BREAD: An Alternate Dwarfing Gene System to Improve Abiotic Stress Tolerance in Cereals

首席研究员：Kulvinder S. Gill（华盛顿州立大学）首席研究员：Johar Singh（旁遮普农业大学，卢迪亚纳，印度）和Devinder Sandhu（威斯康星大学-史蒂文斯点）Kanwarpal S. Dhugga（先锋杂交国际公司）、Gurmukh S. Johal（普渡大学）、Mustafa Shafqat（巴基斯坦阿伯塔巴德COMSATS大学）、Harindra S. Balyan和Pushpendra K. Gupta（印度密鲁特大学）和Madhu Meeta Jindal（印度卢迪亚纳旁遮普农业大学）影响植物高度的基因使小麦和水稻产量翻了一番，从而彻底改变了农业。在环境胁迫条件下，应用最多的小麦半矮秆突变体rht1和rht2对胚芽和第一叶长、根长、生物量以及耐旱性等农艺性状均产生不利影响。这些不利影响限制了非生物胁迫条件下的小麦产量，而非生物胁迫通常影响美国85%以上的地区和约50%的世界小麦产区。该项目的主要目标是确定小麦和其他谷物的另一种矮化基因系统的特征，以减轻目前使用的矮化基因的不利影响。目前在小麦中使用的矮化基因系统通过中断植物生长激素赤霉素的产生或信号传导来降低植株高度，赤霉素对植物应对胁迫条件特别重要。先前的研究表明，编码参与生长素极性运输的p -糖蛋白（PGPs）的玉米brachytic2 （br2）和高粱dwarf3 （dw3）基因发生突变，会导致植株高度降低，而不会出现目前使用的小麦矮化突变体通常出现的任何不良表型效应。在此基础上，本项目将进一步研究玉米Br2基因的小麦同源基因TaBr2能否作为小麦矮化基因的替代体系。具体目标是克隆TaBr2，并利用病毒诱导的基因沉默和RNAi等多种反向遗传学工具研究其在小麦中的表达和功能。此外，TaBr2突变将通过表型和TILLING筛选进行分离，以确定理想的矮化突变体。该项目的好处，特别是对拥有小块土地的农民来说，将来自增值基因的渗入，包括抗条锈病基因以及新开发的矮化基因突变体，这些基因被引入印度、巴基斯坦和美国的流行品种。此外，该项目将为作物植物生长素信号传导和运输过程提供新的见解。该项目将为本科生和研究生以及研究助理/访问科学家提供高度跨学科和国际研究培训的机会。pi积极参与外联活动，包括农民田间日，与种植者团体交谈，组织实验室演示和向种植者团体和广大公众展示。项目信息和调查结果将通过这些工作和电子手段与公众沟通。将开发一个项目网站，作为获取该项目的所有资源的“一站式”地点。每个研究者的网页也会提供到这个项目网页的链接。表达和序列数据将立即提交给GenBank (http://www.ncbi.nlm.nih.gov/)，根据目前接受的社区标准(例如Bermuda/Ft.；劳德黛尔协议)。各种小麦品系上选定基因的实时表达数据将首先通过出版物免费提供，然后在项目网页和Gramene （http://www.gramene.org/）上提供。地图数据将在GrainGenes数据库（http://wheat.pw.usda.gov/GG2/index.shtml）上提供。本项目产生的所有VIGS和RNAi构建物及种质将保存在pi的实验室中，并向公众开放。在印度和巴基斯坦开发的基因渐渗系将通过各自国家的品种测试计划，作为公共品种发布。在美国开发的渐渗系将作为公共品种发布，可能通过USDA-ARS国家遗传资源保护中心和植物品种保护办公室。

PI: Kulvinder S. Gill (Washington State University)CoPIs: Johar Singh (Punjab Agricultural University, Ludhiana, India) and Devinder Sandhu (University of Wisconsin-Stevens Point)Key Collaborators: Kanwarpal S. Dhugga (Pioneer Hi-Bred International, Inc.), Gurmukh S. Johal (Purdue University), Mustafa Shafqat (COMSATS University, Abbottabad, Pakistan), Harindra S. Balyan and Pushpendra K. Gupta (Meerut University, India), and Madhu Meeta Jindal (Punjab Agricultural University, Ludhiana, India)Genes influencing plant height have revolutionized agriculture by doubling the wheat and rice production. Under conditions of environmental stress, the most predominantly used wheat semi-dwarf mutants rht1 and rht2 exhibit adverse effects on agronomic traits including coleoptile and first leaf length, root length and biomass, as well as drought tolerance. These adverse effects limit wheat yields under abiotic stress conditions that regularly affect more than 85% of the US and about 50% of the world wheat production area. The main goal of the project is to identify and characterize an alternative dwarfing gene system for wheat and other cereals in order to alleviate adverse effects of the currently used dwarfing genes. Currently used dwarfing gene systems in wheat reduce plant height by interrupting production or signaling of plant growth hormone gibberellins that are particularly important for plants to deal with stressful conditions. Previous studies have shown that mutations in the maize brachytic2 (br2) and the sorghum dwarf3 (dw3) genes that encode P-glycoproteins (PGPs) involved in polar transport of auxin, result in a reduction in plant height without any of the adverse phenotypic effects usually associated with the currently used wheat dwarfing mutants. Based on these observations, this project will test whether the wheat ortholog (TaBr2) of the maize Br2 gene can be used as an alternative dwarfing gene system in wheat. Specific objectives are to clone TaBr2 and to study its expression and function in wheat using various reverse genetics tools including virus-induced gene silencing and RNAi. In addition, mutations in TaBr2 will be isolated using phenotypic as well as by TILLING screens in order to identify the ideal dwarfing mutant. The benefit of the project, especially to farmers with small land holdings, will come from the introgression of value-added genes, including stripe rust resistance genes as well as newly-developed dwarfing gene mutants, into popular varieties of India, Pakistan, and the US. In addition, the project will provide new insight into the process of auxin signaling and transport in crop plants. The project will provide highly interdisciplinary and international research training opportunities for undergraduate and graduate students, as well as for research associates/visiting scientists. The PIs are actively involved in outreach activities including farmers' Field Days, talking to grower groups and organizing lab demonstrations and displays to grower groups and the public at large. The project information and findings will be communicated with the public via these efforts as well as through electronic means. A project website will be developed that will serve as a "one-stop" location for access to all resources generated in this project. Links will be provided to this project webpage from each of the investigator's web pages as well. Expression and sequence data will be immediately submitted to GenBank (http://www.ncbi.nlm.nih.gov/), according to the currently accepted community standard (e.g. Bermuda/Ft. Lauderdale agreement). Real-time expression data of selected genes on various wheat lines will be made freely available first via publications and then by hosting on the project webpage and on Gramene (http://www.gramene.org/). Mapping data will be available at GrainGenes database (http://wheat.pw.usda.gov/GG2/index.shtml). All VIGS and RNAi constructs and germplasm generated in this project will be maintained in the PIs' lab and will be available to the public. Gene introgression lines developed in India and Pakistan will be released as public varieties after going through variety testing programs of the respective countries. Introgression lines developed in the US will be released as public varieties, possibly through the USDA-ARS National Center for Genetic Resources Preservation and the Plant Variety Protection Office.