Genetic divergence and gene flow among Mesorhizobium strains nodulating the shrub legume Caragana
Genetic divergence and gene flow among Mesorhizobium strains nodulating the shrub legume Caragana
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灌木豆科锦鸡儿根瘤菌菌株的遗传分化和基因流
DOI：
10.1016/j.syapm.2015.02.007
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发表时间：
2015-05-01
影响因子：
3.4
通讯作者：
Chen, Wenfeng
中科院分区：
文献类型：
--
作者：
Ji, Zhaojun;Yan, Hui;Chen, Wenfeng
虽然根瘤菌的分子生物学研究已经得到广泛的研究，但对根瘤菌受土壤环境影响和被豆科植物选择的适应性分子进化却知之甚少。本研究对北方半固定荒漠带锦鸡儿根瘤菌的微进化进行了研究。对72株代表性中根瘤菌的5个核心基因atpD、glnII、gyrB、recA和rpoB、6个热激因子基因clpA、clpB、dnaK、dnaf、grpE和hlsU以及5个促生长基因clpA、clpC、clpD、clpG和clpP进行了遗传变异研究。共有21个基因种被定义的基础上的平均核苷酸同一性（ANI）的串联核心基因使用的阈值为96%的相似性，并通过系统发育分析的核心/热休克因子基因。半固定荒漠带（A ~ E区）和云南省（F区）的基因种间存在明显的遗传分化，这种遗传分化与环境条件和地理距离密切相关。基因流在A ~ E区和B区3个位点的基因种间发生的频率高于F区和其他5个位点间的频率。菌株间热休克因子基因的突变频率高于其他基因。结果最终表明，锦鸡儿属相关的中慢根瘤菌根据其地理分布而发生了分化进化，并且不仅受到环境条件的选择，而且还受到宿主植物的选择。(C)2015 Elsevier GmbH. All rights reserved.
Although the biogeography of rhizobia has been investigated extensively, little is known about the adaptive molecular evolution of rhizobia influenced by soil environments and selected by legumes. In this study, microevolution of Mesorhizobium strains nodulating Caragana in a semi-fixing desert belt in northern China was investigated. Five core genes-atpD, glnII, gyrB, recA, and rpoB, six heat-shock factor genes-clpA, clpB, dnaK, dnaf, grpE, and hlsU, and five nodulation genes-nodA, nodC, nodD, nodG, and nodP, of 72 representative mesorhizobia were studied in order to determine their genetic variations. A total of 21 genospecies were defined based on the average nucleotide identity (ANI) of concatenated core genes using a threshold of 96% similarity, and by the phylogenetic analyses of the core/heat-shock factor genes. Significant genetic divergence was observed among the genospecies in the semi-fixing desert belt (areas A-E) and Yunnan province (area F), which was closely related to the environmental conditions and geographic distance. Gene flow occurred more frequently among the genospecies in areas A-E, and three sites in area B, than between area F and the other five areas. Recombination occurred among strains more frequently for heat-shock factor genes than the other genes. The results conclusively showed that the Caragana-associated mesorhizobia had divergently evolved according to their geographic distribution, and have been selected not only by the environmental conditions but also by the host plants. (C) 2015 Elsevier GmbH. All rights reserved.