Harnessing large-scale genomics-based screening for the identification of expansin genes responsive to abiotic stress in Peucedanum praeruptorum

Introduction Expansins are crucial for cell wall relaxation and significantly impact plant growth and development. However, the expansin gene family in Peucedanum praeruptorum remains to be systematically characterized. Methods Here, we systematically identified expansin genes in P. praeruptorum and analysed their molecular characteristics, evolutionary patterns, and expression profiles in response to methyl jasmonate (MeJA). Subcellular localization prediction, gene structure analysis, chromosomal localization, collinearity analysis, and cis-acting element analysis were performed. Based on cis-element screening, PpdEXPA01, PpdEXPA10, PpdEXPA13, PpdEXPB1, and PpdEXPB2 were selected to validate their expression under exogenous MeJA stress. Results A total of 39 PpdEXP genes were identified and classified into four subfamilies: EXPA (24 genes), EXPB (9 genes), EXPLA (2 genes), and EXPLB (4 genes). Subcellular localization predictions indicated that all members are localized in the cell wall, and all expansin proteins are hydrophilic. Gene structural analysis showed that the number of introns ranged from one to four and that all genes contained two conserved domains: DPBB_EXPA_N and Expansin_C. Chromosomal localization analysis showed that the 39 PpdEXP genes were distributed across 11 chromosomes, with tandem duplication events occurring on chromosomes 3, 4, and 7. Collinearity analysis indicated that segmental and whole-genome duplication were the main driving forces behind the expansion of the expansin gene family. Analysis of cis-acting elements revealed 1,237 elements in total, which were primarily classified into three categories: hormone response, light response, and stress response. Expression profiling revealed that PpdEXP genes exhibit significant tissue specificity. The five selected genes had significant tissue- and time-specific expression patterns in roots, stems, and leaves under exogenous MeJA stress. Discussion This study systematically elucidated the molecular basis and expression regulation patterns of the P. praeruptorum expansin family, providing a foundation for further functional characterization of PpdEXP genes and their potential roles in growth, development, and stress responses.