Breeding of disease-resistant seedless grapes using Chinese wild Vitis spp.: I. In vitro embryo rescue and plant development

Seedless grape cultivars (Vitis vinifera L.) are widely grown in Europe, America and Asia. Fungal diseases are a great threat of them. Several wild Chinese Vitis species showed high resistance to many fungal diseases. Therefore, an investigation was conducted to assess the potential to incorporate these species in a breeding project for development of the disease-resistant seedless cultivars. Hybridization was conducted using V. vinifera as female parents and the wild Chinese Vitis spp. as male parents. In-ovulo embryo rescue was used to develop hybrid plants from the seedless females. An efficient protocol is reported here for the in vitro embryo rescue and plant development from the cross Emerald Seedless × Beichun. Ovules were excised from immature fruits 7 weeks after pollination (WAP) and cultured in the double-phase ER medium supplemented with 6.0% sucrose and 0.3% activated charcoal (AC). Following 8–12 weeks of culture, embryos were removed from the ovules and transferred onto WPM supplemented with 1.0 μM 6-benzyladenine (6-BA), 2.0% sucrose and 0.2% AC and solidified with 0.6% agar. After 8 weeks of culture, the embryos germinated and subsequently grew into whole plantlets. With the optimized parameters developed in the present study, about 34.0%, 91.2% and 77.4% of embryo formation, embryo germination and plant development were obtained, respectively. When this protocol was applied to 11 other cross combinations, genotype was found to significantly influence embryo formation, embryo germination and plant development, with different frequencies of hybrid plants successfully obtained in all crosses.