Genome-Wide Identification and Expression Analysis of the Aspartic Protease Gene Family and Their Responses to Abiotic Stress in Talaromyces marneffei

Aspartic proteases (APs), a class of proteolytic enzymes involved in protein maturation, degradation, and signaling, are known to contribute to fungal virulence and pathogenicity. However, the AP gene family in Talaromyces marneffei (T. marneffei), a dimorphic opportunistic pathogenic fungus, has not yet been functionally analyzed. In this study, we identified 27 AP genes from the T. marneffei genome, and the encoded APs retained conserved domains and exhibited similar motifs and structural properties crucial for catalytic activity. Phylogenetic and collinearity analyses found that TmAPs were most recently homologous to Aspergillus gene families, with both tandem and segmental duplications contributing to their expansion. Expression patterns, combined with RNA-sequencing data, revealed the specialized roles of TmAP1 and TmAP2 in the dimorphic conversion between the yeast and mycelial phases. Protein–protein interaction network analysis uncovered links to cell fusion, mitochondrial function, and programmed cell death. Under abiotic stress conditions, several TmAP genes displayed significant transcriptional changes, implying their involvement in short-term adaptation and stress responses. This study provides the first comprehensive and systematic analysis of the AP gene family in T. marneffei, highlighting their potential biological roles in fungal development, dimorphic conversion, and stress adaptation. Our findings offer valuable insights into further functional characterization of AP genes in T. marneffei and may facilitate the development of novel therapeutic targets and intervention strategies against T. marneffei infection.