Mycotoxin production and pathogenicity of Fusarium species and wheat resistance to Fusarium head blight

In vitro production of trichothecene mycotoxins, deoxynivalenol, nivalenol, T-2 toxins, and their derivatives was studied in rice culture using 30 strains from seven Fusarium species. Six strains of three Fusarium species were selected for the evaluation of mycotoxin production and pathogenicity after artificial inoculation to seven wheat lines with different levels of resistance or susceptibility and their eight F1's. Three criteria were used for the evaluation: the reduction of seed set, the reduction of grain weight, and the concentration of mycotoxins in infected grain. Significant variability was observed among Fusarium strains, wheat genotypes, and in the interaction between them. The contribution of Fusarium strains, however, was far greater than that of the other two factors. The kinds and relative amounts of mycotoxins produced in rice culture were consistent with those present in infected grain with some exceptions. Significant correlations were found between the grain weight reduction and the mycotoxin concentration and between the level of resistance of the wheat genotypes under the artificial and natural conditions of infection. The biological role of Fusarium mycotoxins in pathogenicity and wheat resistance to Fusarium head blight is discussed. Key words: Fusarium head blight (scab), Fusarium mycotoxins, Fusarium pathogenicity, wheat resistance to Fusarium head blight.