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

描述（由申请人提供）：本研究将在玻利维亚的Proinpa基金会与Jean Greenberg博士合作进行，作为NIH拨款R01 GM 054292的延伸。人们普遍认识到细菌性病原体会造成巨大的生命损失。人们可能不太了解细菌病原体、植物和人类健康之间关系的重要性。在发展中国家，人类健康始于有充足的营养食物供应，这些食物通常来自植物。安第斯山脉国家（玻利维亚、秘鲁和厄瓜多尔）最重要的农作物之一是土豆。高地地区的大多数小农依靠马铃薯作为他们日常食物和收入的主要来源。在玻利维亚，马铃薯作物受到由番茄枯萎病（Ralstonia solanacearum, Rs）引起的细菌性枯萎病的严重影响，这是一种最具侵略性的病原体，导致马铃薯产量损失高达90%。目前，控制Rs的唯一方法是促进农业实践，最大限度地减少受感染植物的细菌传播。了解抗病马铃薯相互作用的分子基础将为培育抗病马铃薯提供重要工具。Rs的致病性主要在于细菌通过专门的III型装置分泌的称为效应物的毒力蛋白联合体的作用。这些蛋白也可以作为无毒因子（Avr）诱导防御反应，激活同源抗性(R)基因的植物的抗病能力。已有3例来自Rs的Avr蛋白被记录（5;12;33）。植物病原体对Avr蛋白分泌的共同防御反应是由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程序性细胞死亡。我们感兴趣的是识别激活马铃薯防御反应的Rs Avr细胞死亡效应物，并确定可能与这些效应物相互作用的植物防御分子。从长远来看，该项目将扩大植物育种者的选择范围，并为植物基因工程提供工具，以获得更持久的抗性。我们之前从玻利维亚Rs菌株中收集了大量的效应物，这些效应物代表了最具侵略性的Rs亚群（2种型，3种，Biovar 2）。这些效应物中的许多足以引起具有抗性但不可食用的马铃薯品种的细胞死亡，这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物具有防御诱导（Avr）特性。对于真正的Avr效应子子集，我们将确定它们在植物细胞中的亚细胞定位。最后，我们将描述Avr效应物与潜在宿主靶蛋白的相互作用。这项工作将有额外的好处，有助于控制2种型3种生物变种2 Rs菌株，这一群体在美国被视为生物恐怖威胁。与公共卫生有关的问题：由青枯病引起的细菌性枯萎病影响马铃薯，马铃薯是玻利维亚农业最重要的作物之一。为了创造更持久和有效的抗性植物，我们将识别防御反应诱导效应器。

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.