Mapping Of The Gene Rf_m For Mor CMS In Brassica Juncea

Prakash has created a cytoplasmic male sterility system, Moricandia arvensis CMS (Mor CMS) by somatic hybrid between Moricandia arvensis (2n=28, MM)+B. juncea (2n=36, AABB), and he also transferred the cytoplasm into mustard by several generation backcrossing with B. juncea. In India, Mor CMS has been used widely in hybrid seed production of Brassica juncea. In this study, we mainly want to find molecular markers tightly linked to the restorer gene (Rfm) of Mor CMS, and construct a genetic linkage map. The markers can be used as the assistant means for the restorer genetic improvement and purity examination in seed production.The research mainly carrys out the following work:(1)Using the restorer line of Mor CMS as the female parent, Chinese B. juncea K7-95, K7-98as male parent, we have constructed two backcross populations (pop A and pop B), the two populations have been built into BC3, pop A (4581individuals), pop B (2821individuals).(2)To test restorability of the restorer line of Mor CMS, the restorer line as a pollinator was used to cross with Mor CMS, Diplotaxis erucoides CMS, Diplotaxis catholica CMS, Diplotaxis berthautii CMS and Oxyrrhina CMS, respectively. Only Diplotaxis catholica CMS can not be restored, and the others can be done.(3)Combining the methods of AFLP and BSA, we screened1536pairs of AFLP primers by using parents bulk, male sterile individuals bulk and male fertile individuals bulk, and finally got38pairs of specific AFLP markers linked to Rfm.(4)According to the AFLP sequence information, we developed92pairs of SCAR primers and derived11stable SCAR markers linked to Rfm.(5)Based on the homology sequence information with Brassica, we developed a total of132pairs of SSR primers, and finally derived17stable SSR markers linked to Rfm.(6)Using28SCAR and SSR markers, we screened large backcross population (BC1+BC2) to estimate genetic distance. The results showed that28markers were located on the same side of the target genc(Rfm), the genetic distance between the farthest marker and Rfm is3.7cM, and that between the nearest marker and Rfm is1.1cM.