Damage of oxidative stress on mitochondria during microspores development in Honglian CMS line of rice.

One of the cytoplasmic male sterility (CMS) types used for hybrid rice (Oryza sativa L.) production in China is the Honglian (HL)-CMS. Previous studies suggested that pollen abortion of the sterile plants was resulted from a special programmed cell death (PCD) program started at meiosis in the microspores. To elucidate the molecular basis of the pollen abortion, we compared the biochemical and physiological properties such as content of reactive oxygen species (ROS), ATP, NADH, total glutathione and ascorbate acid, the activities of dehydroascrbate reductase, glutathione reductase, ascorbate peroxides and superoxide dismutase, and the integrity of mitochondrial genome DNA isolated from an HL-CMS line, Yuetai A and its maintainer line, Yuetai B. Our results indicated that the mitochondria of the HL-CMS line suffered from a serious oxidative stress during microspores development. Oxidative stress induced by abnormal increased ROS at meiosis stage resulted in the depletion of ATP and NADH, and the degradation of mitochondrial genomic DNA. This suggests that the presence of redox signal originated in mitochondria affects the rest of the cell. Therefore, it is possible that the abortion of premature microspores in HL-CMS line is induced by the chronic oxidative stress in mitochondria in the early stage of pollen development.