Microspore derived population developed from an inter-specific hybrid (Brassica oleracea × B. carinata) through a modified protocol provides insight into B genome derived black rot resistance and inter-genomic interaction

Inter-specific hybridization between different species of Brassicas is widely practiced to broaden the genetic base and inter-genomic transfer of desirable traits. A large population of inter-specific hybrids (B. oleracea × B. carinata) were developed through direct embryo culture for introgression of black rot resistance from B into C sub-genome of Brassicas. Inter-specific hybrids were resistant to race 1 and 4 of black rot. A large set of microspores derived (MD) plants were developed using partially fertile inter-specific hybrids for the first time using a modified culture density, temperature shock treatment and polyamine supplement. Forty-three B and 323 C sub-genome specific SSRs were analysed in 117 MD plants along with their ploidy analysis. Frequent occurrence of unreduced and B. carinata like gametes and large number of anueploids in the MD plants was because of single set of B sub-genome (BCC) in the mother plant. Aneuploids for C sub-genome indicate meiotic abnormality in paring between C sub-genome of B. oleracea and B. carinata. Role of B7 and B5 for resistance to Xcc1 and B6 and B2 for resistance to Xcc4 was established. The unique MD population developed will be instrumental in broadening the genetic base of B. oleracea and studying the genetics for various traits using chromosome addition/deletion lines and aneuploids.