Genotypic Diversity and Host-Specificity of Frankia Bacteria Associated with Sympatric Populations of Alnus rubra and Alnus rhombifolia in Oregon
Genotypic Diversity and Host-Specificity of Frankia Bacteria Associated with Sympatric Populations of Alnus rubra and Alnus rhombifolia in Oregon
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DOI：
10.3955/046.093.0307
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发表时间：
2019-06-01
影响因子：
0.4
通讯作者：
Ballhorn, Daniel J.
中科院分区：
文献类型：
--
作者：
Balkan, Mehmet A.;Stewart, Nathan U.;Ballhorn, Daniel J.
生物固氮是在全球范围内促进生态系统生产力和稳定性的最关键过程之一。在北半球温带气候中，弗兰基亚属植物根相关细菌是森林环境中的主要固氮剂。桤木属树木是太平洋西北地区弗兰克氏菌最广泛的宿主，无数的生物和非生物因素可以影响这种共生关系的稳健性。宿主身份和菌株是影响桤木-弗兰基亚关联的重要特征，但人们对自然环境中共存的属内宿主之间的相互作用知之甚少。在这项研究中，我们研究了与俄勒冈州同域分布的红桤木（Alnus rubra）和菱叶桤木（Alnus rhombifolia）种群相关的 Frankia 细菌的遗传多样性和宿主特异性。根据从 mot 结节中回收的 nifty 基因的序列分析，我们发现总体细菌多样性较低。一种显性 Frankia 基因型与两种宿主物种相关，表明该系统缺乏强宿主特异性。我们的结果表明，某些具有重叠分布的属内植物宿主表现出与共生放线菌的交叉相容性，并且这些细菌的低菌株多样性可以在混合宿主群体中持续存在。
Biological nitrogen fixation is one of the most critical processes contributing to ecosystem productivity and stability on a global scale. In temperate climates of the northern hemisphere, plant-root associated bacteria of the genus Frankia are the major nitrogen fixers in forest environments. Trees belonging to the genus Alnus are the most widespread hosts of Frankia in the Pacific Northwest, and a myriad of biotic and abiotic factors can influence the robustness of this symbiosis. Host identity and bacterial strain are important features that can impact Alnus-Frankia association, but little is known about the interplay of intrageneric hosts that co-occur in natural settings. In this study we investigated the genetic diversity and host specificity of Frankia bacteria associated with sympatrically occurring populations of Alnus rubra (red alder) and Alnus rhombifolia (white alder) in Oregon. Based on sequence analysis of the nifty gene recovered from mot nodules we found low overall bacterial diversity. One dominant Frankia genotype was associated with both host species, indicating a lack of strong host specificity in this system. Our results suggest that certain intrageneric plant hosts with overlapping distributions show cross-compatibility with symbiotic actinorhizal bacteria, and that low strain diversity of these bacteria can persist across mixed host populations.