Host-induced gene silencing of multiple genes of Fusarium graminearum enhances resistance to Fusarium head blight in wheat.

Abstract

Fusarium head blight (FHB) caused primarily by Fusarium graminearum is a devastating disease of wheat worldwide. FHB infection not only leads to serious yield lossses, but also results in critical health issues because of mycotoxin contamination, especially deoxynivalenol (DON). Novel approaches are therefore urgently required to combat FHB, due to the development of fungicide resistance in F. graminearum and the unavailability of FHB-resistant wheat cultivars. We here evaluated the use of host-induced gene silencing (HIGS) in transgenic wheat plants as a strategy to control FHB by simultaneously silencing multiple genes of F. graminearum. A chimeric hairpin RNA interference (RNAi) construct targeting to the pathogenicity and essential genes including FgSGE1, FgSTE12, and FgPP1 was able to simultaneously reduce target gene expression and caused defects of growth, conidiation and virulence in transgenic F. graminearum strains. Two transgenic wheat lines of T2 and T3 generations expressing the RNAi construct in a susceptible wheat cultivar Yangmai16 displayed high levels of stable and consistent resistance to F. graminearum, and reduced DON production in wheat. Development of fungal infection structures was dramatically impaired in the transgenic wheat lines. Small RNA sequencing confirmed the presence of small interfering RNAs specific to the three targeted fungal genes in the transgenic wheat plants, which is consistent with the reduced expression of the target genes in the invading fungus. These results demonstrate that HIGS targeting multiple genes of the fungus is effective and can be used as an alternative approach for developing FHB-resistant crops.