Characterization of a partial male fertility derived from Ogura-cms in progeny of a resynthesized Brassica napus

Abstract

The inheritance of a partial male fertile phenotype in somatic hybrid B. napus plants that carried novel mtDNA was investigated over five backcross generations to B. napus ‘Triton.’ The recurrent parent and the original somatic hybrid both contained chloroplasts resistant to atrazine. The F1 population contained mainly plants that were partial fertile, and some of the plants differed in mtDNA. The partial fertility predominated in the progeny of each backcross generation, but fully male sterile and fertile plants were also obtained. However, the sterility/fertility of these latter plants was not stable; both the fully male sterile and the male fertile plants produced progeny that were again predominantly partial male fertile. This pattern of predominant partial fertility but occasional sterile and fertile plants persisted in different nuclear backgrounds. Neither the male sterility nor the male fertility could be fixed and made stable. Test crosses indicated that restorer genes were probably not associated with appearance of male fertile plants. The evidence indicates that the behavior of the partial male fertility is cytoplasmic, and probably controlled by the chondriome.