16AGRITECHCAT5: Integrated control of Leptosphaeria pathogens on UK winter oilseed rape

油菜茎溃疡病是英国油菜的一种重要的经济病害，每年造成的产量损失高达100亿英镑。这种疾病是由两种密切相关的病原体引起的：大叶钩端绦虫和maculans。然而，目前对这种疾病的控制只集中在黄斑乳杆菌上，而没有考虑到由大叶乳杆菌引起的流行病。这就是为什么在英国，尽管使用杀菌剂每年要花费2000万英镑，但这种疾病仍然造成大量产量损失的原因之一。最近的研究结果表明，大圆圆乳杆菌与黄斑乳杆菌一样具有破坏性，而且大圆圆乳杆菌对三唑类杀菌剂的敏感性低于黄斑乳杆菌。因此，由于没有开发出控制它的方法，大叶螟对英国油菜生产的威胁越来越大。以往的研究主要集中在利用品种抗性和杀菌剂来提高对黄斑乳杆菌的防治，而对大叶乳杆菌的防治研究很少。本项目旨在了解由大叶乳杆菌引起的茎溃疡病的流行情况，并针对两种病原菌（大叶乳杆菌和黄斑乳杆菌）制定新的防治策略。本项目将利用分子技术研究不同地区空气样本病原菌种群中大叶裂裂菌和黄斑裂裂菌比例的差异，以及不同田间试验和农民田间取样的严重溃疡病油菜茎中大叶裂裂菌和黄斑裂裂菌比例的差异。研究结果将用于指导在相应病原菌（大叶扁豆菌或黄斑扁豆菌）占优势的地区部署具有适当抗性的品种。控制严重的茎溃疡病流行涉及杀菌剂。然而，目前的杀菌剂控制仅针对黄斑乳杆菌，并依赖于三唑类杀菌剂的使用。最近的研究表明，大叶乳杆菌对三唑类杀菌剂的敏感性低于黄斑乳杆菌。本项目将研究三唑类和非三唑类杀菌剂对大叶乳杆菌和黄斑乳杆菌的防治效果。对不同杀菌剂对两种病原菌的防治效果的新认识，结合大叶乳杆菌和黄斑乳杆菌在病原菌种群中所占比例的信息，将有助于有针对性地施用杀菌剂，更好地防治病害。本项目还将研究不同杀菌剂对大叶乳杆菌和黄斑乳杆菌敏感性变化的机制。这些新知识将用于指导现有杀菌剂的使用和新杀菌剂的开发。利用寄主抗性是一种有效、环保的植物病害防治方法。然而，以往关于油菜茎溃疡病抗性的研究主要集中在对maculans的抗性研究上，而没有对biglobosa的抗性研究。本项目将对大叶裂叶菌的抗性品种和预育种材料进行评估，并利用基因组学的最新进展来鉴定候选抗性基因。这将为改良育种和利用品种抗性防治病害提供新的知识。本项目获得的关于两种病原菌、宿主耐药性和不同杀菌剂防治效果的新知识将用于制定综合防治策略，以更好地防治瘤茎溃疡病。该项目将通过开发针对这两种病原体的有效控制方法来减少产量损失，从而使种植者受益。它还将解决粮食安全的挑战。通过有针对性的杀菌剂应用，减少杀菌剂的使用也将使环境受益。

Phoma stem canker is an economically important disease of oilseed rape in the UK, leading to annual yield losses > £100M. This disease is caused by two closely related pathogens: Leptosphaeria biglobosa and L. maculans. However, current control of this disease focuses only on L. maculans and does not account for epidemics caused by L. biglobosa. This is one reason why this disease still causes substantial yield losses in the UK, despite the use of fungicides costing £20 M p.a. Results of recent work showed that L. biglobosa can be as destructive as L. maculans and that L. biglobosa is less sensitive to triazole fungicides than L. maculans. Therefore, L. biglobosa is a growing threat to oilseed rape production in the UK since no methods have been developed to control it. Previous research has mainly focused on improving control of L. maculans by both cultivar resistance and fungicides and little work has been done on control of L. biglobosa. The aims of this project are to understand stem canker epidemics caused by L. biglobosa and to develop new strategies for better control of phoma stem canker by targeting both causal pathogens (L. biglobosa and L. maculans). This project will use molecular techniques to investigate the differences between different regions in proportions of L. biglobosa and L. maculans in pathogen populations from air samples and differences in proportions of L. biglobosa and L. maculans in oilseed rape stems with severe canker symptoms sampled from different field trials and farmer's fields. Results will be used to guide deployment of cultivars with suitable resistance for the region where the corresponding pathogen species (L. biglobosa or L. maculans) is predominant. Control of severe stem canker epidemics involves fungicides. However, current fungicide control targets only L. maculans and has relied on use of triazole fungicides. Recent work showed that L. biglobosa is less sensitive to triazole fungicides than L. maculans. This project will investigate efficacy of triazole and non-triazole fungicides for control of L. biglobosa as well as L. maculans. The new knowledge about efficacy of different fungicides for control of the two pathogens, combined with the information about proportions of L. biglobosa and L. maculans in pathogen populations, will enable better control of the disease by targeted fungicide application. This project will also investigate the mechanisms of changes in sensitivity to different fungicides in L. biglobosa and L. maculans. The new knowledge will be used to guide use of existing fungicides and development of new fungicides.Use of host resistance is an effective and environmentally friendly way to control plant diseases. However, previous work on oilseed rape resistance against phoma stem canker has been focused on resistance against L. maculans with no work done on resistance against L. biglobosa. This project will assess cultivars and pre-breeding material for resistance against L. biglobosa and use recent developments in genomics to identify candidate resistance genes. This will provide new knowledge for improving breeding and using cultivar resistance to control the disease.New knowledge obtained from this project about the two causal pathogens, host resistance and efficacy of different fungicides for controlling them will be used to develop integrated control strategies for better control of phoma stem canker. This project will benefit growers by reducing yield losses through development of effective control methods targeting both pathogens. It will also address the challenge of food security. The environment will also benefit from reduced use of fungicides through targeted fungicide applications.