Abstract
Plants respond to various biotic stresses by activating NADPH oxidase to generate reactive oxygen species (ROS) which are used to kill invading pathogens directly or to trigger defense signaling, or both. Although, rboh genes encoding NADPH oxidase have been cloned from various plants, the molecular regulatory mechanism of NADPH oxidase activation remains to be understood. In our previous studies, a small GTP-binding protein, OsRac1, was shown to regulate NADPH oxidase-dependent ROS generation in the rice cells during defense response. In the present study, we report that OsRac1 could interact with plant rbohs in yeast two-hybrid system. In addition, a sphingolipid elicitor, which induces OsRac1-dependent ROS production in rice cell cultures, was able to induce rboh mRNA expression. We will discuss the possibility of NADPH oxidase as a downstream target of OsRac in plant defense signaling.
