A Novel orf108 Co-Transcribed with the atpA Gene is Associated with Cytoplasmic Male Sterility in Brassica juncea Carrying Moricandia arvensis Cytoplasm

Mitochondrial atpA transcripts were examined in cytoplasmic male sterile (CMS) and fertility restorer lines of CMS (Moricandia arvensis) Brassica juncea. Male sterile flowers had longer atpA transcripts than male fertiles. The mitochondrial atpA region of the CMS line was cloned and sequenced. The 5' and 3' ends of the atpA transcripts of the CMS and the fertility restorer lines were mapped and full-length transcripts were cloned and sequenced. A novel orf108 (open reading frame 108) co-transcribed with the atpA gene was found in the male sterile flowers. In the fertility restorer line, the transcript was cleaved within orf108 to yield monocistronic atpA transcripts.