Chocolate spot: Pathogenicity dynamics, population diversity and host resistance to Botrytis fabae

由蚕豆灰霉病引起的巧克力斑病是蚕豆上的一种重要病害，可造成严重的农作物损失。蚕豆是经济上最重要的寄主，目前还没有抗病的商业品种，尽管在英国和其他地方已经发现了部分抗病的品系。然而，目前尚不清楚这种耐药性是否普遍有效，或者是否存在菌株特异性。已发表的抗性筛选结果，包括部分抗性蚕豆品系，一直没有定论或相互矛盾，这表明后者可能是这种情况。目的/方法：本项目将通过a)改善寄主的遗传抗性知识(建立部分抗性品系的抗性遗传基础)，b)扩大筛选蚕豆新的抗性来源，以及c)研究病原菌的不同毒力，来研究品系对蚕豆赤霉病的特异性抗性。该项目还将研究寄主与病原体的相互作用，通过构建从头基因组组件并将转录分析的读数映射到该组件上来识别可能的效应分子。学生将尝试确定位置数量性状基因座(QTL)，并在选定的作图群体中表征巧克力斑病抗性的遗传基础。在更广泛的品种中筛选巧克力斑点抗性将有助于鉴定潜在的新抗源。结合鉴定寄主的抗源，将探索该病原菌的遗传多样性和不同毒力的潜力。虽然蚕豆芽孢杆菌已被列入灰霉病菌属的分类学研究，但迄今为止还没有大规模的研究来检验这种病原菌的遗传多样性。NIAB拥有稳步增长的200多个英国蚕豆芽孢杆菌分离物，这将成为这名学生努力描述主要在英国蚕豆芽孢杆菌种群中遗传多样性的基础。这将包括通过筛选蚕豆面板来鉴定不同的毒力，并在形态、分子和基因组水平上研究病原菌的多样性。该项目将使我们能够解决以下问题：英国境内的蚕豆灰霉菌与其他国家相比有多大的遗传多样性？是否有不同的蚕豆菌株具有不同的毒力特征？这些菌株在英国各地是如何分布的？这种分布是否会随着时间的推移而变化？这种分布是否会随着时间的推移而变化？这种分布在多大程度上会发生变化？蚕豆中的哪些基因对毒力/致病作用有贡献

Chocolate spot, caused by Botrytis fabae, is an important disease of faba bean (Vicia faba) which can cause severe crop losses. B. fabae has a narrow host range with faba bean being the most economically important host.Currently there are no resistant commercial cultivars available, although partially resistant lines have been identified in the UK and elsewhere. However, it is currently unknown if this resistance is universally effective or whether strain specificity occurs. Published results of resistance screens, including partially resistant faba bean lines, have been inconclusive or contradictory, which suggest that the latter may be the case.Aim/approach: This project will investigate whether strain -specific resistance to B. fabae occurs by a) improving the knowledge on genetic resistance in the host (establishing the genetic basis of resistance in partially resistant lines), b) extend screening for novel sources of resistance in Vicia faba, and by c) studying differential virulence in the pathogen. The project will also investigate host-pathogen interactions to identify putative effector molecules by constructing a de novo genome assembly and mapping reads from transcriptomic analyses onto this.The student will attempt to identify the location Quantitative trait loci (QTL) and characterise the genetic basis of resistance of chocolate spot resistance in selected mapping populations. Screening for chocolate spot resistance in a more extensive number of cultivars will aid identification of potential novel sources of resistance.In conjunction with identifying sources of resistance in the host, the genetic diversity and potential for differential virulence in the pathogen will be explored. Although B. fabae has been included in taxonomic studies of the Botrytis genus, no large-scale studies to examine this pathogen's genetic diversity have so far been undertaken . NIAB holds a steadily growing collection of more than 200 UK-isolates of B. fabae which will form the basis of the student's efforts to characterise the genetic diversity mainly within the UK's populations of B. fabae. This will involve the identification of differential virulence through screening of panels of Vicia faba as well as studying the pathogen's diversity on a morphological, molecular and genomic level.The project will enable us to address the following questions including:How genetically diverse is Botrytis fabae within the UK and compared to other countries??Are there distinct strains of B. fabae with differential virulence profile?How are these distributed geographically across the UK and does that distribution change over time and to what extent?Which genes in B. fabae are contributing to virulence/pathogenesis