Abstract

Introduction Pear ( Pyrus pyrifolia ) chlorotic leaves severely impair photosynthesis and the accumulation of photosynthetic products, primarily due to abnormal chloroplast development. DYW-type PPR proteins play a crucial role in regulating chloroplast development and maintaining structural integrity. Methods To comprehensively characterize the involvement of DYW-type PPR proteins in pear leaf and chloroplast development, we performed a genome-wide identification of 129 DYW-type PPR proteins in pears and systematically analyzed their sequence diversity, protein domain architecture, and evolutionary relationships. Results Compared with the wild-type ‘Chuxialv’, the ‘Chuxialv’ bud mutant exhibits reduced chlorophyll and ferrous ion content, along with disrupted chloroplast ultrastructure in leaves. Using this paired material, we conducted high-depth whole-genome resequencing to identify structural variations within the DYW-type PPR gene family. Furthermore, RNA-seq was performed on leaf samples from yellow to green, spanning five distinct developmental stages to construct a temporal expression profile of DYW-type PPR genes. Six DYW-type PPR genes exhibiting differential expression were identified, and protein-protein interaction network analysis of them, coupled with functional enrichment analysis, provided the underlying regulatory mechanism in chloroplast development and photosynthesis. Coexpression and functional regulatory networks of DYW-type PPR genes were constructed by integrating weighted gene co-expression network analysis with gene ontology enrichment analysis. Notably, only the coexpression module centered on PpPPR115 was enriched in photosynthesis-related biological processes. Furthermore, the MYB transcription factor binding motif was identified in the promoter region of PpPPR115 . Six MYB transcription factors down-regulated in the CM1 compared wit