PS 45-104 - CANCELLED - Drivers of phyllosphere plant-bacterial associations across the plant tree of life

Wednesday, August 17, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

SD

Salix Dubois

Université du Québec à Montréal
Montréal, Quebec, Canada

Coauthor(s)

SK

Steven W. Kembel

Professor
Université du Québec à Montréal, Quebec, Canada
GL

Geneviève Lajoie

Institut de recherche en biologie végétale
Montréal, Quebec, Canada

Background/Question/Methods

The phyllosphere (plant leaves) is a habitat that harbours taxonomically diverse bacterial assemblages that contribute to the health of their hosts, in particular by promoting plant growth and resistance to stress. The composition of these phyllosphere microbial communities is in turn influenced by the attributes of the host plant as well as its environment (habitat characteristics). Host plant taxonomy, ecology and the environment have been identified as drivers of plant-bacteria associations in the phyllosphere by several studies. However, most of these studies have focused on spatially, ecologically or phylogenetically restricted sets of host taxa, and thus phyllosphere plant-bacteria associations at the scale of the plant tree of life remain poorly understood. Here we address the following questions: 1) What is the relative importance of potential drivers of phyllosphere plant-bacteria associations across the plant tree of life? 2) How does the importance of these factors vary across host clades and habitats? To answer these questions, we sampled epiphytic bacteria from the phyllosphere of approximately 400 species of host plants at the Montreal Botanical Garden. Bacterial DNA was amplified by targeting 16S rRNA gene and sequenced on the Illumina MiSeq platform. Host plant traits and phylogeny data were collected from existing databases.

Results/Conclusions

We found significant variation in the composition and diversity of phyllosphere bacterial communities across major plant host clades. The bacterial taxaBacteroidota, Deinococcota, Actinobacteriota and Alphaproteobacteria dominated these communities. The bacterial phylum Deinococcota was more strongly associated with hosts from the class Magnoliopsida while the bacterial class Alphaproteobacteria was more strongly associated with the host class Pinopsida. Host attributes including plant traits, biogeography, and environmental characteristics influenced phyllosphere bacterial community structure, and the relative importance of these factors differed across major plant clades. Using an evolutionarily informed approach to quantify relationships between these drivers and phyllosphere bacterial communities, we were able to identify evolutionary associations among numerous plant and bacterial clades that arose at different phylogenetic depths in the plant and bacterial trees of life. Our results highlight the importance of considering different phylogenetic and spatial/environmental scales, and we provide the first truly comprehensive evaluation of the drivers of plant-bacterial associations on leaves across the plant tree of life.