Effect of chitosan on Fusarium graminearum-Brachypodium distachyon interaction

Fusarium graminearum is one of the causal agents of Fusarium head blight (FHB) in wheat (Triticum aestivum L.), which is considered one of the most severe diseases in this crop. Brachypodium distachyon, the model plant for wheat research, is also susceptible to FHB. Chitosan is a partially deacetylated polymer of glucosamine derived from chitin, and both chitin and chitosan are found in fungal cell walls. Interestingly, chitosan has been shown to have antimicrobial properties and is also an inducer of plant defense responses. The objective of this study is to assess chitosan as an alternative to classical pesticides for controlling FHB disease. Different chitosan concentrations were assessed in their ability to inhibit mycelial growth of F. graminearum. The protective effect of the polymer in B. distachyon cultivar 21(Bd21) inoculated with F. graminearum was also evaluated. The antimicrobial assays showed a fungistatic, but not fungicidal, effect at concentrations of 3.0 g.L-1. Preliminary results related to the protective effect show a reduced number of infected spikelets when pretreated, 24 h before inoculation, with 0.1 and 1.0 g.L-1 of the polymer compared to the control.