Evaluation of the control efficacy of antagonistic bacteria from V-Ti magnetite mine tailings on kiwifruit brown spots in pot and field experiments

Yongliang Cui; Yuhang Zhu; Guanyong Dong; Yanmei Li; Jing Xu; Zuqiang Cheng; Lijun Li; Guoshu Gong; Xiumei Yu

doi:10.3389/fmicb.2024.1280333

Evaluation of the control efficacy of antagonistic bacteria from V-Ti magnetite mine tailings on kiwifruit brown spots in pot and field experiments

Front Microbiol. 2024 Mar 12:15:1280333. doi: 10.3389/fmicb.2024.1280333. eCollection 2024.

Authors

Yongliang Cui^#^{1

2}, Yuhang Zhu^#³, Guanyong Dong⁴, Yanmei Li³, Jing Xu³, Zuqiang Cheng^{1

2}, Lijun Li¹, Guoshu Gong³, Xiumei Yu³

Affiliations

¹ Sichuan Provincial Academy of Natural Resource Sciences, Chengdu, China.
² Wild Plants Sharing and Service Platform of Sichuan Province, Chengdu, China.
³ College of Resources and College of Agronomy, Sichuan Agricultural University, Chengdu, China.
⁴ Kiwifruit Industry Development Bureau of Cangxi, Guangyuan, China.

^# Contributed equally.

Abstract

Seemingly barren heavy-metal-polluted vanadium (V) and titanium (Ti) magnetite mine tailings contain various functional microbes, yet it is unclear whether this includes microbial resources relevant to the biological control of plant diseases. Kiwifruit brown leaf spot disease, caused by Corynespora cassiicola, can seriously reduce kiwifruit yield. To discover effective control measures for kiwifruit leaf spot, 18 bacteria strains among 136 tailing-isolated bacteria from V-Ti magnetite mine tailings were identified as inhibiting C. cassiicola by the confrontation plate method, indicating that antagonistic bacteria surviving in the V-Ti magnetite mine tailings were present at a low level. The 18 antagonistic strains could be divided into two BOX-A1R clusters. The 13 representative strains that were selected for phylogenetic tree construction based on their 16S rRNA sequences belonged to the Bacillus genus. Five predominant strains exhibited different toxin-production times and intensities, with four of them initiating toxin production at 32 h. Among them, Bacillus sp. KT-10 displayed the highest bacteriostatic rate (100%), with a 37.5% growth inhibition rate and an antagonistic band of 3.2 cm against C. cassiicola. Bacillus sp. KT10 also showed a significant inhibitory effect against the expansion speed of kiwifruit brown spots in the pot. The relative control effect was 78.48 and 83.89% at 7 days after the first and last spraying of KT-10 dilution, respectively, confirming a good effect of KT-10 on kiwifruit brown leaf spots in the field. This study demonstrated for the first time that there are some antagonistic bacteria to pathogenic C. cassiicola in V-Ti magnetite mine tailings, and Bacillus sp. KT10 was found to have a good control effect on kiwifruit brown leaf spots in pots and fields, which provided an effective biological control measurement for kiwifruit brown leaf spots.

Keywords: Bacillus; biological control; field efficacy; inhibitory effect; kiwifruit disease.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was supported by the Demonstration Project of Transfer and Transformation of Scientific and Technological Achievements in Sichuan Province [2022ZHCG0030], the Basic Scientific Research Operating Expenses Project of Sichuan Province [2022JDKY0022], the Key Research Project of Deyang City [2022NZ015], Science and technology projects in Sichuan Province [2021YFN0035], Wild Plants Sharing and Service Platform of Sichuan Province, and Sichuan Province talent introduction and cultivation project.