific achievements to date. This will be accompanied by a letter of recommendation from a scientist who has agreed to support the application. For the second round, shortlisted candidates are invited to write a single-authored Tansley insight article on the subject area to which their research has contributed. Manuscripts are handled by relevant subject Editors and sent for external peer review, subject to the same rigours as any regular New Phytologist submission. All competition articles that are recommended for acceptance will be published in the prestigious Tansley review series of New Phytologist and the Tansley Medal winner selected by the judges from these final papers. We encourage applications from across the breadth of the plant science community and invite you to bring the Tansley Medal competition to the awareness of your colleagues and students world-wide. The 2022 competition is open for applications until 15 January 2022. Further information is available on the Tansley Medal pages of the New Phytologist Foundation website at: https://www.newphytologist.org/awards/tansleymedal. We offer our warmest congratulations to Tommaso and his fellow finalists, and we wish them continued success in their future careers. The judging panel for the 2020 Tansley Medal was comprised of the following New Phytologist Editors: Amy Austin (Buenos Aries, Argentina), Liam Dolan (Vienna, Austria) and Elena Kramer (Harvard, MA, USA).

The sudden death of Gopi Krishna Podila was a staggering blow to his immediate colleagues and to all those who knew this wise, amiable man with a great smile and infectious laugh. The world of plant and microbial sciences has lost one of its leading figures and a most respected champion of mycorrhizal biology and genetics. As such, he was an active member of the Advisory board to New Phytologist and an Editor of Symbiosis and Journal of Plant Interactions. That Gopi has been taken from us whilst at the height of a productive career is tragic, and particularly so given that he died alongside two colleagues after a shooting at the University of Alabama (Huntsville). He is survived by his wife and two daughters, his mother and his three brothers. Gopi was born in 1957 at Guntur, Andhra Pradesh, India. He initiated his academic career at the Nagarjuna University, India, where he obtained training in the fields of biology, plant pathology and soil microbiology at both undergraduate and postgraduate levels. Gopi followed this with a move to the USA, where he studied plant pathology at Louisiana State University, ultimately graduating with a Masters degree. He continued his graduate education at Indiana State University where he obtained a PhD in Molecular Biology in 1987 before undertaking a postdoctoral fellowship at the Ohio State University under the guidance of Dr Pappachan Kolattukudy. Gopi joined the Department of Biological Sciences at Michigan Technological University as Assistant Professor in 1990 and rose through faculty ranks to become the Professor and Adjunct Associate Professor in the School of Forestry within a short period of time. In 2002 Gopi moved to the University of Alabama in Huntsville, where he had been appointed to lead the Department of Biological Sciences both as Professor and Chair. In this dual role, Gopi was instrumental in strengthening both the teaching program in Huntsville as well as developing links with the broader biology community in the area, in particular the biotechnology industry. To top his scientific achievements, he was an excellent teacher, a trait he demonstrated with great enthusiasm while interacting with students of all levels, from high school through undergraduate to doctoral levels. Never to raise his voice, he was a patient, amicable and polite teacher and co-worker. A brief review of his work, which led to so many insights, shows that, above all, he had the knack of seeing how new molecular techniques could be used to decipher complex signalling mechanisms of plant–microbe interactions. A series of landmark papers published in Science, Proceedings of the National Academy of Sciences(USA) and Nature with several colleagues in Dr Kolattukudy’s laboratory, concerned the rather puzzling signalling pathways between the phytopathogenic fungus Fusarium solani pisi and its host plant. These early works set the stage for a lifelong interest in how fungi interact with plants. At Michigan Technological University, his group identified several symbiosis-related genes regulated during ectomycorrhizal symbiosis development. His laboratory was one of the first to genetically engineer mycorrhizal fungi for functional genomic studies. As an expert in symbiosis research, Gopi is perhaps now chiefly remembered for his contributions to our understanding of the mechanics of signalling that lead to ectomycorrhizal development, many of his papers having been published in New Phytologist. Gopi’s efforts were instrumental to the success of the project leading to the sequencing of the genome of the ectomycorrhizal fungus Laccaria bicolor, the first, and only, mycorrhizal fungus genome to be sequenced to date. Only a few days before his tragic death, he was discussing how to use RNA-Seq data to improve the most recent annotation of this genome. There were, however, many other areas, such as poplar genomics, in which he laid a firm foundation on which later work could thrive. As an aficionado of symbiotic systems, Gopi was a key member of the International Society for Symbiosis: he was a Governing Councilor of the Society for over 10 yr, and was among the most active editors of its journal Symbiosis since 2000. Present at all meetings of the Society, he contributed very often to the creation of cross-disciplinary interactions and to links between the different models. To those who were fortunate enough to know him, his death leaves an empty space. He would listen attentively, with his head slightly tilted to one side and a twinkle in his eye, and then he would ask a question which would go straight to the heart of the matter. He was never harsh or malicious. His criticisms were kindly and his suggestions invariably constructive. An ardent lover of music, and a researcher to the core with an eye to catch the minutest detail, he was an excellent colleague and friend who shall be missed dearly; we will all remember his periodic emails of good wishes and seasonal greetings, and his infectious laugh, which enlightened our days no matter where we were in the world.