A Zn2-Cys6 transcription factor, TgZct4, reprograms antioxidant activity in the fungus Trichoderma guizhouense to defend against oxidative stress

Fungi have evolved different strategies to cope with oxidative stress in competitive environments, however, the understanding of mechanisms that govern antioxidant response specificity and adequacy remains rudimentary. Trichoderma guizhouense NJAU 4742, a biocontrol fungus with strong viability, exhibits notable resistance to oxidative stress. This study characterizes a previously unidentified antioxidant-related Zn₂-Cys₆ transcription factor, TgZct4, in T. guizhouense based on genomic and transcriptomic profiles. Unlike the well-conserved transcription factors, TgZct4 has a positive role in the regulation of antioxidant response to both low and high concentrations of hydrogen peroxide. TgZct4 responds rapidly to oxidative stress, with its transcript levels showing a positive correlation with increasing hydrogen peroxide concentrations. In addition, TgZct4 is found to modulate T. guizhouense's defense response by reprogramming antioxidant activity through classic antioxidant enzymes according to transcriptomic analysis. And the catalase TgCat1, regulated by TgZct4, confers protection against oxidative stress either independently or in conjunction with another TgZct4-dependent catalase TgCat2 in T. guizhouense. Overall, this work reveals TgZct4 as an important factor regulating the oxidative stress response in T. guizhouense, which provides valuable insights into fungal stress tolerance mechanisms and may contribute to the future genetic enhancement of this fungi for use as a biological control agent.