OsRbohB-mediated ROS production plays a crucial role in drought stress tolerance of rice

Key message We found that a rice NADPH oxidase geneOsRbohBcontributes drought tolerance and its functions are involved in the interaction of the OsRbohB-mediated ROS production and ABA signaling. The plasma membrane NADPH oxidases, also known as respiratory burst oxidase homologs, are the key producers of ROS under both normal and stress conditions in plants. However, their functions in rice development and stress tolerance are still under investigation. Here, we found that a rice NADPH oxidase geneOsRbohB, also namedOsNOX1, is expressed in all tissues examined throughout the development stages with higher transcripts in leaves. The transcriptional expression ofOsRbohBis also strongly stimulated by dehydration, salt and several phytohormonal treatments. Compared with wide-type and theOsRbohB-overexpressing transgenic plants,osrbohB, a Tos17 insertion knockout mutant ofOsRbohB, shows lower ROS production, abscisic acid (ABA) content and transcripts of a series of stress-related genes. TheosrbohBmutant also exhibits lower seed germination rate, organ size and thousand seed weight, but higher stomatal aperture and sensitivity to drought. Moreover, a number of genes involved in plant development, stress response, transcriptional regulation, and particularly ABA signaling are differentially expressed inosrbohBplants under both normal growth and drought conditions. All these results suggest the roles ofOsRbohBin drought tolerance of rice, which probably performed through the interaction of the OsRbohB-mediated ROS production and ABA signaling.