Resistance to Fusarium Head Blight in Winter Wheat: Heritability and Trait Associations

Abstract

Fusarium head blight (FHB) or scab caused by Fusarium Link: Fr. spp. is a widespread disease of cereals, causing significant yield losses and contaminating cereal products with mycotoxins. The complex inheritance of resistance has hampered progress in breeding resistant, agronomically adapted cultivars. To streamline breeding for FHB resistance, we estimated genetic and environmental variance components and broad‐sense heritability in two winter wheat (Triticum aestivum L.) populations, determined the association of FHB resistance with other traits (flowering date, plant height, and awnedness), and determined the level of maternal effects on FHB resistance. The moderately susceptible Austrian cultivar Capo was crossed with two resistant lines, one from Hungary (UNG‐226) and one from the Netherlands (SVP‐72017). A hierarchical design was applied to develop recombinant F4‐derived lines. Head blight resistance was measured by visual assessment of disease symptoms in artificially inoculated, mist‐irrigated field experiments during 2 yr. Artificial inoculation and mist irrigation led to reproducible FHB infections. High broad‐sense heritabilities (H > 0.75) were measured for FHB resistance, allowing for considerable progress by selection. The magnitude of additive genetic variance was greater than additive × additive epistatic variance. Despite a significant negative correlation between visual FHB symptoms and plant height , the successful selection of short and FHB resistant genotypes should be feasible. In only one population, awned progeny showed slightly reduced FHB. Reciprocal effects were significant in one cross only. The development of FHB resistant cultivars should be possible by phenotypic selection under epidemic conditions, and should be largely independent of plant height, flowering date, awnedness, and genotype of the maternal parent within a cross.