Exploring root resistance to take-all disease from wheat landraces and ancestral wheat relatives

小麦被认为是人类热量摄入和牲畜饲料的三大重要作物之一。该项目旨在进一步确定小麦祖先近亲单球菌（T. monococum）对全病的抗性，并从基因上确定其特征。描述抗性机制将增强我们对这种相互作用的认识，并可能导致疾病控制和改善根系健康的新方法，这些方法可用于世界各地的小麦耕作实践。通过将这些基因引入到商业化种植的小麦品种中，确定赋予这种抗性的位点将具有未来的应用价值。全蚀病与小麦产量损失高达60%有关，但控制方法非常有限，目前还没有确定的抗性基因。因此，本研究的结果可以通过培育具有根病遗传抗性的新品种来提高小麦的生产性能，减少对轮作或化学干预的依赖。本抗全病/小麦根系健康研究将包括以下可能的实验：利用由MDR031（抗性）与MDR043（易感）杂交而成的二倍体小麦Triticum monococum （Tm）定位群体研究抗性的遗传基础。已经在2017年和2018年进行了第三次麦田试验，并将在2019年进行重复试验。将取样和储存的根系进行视觉评分，以测定其抗全蚀性。2. 利用限制性位点相关DNA （RAD）测序的SNP信息以及来自defra资助的WGIN3小麦启动组捕获实验的数据，将已知的SSR标记和新开发的KASP标记结合起来，生成MDR031 x MDR043群体的分子标记图谱。在抗性QTL或QTL的侧翼处确定分子标记。MDR031中存在的抗性目前正在渗入到六倍体小麦cv中。Paragon是defra资助的WGIN4项目的一部分。一旦回交一代达到第4阶段，相关的分子标记将被用于植物上，以确定哪个含有感兴趣的QTL。将从亲本Tm系和赫里沃德六倍体小麦的田间样品中回收一组全价分离株，并对其类型、对化学硅硫棉的敏感性和ITS测序进行鉴定。这个新集合的属性将与主要的RRes集合的属性进行比较。通过设计一种新的麦穗取样方案，探讨全蚀病对MDR031和MDR043产量的影响。Tm对全身性疾病的耐受性以前没有被研究过。一个潜在的易感黑麦品种将首先在盆栽试验中重新调查。如果被证明是易感的，这个黑麦品种将被杂交成一个抗性黑麦，并在后代中探索抗性的遗传基础。这两种黑麦也将在第一次和第三次麦田试验中进行种植和评估，以确定成株的表现，并恢复能够在黑麦根部定殖的全毒分离株。黑麦对全蚀病的易感性和抗性机制也将在盆栽试验和其他类型的试验中进行研究。近等基因系（NILs）。7 .我们将在盆栽试验和第1、3次田间试验中研究中国春对全蚀性侵染的反应，并对其根系构型的变化进行量化。利用Tm亲本系和赫里沃德在田间试验中进行比较微生物组分析，以探索MDR031带来的抗性是否会改变根际和内圈的物种分布。

Wheat is regarded as one of the three most important crops for human calorie intake and livestock feed. This project aims to further characterise and genetically define resistance to take-all disease found in an ancestral wheat relative, T. monococcum. Characterising the mechanism of resistance will enhance our knowledge of such interactions and potentially lead to new methods of disease control and improved root health that could be used in farming practices of wheat worldwide. Identifying the locus/ loci conferring this resistance will have future applications through introducing such genes into commercially grown wheat varieties. Take-all disease has been linked to yield losses of up to 60% in wheat and yet control methods are very limited, with currently no identified genes for resistance. Therefore, outcomes of this research could improve wheat performance from new cultivars with genetic resistance to root disease, reducing the reliance on crop rotation or chemical interventions. This take-all disease resistance/wheat root health study will involve the following possible experiments:1.The genetic basis of resistance will be investigated using the diploid wheat Triticum monococcum (Tm) mapping population derived from a cross MDR031 (resistant) x MDR043 (susceptible). Third wheat field trials have already been carried out in 2017 and 2018, and this will be replicated in 2019. Sampled and stored root systems will be visually scored for resistance to take-all. 2. A molecular marker map will be generated for the MDR031 x MDR043 population based on a combination of known SSR markers and newly developed KASP markers using SNP information from restriction-site associated DNA (RAD) sequencing as well as the data from the defra funded wheat promotome capture experiment within WGIN3. Molecular markers closely flanking the resistance QTL or QTLs will be determined.3. The resistance present in MDR031 is currently being introgressed into the hexaploid wheat cv. Paragon as part of the defra funded WGIN4 project. Once the backcross generation has reached stage 4, the associated molecular markers identified (in 2 above) will be used on plants to determine which harbour the QTL of interest.4. A collection of take-all isolates will be recovered from the parental Tm lines as well as hexaploid wheat Hereward from field samples and characterised for type, sensitivity to the chemistry silthiofam and via ITS sequencing. The properties of this new collection will be compared with those of the main RRes collection.5. The influence of take-all on the yield of MDR031 and MDR043 will be explored by devising a new ear sampling protocol when Tm is grown in 1st and 3rd wheat situations. Tolerance of Tm to take-all disease has not previously been explored.6. A potentially susceptible rye species will initially be re-investigated in pot tests. If proven to be susceptible, this rye accession will be crossed to a resistant rye and the genetic basis of resistance explored in subsequent generations. The two ryes will also be grown and evaluated in 1st and 3rd wheat field trials to determine adult plant performance and to recover take-all isolates able to colonise rye roots. The mechanisms underlying susceptibility and resistance of rye to take-all will also be studied in pot tests and other types of assays.7. Near isogenic lines (NILs) in the cv. Chinese Spring harbouring the 3N QTL introgressed from Aegilops uniaristata, conferring prolific root development will be studied for their response to take-all infection in pot and 1st and 3rd field experiments and the altered root architecture quantified.8. A comparative microbiome analysis will be done using the Tm parental lines and Hereward in field trials to explore whether the species profile in the rhizosphere and endosphere is altered in the presence of the resistance conferred by MDR031.