The Major Cause of Deoxynivalenol Accumulation in Normal-Looking Kernels of Winter Wheat

Abstract

We examined the deoxynivalenol (DON) accumulation in visually unaffected (normal-looking) kernels of winter wheat during the ripening stage. Normal-looking kernels were collected from diseased heads with Fusarium head blight symptoms and visually symptomless heads (normal-looking heads) at the soft dough, hard dough, and harvest-ripe grain stages, and their Fusarium graminearum isolation freguency and DON levels were analyzed. In the normal-looking kernels obtained from diseased heads, DON levels and isolation frequency increased during the later stages of kernel development, and high levels of DON were detected at the harvest-ripe grain stage. Conversely, in the normal-looking kernels of symptomless heads, F. graminearum and DON were detected at the harvest-ripe grain stage; however, the isolation frequency and DON levels were low compared to those in the diseased heads. The results suggest that the secondary infection in diseased heads is the major cause of DON accumulation in normal-looking kernels.