Potential biocontrol agents for Fusarium head blight and deoxynivalenol production in wheat

Fusarium head blight (FHB) caused by Gibberella zeae (anamorph=Fusarium graminearum) is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. During the last 50 years, several epidemics of FHB of varying degrees of severity have occurred in Argentina. Besides the economic losses due to reduction in grain quality, the main problem is the potential mycotoxin contamination of wheat mainly with deoxynivalenol (DON). Biological control offers an additional strategy that can be used as part of an integrated management to control FHB. A survey was done to search for potential biocontrol agents (BCA) isolated from wheat anthers in Argentina. A total of 354 bacterial strains were screened in two selection steps using a index of dominance (ID) assay considering environmental parameters such as temperature and water activity in the interaction between pathogen and antagonist. Among the evaluated strains, 22 strains (6%) were able to reduce the growth of F. graminearum. The 22 selected strains reduced the production of DON on irradiated wheat grains by 60–100%. The ability of these strains to control FHB and DON production was evaluated under greenhouse conditions. Nine strains (40.9%) significantly reduced the disease severity by 49–71% (P⩽0.05). The DON content in spikes, produced by plants in the greenhouse trial, was significantly reduced by 32–100% compared with the control. Five strains decreased mycotoxin content to undetectable levels. From this study we identified two strains, Brevibacillus sp. BRC263 and Streptomyces sp. BRC87B, to be tested in combination for potential control of FHB.