Effect of Fusarium head blight on deoxynivalenol levels in whole grain and patent flours from different wheat genotypes

Abstract

Fusarium head blight (FHB) or scab, caused by Fusarium graminearum, is a highly destructive disease of wheat that can affect wheat grain yield and quality and contaminate grains and grain products with trichothecene mycotoxins, such as deoxynivalenol (DON). The purpose this study was to evaluate FHB resistance and DON accumulation in whole grain flour (WGF) and patent flour (PF) from different wheat genotypes developed for the humid subtropical conditions in southern Brazil. Three types of physiological resistance were evaluated: resistance against initial infection, resistance to kernel infection, and resistance to DON accumulation, known as the type I, III and V resistance reactions to FHB, respectively. The experimental design was factorial, and the factors studied were genotypes (n=23), type of flour (WGF and PF), inoculation (uninoculated or inoculated), and growing season (2011 and 2012). The genotypes were screened with natural infection and were artificially inoculated by spraying a conidial suspension at mid-anthesis. DON content in WGF and PF was significantly affected by all the tested sources of variation and their interactions. Averaged among genotypes, the increase in DON content in WGF compared with PF was 29.3%, ranging from 1.7 to 66.4%. Significant differences in FHB incidence and severity, Fusarium-damaged kernels, yield and test weight (Tw) were observed among wheat genotypes. Artificial inoculation significantly affected the DON content of WGF and PF but not the other variables, indicating its utility in southern Brazil. Linear correlations between DON accumulation in WGF or PF and resistance to FHB variables, yield and Tw were also determined.