Bacillus velezensis BM21, a potential and efficient biocontrol agent in control of corn stalk rot caused by Fusarium graminearum

Shuang Wang,Yonggang Li,Fengqin Chi,Xiaoyu Hao,Jingyang Bian,Lei Sun,Wu Zhang

doi:10.1186/s41938-020-0209-6

Shuang Wang, Yonggang Li + Show 5 more

Open Access

https://doi.org/10.1186/s41938-020-0209-6

Copy DOI

Abstract

The present work was conducted to screen and identify biocontrol bacteria that effectively reduce the severity of corn stalk rot (CSR) and clarify the antifungal activity of secondary metabolites. The bacterial strain (BM21) was isolated from corn rhizosphere soil that effectively reduced CSR in pot experiments. On the basis of phylogenetic reconstructions, 16S rRNA sequence analysis, and biochemical and physiological reactions, BM21 was identified as Bacillus velezensis. The strain exhibited remarkable antifungal activity against Fusarium graminearum, a pathogenic fungus that causes CSR. Extracellular antifungal substances (10%) isolated from BM21 inhibited F. graminearum mycelial growth by 79.2%, conidial germination by 84.0%, and conidial production by 78.1%. In addition, the extracellular antifungal substances caused mycelial malformation and ultra-structural changes. The extracellular antifungal substances were sensitive to heat and showed a degree of resistance to ultraviolet radiation. The optimum pH for antifungal activity was 6–8. In pot experiments, irrigation with aqueous extracts from BM21 (1.0 mL/plant) reduced CSR incidence by 72.4–77.4%. B. velezensis BM21 effectively reduced CSR incidence and showed a potential as a biocontrol agent to control CSR.

Highlights

Corn (Zea mays L.) is an important food crop and feedstuff worldwide and provides at least 30% of the food calories to more than 4.5 billion people in 94 developing countries (Shiferaw et al 2011; Fu et al 2014)
Corn stalk rot (CSR) is a serious soilborne disease caused by Fusarium spp., predominantly, F. verticillioides, F. proliferatum, F. subglutinans, F. graminearum, F. incarnatum, and F. temperatum (Scauflaire et al 2011; Varela et al 2013; Gai et al 2016), and results in severe losses in corn production
The objectives of the study were to screen bacterial biocontrol agents for reduction of CSR severity caused by F. graminearum, to identify bacterial species that exhibit antagonistic activity, and to design a series of preliminary tests to evaluate the potential value of a bacterial species as a biological control agent

Summary

Introduction

Corn (Zea mays L.) is an important food crop and feedstuff worldwide and provides at least 30% of the food calories to more than 4.5 billion people in 94 developing countries (Shiferaw et al 2011; Fu et al 2014). Crop pathogens reduce the yield and quality of agricultural production, which could cause substantial economic losses and reduce food security at household, national, and global levels (Savary et al 2019). Corn stalk rot (CSR) is a serious soilborne disease caused by Fusarium spp., predominantly, F. verticillioides, F. proliferatum, F. subglutinans, F. graminearum, F. incarnatum, and F. temperatum (Scauflaire et al 2011; Varela et al 2013; Gai et al 2016), and results in severe losses in corn production. CSR caused by F. graminearum is among the most devastating diseases of corn worldwide (Li et al 2016a). Excessive use and misuse of these chemicals have caused food contamination, weed and disease resistance, and negative environmental outcomes with a serious impact on human health (Alori and Babalola 2018). Biological control may overcome the shortage of chemical agents and ensure healthy growth of corn plants throughout the entire growth

Objectives

Methods

Results

Conclusion