PCIB an antiauxin enhances microspore embryogenesis in microspore culture of Brassica juncea

An efficient protocol to improve microspore embryogenesis is established in an important oleiferous crop, Brassica juncea (Indian mustard). Colchicine was used for enhancing microspore embryogenesis and also to obtain doubled haploid embryos. Colchicine at high concentrations (> 10 mg l(-1)), for 24 h, proved convenient for direct recovery of diploid embryos. Higher temperature treatment and an antiauxin PCIB (p-chlorophenoxyisobutyric acid) enhanced microspore embryogenesis significantly as compared to colchicine. An increase in temperature from 32 degrees C to 35 degrees C proved very efficient in increasing embryogenesis by 10-fold. The highest embryogenesis rate was obtained when PCIB was added at 35 degrees C in the culture after 1 day of culture initiation. 20 mu M PCIB could enhance microspore embryogenesis by 5-fold. Different abnormal shapes of embryos like lemon, banana, flask and fused cotyledons were observed. Both normal and fused cotyledonous embryos showed normal germination when transferred on the B-5 basal medium.