Fitness attributes of Fusarium graminearum isolates from wheat in New York possessing a 3-ADON or 15-ADON trichothecene genotype

In all, 50 isolates of Fusarium graminearum from wheat spikes in New York, including 25 isolates each of the 15-acetyl-deoxynivalenol (15-ADON) and 3-ADON genotype, were tested to determine whether 3-ADON isolates are more fit for saprophytic survival and pathogenicity on wheat spikes than are 15-ADON isolates. The isolates were characterized and compared for 14 different attributes of saprophytic fitness and pathogenic fitness on a susceptible wheat variety. Isolates of the two genotypes could not be differentiated for most of these traits. Three principle components-ascospore production on corn stalks, total trichothecene amount in wheat kernels, and incidence of diseased spikelets up from the point of inoculation-accounted for 29.4, 18.9, and 10.8% of the variation among the isolates, respectively. A bootstrapping procedure grouped the isolates into two distinct groups, with 27 and 23 isolates each, with isolates from both genotypes represented in similar proportions (15-ADON/3-ADON, n = 14/13 and 11/12). Within the contemporary population of F. graminearum causing wheat head blight in New York, isolates with a 3-ADON genotype did not possess any detectable advantage over isolates with a 15-ADON genotype in saprophytic fitness or in pathogenic fitness on a susceptible wheat cultivar.