OsRbohI Regulates Rice Growth and Development through Jasmonic Acid Signal.

ROS are highly reactive molecules, generated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases encoded by respiratory burst oxidase homologs (Rbohs). The functions of the OsRbohs family in rice are diverse and poorly understood. TheOsRbohI was recently identified as a novel evolved gene in the rice OsRbohs gene family. However, the function of OsRbohI in regulating rice growth is not yet reported. In this study, our results showed that knockout (KO) OsRbohI mutants showed significantly shorter shoot and primary roots, along with lower ROS content than those of the control lines; whereas the overexpression (OE) lines displayed contrasting results. Further experiments showed that the abnormal length of the shoot and root is mainly caused by altered cell size. These results indicate that OsRbohI is regulating rice shoot and root growth through ROS signal. More importantly, our RNA-seq analysis and jasmonic acid (JA) treatment demonstrated that OsRbohI regulates rice growth through JA synthesis and signaling pathways. Compared with the control, the results showed that the KO mutants were more sensitive to JA, whereas the OE lines were less sensitive to JA. Collectively, our results reveal a novel pathway that OsRbohI regulates rice growth and development by JA synthesis and signaling pathway through affecting rice ROS homeostasis.