A chimeric mitochondrial gene FA323 confers male sterility in Fujian cytoplasmic male sterile rice

Abstract Based on gene homology, combined with chromosome walking technique, we isolated a candidate cytoplasmic male sterility gene FA323 specific to the cytoplasm of the CMS-FA line. Genetic transformation tests showed that most of the transgenic plants harbouring FA323 exhibited abnormal anthers which could not be stained with 1% I2-KI (potassium iodide)，and that both natural and bagged seed-setting rate were zero. The F1 generation of a positive transgenic plant × the japonic variety Zhonghua11 (ZH11) displayed 1 fertile plants without FA323:1 sterile plants with FA323 segregation. Western blot analysis detected the accumulation of FA323 protein in the CMS-FA line, but not in the iso-cytoplasmic restorer line with the restoring gene OsRf19. qRT-PCR analysis showed that OsRf19 could significantly reduce the transcript amounts of FA323. All these results demonstrated that FA323 could lead to male sterility in rice, it was another cytoplasmic male sterility gene for CMS-FA besides FA182, and OsRf19 might restore the male fertility of CMS-FA lines by degrading FA323 mRNA or suppressing the production of the mRNA. Our results laid a solid foundation for the further elucidation of the molecular mechanism underlying this kind of cytoplasmic-nuclear interaction. Author contribution statement LY designed the study and wrote the manuscript. CXM，ZYT，HFR，SXQ and AM performed the research. Conflict of interest The authors declare that they have no conflicts of interest.