A Honglian CMS line of rice displays aberrant F0 of F0F1-ATPase

Honglian (HL) is one of the three major types of cytoplasmic male sterility (CMS) of rice (Oryza sativa L) that has been commercially used in hybrid production. In previous studies, the CMS in HL is shown to be associated with a chimeric gene orfH79 that is cotranscribed with an extra atp6 in mitochondria. This study demonstrated that the intact F0F1-ATPase in HL CMS line was specifically reduced in both of its protein quantity and enzyme activity, whereas its F1 sector was not affected. It implies that the F0 sector presents a labile linkage with F1. In the presence of fertility restorer gene, F0F1-ATPase can be recovered. Furthermore, orfH79 transcripts were preferentially polyadenylated, and consequently degraded rapidly in florets of the restored hybrid plants, indicating that the atp6-orfH79 is involved in the sterile phenotype. With inhibition of cytochrome pathway of electron transfer chain, the biomass of the sterile plants grown in dark was significantly lower than that of the fertile lines. However, the respiration measurements showed an increase in the electron transferring capacity in the sterile plants, suggesting that the reduction of biomass in sterile line was caused by the disruption of F0F1-ATPase.