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

蚕豆巧克力斑病是蚕豆（Vicia faba）的一种重要病害，由豆孢杆菌（Botrytis fabae）引起，可造成严重的作物损失。蚕豆寄主范围窄，蚕豆是最重要的经济寄主。目前还没有抗药的商业品种，尽管在英国和其他地方已经发现了部分抗药的品种。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，都是不确定的或相互矛盾的，这表明后者可能是情况。目的/途径：本项目将通过a)提高对寄主遗传抗性的认识（在部分抗性品系中建立抗性的遗传基础），b)扩大对蚕豆新抗性来源的筛选，以及c)研究病原菌的不同毒力来研究菌株对蚕豆的特异性抗性是否发生。该项目还将研究宿主-病原体相互作用，通过构建一个从头开始的基因组组装和从转录组学分析中绘制读数来识别可能的效应分子。该学生将尝试确定数量性状位点（QTL）的位置，并在选定的绘图群体中描述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病抗性将有助于鉴定潜在的新抗性来源。在确定宿主耐药来源的同时，将探索病原体的遗传多样性和不同毒力的潜力。虽然豆瓣芽孢杆菌已被纳入孢霉属的分类研究，但迄今为止尚未开展大规模的研究来检查这种病原体的遗传多样性。NIAB拥有200多个fabae英国分离株的稳定增长收集，这将形成学生努力描述主要在英国fabae种群内的遗传多样性的基础。这将包括通过筛选蚕豆组来鉴定不同的毒力，以及在形态、分子和基因组水平上研究病原体的多样性。该项目将使我们能够解决以下问题，包括：与其他国家相比，英国的豆芽孢杆菌的遗传多样性如何？？是否存在具有不同毒力特征的不同菌株？这些在英国的地理分布是怎样的，这种分布是否随着时间的推移而变化，变化的程度是什么？蚕豆芽胞杆菌中哪些基因与毒力/发病机制有关

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