An in vitro assay for pre-screening resistance to Fusarium head blight in durum wheat

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a wheat disease that causes yield losses and mycotoxin accumulation in the grain. In germplasm of durum wheat (Triticum turgidum L. ssp. durum), genetic variability for resistance is scarce. To develop an improved assay for FHB resistance in wheat, we evaluated the effect of F. graminearum inoculation on seed germination and seedling growth and relationships of these parameters with disease severity. A genotype set was examined, comprising ten durum wheats as well as two common wheats, including susceptible and introgressed resistant lines. Genotypes were additionally screened using molecular markers linked to known FHB resistance QTLs. Significant differences were detected among inoculated genotypes for germination, coleoptile length, coleoptile weight, root weight and disease severity. Seedling variables were shown to be correlated across experiments validating repeatability of the in vitro assay. Using multiple regression analysis, coleoptile length was correlated with FHB severity (P