文摘
Backcross substitution of Brassica juncea (2n = 36; AABB) nucleus into the cytoplasm of a wild crucifer, Brassica fruticulosa helped in development of a new cytoplasmic male sterility (CMS) system. Male sterility was complete, stable, and expressed as rudimentary anthers containing sterile pollen grains. There was no impact on other floral as well as vegetative characters. All the natural B. juncea genotypes evaluated maintained the sterility. Gene for fertility restoration could be successfully introgressed from cytoplasm donor species. Genomic in situ hybridization studies revealed B. fruticulosa intogression in at least three chromosomes of the recipient species. Genetic studies carried out on F1, F2 and test cross progenies derived from hybridizing cytoplasmic male sterile and fertility restoring genotypes revealed a monogenic dominant control for the fertility restoration. Bulked segregant analysis with 588 SSR and 30 ISSR primers allowed identification of putative primers associated with fertility restoration. Co-segregation analysis of ten such primers with Rff gene revealed that Rf was flanked by two markers, namely cnu_m316 and nia_ m22, which were located 27.1 (LOD = 3.0) and 19.7 cM (LOD = 3.0) respectively around the gene in question. Distinctness of new CMS system from the ogura CMS was also demonstrated. This newly developed CMS-fertility-restorer system has a significant potential for hybrid seed production programs in mustard as an alternative to currently popular ogura CMS system.KeywordsCytoplasmic substitutionAlien introgressionMale sterilityHybridsorfFertility restoration
