National Clonal Germplasm Repository for Tree Fruit, Nut Crops, and Grapes

BACKGROUND AND AIMS: Condensed tannins, responsible for berry and wine astringency, may have been selected during grapevine domestication. This work examines the phylogenetic distribution of condensed tannins throughout the Vitaceae phylogenetic tree. METHODS: Green berries and mature leaves of representative true-to-type members of the Vitaceae were collected before 'véraison', freeze-dried and pulverized, and condensed tannins were measured following depolymerization by nucleophilic addition of 2-mercaptoethanol to the C4 of the flavan-3-ol units in an organic acidic medium. Reaction products were separated and quantified by ultrahigh pressure liquid chromatography/diode array detection/mass spectrometry. KEY RESULTS AND CONCLUSIONS: The original ability to incorporate epigallocatechin (EGC) into grapevine condensed tannins was lost independently in both the American and Eurasian/Asian branches of the Vitaceae, with exceptional cases of reversion to the ancestral EGC phenotype. This is particularly true in the genus Vitis, where we now find two radically distinct groups differing with respect to EGC content. While Vitis species from Asia are void of EGC, 50 % of the New World Vitis harbour EGC. Interestingly, the presence of EGC is tightly coupled with the degree of leaf margin serration. Noticeably, the rare Asian EGC-forming species are phylogenetically close to Vitis vinifera, the only remnant representative of Vitis in Eurasia. Both the wild ancestral V. vinifera subsp. sylvestris as well as the domesticated V. vinifera subsp. sativa can accumulate EGC and activate galloylation biosynthesis that compete for photoassimilates and reductive power.

Abstract The USDA‐ARS National Laboratory for Genetic Resources Preservation (NLGRP) has developed a pollen cryobank that currently conserves desiccation‐tolerant pollen for six crops within the USDA National Plant Germplasm System (NPGS): Carya (pecan), Corylus (hazelnut), Juglans (walnut), Phoenix (date), Pistacia (pistachio), and Prunus (stone fruits). These crops were selected because there was stakeholder interest, ample quantities of desiccation tolerant pollen, and field site capacity for pollen harvest and shipment. Pollen samples from these genera were collected in the field, air‐dried, sifted, and sent to NLGRP for moisture adjustment, viability assessment, and long‐term storage in the vapor phase of liquid nitrogen. For routine pollen cryopreservation of the six genera, the adjusted moisture content was between 4.4% and 13.3% (fresh weight basis) and between 4.2% and 16.6% dry weight basis prior to liquid nitrogen exposure. Currently, 235 NPGS accessions have been cryopreserved as pollen. In 2025, a subset of cryopreserved pollen inventories was warmed and assessed for viability, as measured by in vitro germination. The results indicate that overall, the viability of the cryopreserved inventories has not changed during cryostorage.