OsPPR8, a pentatricopeptide repeat protein, regulates splicing of mitochondrial nad2 intron 3 to affect grain quality and high‐temperature tolerance in rice

Pentatricopeptide repeat (PPR) proteins, a large family of plant proteins, play critical roles in regulating various biological functions. However, their contributions to rice grain quality and high-temperature (HT) tolerance remain poorly understood. In this study, we identified OsPPR8, a canonical P-type PPR protein characterized by eight PPR motifs. Mutants of OsPPR8 exhibited compromised grain quality and reduced HT tolerance. Mechanistically, OsPPR8 was found to be dually localized in both the mitochondria and the nucleus, and it is involved in the cis-splicing of mitochondrial nad2 intron 3. Disruption of OsPPR8 resulted in abnormal mitochondrial ultrastructure, decreased complex I activity, and impaired ATP production, which is essential for starch synthesis in developing endosperm and for HT tolerance. Furthermore, natural variations in OsPPR8 appear to be associated with environmental temperature adaptation and the demand for grain quality during rice domestication. In conclusion, our findings highlight the significant role of OsPPR8 in maintaining mitochondrial function to provide energy for starch synthesis and HT tolerance, thereby offering a novel target for the coordinated improvement of grain quality and HT tolerance in rice.