Exploring virulence and mating in Colletotrichum lentis

扁豆炭疽菌(Colletotrichum Lentis)是引起扁豆叶部病害的一种真菌。感染，被称为半生物营养，是复杂的，因为扁豆芽孢杆菌最初感染时没有被植物察觉(生物营养阶段)，然后积极地杀死宿主细胞(死亡营养阶段)。从生态学的角度了解扁豆的生物学以及它与小扁豆的相互作用是我研究计划的长期目标。在加拿大种群中，描述了两个小种，强毒小种0和弱毒小种1。在过去的研究中，我们成功地交配了这两个小种的分离物，并培育了大量的后代分离物。对扁豆的基因组进行了测序，在我们种群的帮助下，我们可以将基因组排列成12个可能代表染色体的连锁群。基于所有染色体上亲本(分子标记)遗传组成的细微差异，我们开发了一种遗传连锁图，可以使用类似于路线图的方向来识别参与控制毒力等特征的基因。利用我们的遗传图谱和后代群体，我们将后代个体之间分子标记存在的差异与他们对不同的小扁豆品种的毒力联系在一起。我们还将这些标记与交配能力联系起来，因为小扁豆有两个交配组，而且只有两个来自不同交配组的个体是可育的。因此，我们可以确定一个与毒力相关的特定染色体区域和另一个与匹配相关的区域，这些区域由许多基因组成，被称为数量性状基因座或QTL。并不是QTL中的每个基因都参与调控感兴趣的性状，因此需要进一步的研究来确定哪些基因是参与调控的。因此，我的计划的短期目标是识别和表征与交配不亲和性QTL和毒性QTL相关的基因，并在交配和毒力方面比较加拿大扁豆分离物和中国野豌豆分离物，这是该物种的第一个外来分离物。根据物种间的保守特征，基因的识别将通过将基因的结构与其他物种中已经与我们的特征相关的基因结构进行比较来实现。然后，实验将通过确定真菌在感染扁豆植物时是否打开或关闭特定基因，和/或通过禁用候选基因并评估特征变化，例如防止真菌感染或两个以前可育的分离株变得不育，来评估这些基因是否影响了特征。了解这些特征将使我们能够在小扁豆品种中繁殖出更好的抗性，因为我们知道小扁豆使用什么“武器”成功感染，以及真菌种群的进化潜力基于其交配系统。

Colletotrichum lentis is a fungal pathogen that causes an important foliar disease on lentil. Infection, referred to as hemibiotrophic, is complex as C. lentis initially infects without being perceived by the plant (biotrophic phase) before aggressively killing host cells (necrotrophic phase). Understanding the biology of C. lentis in terms of its ecology and its interaction with lentil is the long-term objective of my research program. In the Canadian population, two races were described, the highly virulent race 0 and the weakly virulent race 1. In past research we succeeded in mating isolates of the two races and developed a large population of offspring isolates. The genome of C. lentis was sequenced and with the help of our population, we could arrange the genome into 12 linkage groups probably representing chromosomes. Based on subtle differences in the genetic make-up of the parents (molecular markers) across all chromosomes, we developed a genetic linkage map that can be used analogues to a road map for direction to identify genes involved in controlling traits such as virulence. Using our genetic map and our offspring population we associated differences in the presence of molecular markers among the individuals of the offspring with their virulence on a differential lentil variety. We also associated the markers with the ability to mate, as there are two mating groups in C. lentis, and only two individuals from different mating groups are fertile. We could thus identify one particular chromosomal region that is associated with virulence and another one associated with mating.These regions consist of many genes and are referred to as quantitative trait loci or QTLs. Not every gene in the QTL will be involved in regulating the trait of interest, so further research is needed to identify those that are. The short-term objectives of my program are therefore to identify and characterize the genes associated with the mating incompatibility QTL and the virulence QTL, and to compare Canada lentil isolates with a Chinese vetch isolate, the first foreign isolate of this species, in terms of mating and virulence. Identification of genes will be achieved by comparing the structure of genes with those that have already been associated with our traits in other species based on conserved features across species. Experiments then will assess whether these genes are affecting the trait by determining whether the fungus “switches on or off” a particular gene when it is infecting a lentil plant, and/or by disabling the candidate gene and assessing changes in the trait, e.g. a prevention of infection by the fungus or two previously fertile isolates becoming infertile. Understanding these traits will enable us to breed for better resistance in lentil varieties because we know what “weapons” C. lentis uses to successfully infect, and what the evolutionary potential of the fungal population is based on its mating system.