摘要Pentatricopeptide repeat(PPR)proteins function in post-transcriptional regulation of organellar gene expression.Although several PPR proteins are known to function in chloroplast development in rice(Oryza sativa),the detailed molecular functions of many PPR proteins remain unclear.Here,we characterized a rice young leaf white stripe(ylws)mutant,which has defective chlor-oplast development during early seedling growth.Map-based cloning revealed that YLWS encodes a novel P-type chloroplast-targeted PPR protein with 11 PPR motifs.Further expression analyses showed that many nuclear-and plastid-encoded genes in the ylws mutant were significantly changed at the RNA and protein levels.The ylws mutant was impaired in chloroplast ribosome biogenesis and chloroplast development under low-temperature conditions.The ylws mutation causes defects in the splicing of atpF,ndhA,rpl2,and rps12,and editing of ndhA,ndhB,and rps14 transcripts.YLWS directly binds to specific sites in the atpF,ndhA,and rpl2 pre-mRNAs.Our re-sults suggest that YLWS participates in chlor-oplast RNA group Ⅱ intron splicing and plays an important role in chloroplast development during early leaf development.