Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar

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.

Endophyte-Promoted Phosphorus Solubilization in Populus

“…Our solubilization experiments confirmed the earlier finding that poplar endophyte strains WP5 and WP42 had the ability to solubilize Ca 3 (PO 4 ) 2 (Khan et al, 2015;Kandel et al, 2017). It is noted that most poplar microbiome studies lack the resolution to determine how common these particular bacterial species are in poplar (Ulrich et al, 2008;Gottel et al, 2011;Shakya et al, 2013;Beckers et al, 2017;Timm et al, 2018;Firrincieli et al, 2020); however, the genera of the two endophyte FIGURE 7 | KEGG functional category enrichment distributions displayed as an overall percent or absolute number of proteins identified in each category for those proteins determined to be significantly changed (p < 0.05) between Control and P-mix inoculated poplar roots using a t-test. A protein was designated to the Control or P-mix group depending on which group it displayed a higher abundance.…”

“…In another study, Burkholderiaceae comprised about 6% of the poplar rhizosphere (Beckers et al, 2017). Members of the Rahnella genus were one of the most abundant ASVs in P. trichocarpa in a poplar microbiome study that included the environment from which these strains were isolated (Firrincieli et al, 2020). Members of the family of Burkholderiaceae were up to about 20% of the microbial population in that study.…”

Mosquito Microbiome Diversity Varies Along a Landscape-Scale Moisture Gradient

“…We use a cross-sectional study design on O 'ahu to test for an association between relatively stable landscape variables (local climate, land use) and the composition of the mosquito microbiome at fine spatial scales. Several studies have used cross-sectional data to gain insights into distinct drivers of variation in host-associated microbiomes, including links between microbiome composition and local climate and land use [9,18,[25][26][27]. Specifically, Aedes albopictus females were captured from 50 sites across the island of O 'ahu (Fig.…”

Distinct Phyllosphere Microbiome of Wild Tomato Species in Central Peru upon Dysbiosis

“…In particular, phyllospheric microbes can be colonizer of the surface (epiphytes | phylloplane) and/or cytosolic compartment (endophytes | endosphere). Epiphytes have to cope continuously with changing microhabitat conditions, like light exposure (ultraviolet), high temperatures, and sparse nutrient and water availability and can be rather variable [37,41,58,71,76]. Besides abiotic stresses, biotic factors incorporate beneficial and pathogenic microbes influencing phyllosphere microbiota assemblies.…”