Exploiting pathogen-induced cell death to create disease resistant plants:R01GM05

描述(由申请人提供)：这项研究将在玻利维亚的普罗因帕基金会与让·格林伯格博士合作完成，作为国家卫生研究院赠款R01 GM 054292的延伸。人们普遍认识到，细菌病原体可以造成巨大的生命损失。也许，细菌病原体、植物和人类健康之间的关系的重要性不太被认识到。在发展中国家，人类的健康始于有足够的营养食物供应，这些食物通常来自植物。安第斯国家(玻利维亚、秘鲁和厄瓜多尔)最重要的农作物之一是土豆。高原地区的大多数小农户以土豆为主要的日常食物和收入来源。在玻利维亚，马铃薯作物受到青枯病引起的青枯病的严重影响，青枯病是最具攻击性的病原体之一，导致马铃薯产量损失高达90%。目前，控制赤霉病的唯一方法是推广农业实践，最大限度地减少受感染植物上细菌的传播。了解Rs与马铃薯相互作用的分子基础将为培育抗病马铃薯提供至关重要的工具。Rs的致病性主要在于一组称为效应器的毒力蛋白的作用，这些蛋白是细菌通过一种特殊的III型装置分泌的。这些蛋白质还可以作为无毒(AVR)因子来诱导防御反应，从而激活携带同源抗性(R)基因的植物的抗病能力。已经记录了3例来自Rs的AVR蛋白(5例；12例；33例)。植物对病原菌分泌的AVR蛋白的一种常见的防御反应是由R基因的特异性作用介导的，并导致抗菌环境的产生和局部的细胞程序性死亡。我们感兴趣的是识别激活马铃薯防御反应的Rs、avr细胞死亡效应，并定义可能与这些效应相互作用的植物防御分子。从长远来看，该项目将为植物育种者提供更多的选择，并提供工具来改造植物，以获得更持久的抗性。我们之前收集了一大批玻利维亚Rs菌株的效应器，代表了最具攻击性的Rs亚群(叶型2，小种3，生物群2)。这些效应器中的许多足以诱导抗性但不能食用的马铃薯品种的细胞死亡，这些品种可以用来寻找可以转移到其他可食用品种的抗性性状。在这里，我们建议确定哪些细胞死亡效应具有防御诱导(AVR)特性。对于真正的AVR效应器的子集，我们将确定它们在植物细胞中的亚细胞定位。最后，我们将表征AVR效应器与潜在宿主靶蛋白的相互作用。这项工作还有一个额外的好处，那就是有助于控制2号生理小种3个生物量2Rs菌株，这是一个在美国被视为生物恐怖威胁的群体。公共卫生相关性：由青枯拉氏菌引起的青枯病影响马铃薯，马铃薯是玻利维亚最重要的农业作物之一。为了创造更耐用和更高效的抗性植物，我们将识别诱导防御反应的效应器。

DESCRIPTION (provided by applicant): This research will be done primary in Bolivia at the Proinpa Foundation in collaboration with Dr. Jean Greenberg, as an extension of NIH Grant R01 GM 054292. It is widely appreciated that bacterial pathogens can cause tremendous loss of human lives. Less appreciated, perhaps, is the importance of the relationship between bacterial pathogens, plants and human health. In the developing world, the human health begins from having an adequate supply of nutritious food, usually derived from plants. One of the most important crops in Andean countries (Bolivia, Peru and Ecuador) is the potato. Most of the small farmers of the highland areas depend on potato as their main daily source of food and income. In Bolivia, the potato crop is severely affected by bacterial wilt caused by Ralstonia solanacearum (Rs), one of the most aggressive pathogens that causes up to 90% losses in potato production. Currently, the only approach to control Rs is to promote agricultural practices that minimize the dispersal of bacteria from infected plants. Understanding the molecular basis of Rs-potato interaction will provide crucial tools for creating disease resistant potatoes. The pathogenicity of Rs lies mainly in the action of consortium of virulence proteins called effectors that the bacteria secrete via a specialized type III apparatus. These proteins can also act as avirulence (Avr) factors to induce defense responses that activate disease resistance in plants harboring the cognate resistance (R) genes. Three cases of Avr proteins from Rs have been documented (5; 12; 33). A common defense response to Avr proteins secreted by pathogens in plants is mediated by the specific action of R genes and leads to the production of an antimicrobial environment and localized programmed cell death. We are interested in identifying the Rs Avr cell death effectors that activate defense responses in potato and defining the possible plant defense molecules that interact with these effectors. In the long term, this project will expand the options available to plant breeders and give tools to engineer plants genetically to achieve more durable resistance. We previously made a large collection of effectors from a Bolivian Rs strain representative of the most aggressive Rs subgroups (Phylotype 2, Race 3, Biovar 2). A number of these effectors are sufficient to elicit cell death in a resistant, but inedible potato variety that could be used to find resistance traits that could be transferred to other edible varieties. Here, we propose to determine which cell death effectors have defense-inducing (Avr) properties. For the subset of bona fide Avr effectors, we will determine their subcellular localization in plants cells. Finally we will characterize the interactions of the Avr effectors with potential host target proteins. This work will have the added benefit of contributing to the control of phylotype 2 race 3 biovar 2 Rs strains, a group considered a bioterror threat in the USA. Public Health Relevance: Bacterial wilt caused by Ralstonia solanacearum affects potato, one of the most important crop of Bolivian agriculture. To create more durable and efficient resistant plants we will identify defense-response inducing effectors.