Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar

Andrea Firrincieli; Mahsa Khorasani; A Carolin Frank; Sharon Lafferty Doty

doi:10.3389/fpls.2020.00203

Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar

Front Plant Sci. 2020 Feb 28:11:203. doi: 10.3389/fpls.2020.00203. eCollection 2020.

Authors

Andrea Firrincieli¹, Mahsa Khorasani¹, A Carolin Frank^{2

3}, Sharon Lafferty Doty¹

Affiliations

¹ School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States.
² Life & Environmental Sciences School of Natural Sciences, University of California, Merced, Merced, CA, United States.
³ Sierra Nevada Research Institute, School of Natural Sciences, University of California, Merced, Merced, CA, United States.

Abstract

Plant-associated microbial communities play a central role in the plant response to biotic and abiotic stimuli, improving plant fitness under challenging growing conditions. Many studies have focused on the characterization of changes in abundance and composition of root-associated microbial communities as a consequence of the plant response to abiotic factors such as altered soil nutrients and drought. However, changes in composition in response to abiotic factors are still poorly understood concerning the endophytic community associated to the phyllosphere, the above-ground plant tissues. In the present study, we applied high-throughput 16S rDNA gene sequencing of the phyllosphere endophytic bacterial communities colonizing wild Populus trichocarpa (black cottonwood) plants growing in native, nutrient-limited environments characterized by hot-dry (xeric) riparian zones (Yakima River, WA), riparian zones with mid hot-dry (Tieton and Teanaway Rivers, WA) and moist (mesic) climates (Snoqualmie, Skykomish and Skagit Rivers, WA). From sequencing data, 587 Amplicon Sequence Variants (ASV) were identified. Surprisingly, our data show that a core microbiome could be found in phyllosphere-associated endophytic communities in trees growing on opposite sides of the Cascades Mountain Range. Considering only taxa appearing in at least 90% of all samples within each climatic zone, the core microbiome was dominated only by two ASVs affiliated Pseudomonadaceae and two ASVs of the Enterobacteriaceae family. Alpha-diversity measures indicated that plants colonizing hot-dry environments showed a lower diversity than those from mid hot-dry and moist climates. Beta-diversity measures showed that bacterial composition was significantly different across sampling sites. Accordingly, we found that specific ASV affiliated to Pseudomonadaceae and Enterobacteriaceae were significantly more abundant in the phyllosphere endophytic community colonizing plants adapted to the xeric environment. In summary, this study highlights that sampling site is the major driver of variation and that only a few ASV showed a distribution that significantly correlated to climate variables.

Keywords: Populus microbiome; endophytes; phyllosphere; plant bacterial microbiome; xeric environment.