Mutation in the coding sequence of atp6 are associated with male sterile cytoplasm in kenaf (Hibiscus cannabinus L.)

ATPase subunit 6 (atp6) is an important mitochondrial functional gene involved in energy supply. In this study, mitochondrial DNA was isolated from a cytoplasmic male sterility line P3A and its maintainer line P3B. The full-length sequence of atp6 was obtained by high-efficiency thermal asymmetric interlaced PCR. Coding sequences (CDSs) were determined using cDNA. P3A and P3B sequences had an overall mean similarity of 73.6 % with other atp6 genes deposited in GenBank. Sequences in atp6 CDSs were different between P3A and P3B, being 1209 and 1239 bp and encoding 402 and 412 amino acids in P3A and P3B, respectively. A 33-bp deletion (including an 18-bp deletion and a separate 15-bp deletion) and a 3-bp insertion in the CDS of atp6 in P3A were characterized. To confirm that the 33-bp deletion and 3-bp insertion were specific to the cytoplasm of male sterile lines, 104 varieties were analyzed. The deletion and insertion were specific to male sterile cytoplasm. A specific molecular marker was developed to distinguish the male sterility cytoplasm from male fertile cytoplasm.