Host species identity, site and time drive temperate tree phyllosphere bacterial community structure.

Christian Messier,Isabelle Laforest-Lapointe,Steven W Kembel

doi:10.1186/s40168-016-0174-1

Christian Messier, Isabelle Laforest-Lapointe + Show 1 more

Open Access

https://doi.org/10.1186/s40168-016-0174-1

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Abstract

BackgroundThe increasing awareness of the role of phyllosphere microbial communities in plant health calls for a greater understanding of their structure and dynamics in natural ecosystems. Since most knowledge of tree phyllosphere bacterial communities has been gathered in tropical forests, our goal was to characterize the community structure and assembly dynamics of phyllosphere epiphytic bacterial communities in temperate forests in Quebec, Canada. We targeted five dominant tree species: Acer saccharum, Acer rubrum, Betula papyrifera, Abies balsamea, and Picea glauca. We collected 180 samples of phyllosphere communities on these species at four natural forest sites, three times during the growing season.ResultsHost functional traits (i.e., wood density, leaf nitrogen content) and climate variables (summer mean temperature and precipitation) were strongly correlated with community structure. We highlight three key findings: (1) temperate tree species share a “core microbiome”; (2) significant evolutionary associations exist between groups of bacteria and host species; and (3) a greater part of the variation in phyllosphere bacterial community assembly is explained by host species identity (27 %) and species-site interaction (14 %), than by site (11 %) or time (1 %).ConclusionsWe demonstrated that host species identity is a stronger driver of temperate tree phyllosphere bacterial communities than site or time. Our results suggest avenues for future studies on the influence of host functional traits on phyllosphere community functional biogeography across terrestrial biomes.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-016-0174-1) contains supplementary material, which is available to authorized users.

Highlights

The increasing awareness of the role of phyllosphere microbial communities in plant health calls for a greater understanding of their structure and dynamics in natural ecosystems
OTUs, and taxonomy Sequencing identified 15,873 bacterial operational taxonomic units (OTUs, sequences binned at 97 % similarity) in phyllosphere samples, an average of 517 ± 16 OTUs per tree sampled
We detected a “core microbiome” [24], defined as OTUs present on 99 % or more of all trees sampled, of 19 bacterial OTUs belonging to two phyla, four classes, and seven families

Summary

Introduction

The increasing awareness of the role of phyllosphere microbial communities in plant health calls for a greater understanding of their structure and dynamics in natural ecosystems. We collected 180 samples of phyllosphere communities on these species at four natural forest sites, three times during the growing season. Aerial plant surfaces (mostly leaves), a habitat known as the phyllosphere, are estimated to sum up to 4 × 108 km on Earth [4], which is almost equivalent to the total surface of the earth. Tree phyllosphere microbial communities are mainly composed of bacteria and endophytic. Many aspects of phyllosphere bacterial metabolism and functional traits are poorly understood, the first censuses have revealed the presence of anoxygenic phototrophic bacteria [21].

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