Root microbiota assembly and adaptive differentiation among European Arabidopsis populations

First author: Thorsten Thiergart; Affiliations: Max Planck Institute for Plant Breeding Research (马普植物育种研究所): Cologne, Germany

Corresponding author: Stéphane Hacquard 

Factors that drive continental-scale variation in root microbiota and plant adaptation are poorly understood. We monitored root-associated microbial communities in Arabidopsis thaliana and co-occurring grasses at 17 European sites across 3 years. We observed strong geographic structuring of the soil biome, but not of the root microbiota. A few phylogenetically diverse and geographically widespread bacteria consistently colonized plant roots. Among-site and across-year similarity in microbial community composition was stronger for the bacterial root microbiota than for filamentous eukaryotes. In a reciprocal transplant between two A. thaliana populations in Sweden and Italy, we uncoupled soil from location effects and tested their contributions to root microbiota variation and plant adaptation. Community differentiation in plant roots was explained primarily by location for filamentous eukaryotes and by soil origin for bacteria, whereas host genotype effects were marginal. Strong local adaptation between the two A. thaliana populations was observed, with differences in soil properties and microbes of little importance for the observed magnitude of adaptive differentiation. Our results suggest that, across large spatial scales, climate is more important than soil conditions for plant adaptation and variation in root-associated filamentous eukaryotic communities, whereas soil properties are primary drivers of bacterial community differentiation in roots.

目前，我们对于驱动植物在大陆规模层面的根部微生物变异和适应的因子所知甚少。作者连续三年在欧洲17个地点监测了拟南芥及共生草类植物根部相关的微生物群落。作者在土壤微生物群落中观察到了十分明显的地理结构，但在根部微生物群落中并未观察到明显的地理结构。一些在系统关系上较远和地理上分布广泛的菌会恒定的附着在植物根部。细菌微生物群落组成在不同地点、年份之间的相似性要远高于丝状真核生物。作者相互移栽了来自瑞典和意大利的两个拟南芥群体，解除了土壤的地点效应，并测试其对于根部微生物变异和植物适应的影响。植物根部的微生物群落分化主要是由丝状真核生物的地点来源以及细菌的土壤来源所解释的，而宿主基因型的影响则微不足道。作者在两个地理来源的拟南芥群体中观察到了强烈的区域适应，并且作者发现所观测到的适应性差异与土壤性质以及微生物的差异关系不大。本文的研究显示在大尺度的空间范围上，气候条件要比土壤条件对于植物的适应性以及根部相关的丝状真核群落变异更加重要，而土壤特性是根部细菌群落分化的主要驱动因素。

通讯：Stéphane Hacquard (https://www.mpipz.mpg.de/hacquard)

个人简介：法国国家农业研究院，博士；2011-2013年，马普植物育种研究所，博士后。

研究方向：植物根际微生物。

doi: https://doi.org/10.1038/s41559-019-1063-3

Journal: Nature Ecology & Evolution

Published date: December 23, 2019