In vitro variation in pathogenicity of Fusarium species causing head blight in relation to their isolation from barley head

Till now, no published study is available on the variation in pathogenicity of Fusarium head blight (FHB) pathogens in relation to their isolation origin in barley head. To end this, two barley cultivars of contrasting quantitative resistance were artificially infected by four FHB species under field conditions over two consecutive growing seasons. Then, pathogenicity tests were conducted under in vitro conditions on single-spore cultures originated from both kernels and glumes in the heads. Different pathogenicity was detected among Fusarium species originated from both kernels and glumes, indicating that the same isolate from glumes and kernels differs in pathogenicity on leaves/seedlings. Isolates of Fusarium culmorum and Fusarium verticillioides originated from infected kernels had shorter latent periods and higher area under disease progress curves compared to isolates originated from glumes, and the reverse was observed for the Fusarium equiseti isolate. In the case of Fusarium solani, isolates originated from kernels or from glumes were equally pathogenic. Primarily findings in this first in-depth study have implications for breeding programs relied principally on actual quantification of pathogenicity in Fusarium species present in a given environment. The sampling of fungi should take into account the presence of Fusarium species of interest on kernels or glumes.