Efficient doubled haploid production in microspore culture of Zengcheng flowering Chinese cabbage (Brassica campestris L. ssp chinensis [L.] Makino var. utilis Tsen et Lee)

Microspore culture has been implemented in breeding programs to produce doubled haploids (DH) and thus accelerate the breeding process. This study aimed to establish an efficient microspore culture protocol for Zengcheng flowering Chinese cabbage, a highly nutritious and valued vegetable, that would be suitable for heterosis breeding. Microspores of three genotypes, 17AY010, 17AY011, and 17AY012 were successfully induced to produce embryos in NLN-13 medium. Two genotypes, 17AY011 and 17AY012 were cultivated in NLN-13 medium supplemented with different concentrations (0, 0.2, 1, 5 or 25 mu M) of L-ascorbic acid sodium salt (Vitamin C Sodium Salt, VcNa) to enhance microspore embryogenesis and plant regeneration without an intervening callus phase. In both genotypes, the addition of 1 mu M and 0.2 mu M VcNa significantly increased the frequency of embryogenesis, 6.55-fold and 10.33-fold as compared with the control, respectively. The optimum concentration of VcNa application that would improve the rates of direct plant regeneration in the two tested genotypes was 1 mu M. Moreover, the doubled haploid rates of regenerated plants of the three genotypes were above 60%. Five DH lines of 17AY012 with high yield were obtained. According to the measurement of the affinity index, they were prospective self-incompatible lines for hybrid breeding.