Biocontrol of the causal brown patch pathogen Rhizoctonia solani by Bacillus velezensis GH1-13 and development of a bacterial strain specific detection method

Gahee Lee; Hyeongju Choi; Haifeng Liu; Yun-Hyeong Han; Narayan Chandra Paul; Gui Hwan Han; Hyunsook Kim; Pyoung Il Kim; Sun-Il Seo; Jaekyeong Song; Hyunkyu Sang

doi:10.3389/fpls.2022.1091030

Biocontrol of the causal brown patch pathogen Rhizoctonia solani by Bacillus velezensis GH1-13 and development of a bacterial strain specific detection method

Front Plant Sci. 2023 Jan 9:13:1091030. doi: 10.3389/fpls.2022.1091030. eCollection 2022.

Authors

Gahee Lee¹, Hyeongju Choi¹, Haifeng Liu¹, Yun-Hyeong Han^{2

3}, Narayan Chandra Paul^{1

4}, Gui Hwan Han⁵, Hyunsook Kim⁶, Pyoung Il Kim⁵, Sun-Il Seo⁵, Jaekyeong Song⁷, Hyunkyu Sang^{1

2

4}

Affiliations

¹ Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, Republic of Korea.
² Division of Food and Biotechnology, Chonnam National University, Gwangju, Republic of Korea.
³ Damyang-gun Agricultural Technology Center, Damyang, Republic of Korea.
⁴ Kumho Life Science Laboratory, Chonnam National University, Gwangju, Republic of Korea.
⁵ Center for Industrialization of Agricultural and Livestock Microorganisms, Jeongeup, Republic of Korea.
⁶ Boran Pharma, Seoul, Republic of Korea.
⁷ Agricultural Microbiology Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Republic of Korea.

Abstract

Brown patch caused by the basidiomycete fungus Rhizoctonia solani is an economically important disease of cool-season turfgrasses. In order to manage the disease, different types of fungicides have been applied, but the negative impact of fungicides on the environment continues to rise. In this study, the beneficial bacteria Bacillus velezensis GH1-13 was characterized as a potential biocontrol agent to manage brown patch disease. The strain GH1-13 strongly inhibited the mycelial growth of turf pathogens including different anastomosis groups of R. solani causing brown patch and large patch. R. solani AG2-2(IIIB) hyphae were morphologically changed, and fungal cell death resulted from exposure to the strain GH1-13. In addition, the compatibility of fungicides with the bacterial strain, and the combined application of fungicide azoxystrobin and the strain in brown patch control on creeping bentgrass indicated that the strain could serve as a biocontrol agent. To develop strain-specific detection method, two unique genes from chromosome and plasmid of GH1-13 were found using pan-genome analysis of 364 Bacillus strains. The unique gene from chromosome was successfully detected using both SYBR Green and TaqMan qPCR methods in bacterial DNA or soil DNA samples. This study suggests that application of GH1-13 offers an environmentally friendly approach via reducing fungicide application rates. Furthermore, the developed pipeline of strain-specific detection method could be a useful tool for detecting and studying the dynamics of specific biocontrol agents.

Keywords: Bacillus velezensis; Rhizoctonia solani; biocontrol; brown patch; detection; pan-genome.

Grants and funding

This study was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry (IPET) through the Useful Agricultural Life Resources Industry Technology Development Program funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) (120042-02) and Rural Development Administration (Project No. PJ01690602), Republic of Korea. This study was also supported by IPET through Agricultural Machinery/Equipment Localization Technology Development Program, funded by MAFRA (122019-3), Republic of Korea.