Pathogenicity and trichothecenes production of Fusarium culmorum strains causing head blight on wheat and evaluation of resistance of the varieties cultivated in Algeria
Résumé
Fusarium head blight (FHB) is a major disease of wheat that has been studied worldwide but never in Algeria where high quantities of both durum wheat and common soft wheat are grown and traditionally consumed as semolina and bread. Fusarium root rot has also been observed in this country. Here we show that Fusarium culmorum seems to be the major pathogen associated with these diseases in Algeria. The type of mycotoxins produced by four F. culmorum isolates and their capacity to confer the disease on spike and accumulate type B trichothecenes in the grain was evaluated. Two strains produced deoxynivalenol, 3-acetyldeoxynivalenol and zearalenone in vitro. The two other strains produced nivalenol and fusarenone X. The four strains were used for artificial spray inoculations on wheat spikes to determine their potential in generating FHB symptoms and accumulating mycotoxins in local field conditions. A panel constituted of four durum wheat and four soft wheat varieties generally cultivated in Algeria and of two newly created durum wheat lines were evaluated. The results show a correlation between the level of invasion of the grain and the quantity of accumulated toxins with a large diversity depending on the cultivars. Interestingly, two local durum wheat varieties and the two new durum lines showed a promising level of resistance to FHB with significantly lower trichothecene accumulation. The content in phenolic compounds of the different varieties was assessed and evaluated as possible factor of resistance to trichothecene accumulation. This is the first report evaluating the wheat varieties cultivated in Algeria for their susceptibility to Fusarium Head Blight caused by local strains of F. culmorum in semi-arid bioclimatic condition.