Evolution and biology of colletotrichum truncatum in Canada

真菌的性兼容性和繁殖是多种多样的，范围从自我繁殖和不需要伴侣进行有性繁殖的生物，到其他具有高度复杂的交配系统的群体。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，一组真菌包括许多重要的植物病原体，物种往往是自我繁殖的，或者需要具有不同交配类型（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真菌种群包括两组，一组是MAT1-1，另一组是MAT1-2，并且每组都需要一个进行有性繁殖。然而，并不是所有的子囊菌都有这个系统，包括炭疽菌（Colletotrichum truncatum），它是引起叶枯萎病或炭疽病的病原体，可以导致扁豆（加拿大草原上的主要作物）产量损失高达70%。交配实验表明，这种真菌也需要基因不同的伴侣进行交配，但所有分离株都有MAT1-2基因，没有MAT1-1基因。本项目的第一个目标是通过进行交配实验和分析MAT1-2基因是否参与有性生殖，来揭示该真菌交配的遗传控制。据报道，这种真菌有两个种族，更具攻击性的种族似乎与两种性相容性群体中的一种特别相关。因此，另一个目标是找出交配和毒性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，但在扁豆田中尚未见过。相容的分离株出现在同一株植物上，因此在田间交配的可能性很高。然而，这种真菌的种群在基因上非常相似，这就提出了这种真菌起源的问题。从国外引进受感染的小扁豆种子是一种选择，另一种选择是生活在许多属于豆科的本地物种中的一种或几种，如小扁豆。所以第三个目标是阐明它在加拿大的起源。

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.