Effects of histone deacetylase inhibitors on microspore embryogenesis and plant regeneration in Pakchoi (Brassica rapa ssp. chinensis L.)

The aim of our study was to investigate the effects of histone deacetylase inhibitors on microspore embryogenesis, and to establish an efficient isolated microspore culture protocol in Pakchoi (Brassica rapa ssp. chinensis L.). The histone deacetylase inhibitors trichostatin A (TSA), suberoylanilide hydroxamic acid (SAHA), and sodium butyrate (NaB) were added to NLN-13 medium to enhance microspore embryogenesis and plant regeneration without an intervening callus phase. Three genotypes of Pakchoi were responded positively to the histone deacetylase inhibitors. The optimum concentration of TSA for genotype 424 was found to be 0.05 μM in NLN-13 medium, which resulted in the largest embryo yields and the highest frequency of plant regeneration. The embryos produced in NLN-13 medium supplemented with SAHA (0.05 μM and 0.10 μM), had the highest direct plant regeneration rates of 75.01% and 87.30%, respectively. We found that 2 μM NaB in NLN-13 medium was the optimum concentration for the three genotypes, which resulted in the highest induction of embryos. Adding histone deacetylase inhibitors to NLN-13 medium, which both improved the rate of microspore embryogenesis and the frequency of direct plant regeneration, can be used routinely for isolated microspore culture in Pakchoi.