Pentatricopeptide repeat (PPR) proteins perform essential functions in post-transcriptional regulation of gene expression, particularly RNA editing and RNA splicing, in plant organelles.  Although research on chloroplast biogenesis and development has been extensive, the functions of most PPR genes in this process in rice (Oryza sativa) remain incompletely understood.  This study identifies a novel P-type PPR protein, YELLOW-GREEN LEAF AND SEEDLING LETHALITY (YGS), which localizes to rice chloroplasts. YGS shows predominant expression in leaves.  The ygs mutants, generated through CRISPR/Cas9-mediated genome editing of the YGS gene, displayed yellow-green leaves and seedling lethality.  These phenotypes corresponded with reduced pigment levels and disrupted chloroplast ultrastructure compared to wild-type plants.  Furthermore, the expression of genes associated with chloroplast development and chlorophyll biosynthesis showed significant alterations in the ygs mutants.  The absence of YGS function affected RNA editing of rpl2 and intron splicing of ycf3-1 in the plastid genome.  Additionally, YGS demonstrated interaction with the chloroplast signal recognition particle protein OscpSRP54b in yeast two-hybrid and bimolecular fluorescence complementation analyses.  These results indicate that YGS participates in RNA editing and RNA splicing in chloroplasts, thus serving a vital role in rice chloroplast development