CONICET | Buscador de Institutos y Recursos Humanos

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a wheat disease that causes yield losses and mycotoxin accumulation in the grain. In durum wheat (Triticum turgidum L. ssp. durum) germplasm, 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 the relationship of these parameters with disease severity. For this we examined a genotype set 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 FHB resistance. Significant differences were detected among inoculated genotypes for germination, coleoptile length, coleoptile weight, root weight and severity. Seedling variables showed to be correlated across experiments suggesting repeatability of the in vitro assay. In multiple regression analysis, the coleoptile length was significant with FHB severity (p < 0.05) and explained 63% of head disease. Introgressed resistant genotypes showed null or slight reductions in seedling growth, in comparison to controls, and lower severity than the corresponding original varieties, suggesting that seedling test can detect genetic differences in FHB resistance. Three varieties performed well in the seedling assay and showed moderate severity even though they lacked the targeted QTLs. Based on relative coleoptile length and Fisher significance a ranking of genotypes consisting of three groups with best, intermediate and poor performance in relation to fungal effect was defined. The advantageous features of this method reside in its statistical basis and predictive ability of head disease. This study describes a rapid in vitro assay that allows early evaluation of resistance/susceptibility to F. graminearum suitable for germplasm collections or segregant progenies screening.