Evolution and biology of colletotrichum truncatum in Canada

真菌的有性亲和性和繁殖是多种多样的，从自我繁殖且不需要伴侣进行有性繁殖的有机体，到具有高度复杂交配系统的其他类群。了解真菌的交配系统是理解这些生物作为生物物种、它们交换遗传信息的潜力、它们的生态和进化的基础。在子囊菌中，包括许多重要的植物病原体的一组真菌，物种往往要么自我繁殖，要么需要具有不同交配型(MAT)基因的配偶。这些基因通常有两种形式：MAT1-1和MAT1-2。具有这种交配系统的子囊菌种群由两个群组成，一个具有MAT1-1，另一个具有MAT1-2，它需要其中之一进行有性繁殖。然而，并不是所有的子囊菌都有这种系统，包括元宝松炭疽菌，它是叶枯病或炭疽病的病原菌，可以导致加拿大草原上的主要作物扁豆产量损失高达70%。交配实验表明，这种真菌也需要遗传上不同的伴侣才能交配，但所有菌株都有MAT1-2，没有一个菌株有MAT1-1基因。这个项目的第一个目标是通过进行交配实验和分析MAT1-2基因是否参与有性繁殖来揭示这种真菌交配的遗传控制。在这种真菌中已经报道了两个小种，更具攻击性的小种似乎与两个性亲和性群体中的一个特别相关。因此，另一个目标是找出交配和毒力之间是否确实存在联系。在实验室中诱导这种真菌有性繁殖很简单，但在小扁豆田里还没有看到过。相容的菌株出现在同一种植物上，因此在田间发生交配的可能性很高。然而，这种真菌的种群在遗传上非常相似，这就提出了这种真菌的起源的问题。从国外引进受感染的扁豆种子是一种选择，生活在许多属于豆科植物的本土物种中的一种或几种上，比如扁豆，另一种。因此，第三个目标是阐明其起源于加拿大。

Sexual compatibility and reproduction in fungi is varied and ranges from organisms that are self-fertile and do not require a partner for sexual reproduction, to other groups that have highly complicated mating systems. Understanding the mating system of fungi is fundamental to understanding these organisms as biological species, their potential to exchange genetic information, their ecology and evolution. Among the ascomycetes, a group of fungi including many important plant pathogens, species tend to be either self-fertile, or require a mate with a different mating type (MAT) gene. These genes typically have two forms: MAT1-1 and MAT1-2. Populations of ascomycetous fungi with this mating system consist of two groups, one with the MAT1-1 and the other with the MAT1-2, and it requires one of each for sexual reproduction. However, not all ascomycetes have this system, including Colletotrichum truncatum, causal agent of leaf blight or anthracnose that can cause yield losses of up to 70% on lentil, a major crop on the Canadian prairies . Mating experiments have shown that this fungus also requires genetically different partners for mating, but all isolates had the MAT1-2, and none had the MAT1-1 gene. The first objective of this project is to unravel the genetic control of mating in this fungus by conducting mating experiments and by analyzing whether the MAT1-2 gene is involved in sexual reproduction. Two races have been reported in this fungus, and the more aggressive race appears to be associated specifically with one of the two sexual compatibility groups. Hence another objective is to find out if there is indeed a connection between mating and virulence. Inducing this fungus to sexually reproduce in the laboratory is simple, but has not been seen in lentil fields. Compatible isolates occur on the same plant, so there is a high likelihood for mating to happen in the field. However, the population of this fungus is genetically very similar, and this raises the question of the origin of this fungus. Introduction on infected lentil seed from abroad is one option, living on one or several of the many native species belonging to the legume family like lentil, the other. So the third objective is to elucidate its origin in Canada.