Somatic embryogenesis in grape

Abstract

Grape (Vitaceae, Vitis spp.) is a deciduous temperate fruit crop of ancient origin. Vitis contains two subgenera, Euvitis Planch., the bunch grape species that all contain 38 somatic chromosomes, and Muscadinia Planch., the muscadine grapes with 40 somatic chromosomes (Einset and Pratt, 1975; Winkler et al., 1974). Species in each subgenus are interfertile but are only partially fertile between subgenera (Jelenkovic and Olmo, 1969). Estimates of the number of Euvitis species range from 28 to 43. These are separated into an American group of 18 to 28 species, an Asian group of 10 to 15 species and a European or central Asian group of one species (Vitis vinifera L.) (Einset and Pratt, 1975). Muscadinia contains three species; Vitis rotundifolia Michaux., Vitis munsoniana Simpson, both native to the southeastern United States and Vitis popenoeii Fennell, native to central America, which comprise the muscadine grape varieties. With the exception of muscadine grapes, which are morphologically and genetically distinct, most cultivated grapes are either pure strains or hybrids of V. vinifera and account for the vast majority of world production. Hybrids of Vitis labrusca L., an eastern North American native (Galet, 1988), and V. vinifera, some with additional native species parentage, are in widespread production in the northeastern United States (Cahoon, 1986). Complex hybrids between V. vinifera and various native American species form a series of disease resistant French-American hybrids (Einset and Pratt, 1975). Certain species and interspecific hybrids are utilized exclusively as rootstocks. A number of other Vitis species are used in breeding programs to adapt high-quality vinifera germplasm to suboptimal environmental regions (Alleweldt and Possingham, 1988).