The pentatricopeptide repeat protein PPR767 modulates plant architecture and drought resistance in rice

The RNA-binding proteins (RBPs) encoded by the nucleus are essential for RNA metabolism in eukaryotes. Pentatricopeptide repeat (PPR) proteins, a large subset of RBPs, are essential for plant development and reproduction by participating in organellar RNA processing. Here, we identified an E-type PPR protein, PPR767, which functions in mitochondria. Knocking out PPR767 resulted in decreased plant height, thinner stems, shorter and narrower blades, and consequently affected yield traits compared with those of the wild-type. PPR767 primarily participated in the RNA editing of 4 sites related to NADH dehydrogenase (Nad), including nad1-674, nad3-155, nad3-172, and nad7-317. PPR767 interacted with multiple organellar RNA editing factors (MORFs), including MORF1 and MORF8, suggesting that the editosome in rice (Oryza sativa) is complex. The mutants showed decreased mitochondrial complex I activity and compromised mitochondrial structure. Furthermore, mutation of PPR767 influenced rice drought tolerance and the expression levels of genes involved in reactive oxygen species (ROS) accumulation. Therefore, PPR767 is essential for complex I activity by properly regulating the RNA editing efficiency of mitochondrial genes and affects drought tolerance by modulating ROS content in rice. Our findings provide valuable insights into the mechanisms by which PPRs fulfill their functions.