PPR767 affects plant architecture and drought resistance by modulating complex I activity and ROS content in rice

The RNA-binding proteins (RBPs) encoded by nucleus are essential for the metabolism of RNAs in eukaryotes. The pentatricopeptide repeat (PPR) proteins, a large subset of RBPs, participate in organellar RNA processing for plant development and reproduction. Here, we identified an E-type PPR protein, PPR767, which functions in mitochondria. Knocking out PPR767 resulted in shorter plant height, thinner stems, shorter and narrower blades, and consequently affected yield traits, compared to those of the wild type. PPR767 primarily participated in the editing of 4 sites, nad1-674, nad3-155, nad3-172, and nad7-317. And PPR767 interplayed with MORF1 and MORF8, suggesting the editosome in rice is complicated. Meanwhile, the activity of mitochondrial complex I was decreased, and the structure of mitochondria was compromised in the mutants. Furthermore, mutation of PPR767 influenced rice drought tolerance and the expression levels of genes involved in the reactive oxygen species (ROS) accumulation. These findings suggest that PPR767 guarantees the complex I activity by properly regulating the RNA editing efficiency of mitochondrial genes and affects drought tolerance by modulating ROS content in rice, providing valuable insights into the mechanisms by which PPRs fulfil their functions.