Molecular basis of copper homeostasis in Trichoderma asperellum Ts93: roles of a peroxidase and Ctr-family transporters.

Copper tolerance mechanisms and copper-related genes are crucial for microbial applications in copper remediation. In this study, we investigated the molecular mechanisms of copper homeostasis in Trichoderma asperellum Ts93, a strain with high copper tolerance. We conducted a comprehensive transcriptomic analysis of gene expression under both copper stress and copper starvation conditions, and functionally characterized key genes involved in these responses. The results indicated that the strain could withstand up to 4.0 mM of copper on PDA plates. Transcriptome analysis revealed that a total of 339 genes were upregulated and 321 genes were downregulated in response to copper stress. Notably, the expression of the peroxidase gene Tspod1 was significantly upregulated, likely due to heightened oxidative stress following copper exposure. Gene knockout experiments demonstrated that the disruption of Tspod1 increased the strain's sensitivity to copper stress. Under conditions of copper starvation, 276 genes were upregulated while 389 genes were downregulated. Significantly, two members of the Ctr family of copper transporters, TsCtr1 and TsCtr3, exhibited substantial upregulation. Knocking out these genes also heightened the strain's sensitivity to copper starvation. These findings provide new molecular insights into the copper homeostasis network in Trichoderma and establish a foundation for future studies aimed at harnessing this organism's potential for copper bioremediation.