Bilateral BBSRC-Embrapa: Uncovering the genetic and functional basis of the unique leaf rust resistance in the Brazilian wheat variety Toropi

全球对小麦的需求正在增加，但严重影响小麦产量的病原菌的分布和侵袭性也在增加。粮食农业组织(FAO)估计，到2050年，小麦产量必须增加60%，才能满足不断增长的人口的需求。引起小麦锈病的真菌病原菌是实现这一增产的主要制约因素，近年来，由于锈菌小种特异性抗性(R-)基因的崩溃，我们看到了许多流行病。小麦锈病病原菌有条锈菌(黄锈菌)、叶锈菌(褐斑病)三种。Triticina)和茎(Black-P.禾本科)锈病。在英国，条锈病最为普遍，每年都会发生。叶锈病仅限于较温暖的地区，在英格兰西南部尤为突出。然而，近年来，英国谷物病原菌毒力调查在遥远的北部与苏格兰边境的小麦上发现了叶锈病。这被认为是由于温暖的冬季增加了病原体越冬的能力，以及温暖的春季使叶锈病在英国以前不被认为是问题的地区滋生。在巴西，叶锈病是主要问题。许多小麦品种的叶锈病抗性来源已被证明是小种特有的，在小麦新品种上部署仅几年就能克服这种抗性，并在小麦疫霉种群中迅速产生毒力。然而，已有少量抗叶锈病的慢锈成株抗病基因的报道。其中包括Lr34、Lr46、Lr67和Lr68。这些叶锈菌APR基因已被证明在长时间、大面积和高疾病压力下有效。其中一些持久的叶锈菌APR基因现在已经被克隆，正如所怀疑的那样，证实了它们在小种特有的叶锈菌R基因中的功能不同。老巴西人的简历。Toropi含有独特的、持久的叶锈菌APR来源。初步研究已经确定了Toropi中的两个基因，这两个基因占到了71%的抗性。然而，这两个基因的定义很差，我们对它们的作用方式也知之甚少，例如，在什么植物生长阶段，叶锈菌APR是有效的，以及温度等环境因素是否会影响这些抗性基因的作用。在本研究中，我们将利用最先进的DNA标记系统和小麦基因组资源，通过构建高密度的Toropi遗传图谱来提高每个基因的遗传分辨率。我们将开发小麦遗传物质，使我们能够解开每个基因的作用模式，并开发标记工具，使每个叶锈病APR基因能够在培育新的改良小麦品种的过程中被识别和跟踪。我们的目标是利用我们开发的标记工具，将这些托罗皮抗性基因整合到巴西的优质小麦品种中，从而为巴西小麦育种者提供可以直接进入小麦育种计划的材料。为了帮助了解这些叶锈菌APR基因的作用模式和生物学基础，我们将在微观水平上研究小麦叶锈病病原菌的发育，在小麦生长的不同阶段和不同温度下侵染小麦植株。该项目还专注于培训年轻的巴西研究人员，并扩大巴西团队的国际合作研究网络。

The global demand for wheat is increasing, but so is the distribution and aggressiveness of the pathogens that seriously impact on wheat productivity. The Food Agricultural Organisation (FAO) estimates that wheat production must increase by 60% by 2050 to meet the demand from the growing human population. The fungal pathogens responsible for rust of wheat are a major constraint to achieving this increase in production and in recent years we have seen numerous epidemics due to the breakdown of rust race-specific resistance (R-) genes. There are three rust pathogens of wheat, stripe (yellow-Puccinia striiformis), leaf (brown-P. triticina) and stem (black-P. graminis) rust. In the UK stripe rust is the most prevalent, occurring every year. Leaf rust has been confined to warmer regions, being prominent in the south-west of England. However, in recent years the UK Cereal Pathogen Virulence Survey has detected leaf rust on wheat as far north as the border with Scotland. This is considered to be as a result of milder winters increasing the ability of the pathogen to overwinter, and warmer springs allowing leaf rust to take hold in regions of the UK where previously it has not been considered a problem.In Brazil leaf rust is the major problem. Many sources of leaf rust resistance used in wheat varieties have proven to be race-specific, with virulence rapidly arising in the P. triticina population, overcoming the resistance after only a few years of deployment in new wheat varieties. However, a small number of slow-rusting, adult plant resistance (APR) genes effective against leaf rust have been reported. These include Lr34, Lr46, Lr67 and Lr68. These leaf rust APR genes have proven effective over long periods of time, large acreages and under high disease pressure. Some of these durable, leaf rust APR genes have now been cloned, confirming, as suspected, that they do not function in the same way at race-specific, leaf rust R-genes. The old Brazilian cv. Toropi contains a unique, durable source of leaf rust APR. Preliminary studies have identified two genes in Toropi which account for 71% of the resistance. However these two genes are poorly defined and we know very little about their mode of action, e.g. at what plant growth stages the leaf rust APR becomes effective and whether environmental factors such as temperature can effect the action of these resistance genesIn this study we will improve the genetic resolution of each gene by generating a high-density genetic map of Toropi using state-of-the-art DNA marker systems, and wheat genomic resources. We will develop wheat genetic materials that will enable us to unravel the mode of action of each gene, and marker tools that will enable each leaf rust APR gene to be identified and followed during the process of breeding new improved wheat varieties. We also aim to incorporate these Toropi resistance genes into elite Brazilian wheat varieties, using the marker tools we develop, thereby providing the Brazilian wheat breeder with materials they can enter directly into their wheat breeding programs.To help understand the mode of action and biology underlying these leaf rust APR genes we will study the development of the leaf rust fungal pathogen in wheat at the microscopic level, infecting wheat plants at different stages of it growth and when grown at different temperatures.This project also focusses on the training of young Brazilian researchers, and on broadening the international collaborative research network of the Brazilian team.