PATHOGENESIS-RELATED PROTEINS: identification, evolution and functional analysis in pear (Pyrus bretschneideri)

Abstract Pathogenesis-related proteins (PRs) are essential for plant defense against both biotic and abiotic stresses. However, knowledge regarding PRs in pears remains limited. In this study, 637 PRs, classified into 16 families, were identified in Pyrus bretschneideri . Phylogenetic, sequence similarity, and secondary structure analyses enabled the classification of several PRs with conserved sequences, including PR-11, PR-8, PR-15, and PR-16. Genomic analysis revealed that the expansion of most PR families resulted from recent whole-genome duplication (WGD) events, occurring approximately 30–45 million years ago (Mya). Various gene duplication mechanisms have collectively contributed to the proliferation of PR families, with purifying selection indicated by the low Ka/Ks ratios. Examination of apoplastic fluid composition showed that only a subset of PRs was present in the apoplast. Transcriptomic data from Pyrus infected with Erwinia amylovora and Colletotrichum fructicola revealed the expression profiles of PR genes post-infection, underscoring the complexity of PR regulation. This study elucidates the evolutionary expansion, regulation, and functional roles of PRs in disease resistance, highlighting certain PRs as reliable markers of pear disease resistance. These findings offer valuable insights for future functional analyses and breeding strategies to enhance pear resistance to pathogens.