Further characterization of the scab resistance of ‘Frontana’ spring wheat and the relationships between resistance mechanisms

With 2 figures and 2 tables ABSTRACT: ‘Frontana’ spring wheat exhibits resistance to Fusarium head blight (FHB), but it is not clear which genes confer resistance to initial infection or spread. This study assessed the FHB resistance of reciprocal backcross monosomic (RBCM) lines previously developed using Frontana and ‘Chris’. Six RBCM lines differing for Frontana and Chris disomic chromosomes 3A, 6A and 4D were evaluated to determine which chromosome prevents disease establishment or spread after either spray or single floret inoculation (SFI). Data were collected for FHB incidence, severity and spread. The RBCM line with Frontana chromosome 3A expressed the lowest FHB severity and incidence after spray inoculation and the lowest disease spread after SFI. This confirms a major role of Frontana chromosome 3A in resistance to FHB establishment and spread. Frontana chromosomes 6A and 4D also influence resistance but have less of an impact compared with 3A. Significant correlations between disease incidence and severity and between severity and visually Fusarium damaged kernels (VFDK) suggest that type I and type II resistant mechanisms do not function independently in Frontana. Therefore, the metrics used to quantify resistance are interrelated.