Trichoderma harzianum Cellulase Gene thph2 Affects Trichoderma Root Colonization and Induces Resistance to Southern Leaf Blight in Maize

, widely distributed all over the world, is commonly found in soil and root ecosystems. It is a group comprising beneficial fungi that improve plant disease resistance and promote plant growth. Studies have shown that cellulases can also improve plant disease resistance. Based on previous studies, we reported that a C6 zinc finger protein (Thc6) regulates two cellulase genes, and , to induce ISR responses in plants. Therefore, in this study, we focused on the role of in the colonization of maize roots by and the induction of systemic resistance against southern leaf blight. The results showed that had a positive regulatory effect on the colonization of maize roots. After the root was treated with , the leaf defense genes , , , and were expressed to resist the attack of . The pure Thph2 protein also resulted in a similar induction activity of the , , , and expression in maize roots, further demonstrating that can induce plant defense responses and that signal transduction occurs mainly through the JA signaling pathway.