OsPDIL1-1 controls ROS generation by modulating NADPH oxidase in developing anthers to alter the susceptibility of floret fertility to heat for rice

High temperature (HT) at meiosis induces heat injury to pollen viability and floret fertility, which is closely associated with HT-induced endoplasmic reticulum (ER) stress and ROS damage in developing anthers. Disulfide isomerase like proteins (PDILs) play an essential role in the formation, reduction, and isomerization of disulfide bonds in nascent secretory proteins for the maintenance of cell viability and ER homeostasis. However, the underlying mechanism by which HT induces ROS burst in rice anthers and its relation to ER stress for the varying existence of PDILs is largely unknown. In this paper, we investigated the action of PDILs in the regulation of heat injury to floret fertility and its association with HT-induced ROS generation in developing anthers under well-controlled climatic conditions. Results showed that knock-down of OsPDIL1–1 by RNAi enhanced the activity of NADPH oxidase and caused the excessive ROS accumulation in developing anthers, consequently the up-grading sensitivity of pollen viability and floret fertility to heat stress. RBOHb is the primary site where HT exposure affected NADPH oxidase activity and triggered ROS generation in rice anthers because OsPDIL1–1 was found to interact with RBOHb in the ER-PM junction. Furthermore, HT exposure triggered the RBOHb-mediated ROS generation in a Ca2+-dependent manner, while the induction of HT exposure to ER stress was not necessarily associated with ROS generation derived from NADPH oxidase.