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Front. Microbiol. | doi: 10.3389/fmicb.2019.02676

Bio-control of Rhizoctonia solani via induction of the defense mechanism and antimicrobial compounds produced by Bacillus subtilis SL-44 on pepper (Capsicum annuum L.)

 Zhansheng Wu1*, Yuanyuan Huang2, Yan Li2, Jiawei Dong2, Xiaochen Liu1 and Chun Li3
  • 1Xi'an Polytechnic University, China
  • 2Shihezi University, China
  • 3Beijing Institute of Technology, China

Pepper seedling wilt disease is the main cause of crop yield reduction. Biocontrol agents are widely used to control plant diseases caused by pathogenic fungi, and activate plant defense systems. Our preliminary work showed that Bacillus subtilis SL-44 played a significant role in the reduction of wilt disease severity on pepper plants. To evaluate biological control mechanism of B. subtilis SL-44 on wilt disease caused by Rhizoctonia solani, the activities of the related enzymes were detected in the pepper seedling with different treatment in this study. Fluorescence microscopy combined with different dyes showed that B. subtilis SL-44 induced a large amount of active oxygen and callose accumulation in pepper leaves. The defense-related enzymes activities in pepper were improved significantly when treated with B. subtilis SL-44, including peroxidase, catalase, superoxide dismutase, polyphenol oxidase and phenylalanine ammonia lyase. The activity of chitinase and β-1,3-glucanase in B. subtilis SL-44 treated pepper was also enhanced. Furthermore, the pepper resistance gene CaPIN II expression level was significantly increased in B. subtilis SL-44 treatment. Besides, B. subtilis SL-44 filtrate led to the death of the pathogenic fungus by fracturing the mycelia and leaking of the cell contents. Surfactin, iturin and fengycin were found in B. subtilis SL-44 crude extracts which could be effective antifungal compounds against R. solani. The results suggest that B. subtilis SL-44 could not only activate Induced Systemic Resistance of pepper seedling against wilt disease caused by R. solani. by Jasmonic acid-dependent signaling pathway, but also produce antifungal compounds to inhibit or even damage the mycelium growth of R. solani. The findings of this study provide novel guidance in plant protection development.

Keywords: pepper, Bacillus subtilis, signaling pathway, ISR, antimicrobial compounds, biological control

Received: 25 Aug 2019; Accepted: 04 Nov 2019.

Copyright: © 2019 Wu, Huang, Li, Dong, Liu and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Zhansheng Wu, Xi'an Polytechnic University, Xi'an, China,