Pulse-Downy Mildew Pathosystem: deploying disease resistance, pathogenomics and microbial biocontrol

豆类，特别是豌豆和蚕豆，在英国和世界范围内都是重要的作物，它们作为广泛的单一栽培而种植。即使长时间轮作，作物也容易受到经济上重要的害虫和疾病的大流行，其中霜霉病（由卵菌生物营养型病原体蚕豆霜霉引起）。sp. pisi（Pvp）和豌豆疫霉P.viciaef.豌豆和菜豆中的蚕豆根瘤菌（Pvf）是最严重的。育种公司面临的挑战是生产具有新抗性基因的品种，并将受益于获得携带新抗性基因的作物野生近缘种。通过部署抗性品种和化学控制来管理该疾病;然而，缺乏关于流行分离物的信息可能导致在受污染场地种植的作物因不知情的品种选择而严重减产。虽然有一套不同的植物品种可用于鉴定Pvp/Pvf致病型中的毒力基因，但该试验太耗时，不能立即用于商业种植者，也不能快速监测流行的分离株。此外，使用当前的方法生成病原体传播的模型是不可能的。卵菌病原体对诸如甲霜灵之类的杀虫剂的抗性的报道加剧了这一问题。如果没有适当的控制制度，豌豆和蚕豆生产将导致更大的作物浪费，因此必须开发方法来减少种植者对农药控制霜霉病的依赖。部署抗流行菌株的豆类品种是最有前途的方法。使用适当的分子工具将使育种者、流行病学家、建模者和种植者能够：a）确定流行的毒性分离物; B）调查疾病的流行; c）监测病原体的移动; d）迅速部署对流行分离物具有抗性的适当栽培品种，从而以环境友好和可持续的方式控制疾病。向种植者提供关于抗性品种的准确建议需要关于当地Pvp/Pvf小种毒力的正确信息。然而，在分离水平上诊断病原体需要正确的工具。该项目中描述的创新方法侧重于开发用于准确鉴定Pvp/Pvf分离株以及抗性育种的分子工具。我们的目标是确定新的抗性来源，包括在育种计划和开发分子标记，使快速识别和监测病原体分离株。我们将使用下一代测序技术来鉴定几种分离株的多态性。然后将利用这些多态性来产生分离物特异性标记。一旦确定，标记将在实验室条件下进行测试，随后也将在商业领域进行检查。此外，我们将使用生物防治剂来防治霜霉病。这将提高作物产量，减少对杀虫剂的依赖，减少病害植物的浪费。

Pulses, in particular peas and broad beans, are important crops both in the UK and worldwide and they are grown as extensive monocultures. Even with long rotations, the crops are vulnerable to major epidemics of economically important pests and diseases, of which downy mildews (caused by the oomycete biotrophic pathogens Peronospora viciae f. sp. pisi (Pvp) and P. viciae f. sp. fabae (Pvf) in peas and beans, respectively) are the most serious. Breeding companies are challenged to produce cultivars with new resistance genes and will benefit from access to crop wild relatives carrying new resistance genes. The disease is managed through deployment of resistant varieties and chemical controls; however a lack of information on prevalent isolates can lead to serious yield losses in crops grown on contaminated sites through uninformed variety selection. Although a differential set of plant cultivars is available to identify the virulence genes in pathotypes of Pvp/Pvf, the test is too time-consuming to be of immediate use to commercial growers and does not allow rapid monitoring of the prevailing isolates. In addition, generating a model for pathogen spread is impossible using current methods. The problem is exacerbated by reports of resistance of oomycete pathogens to pesticides such as metelaxhyl. Without adequate control regimes, pea and broad bean production will incur greater crop wastage and it is therefore imperative that methods are developed to decrease growers' reliance on pesticides for the control of downy mildew. Deployment of pulse cultivars resistant to prevailing isolates is the most promising approach. Use of appropriate molecular tools will enable breeders, epidemiologists, modellers and growers to: a) identify the prevailing virulent isolate; b) investigate the epidemics of disease; c) monitor pathogen movement and d) deploy the appropriate cultivar(s) resistant to the prevailing isolate rapidly and thus control the disease in an environmentally friendly and sustainable manner. Accurate advice to growers about resistant cultivars requires correct information on the virulence of Pvp/Pvf races within the locality. However, diagnosing the pathogen at the isolate level requires the right tools. The innovative approach described in this project focuses on the development of molecular tools for accurate identification of Pvp/Pvf isolates as well as for breeding for resistance. We aim to identify new resistance sources to include in breeding programmes and develop molecular markers to enable rapid identification and monitoring of pathogen isolates. We will use next generation sequencing to identify polymorphisms in several isolates. These polymorphisms will then be utilised to generate isolate-specific markers. Once identified, markers will be tested under laboratory conditions and subsequently will also be checked in commercial fields. In addition, we will use biological control agents to control downy mildew disease. These will lead to increased crop productivity, reduced reliance on pesticides and less wastage from diseased plants.