Fusarium in winter wheat: mycotoxin accumulation in straw and a survey of roots

Fusarium;winter wheat;mycotoxins;wheat straw

Bissonnette, Kaitlyn Marie

关键词: Fusarium;    winter wheat;    mycotoxins;    wheat straw;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/92895/BISSONNETTE-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Fusarium species are common pathogens of cereal crops worldwide and are responsible for many diseases including Fusarium root rot (FRR), Fusarium crown rot (FCR), and Fusarium head blight (FHB). In recent years, Fusarium mycotoxins, primarily deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADON), and 15-acetyldeoxynivaleol (15ADON), have been detected in conjunction with wheat straw, a substrate commonly used for livestock bedding. Little is known about how or why these mycotoxins are accumulating in the straw, or more importantly, how to manage them. With FHB being the predominant Fusarium-associated disease of winter wheat in Illinois, management practices associated with the control of FHB were assessed for their effectiveness in reducing Fusarium-mycotoxin accumulation in straw. Three studies were conducted from 2011 to 2014 to determine the efficacy of fungicides, host resistance, and the use of integrated disease management strategies in controlling FHB and the subsequent mycotoxin accumulation in the straw. These studies determined that: i) the demethylation inhibitor (DMI) fungicides did not provide significant control of mycotoxin accumulation in the straw over non-treated control plots, but significantly decreased mycotoxin accumulation over the application of quinone outside inhibitor (QoI) fungicides; ii) the use of a moderately resistant cultivar offered significant control of mycotoxin accumulation in the straw over a susceptible cultivar regardless of whether or not a fungicide was applied; iii) the selection of a moderately resistant cultivar offers effective control of DON accumulation in the grain and mycotoxin accumulation in the straw. Two additional studies investigated the accumulation of Fusarium mycotoxins by straw portion and their relationship to the presence of Fusarium graminearum DNA. A field trial and a greenhouse trial were conducted using soft red winter wheat cultivars ranging in susceptibility to FHB to determine when in the growing season mycotoxins begin accumulating in the straw and if mycotoxin accumulation in the straw is related to the presence of F. graminearum DNA. Results indicated that: i) mycotoxin accumulation by 28 DAA significantly differed between the top and bottom portion of the stem in the susceptible cultivars; ii) mycotoxin concentrations and F. graminearum DNA concentration differed significantly by stem portion based on the point of inoculation. The final study was a comprehensive survey of winter wheat roots in Illinois to determine the primary Fusarium species present and if these species produce DON, potentially contributing to DON accumulation in the straw. Isolates were identified to species using TEF 1-α primers specific for Fusarium, and sequences were verified using the Fusarium Multi-Locus Sequence Typing (MLST) database. The primary species associated with winter wheat roots was F. acuminatum, followed by F. graminearum, F. sporotrichoides, and isolates from the F. incarnatum-equiseti species complex. Though not the primary species associated with wheat roots in this survey, the recovery of F. graminearum in this study may serve as a means by which Fusarium mycotoxins may accumulate in the straw, especially if environmental conditions are conducive to infection. Results from these studies indicate that the control measures typically used to manage Fusarium mycotoxins in wheat grain, primarily the selection of resistant cultivars, may be an effective means to reduce mycotoxin accumulation in the straw and that fungal colonization of the crown may be related to mycotoxin accumulation in the straw, especially when F. graminearum is present as a crown rotting pathogen.