Fusarium head blight biocontrol using cyclic lipopeptides produced by Bacillus velezensis RC218

Abstract

Cyclic lipopeptides (CLPs) produced by Bacillus species have been reported to have several antimicrobial effects against plant /pathogens through different mechanisms such as destabilisation of plasma membrane and loss of electrolytes. The present study focused on the production, extraction, identification of CLPs produced by B. velezensis RC218 and evaluation of their activity against the phytopathogen Fusarium graminearum. Mass spectroscopy confirmed the presence of these lipopeptides, with several carbon-length variants in each family. Other antimicrobial molecules such as macrolactin, dificidin and bacilysin were also detected. In vitro experiments showed a significant reduction in the mycelial radial growth (up to 84%) of three F. graminearum sensu stricto strains isolated from a Fusarium head blight (FHB) epidemic. Green house experiments were carried out on BioINTA1005 (FHB-susceptible wheat) and the tolerant variety Cronox.Application of the pure extract to flowering heads, prior to thepathogen inoculation, resulted in reduced disease incidence and severity in both cultivars. The biocontrol effect was more pronounced in the susceptible variety (78.5% reduction in incidence and 82.5% in severity) compared to the tolerant Cronox(69.3% and 66.3% reductions, respectively). Given that metabolites production by bacteria at the in planta level can be altered by the plant-environment interaction, applying the purified lipopeptide extract from B. velezensis RC218 as a preventive against FHB emerges as a promising method to control pathogens.