Within-host competitive exclusion among species of the anther smut pathogen
Within-host competitive exclusion among species of the anther smut pathogen
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DOI：
10.1186/1472-6785-9-11
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发表时间：
2009-05-07
期刊：
影响因子：
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通讯作者：
Hood, Michael E.
中科院分区：
文献类型：
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作者：
Gold, Alexander;Giraud, Tatiana;Hood, Michael E.
背景资料：宿主个体代表了病原体争夺资源和传播机会的竞技场，对毒力的进化和种群结构具有重要意义。迄今为止的研究主要集中在病原体物种之间的竞争性相互作用，并且拮抗作用的水平往往随着竞争对手之间的遗传距离而增加。微葡萄孢属（Microbotryum）的花药黑穗病真菌是一种易处理的寄主内竞争模型。在这里，使用两种病原体的物种，经常发现在同域，我们调查是否在同一物种的基因型之间的拮抗级联影响病原体species.Results之间的竞争：顺序接种的主机显示，居民感染最经常排除一个具有挑战性的病原体基因型，这是与以前的研究一致。然而，挑战性的病原体是显着更有可能入侵已经感染的主机，如果居民感染是同种基因型相比，涉及密切相关的物种的挑战。此外，当种间共感染发生时，病原体在宿主内被高度隔离，与种内共infection.Conclusion：我们的证据表明，在感染过程中的竞争性排斥可以更大的密切相关的病原体物种之间的物种内的基因型。这种模式遵循先前的研究表明，遗传距离和拮抗相互作用是正相关的微孢霉。真菌营养体不亲和性是直接竞争干扰的可能机制，并且已经在一些真菌中显示出在种内和种间界限内都有效。对于相关病原体物种经常共同出现在同一宿主种群中的系统，这些竞争动态可能会显著影响病原体物种的空间分离。
Background: Host individuals represent an arena in which pathogens compete for resources and transmission opportunities, with major implications for the evolution of virulence and the structure of populations. Studies to date have focused on competitive interactions within pathogen species, and the level of antagonism tends to increase with the genetic distance between competitors. Anther-smut fungi, in the genus Microbotryum, have emerged as a tractable model for within-host competition. Here, using two pathogen species that are frequently found in sympatry, we investigated whether the antagonism seen among genotypes of the same species cascades up to influence competition among pathogen species.Results: Sequential inoculation of hosts showed that a resident infection most often excludes a challenging pathogen genotype, which is consistent with prior studies. However, the challenging pathogen was significantly more likely to invade the already-infected host if the resident infection was a conspecific genotype compared to challenges involving a closely related species. Moreover, when inter-specific co-infection occurred, the pathogens were highly segregated within the host, in contrast to intra-specific co-infection.Conclusion: We show evidence that competitive exclusion during infection can be greater among closely related pathogen species than among genotypes within species. This pattern follows from prior studies demonstrating that genetic distance and antagonistic interactions are positively correlated in Microbotryum. Fungal vegetative incompatibility is a likely mechanism of direct competitive interference, and has been shown in some fungi to be effective both within and across species boundaries. For systems where related pathogen species frequently co-occur in the same host populations, these competitive dynamics may substantially impact the spatial segregation of pathogen species.