Combined physiological and transcriptomic analysis revealed the defense mechanism of Agaricus bisporus against Trichoderma harzianum infection

Trichoderma harzianum (T. harzianum) infection causes black lesions on the surface of Agaricus bisporus (A. bisporus) and soft rot of the infected tissues, thereby severely compromising mushroom quality. To investigate the host response, T. harzianum was inoculated onto the fruiting bodies of A. bisporus. This study aimed to comprehensively elucidate the resistance mechanisms of A. bisporus by analyzing defense-related enzyme activities and transcriptomic profiles. Physiological analyses revealed that antioxidant enzymes (SOD, POD, CAT), defense-related enzymes (CHT, PAL, GLU, PRs), and glutathione-associated enzymes (GR, GST, GSH) were activated, with their activities markedly increased during the early stages of infection. Transcriptomic analysis at 0, 18, 24, and 36 h post-inoculation identified 4,530 differentially expressed genes. Notably, genes involved in the glutathione metabolism pathway (GR, GSH, GST) were up-regulated, consistent with the observed enzyme activity changes. In addition, key genes associated with glycolysis (EMP), the tricarboxylic acid cycle (TCA), oxidative phosphorylation (OXPHOS), and the mitogen-activated protein kinase (MAPK) cascade exhibited enhanced expression. Collectively, these findings indicate that A. bisporus mounts defense responses by activating glutathione metabolism, EMP, TCA, OXPHOS, and MAPK pathways, thereby enhancing antioxidant and defense enzyme activities and improving resistance. This study elucidates the molecular mechanisms underlying the response of A. bisporus to T. harzianum infection and provides a theoretical basis for developing strategies to control postharvest mushroom diseases.