Investigation of host resistance to Fusarium graminearum in common wheat (Triticum aestivum L.)

赤霉病是一种毁灭性的小麦病害，自20世纪80年代初以来，已给加拿大农民造成了超过10亿美元的损失。在加拿大，这种疾病的主要病原体是真菌病原体禾谷镰刀菌。感染禾谷镰刀菌会导致籽粒萎缩或干缩，从而降低作物产量并损害最终使用质量。真菌毒素，如脱氧雪腐镰刀菌烯醇(DON)，会在受感染的谷物中积累。霉菌毒素对人类和一些动物是有毒的，并限制了谷物的销售性和价值。食品和饲料中真菌毒素的国际限量较低，对加拿大谷物的销售性构成威胁。在小麦品种中加入遗传抗性是多管齐下控制赤霉病的重要组成部分。小麦对赤霉病有五种抗性类型。科学家已经很好地描述了对初始感染的抵抗力(I型)和对感染扩散的抵抗力(II型)，并确定了许多抵抗源。然而，即使具有I型和II型抗性，一些小麦基因型积累的真菌毒素水平也明显高于其他基因型。DON含量对食品和饲料安全构成最大威胁，被认为是导致受镰刀菌感染的小麦病情发展的主要因素。本研究的长期目标是了解小麦抗性和管理措施在小麦DON积累中的作用。这将通过以下几个方面来实现：1)定位冬小麦群体中控制DON积累以及发病率、严重程度、指数和镰刀菌危害籽粒的基因，并研究FHB反应不同指标之间的关系；2)研究候选抗性基因与DON积累的关系；3)确定管理、侵染时间、收割前和收获条件在籽粒DON积累中的作用。这项研究将大大减少赤霉病的损失，提高世界各地小麦生产的食品和饲料安全。

Fusarium head blight (FHB) is a devastating disease of wheat that has cost Canadian producers in excess of one billion dollars since the early 1980s. The primary causal agent of this disease in Canada is the fungal pathogen Fusarium graminearum. Infection with F. graminearum leads to development of shrunken or shrivelled kernels which reduce crop yield and compromise end-use quality. Mycotoxins such as deoxynivalenol (DON) accumulate in the infected grain. Mycotoxins are toxic to humans and some animals, and limit the marketability and value of the grain. Low international limits for mycotoxins in food and feed pose a threat to marketability of Canadian grain. Incorporation of genetic resistance in wheat cultivars is an essential component of the multi-pronged strategy for FHB control. Five types of FHB resistance have been described in wheat. Resistance to initial infection (Type I) and resistance to spread of infection (Type II) have been well characterized by scientists and numerous sources of resistance have been identified. However, even with Type I and II resistance, some wheat genotypes accumulate significantly higher levels of mycotoxin than others. DON content poses the biggest threat to food and feed safety and is considered to be a major contributor to disease progression in Fusarium infected wheat. The long term objectives of this research are to understand the role of wheat resistance and management practices in DON accumulation in wheat. This will be achieved by: 1) Mapping genes controlling DON accumulation as well as disease incidence, severity, index and Fusarium damaged kernels in winter wheat populations and examining the relationship between the different measurements of FHB reaction, 2) Investigating the relationship between candidate resistance genes and DON accumulation, and 3) Determining the role of management, timing of infection, pre-harvest and harvest conditions in DON accumulation in grain. This research will significantly reduce losses to FHB, improve food and feed safety of wheat produced around the world.