Production and utilization of doubled haploids in Brassica oleracea vegetables

A possibility to increase the efficiency of plant regeneration from microspore-derived embryos of selected botanical varieties of Brassica oleracea was investigated from 2001 to 2004. More than 400 regenerants of R1 generation were derived in kohlrabi, cabbage and cauliflower by means of different modifications of microspore culture technique. Distinct genotype differences in embryogenic responsibility and regenerative ability of microspore embryos to whole plants were detected. The highest frequency of embryogenesis and subsequent regeneration of plants were achieved in cauliflower cultivar Siria F1, kohlrabi line P7 and some experimental F1 hybrids of cauliflower. The best production of embryos was obtained when donor plants were grown in the growth chamber under controlled light and temperature conditions. The regeneration of plantlets was considerably improved by repeated subculture of cotyledonary embryos on media with various combinations of phytohormones and excision of the cotyledons from mature embryos. The percentage of plant regeneration from subcultured embryos in kohlrabi ranged from 11.11 to 63.64%, in cauliflower from 23.53 to 46.19% and in cabbage from 5.88 to 52.00%. The utilization of regenerants for doubled haploid line production is often complicated by male sterility also in plants with the normal diploid chromosome number.