Characterization of Resistance to Fusarium Head Blight in an Eastern US Soft Red Winter Wheat Population

Host resistance is important to control Fusarium head blight (FHB)), caused by the fungus Fusarium graminearum (Schwabe) [teleomorph: Gibberella zeae (schw.) Petch], in wheat (Triticum aestivum L.). Effective breeding requires understanding the genetics of resistance in breeding populations. Our objective was to deduce the genetics of FHB resistance in eastern U.S. soft red winter wheat (SRWW) by estimating heritability, means, and phenotype frequencies. We evaluated the FHB index of 2983 lines from 223 parents in a series of single- and multiyear trials conducted in inoculated FHB nurseries. The mean index of all lines (23.8%) was similar to that of the moderate resistant check (19.7%), and the distribution was often skewed toward low index values. Without selection, 41% of all lines had moderate resistance and 70% of all crosses produced such lines. Entry-mean heritability for index generally exceeded 0.65 and selection for lower index reduced the index by -37%. The moderate resistance arose from many SRWW parents with varying levels of FHB resistance. The genetics of resistance in this population is probably characterized by a relatively high frequency of resistance alleles at multiple loci, dispersed over many parents that differ in allele content at loci controlling FHB resistance. This population should provide excellent gain from recurrent selection and complement current marker-assisted selection efforts.