Construction of the Near-Isogenic Lines of the MI CMS Restorer Gene in Rapeseed (Brassica napus) and Allelic Analysis

In this research, we employed Ning R7, an elite restorer for MI CMS, as the restorer gene donor to develop restorer gene candidate near-isogenic lines (NILs) by using three elite germplasms, T78, T84 and ZS9, as recurrent parents based on the advanced backcross approach. The characteristics of agronomic traits were phenotyped at the maturity stage and genetic similarity was calculated based on the SSR data. The results showed most agronomic traits of the candidates had quite similar with that of recurrent parents besides the trait of plant height and the height of the initiate branch based on t-test.  Further, in order to figure out the similarity of the genetic background, we used 75 SSR markers to generate total 157 SSR loci in the 21 candidate NILs. The average genetic similarity coefficient of the candidate NIL background reached 0.86, 0.92 and 0.98 corresponding to their own recurrent parent, respectively. With the comprehensive assessment, three candidate NILs, wh13, wh59 and wh118, were chosen as potential restorer NILs, which might be used in our future breeding program.