Effect of thidiazuron on microspore embryogenesis and plantlet regeneration in Chinese flowering cabbage (Brassica rapa. var. parachinenis)

Traditional breeding methods require more than 6 years to obtain homozygous inbred lines, while isolated microspore culture (IMC) is an effective way to cultivate double haploid homozygous lines in only 2 years. However, low embryogenesis induction frequency in Chinese flowering cabbage remains a key obstacle to the practical application of this technique. Thidiazuron was added at different concentrations to NLN-13 medium to estimate its effects on microspore embryogenesis and plantlet regeneration. Results showed that three genotypes responded positively. Optimum thidiazuron concentrations produced embryo yields of up to 14.67 embryos per bud and increased microspore embryogenesis frequency with up to 100% survival. Plantlet regeneration rates were up to 81.67%, and the treatment groups showed lower callus formation. We obtained up to 552 diploid plants from the tested genotypes, and the percentage of doubled haploid at different TDZ concentrations showed slight differences, and doubled haploid rates in the three genotypes were above 70%. They showed a high uniformity and can be directly used for hybrid breeding. This method accelerates microspore application in Chinese flowering cabbage hybrid breeding.