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A pipeline for rapid cloning of stem rust resistance genes effective against Ug99 from wild diploid wheat relatives

快速克隆对野生二倍体小麦近缘种 Ug99 有效的茎锈病抗性基因的管道

基本信息

批准号：
BB/J003166/1
负责人：
Brande Wulff
金额：
$ 54.28万
依托单位：
University of East Anglia
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FJ003166%2F1
关键词：
pipeline rapid cloning stem rust

项目摘要

Wheat is arguably the most important cereal crop in the world, with more than 600 million tons produced annually, supplying greater than nineteen percent of human dietary calories. The limited genetic diversity of wheat however renders it vulnerable to new diseases. The wheat stem rust fungus, known as the 'polio of agriculture', has caused repeated widespread crop failures throughout recorded history in North America, Europe, Asia and Australia. In the 1950s Norman Borlaug, father of the Green Revolution, successfully bred for resistance to the disease. This resistance held until the end of the '90's, when a new, super-virulent race of wheat stem rust called Ug99 emerged in Africa. Ug99 is capable of causing disease on greater than ninety percent of the world's wheat varieties. First detected in Uganda, it has spread at an alarming rate through sub-Saharan Africa and across the Arabian Peninsula, appearing in Iran in 2008. Because wind-borne rust spores can travel long distances, it is only a matter of time before this scourge reaches Pakistan and India, the source of nineteen percent of the world's wheat and home to 1 billion people. Changing climate will expose Europe to enhanced risk of the disease. New sources of stem rust resistance are urgently needed. Although traditional breeding can introduce new genes into wheat from other related species, this process is laborious, time-consuming, and difficult to control, often causing the simultaneous introduction of deleterious characteristics along with the desired trait ('linkage drag'). Moreover, when new resistance genes are deployed one-at-a-time, the pathogen typically overcomes the resistance gene within one or two growing seasons, rendering it useless. This problem can be alleviated by introducing more than one resistance gene at a time, but that turns out to be impractical if not impossible by conventional breeding methods. The work proposed here aims to identify new resistance genes from a wild relative of wheat, Aegilops sharonensis. This grass, native to the Levant, is closely related to one of wheat's progenitors, and contains a rich trove of new, unexploited resistance genes. Our long-term strategy is to isolate, by molecular cloning, as many new resistance genes as possible from this species, and introduce them in combinations using GM methods. Molecular cloning makes it possible, indeed straightforward, to put several new genes together in the same location in the genome, allowing breeders to work with them as a 'single' gene. This holds tremendous advantages for disease resistance breeding, and is a clear case where GM technology is not only vastly superior to conventional breeding, but indeed required for sustainable food security. Our proposal has the specific goals of i) cloning the first of these genes, based on preliminary genetic mapping information already in hand, and ii) developing a novel method for quickly identifying the position in the genome of any gene of interest. This novel method will use a combination of classical genetics and 'next-generation' ultra-high-throughput sequencing technology, which now makes experiments that would have been prohibitively expensive only a few years ago both feasible and affordable. The platform we are developing will have as a primary output new lines of wheat that harbour three or more new stem rust resistance genes at a single genetic locus. These lines will be made available to public breeding programs that develop new breeding material for developing countries in harm's way from stem rust. Aegilops also harbors genetic diversity for other useful traits, including water and nitrogen use efficiency. Thus, the genomic data and methodology we will develop in this project will benefit wheat improvement generally.

小麦可以说是世界上最重要的谷类作物，每年生产超过6亿吨，提供超过19%的人类膳食卡路里。然而，小麦有限的遗传多样性使其容易受到新疾病的影响。被称为“农业脊髓灰质炎”的小麦秆锈菌在北美、欧洲、亚洲和澳大利亚的历史上多次造成大范围的作物歉收。20世纪50年代，绿色革命之父诺曼·布劳格（Norman Borlaug）成功培育了抗该病的基因。这种抗性一直持续到90年代末，当时非洲出现了一种名为Ug99的新的超级毒性小麦秆锈病。Ug99能够在世界上90%以上的小麦品种上引起疾病。首先在乌干达发现，它以惊人的速度蔓延到撒哈拉以南非洲和整个阿拉伯半岛，2008年出现在伊朗。由于风传播的锈菌孢子可以传播很长的距离，这种祸害到达巴基斯坦和印度只是一个时间问题，这两个国家是世界上19%小麦的来源地，也是10亿人口的家园。气候变化将使欧洲面临更大的疾病风险。迫切需要新的抗秆锈来源。虽然传统育种可以从其他相关物种中引入新的基因到小麦中，但是这个过程是费力的、耗时的并且难以控制，经常导致有害特性沿着期望的性状（“连锁阻力”）的同时引入。此外，当新的抗性基因一次一个地部署时，病原体通常在一两个生长季节内克服抗性基因，使其无用。这个问题可以通过一次引入一个以上的抗性基因来缓解，但这被证明是不切实际的，如果不是不可能通过传统的育种方法。本文提出的工作旨在从小麦的野生近缘种沙融山羊草（Aegilops sharonensis）中鉴定新的抗性基因。这种草原产于黎凡特，与小麦的祖先之一密切相关，并含有丰富的新的未开发的抗性基因。我们的长期战略是通过分子克隆从该物种中分离出尽可能多的新抗性基因，并使用转基因方法将它们组合引入。分子克隆技术使得将几个新基因放在基因组的同一位置上成为可能，而且确实很简单，使育种者能够将它们作为一个“单一”基因进行研究。这为抗病育种带来了巨大的优势，也是转基因技术不仅大大上级传统育种，而且确实是可持续粮食安全所必需的一个明显例子。我们的建议有以下具体目标：i）基于已经掌握的初步遗传图谱信息，克隆这些基因中的第一个，以及ii）开发一种快速识别任何感兴趣基因在基因组中的位置的新方法。这种新方法将使用经典遗传学和“下一代”超高通量测序技术的组合，这使得几年前昂贵得令人望而却步的实验变得可行和负担得起。我们正在开发的平台将主要产出新的小麦品系，这些品系在一个遗传位点上含有三个或更多新的抗秆锈基因。这些品系将提供给公共育种计划，为发展中国家开发新的育种材料，以防止茎锈病的危害。山羊草还具有其他有用性状的遗传多样性，包括水和氮的利用效率。因此，我们将在本项目中开发的基因组数据和方法将有利于小麦的改良。