Resistance to Fusarium head blight (FHB) in a population derived from the cross of bread wheat and Triticum timopheevii

Fusarium head blight (FHB) caused mainly by Fusarium graminearum is one of the most important diseases in many wheat growing areas of the world. In this study a F(7) wheat population consisting of 230 recombinant inbred lines (RILs) wits developed from the cross of two wheat genotypes: A FHB susceptible bread wheat cultivar (Brio) and a resistant line derived from Triticum timopheevii (Tc 67). Response of the RILs and their parents to FHB infection was evaluated for resistance to initial infection (Type I resistance) in spray-inoculated field trials in two locations, for resistance to fungal spread within the spike (Type II resistance) in the greenhouse using single-floret inoculation, and for resistance to kernel damage in field conditions in two locations. FHB incidence, severity, and index were assessed 21 days after inoculation and Fusarium-damaged kernels (FDK) after harvest. Results of analysis of variance of disease incidence (field data) showed that the genotypes differed significantly at rho <= 0.01, genotype x location interaction was significant at rho <= 0.05, but the effect of location on disease incidence was not significant. Analysis of variance of disease severity (greenhouse data) showed highly significant differences between the genotypes at rho <= 0.01. There was a high positive correlation among disease incidence, severity, and index, but a very low correlation with FDK. In addition, (here was a relatively low negative correlation between visual FHB symptoms and number of days from seeding date to anthesis. Distribution of disease incidence, severity, and index in the population was continuous, indicating polygenic and quantitative inheritance of resistance to FHB. The RILs are being genotyped with microsatellite markers tinder laboratory conditions. Genotypic data along with phenotypic data front this study will be used later to map and characterize quantitative trait loci (QTL) of resistance to FHB among the population.