Bilateral BBSRC-Embrapa: Exploiting natural and induced variation to increase Fusarium head blight and brusone resistance in wheat

小麦赤霉病（FHB）和小麦稻瘟病（brusone）是造成巴西重大产量损失的两种破坏性小麦病害。这两种病原菌都严重影响麦穗，在品质和产量方面对籽粒造成直接损害。在缺乏抗病品种的情况下，目前的疾病控制严重依赖杀菌剂，这些杀菌剂价格昂贵，对巴西来说是不可持续的，而且只是部分有效。由稻瘟病菌引起的布鲁松病于1985年首次在巴西南部被发现，但后来蔓延到阿根廷、玻利维亚和巴拉圭。该疾病可导致总产量损失，2009年巴西小麦产量因布鲁松病减少30%。重要的是，巴西品种对面包的易感性阻碍了它们在塞拉多地区的种植，这一地区有500万公顷未利用的潜力可以扩大，从而提高巴西对这种重要主食的自给自足。镰刀菌头疫病是巴西和英国的一种严重疾病，主要由真菌镰刀菌引起。除了非常显著的产量和质量损失外，粮食赤霉病的一个主要问题是粮食受到脱氧雪腐镰刀菌醇（DON）等霉菌毒素的污染。欧盟和巴西都规定了谷物和谷类产品中DON的最大允许含量。在巴西，严重的FHB暴发频率有所增加。2014年，FHB非常严重，导致南巴西格兰德州60%以上的小麦减产，2014年在西部地区，一些农民因brusone + FHB的组合损失超过80%。目前迫切需要确定对FHB和brusone的耐药性来源并确定其特征，并确保引入控制一种疾病的基因不会损害对另一种疾病的耐药性。已在巴西小麦中发现了中等程度的brusone抗性，但这种抗性的遗传基础尚不清楚。在幼苗中表达的抗性并不总是在成年植株中表达，因此有必要在成年植株中评估抗性。对赤霉病的抗性通常由几个中等或弱作用的基因控制，这些基因在遗传学上被定义为数量性状位点（QTL）。尽管巴西小麦品种对Fhb1的抗性差异很大，其中一些具有中等抗性，但没有发现品种具有源自亚洲来源的Fhb1主要抗性。因此，最具fhb抗性的巴西品种的遗传基础尚不清楚，这表明它们含有新的抗性，可以与其他地方的抗性结合，培育出非常高抗性的小麦品种。该项目将使用一系列尖端方法来确定对布鲁松和FHB疾病的抗性的遗传基础。我们将确定基因组的哪些部分包含增加FHB和/或brusone抗性的基因，并确定对一种疾病的抗性增加是否与对另一种疾病的易感性增加相关。我们还将确定小麦中降低对这两种疾病抗性的基因。这将为提高小麦对赤霉病的抗性提供一种补充方法。我们将制作DNA标记，使植物育种者能够在其育种计划中跟踪有益基因的存在，并确保其品种对这两种疾病具有高度抗性。这项工作的结果将使巴西和世界上这些疾病流行的其他地方的植物育种者受益。这将降低种植者遭受作物损失的风险，并降低消费者因真菌毒素在谷物中积累而面临的风险。这将减少对杀菌剂的依赖来控制这些疾病，从而使种植者和环境受益。

Fusarium head blight (FHB) and wheat blast (brusone) are two devastating diseases of wheat that cause major yield losses in Brazil. Both pathogens severely affect wheat heads with direct damage to the grain, both in terms of quality and yield. In the absence of resistant varieties, current disease control relies heavily on fungicides that are costly, non-sustainable for Brazil, and only partially effective.Brusone, caused by the fungus Magnaporthe oryzae, was first identified in southern Brazil in 1985 but has since spread into Argentina, Bolivia, and Paraguay. The disease can cause total yield loss of yield and in 2009 brusone cut Brazilian wheat production by up to 30%. Importantly, the susceptibility of Brazilian varieties to brusone precludes their cultivation in the Cerrado region, an unused potential of 5 million ha for expansion that would improve Brazilian self-sufficiency of this essential staple.Fusarium head blight, caused primarily by the fungus Fusarium graminearum, is a serious disease in both Brazil and the UK. In addition to the very significant yield and quality losses, a major concern with FHB is the contamination of grain with trichothecene mycotoxins such as deoxynivalenol (DON). Both the European Union and Brazil have imposed maximum permissible levels for DON in cereals and cereal products. In Brazil, severe FHB outbreaks have increased in frequency. In 2014 FHB was so severe that more than 60% of wheat yield was lost in the State of Rio Grande do Sul and in the western region in 2014 some farmers lost more than 80% to the combination of brusone + FHB.There is an urgent need to identify and characterise sources of resistance to both FHB and brusone and ensure that the introduction of genes to control one disease does not compromise resistance to the other. Moderate levels of resistance to brusone have been identified in Brazilian wheat but the genetic basis of this resistance is unclear. Resistance expressed in seedlings is not always expressed in adult plants making it essential that resistance is assessed in adult plants.Resistance to FHB is generally controlled by several genes of moderate/weak effect that are defined genetically as quantitative trait loci (QTL). Although Brazilian wheat varieties differ widely in their resistance to FHB with some being moderately resistant, no variety was found to possess the major Fhb1 resistance originating from Asian sources. Thus the genetic basis of the most FHB-resistant Brazilian cultivars is not known and suggests that they contain novel resistances that could be combined with those from elsewhere to breed very highly resistant wheat varieties.This project will use a range of cutting-edge approaches to identify the genetic basis of resistance to brusone and FHB disease. We will identify which parts of the genome contain genes that increase FHB and/or brusone resistance and determine whether increased resistance to one disease is associated with increased susceptibility to the other. We will also identify genes in wheat that reduce resistance to the two diseases. This will provide a complementary approach to increasing resistance to FHB and brusone in wheat. We will produce DNA markers to enable plant breeders to follow the presence of the beneficial genes in their breeding programmes and ensure that their varieties are highly resistant to both diseases. The results from this work will benefit plant breeders in Brazil and elsewhere across the world where these diseases are prevalent. This should lead to reduced risk of crop losses to growers and reduced risk to consumers from mycotoxins accumulating in grain. It will lead to a reduced reliance on fungicides to control these diseases which, in turn will benefit, growers and the environment.