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，它们被广泛种植。即使长时间轮作，作物也容易受到重要经济病虫害的重大流行，其中霜霉病（分别由豌豆和豆类中的卵菌生物营养病原体Peronospora viciae f. sp. pisi （Pvp）和P. viciae f. sp. fabae （Pvf）引起）最为严重。育种公司面临着生产具有新抗性基因的品种的挑战，并将从获得携带新抗性基因的作物野生近缘中获益。通过部署抗性品种和化学控制来控制该病；然而，缺乏流行分离株的信息可能会导致在受污染地点种植的作物因不知情的品种选择而严重减产。虽然有一组不同的植物品种可用于鉴定Pvp/Pvf病型中的毒力基因，但该测试过于耗时，无法立即用于商业种植者，并且无法对主要分离株进行快速监测。此外，利用目前的方法无法建立病原体传播的模型。有报道称卵菌病原体对甲叶霉等杀虫剂具有耐药性，这使问题更加严重。如果没有适当的控制制度，豌豆和蚕豆的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的依赖来控制霜霉病。部署对流行菌株具有抗性的脉冲品种是最有希望的方法。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)调查疾病流行；C)监测病原体的移动和d)迅速部署对主要分离株具有抗性的适当品种，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，需要在当地获得关于Pvp/Pvf品种毒力的正确信息。然而，在分离物水平上诊断病原体需要正确的工具。本项目所描述的创新方法侧重于开发分子工具，用于准确鉴定Pvp/Pvf分离物以及抗性育种。我们的目标是确定新的耐药来源，将其纳入育种规划，并开发分子标记，以便能够快速识别和监测病原体分离物。我们将使用下一代测序来鉴定几个分离株的多态性。然后利用这些多态性来产生分离特异性标记。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防治霜霉病。这将提高作物产量，减少对农药的依赖，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.