Acid-resistant effectively controls pathogenic and improves plant health through metabolic interactions.

UNLABELLED

is the etiological agent of Capsicum anthracnose. has traditionally been recognized as an effective biocontrol agent; however, its efficacy decreases due to soil acidification. In this study, we domesticated XY40-1 along an acid resistance gradient, resulting in a strain capable of growth at pH 4, and might adapt to acidic environments by regulating genes related to spore formation. Notably, the domesticated XY40-1 exhibits significant antagonistic activity against in acidic dual cultures and effectively reduces the disease index in . The domesticated strain employs a direct antifungal strategy under acidic conditions, with the production of amylocyclicin, regulated by , potentially serving as a primary mechanism through which combats . Conversely, under neutral conditions, domesticated focuses on bolstering its defense mechanisms by increasing the expression of , , and genes to detoxify peroxides. In addition, a dual RNA-Seq analysis comprehensively investigated the acid tolerance mechanisms and defensive responses of and the pathogenic mechanisms of , providing a foundation for the practical application of as a biocontrol agent. These findings offer important insights into the impact of soil acidification on plant disease suppression and contribute to the development of sustainable agricultural practices.

IMPORTANCE

Recently, the increasing issue of soil acidification has worsened anthracnose disease in Capsicum, caused by . Our study demonstrated that can effectively inhibit the growth of . However, the molecular mechanisms underlying the interaction between and remain largely unexplored. Here, we developed an interaction system between and to explore their dynamic relationship. By employing dual RNA-Seq methods, we were able to comprehensively investigate the acid tolerance mechanisms and defense responses of , alongside the pathogenic mechanisms of . This establishes the groundwork for utilizing as an effective biocontrol agent in agriculture.