Bacillus velezensis RC218 and emerging biocontrol agents against Fusarium graminearum and Fusarium poae in barley: in vitro, greenhouse and field conditions

Fusarium head blight (FHB) is one of the most common diseases in Argentina, affecting the quality and yield of barley grains. Fusarium graminearum sensu stricto (ss) and Fusarium poae are causal agents of FHB and potential sources of mycotoxin contamination in barley. Conventional management strategies do not lead to a complete control of FHB; therefore, biological control emerges as an eco-friendly alternative in the integrated management of the disease. In the present work, Bacillus velezensis, Bacillus inaquosorum, Bacillus nakamurai and Lactobacillus plantarum were evaluated as potential biocontrol agents against F. graminearum ss and F. poae on barley-based media. Bacillus velezensis RC218 was selected to carry out greenhouse and field trials in order to reduce FHB and mycotoxin accumulation. This strain was able to control growth of both Fusarium species and reduced deoxynivalenol (DON) and nivalenol (NIV) production by 66 % and 79 %, respectively. Bacillus inaquosorum and B. nakamurai were more effective in controlling F. poae growth, and the mean levels of reduction in DON accumulation were 50 and 38 %, and 93 and 26 % for NIV, respectively. Lactobacillus plantarum showed variable biocontrol capacity depending on the strain, with no significant mycotoxin reduction. The biocontrol on incidence and severity of FHB in the greenhouse and field trials was effective, being more efficient against F. graminearum ss and DON accumulation than against F. poae and NIV occurrence. This study provides valuable data for the development of an efficient tool based on biocontrol agents to prevent FHB-producing Fusarium species development and mycotoxin occurrence in barley, contributing to food safety.