Exploring effectors in Puccinia striiformis f. sp. tritici and identifying new sources of host resistance

农作物病原菌危害全球粮食生产，而小麦条锈病/黄锈病的病原小麦条锈病（Pst）是加拿大乃至世界范围内最具破坏性的小麦病原菌之一。真菌脲孢子通过反复的感染循环在小麦上无性繁殖，在有利的环境中可引起疾病流行；这种多循环的疾病循环可以在一株易感小麦上产生无数的孢子，而在一片作物地里，孢子的数量是不可想象的。在这种情况下，即使是最低的随机突变率加上宿主选择压力也能在种群中产生新的变体/种族。Pst生理小种或毒力表型以携带已知抗条锈病基因（Yr基因）的小麦基因型为特征，通过我们过去的研究，我们在加拿大西部鉴定了bbb35个Pst小种。小麦- pst的发病机制遵循经典的基因对基因的关系；为了成功感染小麦并克服部署的Yr基因，Pst使用了一系列武器，其中最重要的是“效应物”或“Avr基因”，这些基因随后被小麦的免疫受体感知以赋予抗性。Pst效应物的鉴定和表征是我研究计划的两个长期目标之一，它会导致小麦Yr基因的毒力。我们对来自加拿大西部的Pst群体的毒力表型和遗传谱系（使用分子标记和全基因组测序）进行了广泛的表征，并产生了巨大的基因组资源。对于小麦锈病管理来说，鉴定Avr效应剂是成功的一半，另一半是加强小麦的免疫系统。小麦及其近缘种的抗条锈病鉴定、遗传鉴定（作图、精细作图、克隆、功能鉴定）以及通过为小麦育种者提供育种前种质来利用这种抗性是我研究计划的另一个主要目标。为此，我们鉴定了几种具有抗性的小麦品种（栽培、野生和地方品种），并从野生小麦组中克隆了两个新的Yr基因（未发表）。短期目标是利用现有的基因组资源，从加拿大和其他国家的Pst品种中获得更多的基因组数据，以鉴定与我们克隆的Yr基因对应的Avr基因，并使用名为AgRenSeq的尖端基因克隆技术从野生小麦和沃特金斯地方品种中克隆新的Yr基因。了解小麦中的效应生物学和新Yr基因的克隆将使我们能够为（加拿大和全球）农民培育出更好的小麦品种，因为该项目将提供有关Pst使用的“武器”和病原体进化潜力的知识。该项目将培养学生（在一个多样化的实验室小组中），使他们成为自信的科学家，并在学术界建立自己的研究项目，或成为行业领导者。

Crop pathogens jeopardize global food production and Puccinia striiformis f. sp. tritici (Pst), the cause of stripe/yellow rust, is one of the most devastating wheat pathogens in Canada and worldwide. Fungal urediniospores are reproduced asexually on wheat via repeated cycles of infections and in conducive environments can cause disease epidemic; this polycyclic disease cycle can produce zillions of urediniospores on a single susceptible wheat plant and the number of spores in a single crop field can be unimaginable. In such scenarios, even the lowest rate of random mutation coupled with host selection pressure can give rise to new variants/races in the population. Physiologic races or virulence phenotypes of Pst are characterized on wheat genotypes carrying known stripe rust resistance genes (Yr genes) and through our past research we have characterized >35 Pst races in western Canada. The wheat-Pst pathosystem follows the classical gene-for-gene relationship; to successfully infect wheat and overcome deployed Yr genes, Pst uses a cocktail of weapons and the most important of those is 'effectors' or 'Avr genes' which are then perceived by immune receptors in wheat to confer resistance. Identification and characterization of Pst effectors, which results in virulence on wheat Yr genes, is one of the two long-term goals of my research program. We have extensively characterized Pst population from western Canada for virulence phenotypes and genetic lineages (using molecular markers and whole-genome sequencing) and have generated enormous genomic resources. For rust management, identification of Avr effectors is half the battle, the other half of the battle is to strengthen wheat immune system. Identification of stripe rust resistance in wheat & wheat relatives, genetic characterization (mapping, fine-mapping, cloning, functional characterization) and utilization of the resistance by generating pre-breeding germ plasm for wheat breeders is the other major goal of my research program. To this end, we have identified several accessions (cultivated, wild, and landraces) of wheat with resistance and have cloned two novel Yr genes (unpublished) from wild wheat panel. The short-term objectives are to utilize available genomic resources, generate more genomic data on Canadian and selected Pst races from other countries to identify Avr genes corresponding to our cloned Yr genes and clone novel Yr genes from wild wheat and Watkins landraces using cutting-edge gene cloning technology named AgRenSeq. Understanding effector biology and cloning of new Yr genes in wheat will enable us breed for better resistance in wheat varieties for farmers (in Canada and globally) because the project will deliver knowledge about the 'weapons' used by Pst and evolutionary potential of the pathogen. The project will train students (in a diverse lab group) to prepare them to become confident scientists & build their own research programs in academia or become leaders in industry.