EAGER: Striga Virulence Effectors: Keys to Halting Parasitic Witchweeds

被子植物寄生性害虫是危害农民农田的顽固性有害生物，严重制约了作物生产。独脚金属的成员“独脚金”尤其具有破坏性，因为它们的主要寄主包括主要谷物（玉米、高粱、大米和小米）和谷物豆类，这些都是全世界的主食。寄生杂草和寄生菌如何识别它们的潜在宿主并克服先天防御系统尚不清楚。本项目利用豇豆（Vigna unguiculata）这一重要的食用和饲料豆科植物与Striga gennerioides的相互作用，试图鉴定寄生虫来源的效应物和毒力蛋白，这些蛋白进入宿主细胞，特异性地改变它们的结构和功能，并在不同水平上抑制防御反应机制，使感染和寄生虫入侵发生。新的植物功能筛选将用于鉴定来自Striga的候选效应物，这些效应物可被豇豆中特定种族的抗性蛋白直接或间接识别，从而在感染点激活超敏反应和相关的下游防御反应。这些功能筛选是由兼容和不兼容宿主-寄生虫关联的比较转录组测序和旨在通过种族特异性基因表达特征识别候选毒力效应物的硅分析来补充的。该项目的研究结果将为被子植物识别和寄生寄主的机制以及寄主如何阻止这种攻击提供新的见解。寄生植物对作物生产力的负面影响每年都在全球范围内增加，随着种子资源在全球范围内流动的扩大，它们对国内农业的潜在影响也越来越大。这项工作的结果将通过提供操纵作物植物抗虫害反应的目标，直接有助于制定改善作物安全的战略。此外，这些研究为在非洲大陆的美国学生提供了新的教育、研究和培训机会。

Parasitic angiosperms are noxious and persistent pests in farmers' fields and serious constraints to crop productivity. The "witchweeds", members of the genus Striga, are particularly devastating since their primary hosts include the major cereals (maize, sorghum, rice and millet) and grain legumes that are dietary staples worldwide. How parasitic weeds and Striga species in particular recognize their potential hosts and overcome the innate defense systems are not known. Using the interaction of cowpea (Vigna unguiculata), an important food and forage legume, with Striga gesnerioides, this project seeks to identify parasite-derived effectors and virulence proteins that enter host cells, specifically altering their structure and function and suppressing the defense response mechanism at various levels, enabling infection and parasite ingress to occur. Novel, in planta functional screens will be used to identify candidate effectors from Striga that are directly or indirectly recognized by race-specific resistance proteins in cowpea leading to activation of a hypersensitive response at the point of infection and associated downstream defense responses. These functional screens are complemented by comparative transcriptome sequencing in compatible and incompatible host-parasite association and in silico analysis aimed at identifying candidate virulence effectors through race-specific gene expression signatures. The outcomes of this project will provide novel insights into the mechanisms by which parasitic angiosperms identify and parasitize their hosts and how hosts block such attack. The negative impact of parasitic plants on crop productivity increases globally each year and their potential for affecting domestic agriculture looms larger as the movement of seed resources expands globally. The outcomes of this work will contribute directly to the development of strategies to improve crop security by providing targets for manipulating pest resistance responses of crop plants. In addition these studies provide new educational, research, and training opportunities for US students on the African continent.