Chromosome doubling effects of selected antimitotic agents in Brassica napus microspore culture

Abstract

Effects of microspore culture treatment with antimitotic agents colchicine, trifluralin and oryzalin on the frequency of embryo formation, embryo development, plant regeneration and diploidization rate in three F<sub>1</sub> hybrids of winter rapeseed cultivars were compared. The ploidy level analysis of 1709 flowering microspore-derived plants showed that in vitro applications of all antimitotic drugs increased the rate of doubled haploid (DH) plants significantly. The mean rate of DH plants from the trifluralin treatment was 85.7%, from colchicine 74.1% and 66.5% in the case of oryzalin, while only 42.3% in the untreated control variant whereas in vivo additional application of colchicine at the plantlet stage did not significantly increase the mean rate of DH plants (55.6%). Although there were no significant differences in diploidization efficiency between the in vitro applications of particular antimitotic agents, trifluralin showed to be the most suitable because of its positive effect on embryo development and conversion into whole plants. In addition, the diploidization rate was sufficient and stable in all genotypes tested. The results indicate that the trifluralin treatment of microspore cultures could provide efficient chromosome doubling for the production of doubled haploid lines from winter oilseed rape breeding materials.