Relationship of metabolism of reactive oxygen species with cytoplasmic male sterility in pepper (Capsicum annuum L.)

Pepper cytoplasmic male sterility (CMS) line 9704A is one of the CMS types used for hybrid pepper (Capsicum annuum L.) production in China. Our previous studies suggested that CMS-9704A may suffer from oxidative stress as its cyanide-resistant respiration is lower than that of the maintainer line. To elucidate the metabolic mechanism of reactive oxygen species (ROS) in the CMS-pepper anthers, the metabolism changes in the production and scavenging of ROS and gene expression related to ROS-scavenging enzymes were investigated in the anther mitochondria of CMS-9704A and maintainer-9704B. At the abortion stage (pollen mother cell meiosis stage), anthers of CMS-9704A had higher contents of O2−, H2O2 and MDA than those of the maintainer. Simultaneously, there were higher activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in scavenging ROS in the anthers of the CMS line than in the maintainer. Abundance of POD, Mn-SOD, CAT1, CAT2 and CAT3 mRNA in anthers of CMS-9704A corresponded with the activities of these three genes, except for that of Cu/Zn-SOD and Irion-SOD. Therefore, it is possible that the sterility in CMS-9704A is related to the abortion of microspores, induced by chronic oxidative stress caused by an abnormal increase in ROS, and also by membrane lipid peroxidation in the mitochondria in the early stage of pollen development.

► We employ CMS and maintainer anthers for studying the relationship between CMS and ROS metabolism.
► CMS anthers had higher contents of O2.-, H2O2, and MDA than those of maintainer in the abortion stage.
► The higher activities of SOD, POD and CAT were measured in the CMS anthers than those in maintainer.
► Abundance of Mn-POD, CAT and SOD was positively correlated with the activities of these genes.
► CMS in pepper suggested to be associated with the lower cyanide-resistant respiration.