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

Abstract

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 F₁, F₂, F₃ and backcross generations of the cross between CMS and fertility-restorer lines. No male-sterile plants were found in F₁-F₃ 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 F₁ was pollinated with non-restorer pollen from a euplasmic line. These results clearly show that restoration is mono-genic and gametophytic. In CMS lines carrying D. catholica cytoplasm, the restorer conferred male fertility to the F₁ and showed 3: 1 and 1: 1 segregations for male fertility and sterility in F₂ and BC₁ generations, respectively, indicating a monogenic, sporophytic mode of fertility restoration. The results were also supported by pollen stainability in the F₁ 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.