Successful application of microspore culture by adding kinetin and methylene blue to improve microspore embryogenesis in Chinese kale breeding.

Microspore culture is an efficient and rapid method that produces doubled haploid (DH) lines for hybrid breeding in crops and vegetables. However, the low frequency of microspore embryogenesis and spontaneous diploidization in Chinese kale still require improvement. In the present work, an efficient microspore culture protocol was constructed and used for DH producing in Chinese kale breeding. The results showed that kinetin (KT) and methylene blue (MB) improved microspore embryogenesis and embryo development. The spontaneous diploidization rates were below 14.48%. Therefore, artificial doubling was used for haploids; the doubled haploid rate was significantly increased, and the highest doubling rate reached 33.75% with pendimethalin. 98 DH lines were obtained in this study. This study also identified the horticultural characters of the DH lines, which showed significant differences between them. All DH lines were self-incompatible. The hybrid crosses were performed using five DH lines selected for the Chinese kale breeding. This study was helpful to accelerate the application of microspore culture and provide DH lines for Chinese kale hybrid breeding.