Abstract:

【Objective】 The objective of this study was to improve breeding efficiency of seedless grape through embryo rescue in vitro, to investigate the effects of various correlative factors on embryo development in vitro. 【Method】 The open pollination ovules from 12 seedless grape varieties (lines), including Thompson Seedless, Black Monukka, Centennial Seedless, Delight, Flame Seedless, Superior Seedless, Autumn Royal, Fantasy Seedless, Dawn Seedless, Otilia Seedless, 00-3-1, Blush Seedless and hybrid ovules of 6 cross combinations Ruby Seedless×Guifeimeigui, Ruby Seedless×Xinyu, Delight×Kyoho, Xinyu×Kyoho, Emerald Seedless×Taishan-2, Delight ×Jiangxi-2 were used to investigate the effect of different ovule development media, different medium phases, low temperature, and light/dark condition on the proportion of embryo development in vitro, and evaluate the optimal sampling dates after bloom for picking the young berries, culturing the excised ovules in vitro in different cultivars and crosses. 【Result】 The results indicated that among the 8 media, Nitsch medium supplemented with 0.5 mg?L-1 GA3 and 1.5 mg?L-1 IAA, MM3 medium were found to be most suitable for embryo development in vitro of seedless grapes, and the next was ER medium. Among the solid, liquid and solid-liquid double phase media, solid-liquid double phase medium had the most positive effect on embryo development of middling ovules of seedless grape cv. Delight, yet three phase media showed no significant different effect on embryo development of bigger ovules of grape line 00-3-1. The results also showed that low temperature at the stage of ovule culture in vitro had a negative effect on embryos development. Dark culture had a positive effect on embryo development in ovule cultures in vitro. The optimal sampling dates after bloom of culturing ovules in vitro dissected from berries varied among different cultivars and crosses, the optimal sampling dates was 35 day after bloom (DAB) in Thompson Seedless, 40 DAB in Centennial Seedless, 40 DAB in Flame Seedless, 60 DAB in Delight, 55 DAB in Dawn Seedless, 70 DAB in Black Monukka, 50 DAB in Superior Seedless, 70 DAB in Autumn Royal, 60 DAB in Fantasy Seedless, 40 DAB in Otilia Seedless, 70 DAB in Ruby Seedless×Guifeimeigui, respectively. 【Conclusion】 The results indicated that Nitsch medium supplemented with 0.5 mg?L-1 GA3 and 1.5 mg?L-1 IAA, MM3 and ER media were suitable for embryo rescue in vitro of seedless grapes. The culture environment of room temperature (25±2)℃, solid-liquid double phase medium and dark culture had a positive effect on improvement of embryo rescue efficiency.

Key words: seedless grape')">seedless grape, ovule, embryo rescue, embryo development