Finding candidate genes under positive selection in Non-model species: examples of genes involved in host specialization in pathogens
Finding candidate genes under positive selection in Non-model species: examples of genes involved in host specialization in pathogens
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DOI：
10.1111/j.1365-294x.2009.04454.x
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发表时间：
2010-01-01
影响因子：
4.9
通讯作者：
Giraud, T.
中科院分区：
文献类型：
--
作者：
Aguileta, G.;Lengelle, J.;Giraud, T.
许多基因在不同的生物体已被证明是积极的选择，特别是基因参与生殖，适应对比环境，杂种不活力，和主机-病原体的相互作用。在病原体中寻找正选择作用下的基因一直是研究共同进化动力学和开发疫苗或药物的优先事项。为了阐明宿主专业化所涉及的功能，在这里，我们的目的是确定候选序列，可能已经演变的正选择密切相关的病原体专门在不同的主机之间。为了达到这个目的，我们对C进行了测序。微葡萄孢属（Microbotryum）4个种的EST序列均为17 000-32 000，微葡萄孢属是引起石竹科植物花药黑穗病的病原真菌。在372个预测的正向选择基因中，有42个基因显示出明显的正向选择信号，这代表了大量的候选基因供进一步研究。对另外9种微葡萄孢菌中的16个基因进行测序证实，它们确实在不同宿主上专门化的病原体物种中迅速进化。显示出显著正选择信号的基因是参与从宿主吸收营养、次级代谢产物合成和分泌、胁迫条件下的呼吸和胁迫反应、菌丝生长和分化以及其他基因表达调控的puerectin。这些基因中的许多具有跨膜结构域，因此也可能参与宿主对病原体的识别。因此，我们的方法显示富有成效的，应该是可行的许多非模式生物的候选基因进行多样化的选择是必要的。
Numerous genes in diverse organisms have been shown to be under positive selection, especially genes involved in reproduction, adaptation to contrasting environments, hybrid inviability, and host-pathogen interactions. Looking for genes under positive selection in pathogens has been a priority in efforts to investigate coevolution dynamics and to develop vaccines or drugs. To elucidate the functions involved in host specialization, here we aimed at identifying candidate sequences that could have evolved under positive selection among closely related pathogens specialized on different hosts. For this goal, we sequenced c. 17 000-32 000 ESTs from each of four Microbotryum species, which are fungal pathogens responsible for anther smut disease on host plants in the Caryophyllaceae. Forty-two of the 372 predicted orthologous genes showed significant signal of positive selection, which represents a good number of candidate genes for further investigation. Sequencing 16 of these genes in 9 additional Microbotryum species confirmed that they have indeed been rapidly evolving in the pathogen species specialized on different hosts. The genes showing significant signals of positive selection were putatively involved in nutrient uptake from the host, secondary metabolite synthesis and secretion, respiration under stressful conditions and stress response, hyphal growth and differentiation, and regulation of expression by other genes. Many of these genes had transmembrane domains and may therefore also be involved in pathogen recognition by the host. Our approach thus revealed fruitful and should be feasible for many non-model organisms for which candidate genes for diversifying selection are needed.