Role of inoculum sources in Rhynchosporium population dynamics and epidemics on barley

大麦轮孢菌叶斑病是由真菌Rhynchosporium secalis引起的，在世界农业生产中的地位日益重要。它是英国冬春大麦上最严重的病害，在全国范围内造成了巨大的损失，尽管每年用于杀菌剂的费用高达5000万英镑。这种疾病很难用杀菌剂控制，因为这种真菌可以在作物中长期存在而不会引起症状。然后，一场严重的疫情可能会毫无征兆地出现。造成这种流行病的感染源还不是很清楚。例如，我们最近发现，受污染的种子可能是该疾病的一个重要主要来源。该项目旨在利用分子技术(定量聚合酶链式反应)阐明流行病的起源和早期动态，该技术可以在症状出现之前检测和量化大麦植株中的病原体DNA。同样的技术还可以检测真菌的遗传特征，如交配类型、毒力和对杀菌剂产生抗药性的基因。每个季节，都会对冬季(10月播种)和春季(3月播种)大麦的疫情进行监测。还将对Rothamsted 150多年来存档的历史春大麦样本进行研究，并对英格兰、苏格兰和爱尔兰至少10个地点的当前作物样本进行研究。我们的目标是研究病原体种群的短期和长期变化。来自该项目的知识将与BBSRC LINK、DEFRA、HGCA和SEERAD(在ADAS以及在苏格兰，SAC和SCRI)资助的相关项目的新信息结合在一起，以制定作物饲养和农艺实践指南，以减少二号黑麦草种群规模和遗传变异，实现大麦轮孢菌病的可持续控制。

Rhynchosporium leaf blotch of barley, caused by the fungus Rhynchosporium secalis, is of increasing importance in world agriculture. It is the most serious disease on winter and spring barley in the UK, causing substantial losses nationally, despite expenditure of £50M per year on fungicides. The disease is difficult to control with fungicides, as the fungus can exist for a long period in the crop without causing symptoms. A severe epidemic may then emerge without warning. The sources of infection responsible for such epidemics are not well understood. We have recently discovered, for instance, that contaminated seed may be an important primary source of the disease. This project aims to clarify the origin and early dynamics of epidemics using molecular techniques (quantitative PCR) that can detect and quantify the DNA of the pathogen in barley plants before symptoms occur. The same techniques can also detect genetic characteristics of the fungus, such as mating type, virulence, and genes responsible for resistance to fungicides. Each season, epidemics will be monitored on both winter (October-sown) and spring (March-sown) barley. Work will also be done on historical spring barley samples archived at Rothamsted over 150 years, and on samples from current crops from at least 10 sites in England, Scotland and Ireland. We aim to study short-term and long-term changes in the pathogen population. Knowledge from this project will be combined with new information from related projects being funded by BBSRC LINK, Defra, HGCA and SEERAD (at ADAS, and in Scotland, SAC and SCRI) to develop guidelines for crop husbandry and agronomic practices to reduce R. secalis population size and genetic variation to achieve sustainable control of rhynchosporium disease of barley.