Plantlet regeneration and ploidy determination of microspore embryoids in Brassica vegetables.

Several physiological factors of microspore embryoids for plant regeneration were investigated in Chinese cabbage,cabbage and purple flowering stalk. The results showed that the frequencies of plant regeneration on 1.0%–1.2% agar media was significantly higher than that in 0.8% agar media. 4 ℃ treatment greatly improved the regeneration frequency in Chinese cabbage and cabbage. The optimal stage of embryoids was 20 to 29 days for plant regeneration in Chinese cabbage and purple flowering stalk,whereas it was 30 to 35 days in cabbage. Nevertheless there were no significant effects of B5 or MS media on plant regeneration. The results of ploidy determination in three Brassica vegetables showed that there were higher doubled haploid frequency (over 70%) in Chinese cabbage and purple flowering stalk,but lower doubled haploid frequency (only about 30%) in cabbage. The results suggested that the culture conditions for plant regeneration and spontaneous diploidization efficiency among different varieties of the same Brassica species were identical.