The P-type pentatricopeptide repeat protein YGS is essential for chloroplast development in rice

Abstract

Pentatricopeptide repeat (PPR) proteins play crucial roles in the post-transcriptional regulation of gene expression, specifically RNA editing and RNA splicing, in plant organelles. Despite longstanding research on chloroplast biogenesis and development, the roles of most PPR genes in this process in rice () remain unclear. In this study, we identified a novel P-type PPR protein, YELLOW-GREEN LEAF AND SEEDLING LETHAL (YGS), that is targeted to rice chloroplasts. is preferentially expressed in leaves. The mutants were obtained by knocking out gene using CRISPR/Cas9-mediated genome editing; these mutants exhibited yellow-green leaves and a seedling-lethal phenotype. Consistent with these phenotypes, the mutants had lower levels of pigment contents and an abnormal chloroplast ultrastructure compared to the wild type. Moreover, the expression levels of genes related to chloroplast development and chlorophyll biosynthesis were significantly altered in the mutants. In addition, loss of function of YGS impaired RNA editing of and intron splicing of in the plastid genome. Finally, YGS interacted with the chloroplast signal recognition particle protein OscpSRP54b in yeast two-hybrid and bimolecular fluorescence complementation assays. These findings suggest that YGS is involved in RNA editing and RNA splicing in chloroplasts, thereby playing a crucial role in chloroplast development in rice.