Obtaining Viable Explants from Immature Embryos of Seedless Grape Cultivars using Embryo Rescue

The embryo rescue method is widely used to develop new seedless varieties. We applied this method to indigenous Kishmish cultivars. In this work, we studied the days after pollination (DAP) intervals of Kishmish cultivars, optimal artificial media and embryo development, as well as the levels of recovering mature plants from them. Measures have been taken to apply the embryo rescue method for local seedless varieties. For this, Kishmish Sugdiyona (KS), Kishmish Rozoviy (KR) and one seeded Toyfi varieties were selected. Embryos were collected from seedless × seedless, seedless × seeded, self-pollinated and naturally pollinated grape clusters at intervals of 0, 20, 30, 40, 50, 60, 70 and 80 DAP. Murashige and Skoog’s (1962) artificial media were used to grow mature plants from embryos. After stratification, embryos were recovered under an XSP-500SM digital microscope in a laminar flow box (HFsafe LC). Statistical analyses were performed in RStudio 2023.12.0 + 369 with ANOVA test P ≤ 0.05 model. Germination did not occur in embryos separated between 0, 20, 30 and 40 DAP intervals of KS and KR varieties. In each of the two cultivars, the germination of embryos in the form of torpedoes and obtaining mature plants from them was more. Embryos entered the torpedo shape at 70 DAP intervals in both cultivars. Over the next 10 days, 80 DAP, the embryos entered an unknown shape and were degraded. When their amount of KNO3, NH4NO3 was 400 and 480 mg/L, the levels of embryo and germination number dropped. Both varieties showed effectiveness in pollination and embryos obtained from self-pollinated clusters (cleistogamy) showed development potential. In the practice of reciprocal hybridization, when KR variety was used only as a female, 78 (25%) out of 306 mature plants obtained in total were related to KR × KS combination and 26% (152) of the 585 mature plants obtained from the variant KS resulted from the combination of KS × KR. In conclusion, the recovery, germination and plantlet rates of embryos of seedless grape varieties were studied in the tested artificial media. The embryos were transparent during the initial day intervals and then their colours darkened. In the following days (80 DAP), the embryos were degraded and some of them became discoloured. Moreover, the extraction of embryos at the veraison stage was more efficient. The state of germination and plantlet rates of more embryos in the form of torpedoes was observed. The method of embryo rescue can be used in the selection of local seedless varieties.

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