Genome-wide identification and expression patterns of the aspartic protease gene family in Epimedium pubescens.

BACKGROUND: Aspartic proteases (APs), proteolytic enzymes involved in protein maturation, degradation, and signaling, are found in various organisms. The plant Epimedium pubescens is known for its pharmacologically active flavonoids and its use in traditional Chinese medicine. Despite this, to date, the AP gene family in this species has not been functionally analyzed. This study aimed to uncover the roles of AP genes in E. pubescens (EpAPs), focusing in particular on their involvement in light stress responses. RESULTS: Genome-wide analysis identified and characterized a total of 103 EpAPs, which were categorized into four phylogenetic groups and revealed conserved motifs crucial for their catalytic function. Structural analysis highlighted the diversity of intron-exon arrangements and the predominant role of tandem duplication in gene expansion. Promoter analysis showed an enrichment of light-responsive elements, indicating potential involvement in light stress responses. Tissue-specific expression patterns revealed specialized roles in various organs, whereas several EpAPs exhibited stage-specific expression during the formation of abscission zones. The analysis of protein-protein interactions identified links to reproductive development, programmed cell death, and stress responses. Under light stress, selected AP genes exhibited dynamic changes in expression, with some showing transient upregulation or recovery phases, which suggests their involvement in short-term adaptation or sustained light stress responses. CONCLUSIONS: This study provides the first comprehensive analysis of AP genes in E. pubescens, highlighting their potential roles in development and stress adaptation. The presence of light-responsive elements and changes in expression under light stress suggest that AP genes may serve as key regulators of environmental responses in this species. Further validation studies could inform strategies to improve light stress resistance in shade-adapted plants.