Karandeni Dewage Chinthani S, Cools Katherine, Stotz Henrik U, Qi Aiming, Huang Yong-Ju, Wells Rachel, Fitt Bruce D L
Centre for Agriculture, Food, and Environmental Management Research, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom.
Rothamsted Research, Harpenden, United Kingdom.
Front Plant Sci. 2022 Feb 4;13:786189. doi: 10.3389/fpls.2022.786189. eCollection 2022.
Use of host resistance is the most economical and environmentally safe way to control light leaf spot disease of oilseed rape (). The causal organism of light leaf spot, , is one of the most economically damaging pathogens of oilseed rape in the United Kingdom and it is considered to have a high potential to evolve due to its mixed reproduction system and airborne ascospores. This necessitates diverse sources of host resistance, which are inadequate at present to minimize yield losses caused by this disease. To address this, we screened a doubled haploid (DH) population of oilseed rape, derived from a secondary gene pool (ancestral genomes) of for the introgression of resistance against . DH lines were phenotyped using controlled-environment and glasshouse experiments with populations obtained from three different geographic locations in the United Kingdom. Selected DH lines with different levels of resistance were further studied in a controlled-environment experiment using both visual (scanning electron microscope - SEM) and molecular (quantitative PCR) assessment methods to understand the mode/s of host resistance. There was a clear phenotypic variation for resistance against in this DH population. Quantitative trait locus (QTL) analysis identified four QTLs with moderate to large effects, which were located on linkage groups C1, C6, and C9. Of these, the QTL on the linkage group C1 appeared to have a major effect on limiting asexual sporulation. Study of the sub-cuticular growth phase of using qPCR and SEM showed that the pathogen was able to infect and colonise both resistant and susceptible Q DH lines and control cultivars. However, the rate of increase of pathogen biomass was significantly smaller in resistant lines, suggesting that the resistance segregating in this DH population limits colonisation/sporulation by the pathogen rather than eliminating the pathogen. Resistance QTLs identified in this study provide a useful resource for breeding cultivar resistance for effective control of light leaf spot and form a starting point for functional identification of the genes controlling resistance against that can contribute to our knowledge on mechanisms of partial resistance of crops against pathogens.
利用寄主抗性是控制油菜叶斑病最经济且对环境安全的方法。油菜叶斑病的病原真菌是英国油菜最具经济破坏力的病原菌之一，因其混合繁殖系统和空气传播的子囊孢子，被认为具有很高的进化潜力。这就需要多种寄主抗性来源，但目前这些来源不足以将该病造成的产量损失降至最低。为解决这一问题，我们筛选了一个油菜双单倍体（DH）群体，该群体源自甘蓝型油菜的次生基因库（祖先基因组），用于导入对油菜叶斑病的抗性。利用来自英国三个不同地理位置的群体，通过控制环境和温室试验对DH系进行表型分析。在控制环境试验中，使用视觉（扫描电子显微镜-SEM）和分子（定量PCR）评估方法，对选择出的具有不同抗性水平的DH系进行进一步研究，以了解寄主抗性的模式。该DH群体对油菜叶斑病的抗性存在明显的表型变异。数量性状位点（QTL）分析确定了四个具有中等到较大效应的QTL，它们位于连锁群C1、C6和C9上。其中，连锁群C1上的QTL似乎对限制无性孢子形成有主要作用。利用qPCR和SEM对油菜叶斑病病原菌的表皮下生长阶段进行研究表明，该病原菌能够感染并定殖于抗性和感病的Q DH系以及对照品种。然而，抗性系中病原菌生物量的增加速率明显较小，这表明该DH群体中分离出的抗性限制了病原菌的定殖/孢子形成，而不是消除病原菌。本研究中鉴定出的抗性QTL为培育抗叶斑病品种提供了有用资源，是控制油菜叶斑病有效抗性基因功能鉴定的起点，有助于我们了解作物对病原菌部分抗性的机制。
