Role of Oxalic Acid and Reactive Oxygen in Sclerotinia Sclerotiorum Disease Development

油菜核盘菌是一种寄主范围极广的杂食性植物病原菌，对大豆、干豆、油菜和马铃薯等经济作物造成了毁灭性的损失。有400多种植物对这种病原菌敏感。目前，还没有针对菌核病的足够的抗性策略(无论是在栽培上还是在化学上)，对这种真菌的抗性育种也没有成功。美国每年因菌核病造成的农作物损失高达数百万美元。菌核病侵袭性强，寄主范围广，防治不力，造成重大经济损失，再加上缺乏抗病品种，因此有必要开发新的防治策略。在这个项目中，将使用基于分子的机制方法来了解真菌为什么如此成功；特别是该项目将研究活性氧物种和草酸作为真菌疾病的关键调节因子所起的作用。该项目得到了最近的观察的支持，这些观察表明，真菌分泌的草酸可以诱导植物寄主中的细胞程序性死亡，并概括菌核病的症状。同样，草酸诱导植物体内的活性氧水平增加，这与程序性细胞死亡和疾病相关，并且是必要的。这些研究的结果将为基于对这些关键真菌致病决定因素的干扰的替代疾病控制策略提供信息。广泛影响本项目中描述的实验为学生提供涵盖多个领域的广泛和全面的培训。目前的研究方法包括微生物学、植物病理学、植物生物学、高通量基因沉默筛选、分子生物学和遗传学。真菌引起植物病害的机制既是基本的，也是具有实际意义的。这一点特别值得注意，因为食品安全、食品污染和食品安全是国家和国际上至关重要的问题。菌核病加剧了这种情况，因为控制措施(遗传和化学)在很大程度上是无效的。这项研究计划将为研究生、博士后研究员和本科生提供一个独特的跨学科培训机会，以参与压力信号和细胞死亡调控的关键领域，同时从概念上解决关于这组特定的重要植物病原体如何实现致病成功的更广泛的概念。该项目还支持来自拉美裔服务机构和德克萨斯州一所土地赠与大学的学生的暑期研究活动。

Intellectual Merit Sclerotinia sclerotiorum is an omnivorous fungal plant pathogen with an extremely broad host range capable of producing devastating losses in economically important food crops, including soybeans, dry beans, canola and potato among many others. Over 400 species of plants are susceptible to this pathogen. Currently, there are no adequate resistance strategies against Sclerotinia diseases (culturally or chemically) and breeding for resistance to this fungus has not been successful. Annual losses of crops from diseases caused by S. sclerotiorum in the U.S. are in the multimillion dollar range. The fact that Sclerotinia is aggressive, broad in its host range, poorly controlled and causes significant economical damage, coupled with the lack of resistant cultivars necessitates the development of alternative control strategies. A molecular based mechanistic approach will be used in this project to understand why the fungus is so successful; in particular the project will examine the roles that reactive oxygen species and oxalic acid play as key modulators of fungal disease. The project is supported by recent observations that demonstrated that fungal secreted oxalate induces a programmed cell death in the plant host and recapitulates S. sclerotiorum disease symptoms. Similarly oxalic acid induces increased reactive oxygen species levels in the plant which correlate with, and are necessary for, programmed cell death and disease. Results from these studies will provide information for alternative disease control strategies based on interference with these key fungal pathogenicity determinants.Broader Impact The experiments described in this project offer broad and comprehensive training for students encompassing a number of fields. Current approaches include microbiology, plant pathology, plant biology, high throughput gene silencing screens, molecular biology and genetics. The mechanisms underlying fungal induced plant disease are both fundamental and of practical importance. This is particularly noteworthy since food safety, food contamination and food security are critically important issues nationally and internationally. This is compounded by Sclerotinia diseases since control measures (genetic and chemical) are largely ineffective. This research program will provide a unique and interdisciplinary training opportunity for a graduate student, postdoctoral fellows, and undergraduate students to participate in a critical area of stress signalling and cell death regulation, while conceptually addressing broader conceptual ideas as to how this particular group of important plant pathogens achieves pathogenic success. The project also supports summer research activities for students from Hispanic Serving Institutions and a Land Grant University in Texas.