A unique introgression from Moricandia arvensis confers male fertility upon two different cytoplasmic male-sterile lines of Brassica juncea

A Brassica juncea line carrying an introgression from Moricandia arvensis restored male fertility to two cytoplasmic male-sterile (CMS) B. juncea lines carrying either M. arvensis or Diplotaxis catholica cytoplasm. Genetics of fertility restoration was studied in the F-1, F-2, F-3 and backcross generations of the cross between CMS and fertility-restorer lines. No male-sterile plants were found in F-1-F-3 generations of the cross between CMS [M. arvensis] B. juncea and the restorer. However, a 1 : 1 segregation for male sterility and fertility was observed when the F-1 was pollinated with non-restorer pollen from a euplasmic line. These results clearly show that restoration is monogenic and gametophytic. In CMS lines carrying D. catholica cytoplasm, the restorer conferred male fertility to the F-1 and showed 3 : 1 and 1 : 1 segregations for male fertility and sterility in F-2 and BC1 generations, respectively, indicating a monogenic, sporophytic mode of fertility restoration. The results were also supported by pollen stainability in the F-1 which was about 65% in M. arvensis-based CMS and > 90% in D. catholica-based CMS. The above results are discussed in the light of previous molecular studies which showed association between CMS and atpA in both systems.