BREAD: Inactivating Rust Resistance Suppressors to Unlock Multiple Defense Responses in Wheat

PI：李黄(蒙大拿州立大学)Copi：Evans Lagudah(CSIRO植物产业--澳大利亚黑山)合作者：Linda Tabe(CSIRO植物产业--澳大利亚黑山)，彭俊华(中国科学院，武汉植物园/研究所，中国)和Davinder Singh(CIMMYT，肯尼亚内罗毕乡村市场)小麦是世界上大部分人口的主要谷物。据估计，世界上大约50%的小麦种植在发展中国家，在那里，小麦是很大一部分自给自足农民的主食。锈病是引起小麦一些最具破坏性的疾病的真菌病原体。叶锈病(Puccinia Triticina)、茎锈病(P.graminis f.sp.)Tritici)和条锈病(P.striiformis f.sp.)小麦(Tritici)是分布最广的小麦病害。这些疾病降低了植物的适合度，导致粮食产量损失5%-95%，这取决于锈病的种类和它感染作物的发育阶段。从历史上看，培育持久的抗锈病在很大程度上取决于不断将新的抗病基因导入适应的品种中，这些品种通常来自野生亲缘关系。这种漫长的遗传过程在消除连锁阻力带来的不利性状方面并不总是完全成功的。此外，有遗传证据表明，在六倍体小麦遗传背景中，导入的抗性基因的功能往往受到抑制。然而，人们对这些“抑制者”的性质或他们的行动机制知之甚少。该项目将研究小麦中的两种抗锈性抑制因子，初步研究表明，这两种抑制因子在灭活后，会暴露出对新出现的毒性茎锈菌株UG99的强大抗性，该菌株目前威胁着非洲和中东的粮食安全。该项目将部署一个多国团队来1)表征这两个抑制因子及其作用机制(S)；2)将这种新的抗性转移到肯尼亚和中国的小麦育种计划中；3)在这一广阔的地区筛选对其他新出现的锈病威胁的抗性项目种质。这项工作有可能解开六倍体小麦基因组中一系列目前未被识别或未被充分利用的隐蔽的抗锈病基因。抗锈性抑制因子尚未在任何实验系统中得到表征，因此该项目的结果将提供有关一类以前未研究过的植物防御反应负调控因子的性质和作用方式的基本新信息。这项研究将通过提供新的、有用的抗锈源和相关的分子标记，对发展中国家的农业产生直接的好处。在培训和外展方面，该项目将提供一个交流项目，向来自肯尼亚和中国的年轻研究人员介绍尖端技术，并为来自美国和澳大利亚的年轻研究人员创造机会，学习肯尼亚和中国的当地知识。该交流项目将培训四名年轻科学家，他们将在肯尼亚和中国的两个实验室工作，提供品种并教育他们国家的小农。此外，该项目将生成三个在线视频协议，以接触到更广泛的受众，包括发达国家和发展中国家的学生、生物教师和小麦育种者。该项目产生的所有数据和生物资源将向公众开放。基因表达数据将提交给基因表达总览(GEO；http://www.ncbi.nlm.nih.gov/geo/).作图和标记数据将提交给GrainGenes(http://wheat.pw.usda.gov/GG2/index.shtml))，种质和育种系信息将通过美国农业部-国家粮食和农业研究所支持的小麦持久抗锈病项目(http://maswheat.ucdavis.edu/).)的网站获得该项目使用和/或开发的小麦品系将通过美国农业部-ARS国家小谷物收藏中心(NSGC)获得。

PI: Li Huang (Montana State University)CoPI: Evans Lagudah (CSIRO Plant Industry-Black Mountain, Australia)Collaborators: Linda Tabe (CSIRO Plant Industry-Black Mountain, Australia), Junhua Peng (Chinese Academy of Sciences, Wuhan Botanical Garden/Institute, Wuhan, China) and Davinder Singh (CIMMYT, Village Market, Nairobi, Kenya)Wheat is a staple cereal for most of the world's population. It is estimated that approximately 50% of the world's wheat is grown in developing countries, where it serves as a staple food for a large proportion of subsistence farmers. Rusts are fungal pathogens that cause some of the most damaging diseases of wheat. Leaf rust (caused by Puccinia triticina), stem rust (caused by P. graminis f. sp. tritici) and stripe rust (caused by P. striiformis f. sp. tritici) are the most widely distributed diseases of wheat. These diseases reduce plant fitness and result in grain yield losses from 5-95%, depending on the rust species and the development stage at which it infects the crop. Historically, breeding durable resistance to rust diseases relies largely on continually introgressing new resistance genes into adapted varieties, often from wild relatives. This long genetic process is not always completely successful in eliminating unfavorable characteristics brought in by linkage drag. Furthermore, there is genetic evidence that the functions of introgressed resistance genes are often suppressed in the hexaploid wheat genetic background. However, little is known about the nature of these "suppressors" or the mechanism by which they act. This project will investigate two suppressors of rust resistance in wheat that preliminary studies have shown, when inactivated, unmask robust resistance to the newly emerged virulent stem rust strain, Ug99, which currently threatens food security in Africa and the Middle East. The project will deploy a multi-national team to 1) characterize these two suppressors and their mechanism of action(s); 2) transfer this new resistance to wheat breeding programs in both Kenya and China; and, 3) screen project germplasm for resistance against other emerging rust disease threats across this broad region.The work has the potential to unlock an extensive array of cryptic rust resistance genes in the hexaploid wheat genome that are either currently unrecognized or have been poorly utilized. Suppressors of rust resistance have not been characterized in any experimental system, so project results will provide fundamental new information about the nature and mode of action of a previously-unstudied class of negative regulators of plant defense responses. This research will have direct benefits for agriculture in the developing world by providing new, useful sources of rust resistance, with associated molecular markers. With respect to training and outreach, the project will provide an exchange program to introduce young researchers from Kenya and China to cutting-edge technologies, and to create opportunities for young researchers from the USA and Australia to learn from local knowledge in Kenya and China. The exchange program will train four young scientists who will work in the two labs in Kenya and China to deliver cultivars and to educate smallholder farmers of their nations. In addition, the project will generate three video protocols available on-line to reach a broader audience, including students, biology teachers, and wheat breeders in both developed and developing countries. All data and biological resources generated by the project will be available to the public. Gene expression data will be submitted to the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/). Mapping and marker data will be submitted to GrainGenes (http://wheat.pw.usda.gov/GG2/index.shtml) and germplasm and breeding line information will be available through the website for the USDA-National Institute of Food and Agriculture supported Durable Rust Resistance in Wheat (DRRW) project (http://maswheat.ucdavis.edu/). Wheat lines used and/or developed by this project will be available through the USDA-ARS National Small Grain Collection (NSGC).