Plant Regeneration of Microspore-derived Embryos and Ploidy Variation in Non-heading Chinese Cabbage

Microspore-derived embryos of non-heading Chinese cabbage were used as explants.Process of the plant regeneration of embryos was studied through optimization of basic culture medium,hormone combination,genotype and rooting condition,and the ploidy of chromosome of regenerated plants were identified.The study showed that the best medium for shoot differentiation of microspore-derived embryos was B5 medium supplemented with 0.1 mg/L GA3,3% sucrose and 1.2% agar.Shoot differentiation rate of cotyledary embryos of No.6,No.14 and No.31 were 53.33%,85.24% and 75.55 %,while the average number of shoots per embryo were 5.66,3.83 and 3.28 respectively.To induce strong roots and raise plant regeneration rate,the most suitable medium for rooting was MS with 0.1 mg/L IBA,3% sucrose and 0.6% agar.Root differentiation rate was 100% and 9.70 roots per explant.The ploidy of 133 regenerated plants was identified,the result showed that the non-heading Chinese cabbage had a high level of spontaneously-produced doubling rate and the case of ploidy variation was complicated.The rate of tetraploid plants was 56.39% which was the highest,the rate of diploid plants was 39.10%,the rate of triploid plants was 3.01% and haploid plants with the rate of 1.50% only.