Exploiting new sources of broad-spectrum resistance to Turnip mosaic virus in brassicas (ExBSR)

芜菁花叶病毒（Turnip mosaic virus, TuMV）是世界上危害多种作物的重要病原菌，是世界上危害大田蔬菜的第二大病毒。它对芸苔类植物（卷心菜、花椰菜、油菜等）的危害最大，并由bb8089种不同蚜虫传播。它的寄主范围非常广泛，而且杀虫剂无法控制它，这强调了开发具有自然抗性的植物的必要性。存在许多不同的TuMV菌株，并且已经描述了对有限范围菌株的抗性。我们已经鉴定出对多种TuMV菌株具有天然抗性的rapa油菜（世界上最重要的蔬菜油菜）品系。我们无法找到任何能够克服这些耐药性的TuMV菌株，这表明它们可能是持久的。在确定了一种抗性来源的基因及其机制后，我们开发了一种简单的测试来鉴定具有不同广谱抗性来源的品系。通过部署对TuMV的额外/新的抗性来源，这将减少对破抗性病毒株的选择压力。该项目旨在充分利用这些新的广谱抗TuMV来源。有必要在商品植物品种中培育这种抗性。这将在华威大学（UoW）、学生和种子公司Sakata UK Ltd.之间的合作中实现。为了显著加快这一过程，学生将开发负责TuMV抗性的植物基因的分子标记。该学生和Sakata将使用这些标记进行标记辅助选择，将抗性基因植入具有商业生产所需的所有其他植物性状的植物品种中。该学生将在UoW接受一系列与植物病理学和分子生物学相关的科学技能的培训，这些技能具有通用的适用性，并在Sakata进行为期3个月的植物育种实习。缺少接受植物病理学和园艺学培训的学生；该学生将有助于解决这些技能差距。学生将学习处理和传播植物病毒，同时测试新的TuMV抗性来源，以对抗来自Sakata和大型Warwick TuMV多样性收集的广泛TuMV分离物。对最广泛的TuMV分离株表现出最极端抗性的rapa菌株将得到进一步研究。然后，学生将把最好的抗病毒植物品系与快速循环植物品系和商业植物品系杂交。后代将通过仔细的目视观察和酶联免疫吸附试验对TuMV进行抗性/敏感性测试。如果来自快速循环杂交的后代是抗性的，他们将回交给敏感的快速循环亲本，如果他们是敏感的，他们将回交给抗性亲本。这样做是为了开发一个大的植物种群来绘制地图。与商业植物品系杂交的后代将与商业亲本回交，以开始将抗性渗入到商业上可接受的植物品系中。大型植物种群将面临TuMV的挑战。基因分型与表型分型相结合将允许抗性基因被定位到植物染色体的区域。这将促进分子标记的发展，使学生和随后的Sakata能够在抗性植物和商业上可接受的植物杂交的后代之间的杂交中跟踪抗性基因。这将大大加快抗tumv品种的培育。利用分子标记识别携带抗性基因的植物进行杂交需要几个小时，而传统方法需要几个月。

Turnip mosaic virus (TuMV) is an important pathogen that infects many crops worldwide (rated 2nd most important virus infecting field vegetables worldwide). It is most damaging in brassicas (cabbage, cauliflower, oilseed rape etc.) and spread by >89 different aphid species. It's very broad host range and the inability of pesticides to control it, emphasise the need for the development of plants with natural resistance to the virus.Many different strains of TuMV exist and resistances to restricted ranges of strains have been described. We have identified Brassica rapa (the most important vegetable brassica worldwide) lines with natural resistance to a broad range of TuMV strains. We have been unable to find any TuMV strains able to overcome these resistances, indicating they may be durable. Having identified the genes responsible for one of the sources of resistance and their mechanism, we developed a simple test to identify lines possessing different sources of broad-spectrum resistance. By deploying additional/new sources of resistance to TuMV, this will reduce the selection pressure for resistance-breaking strains of the virus. This project aims to exploit the best of these new sources of broad-spectrum resistance to TuMV. It will be necessary to breed the resistance into commercial plant varieties. This will be achieved in a collaborative venture between the University of Warwick (UoW), the student and the seed company, Sakata UK Ltd. To significantly speed up this process, the student will develop molecular markers for the plant genes responsible for TuMV resistance. The student and Sakata will use these markers in a process known as marker-assisted selection to get the resistance genes into plant varieties that have all the other plant traits needed for commercial production.The student will be trained at UoW in a range of scientific skills related to plant pathology and molecular biology with generic applicability and in plant breeding during a 3 month placement at Sakata. There is a lack of students being trained in plant pathology and horticulture; this student will help to address these skills gaps. The student will learn to handle and transmit plant viruses whilst testing the new sources of TuMV resistance against a broad range of TuMV isolates from Sakata and from the large Warwick TuMV diversity collection. The B. rapa line showing the most extreme resistance to the broadest range of TuMV isolates will be taken forward.The student will then cross the best virus-resistant plant line to a rapid-cycling plant line and commercial plant lines. The offspring will be tested for resistance / susceptibility to TuMV with careful visual observation and ELISA testing of plants for TuMV infection. If the offspring from the rapid-cycling cross are resistant, they will be backcrossed to the susceptible rapid-cycling parent and if they are susceptible, they will be backcrossed to the resistant parent. This will be done to develop a large plant population for mapping. The offspring of the cross with the commercial plant lines will be back-crossed with the commercial parents to commence introgression of the resistance in to commercially acceptable plant lines.The large plant population will be challenged with TuMV. Genotyping combined with the phenotyping will allow the resistance gene(s) to be mapped to regions of the chromosomes of the plant. This will acilitate the development of molecular markers that will make it possible for the student and subsequently Sakata, to track the resistance genes in later crosses between the offspring of crosses with the resistant plants and commercially acceptable plants. This will dramatically speed up the breeding of TuMV-resistant varieties. Using molecular markers to identify plants carrying the resistance genes for crossing will take hours, conventional means take months.