Effects of pre-bloom spraying thidiazuron and different embryo development media on seedless grape embryo rescue

Embryo rescue technology has been widely applied in seedless grape breeding, but its success depends on many factors. Here, two Vitis vinifera seedless varieties ‘Qinhong No.2’ and ‘Qinhong No.10’ were used as research objects, the inflorescences were sprayed with 0.5 mg·L−1 thidiazuron 10 days before flowering, and then the ovules from open- and self-pollination of them were cultured in solid–liquid biphase MM3 media to investigate the effect of thidiazuron on embryo rescue. Under natural condition, the ovules of open- and self-pollination were inoculated onto three solid–liquid biphase media NN, ER, and MM3 to compare the efficiency of embryo rescue. The results showed that pre-bloom spraying thidiazuron significantly promoted ovule development and further improved the effect of embryo rescue in vitro. After applying thidiazuron, the embryo development rate, germination rate, and seedling rate of the four combinations reached 30.77%–42.62%, 29.36%–41.64%, and 22.02%–40.33%, respectively. Open-pollination of the two varieties provided better effects for culturing than their self-pollination, and the MM3 medium was always more suitable for embryo development than either the ER or NN medium. Furthermore, the germination rate of bare embryos of ‘Qinhong No. 10’ open-pollination on solid WPM medium surpassed that of ovules (without embryo stripping) on solid NN medium. HIGHLIGHTSPre-bloom spraying TDZ could improve the effect of embryo rescue of seedless grape.The embryo rescue effect was better in open- than self-pollinated seedless grapes.Solid–liquid biphase MM3 was more suitable for embryo rescue than an ER or NN medium.The seedling rate of bare embryos on WPM medium exceeded that of ovules on NN medium.Overall, 2312 hybrids from the four combinations were obtained via embryo rescue.