Submitted to: Journal of American Pomological Society
Publication Type: Proceedings
Publication Acceptance Date: October 1, 2009
Publication Date: March 1, 2010
Citation: Stover, E.W., Aradhya, M.K., Dangl, G., Simon, C.J., Prins, B.H. 2010. Introduction to the Workshop and Genetic Resources for Table Grapes in the National Plant Germplasm System. Journal of American Pomological Society. 64:66-71.
Grapes, members of the genus Vitis, have been used by man for at least 23,000 years and actively cultivated for 5000+ years. Grape germplasm has long been selected for table use, as many old cultivars have markedly larger fruit, crisp flesh, larger clusters, seedlessness, and other traits very different from wild grapes. Actively breeding grape varieties specifically for table use was initiated in Europe at the end of the 19th century.
Seedlessness has become the first requirement of a table grape in the minds of most consumers in the US. This is not true in most of the world, where seedlessness is critical only for raisins, and flavor may be of greater importance for table use. The US table grape industry has been far more receptive to new varieties than the wine industry. USDA/ARS release ‘Flame Seedless’ and ‘Thompson Seedless’ are the most widely planted varieties for table use in California, with other new releases such as ‘Autumn Royal’ and ‘Princess’ gaining in acreage. Most taxonomic assessments conclude that there are as many as 60 species in the genus Vitis, with about half native to North America. Development of new table grape varieties falls into three broad categories. Most table grapes are pure Vitis vinifera, and breeding for improved varieties within this species likely remains the dominant component of table grape breeding around the world and within the US. Use of interspecific hybridization largely focuses on introgression of characteristics from non-vinifera grapes such as different and interesting flavors, colors, and improved adaptation to biotic and abiotic stress, into hybrids with largely vinifera-like fruit quality and often seedlessness. Finally, there are several active programs breeding for improved varieties within other species. The National Clonal Germplasm Repository (NCGR) in Davis houses most of the Mediterranean-adapted fruit and nut crop collections in the U.S., including grapes. The sister repository in Geneva, N.Y. includes most cold-adapted grape accessions. The Davis NCGR collection houses the world’s largest grape species collection, including 46 Vitis species and totaling around 700 accessions. We also maintain a collection of over 1200 accessions of V. vinifera, about half of which are “wine grapes” and the other half “table grapes”. In addition, we have over 900 designated hybrids, ranging from recognized “French hybrids” to labrusca types and breeders’ selections. Our collection is further complimented by ~100 V, rotundifolia cultivars, wild collected material, and breeders’ selections. Over 1300 Davis-NCGR accessions are considered “table grapes.” These include 574 named V. vinifera cultivars, 626 “hybrids” (203 American hybrids, 171 French hybrids and 52 V. rotundifolia hybrids and 113 advanced breeder selections), 23 V. labrusca cultivars and 123 V. rotundifolia. The amazing diversity in this collection offers the opportunity for breeders to select parents providing a host of distinctive traits and also may provide interesting niche varieties for small acreage plantings. The Geneva, NY genebank is known as the Plant Germplasm Resources Unit (PGRU), and is located in western New York. The PGRU grape collection includes roughly 1500 accessions, focusing on cold hardy material, and therefore few Vitis vinifera accessions are maintained.