Deoxynivalenol (DON) content and Fusarium head blight resistance in segregating populations of winter rye and winter wheat

Fusarium head blight (FHB), caused by Fusarium graminearum Schw. [teleomorph: Gibberella zeae (Schw.) Petch] and Fusarium culmorum (W.G. Sm.) Sacc., is a devastating disease in cereals, resulting in yield loss and contamination of harvested grains with mycotoxins, mainly deoxynivalenol (DON) and 3-acetyl DON (3-ADON). This study was undertaken to evaluate the possibility of selecting to reduced DON content and FHB resistance early in a breeding program. We estimated the genetic variance among F3 lines in winter rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) and the association between the two traits. In field experiments, four rye and one wheat populations with a total of 218 and 77 progenies, respectively, together with their parental lines were inoculated in four location-year combinations (environments) with an isolate of F. culmorum that produced high levels of DON. Grain DON and 3-ADON contents were determined by an enzyme immunoassay and head blight severity was assessed. Additionally, a total of 166 rye samples were analyzed by gas chromatography with mass spectrometry (GC-MS). The two methods were highly correlated (0.9). Mean DON contents ranged from 20 to 129 mg kg(-1), and mean disease severity from 3.8 to 6.8 on the 1-to-9 scale. The parental means generally resembled the means of their respective F3 progenies. Significant (P = 0.01) genotypic variance was detected, but genotype x environment interaction was also high (P = 0.01) for the two traits. Grain DON content, however, showed lower heritabilities than head blight rating, especially in rye. Coefficients of phenotypic correlation between FHB severity and DON content, therefore, were only in the medium range for rye (0.3-0.7) and higher for wheat (0.8). Genotypic correlation coefficients generally showed a tight association in both rye and wheat (0.8-0.9). Transgressive segregants for higher DON content were found in three rye populations and for higher FHB resistance in one rye population. Selection for lower grain DON content and FHB resistance can be effectively started by plant breeders as early as in the F3 generation. Lines with low DON content can be indirectly achieved by selecting for reduced head blight severity across environments.