Genetic Improvement of Leaf and Stripe Rust Resistance in Canadian Spring Wheat

小麦叶锈病（锈病）和小麦条锈病（黄锈病）是加拿大西部小麦最常见的两种病害。它们是造成重大产量损失和粮食品质恶化的罪魁祸首。虽然这两种病害的严重程度可以通过农艺管理措施和施用叶面杀菌剂来降低，但开发抗病品种是一种更经济、更环保的控制锈病的方法。文献中已经报道了与这两种疾病相关的各种单基因和数量性状位点（QTL），但只有4个叶锈病基因（Lr16、Lr21、Lr22a和Lr34/Yr18）和5个条锈病基因（Yr7、Yr10、Yr17、Yr18/Lr34和Yr36）对加拿大西部流行品种的抗性起主要作用。分子标记可用于利用标记辅助选择（MAS）渗入每个基因。在苗期表达的质性抗病是由单个主效基因控制的，随着时间的推移，这些基因会因病原体种群的变化而失去效力。数量抗性在成虫期表达，由加性效应较小的基因和/或qtl控制，具有较强的耐受性，但需要多个基因/ qtl渗入到相同的遗传背景中。在这里，我们建议培训年轻的专业人员使用双单倍体（DH）技术进行品种/品系开发，使用MAS进行基因金字塔分析，以及使用全基因组关联研究（GWAS）鉴定抗锈病的新来源。该项目的具体目标如下：(1)利用DH技术和MAS技术的结合，开发由至少三种抗叶锈病和/或条锈病基因的新组合组成的改良小麦种质；(2)通过评价220个历史和现代加拿大春小麦品种以及国际玉米小麦改良中心（CIMMYT）的30个春小麦品系在温室条件下的幼苗抗性和田间和温室条件下的成株抗性，确定抗叶锈病和条锈病的新来源；(3)在小麦育种与遗传学方面培养2名研究生（1名博士和1名硕士）。

Leaf rust (Puccinia triticina) and stripe (yellow) rust (Puccinia striiformis f. sp. tritici) are two of the most common diseases of wheat in western Canada. They are responsible for major yield losses and grain quality deterioration. Although the severity of both diseases can be reduced through agronomic management practices and application of foliar fungicides, the development of resistant cultivars is a more economical and environmentally friendly approach to control rusts. Various single genes and quantitative trait loci (QTL) associated with the two diseases have been reported in the literature, but only four genes for leaf rust (Lr16, Lr21, Lr22a and Lr34/Yr18) and five genes for stripe rust (Yr7, Yr10, Yr17, Yr18/Lr34 and Yr36) contribute most of the resistance against the prevalent races in western Canada. Molecular markers are available for introgressing each gene using marker-assisted selection (MAS). Qualitative disease resistance, expressed at seedling stage, is controlled by single major effect genes that lose their effectiveness over time due to changes in pathogen populations. Quantitative resistance, expressed at adult plant stage, is controlled by genes and/or QTLs with small additive effects, which is more durable, but requires the introgression of multiple genes/QTLs in to the same genetic background. Here, we propose to train young professionals on cultivar/line development using doubled haploid (DH) technology, gene pyramiding using MAS, and identification of new sources of resistance to rusts using genome-wide association studies (GWAS). The specific objectives of the project are the following: (1) to develop improved wheat germplasm that consist of new combinations of at least three leaf rust and/or stripe rust resistant genes using a combination of DH technology and MAS; (2) to identify new sources of leaf and stripe rust resistance by evaluating 220 historical and modern Canadian spring wheat cultivars along with 30 spring wheat lines from the International Maize and Wheat Improvement Center (CIMMYT) for their reaction to seedling resistance under greenhouse and adult plant resistance under both field and greenhouse conditions; and (3) to train two graduate students (1 PhD and 1 MSc) in wheat breeding and genetics.