Seed abortion in crosses between diploid and tetraploid grapes (Vitis vinifera and V. complex) and recovery of triploid plants through embryo culture

Abstract

Interploid crosses between two diploid and two tetraploid grape cultivars were carried out to produce abortive seeds with underdeveloped triploid embryos. Growth regulators influencing the recovery of triploid plants from the underdeveloped embryos were individually examined in vitro using MS medium. Of six growth regulators added to the medium, malt extract (25-1600 mg/l), casein hydrolysate (20-1500 mg/l), BA (0.01-1.25 mg/l) and GA3 (0.1-1 mg/l) did not show obvious effect on the recovery, whereas IAA and NAA showed small promotive effect at the concentration of 0.25 and 1.25 mg/l, and 0.01 mg/l respectively. Secondly, 23 interploid crosses with four diploid and four tetraploid grape cultivars were carried out reciprocally to produce triploid plants through embryo culture using MS medium supplemented with 1 mg/l GA 3 and 100 mg/l casein hydrolysate. In the 2x x 4x crosses, 50 triploid seedlings were successfully recovered from 7.3% of underdeveloped embryos cultured, while 33 seedlings were recovered from 2.8% of those in the reciprocals. Of a total of 88 seedlings recovered, 38 were obtained through secondary embryo formation in vitro. From these results, it was suggested that the production rates of triploid plants from the interploid crosses increase with the aid of embryo culture, and that in this case in vitro formation of secondary embryos is an important key factor to increase the rates.