Germination and growth of biocontrol microorganisms in soil are often inhibited by soil fungistasis (SF), resulting in unsatisfactory control efficacy. Therefore, exploring mechanisms underlying SF is important for developing efficient biocontrol agents. Benzaldehyde has a strong fungistatic effect against the nematophagous fungus Arthrobotrys oligospora. Our transcriptome analysis suggested a fungistatic model by which benzaldehyde induces reactive oxygen species (ROS), leading to energy deficiency and in turn activating the AMPK-mTOR pathway. The ROS-inducing compound retinol enhanced benzaldehyde fungistasis (BF), whereas the antioxidant substance N-acetyl cysteine reduced ROS production and enhanced BF resistance in A. oligospora. Inhibiting the glutathione antioxidant system by blocking the supply of NADPH decreased BF resistance in A. oligospora. Furthermore, the AMPK activator acadesine bolstered BF resistance in A. oligospora, while the AMPK inhibitor dorsomorphin dihydrochloride or knocking out the AMPK gene had the opposite effect. These results strongly support a fungistatic mechanism of action for benzaldehyde. Finally, we found that the fungistatic mechanism of benzaldehyde similarly underlies SF, with the AMPK activators acadesine or metformin effectively increasing the SF resistance of A. oligospora. This study suggests a mechanism by which soil inhibits fungi and offers a potential method for improving SF resistance of fungal biocontrol agents.
Tan et al. (Tue,) studied this question.
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