BACKGROUND:

Pollen development is an energy-consuming process that particularly occurs during meiosis. Low levels of adenosine triphosphate (ATP) may cause cell death, resulting in CMS (cytoplasmic male sterility). DNA sequence differences in ATP synthase genes have been revealed between the N- and S-cytoplasms in the cotton CMS system. However, very few data are available at the RNA level. In this study, we compared five ATP synthase genes in the H276A, H276B and fertile F1 (H276A/H268) lines using RNA editing, RNA blotting and quantitative real time-PCR (qRT-PCR) to explore their contribution to CMS. A molecular marker for identifying male sterile cytoplasm (MSC) was also developed.

RESULTS:

RNA blotting revealed the absence of any novel orf for the ATP synthase gene sequence in the three lines. Forty-one RNA editing sites were identified in the coding sequences. RNA editing showed that proteins had 32.43% higher hydrophobicity and that 39.02% of RNA editing sites had proline converted to leucine. Two new stop codons were detected in atp6 and atp9 by RNA editing. Real-time qRT-PCR data showed that the atp1, atp6, atp8, and atp9 genes had substantially lower expression levels in H276A compared with those in H276B. By contrast, the expression levels of all five genes were increased in F1 (H276A/H268). Moreover, a molecular marker based on a 6-bp deletion upstream of atp8 in H276A was developed to identify male sterile cytoplasm (MSC) in cotton.

CONCLUSIONS:

Our data substantially contributes to the understanding of the function of ATP synthase genes in cotton CMS. Therefore, we suggest that ATP synthase genes might be an indirect cause of cotton CMS. Further research is needed to investigate the relationship among ATP synthase genes in cotton CMS.