Bacterial communities differ between plant species and soil type, and differentially influence seedling establishment on serpentine soils

Abstract

Root-associated microbial communities influence plant phenotype, growth and local abundance, yet the factors that structure these microbial communities are still poorly understood. California landscapes contain serpentine soils, which are nutrient-poor and high in heavy metals, and distinct from neighboring soils. Here, we surveyed the rhizoplane of serpentine-indifferent plants species growing on serpentine and non-serpentine soils to determine the relative influence of plant identity and soil chemistry on rhizoplane microbial community structure using 16S rRNA metabarcoding. Additionally, we experimentally examined if locally adapted microorganisms enhance plant growth in serpentine soil. Plant species, soil chemistry, and the interaction between them were important in structuring rhizoplane bacterial communities in both the field and experimental soils. In the experiment, rhizoplane microbial community source influenced seedling survival, but plant growth phenotypes measured were largely invariant to microbial community with a few exceptions. Results from the field sampling suggest that plant species associate with specific microbial communities even across chemically distinct soils, and that microbial communities can differentially influence seedling survival on harsh serpentine soils.

Plant phenology influences rhizosphere microbial community and is accelerated by serpentine microorganisms inPlantago erecta

“…Soils were collected from McLaughlin Natural Reserve in June 2018 from three serpentine and three nonserpentine sites (Sites 1, 2, and 3 from Igwe and Vannette 2019). McLaughlin Natural Reserve is characterized by a Mediterranean climate with hot and dry summers from April to October.…”

“…While most plants cannot grow on serpentine soils and other plants can only grow on serpentine soil, serpentine-indifferent plants are able to thrive on serpentine soils and compete on non-serpentine soils (Safford et al 2005). Serpentine-indifferent plants, with their ability to grow both on and off serpentine soils, are an excellent tool with which to study how soil chemistry influences microbial composition and phenology (Igwe and Vannette 2019). In addition, by utilizing soil treatments with non-adapted microorganisms we can understand how phenology is influenced by different microbial communities.…”

Potentilla anserina L. developmental changes affect the rhizosphere prokaryotic community

“…Rhizosphere microbial diversity is also determined by the genotype of the host plant 21 – 28 and soil physicochemical characteristics, including nutrient composition (nitrogen and phosphorus contents), pH value, the ratio of carbon to nitrogen, and texture 26 , 29 – 33 . Evidence suggests that novel plant varieties capable of producing new carbon compounds rapidly select and accumulate bacteria capable of metabolizing these compounds during rhizosphere development 34 .…”

Invasive grass dominance over native forbs is linked to shifts in the bacterial rhizosphere microbiome

“…Their invasion into finer-textured serpentine areas is promoted through nutrient addition and increased rainfall [42], which leads to a fungal community more like that of heavily-invaded nonserpentine soils [43]. In native-dominated serpentine areas, microbes have been shown to increase seedling survival [44] and facilitate their ability to thrive in heavy metal soils [45]. With the invasion of grasses, changes in the microbiome may strengthen the advantage that these grasses have over native forbs if they are able to recruit beneficial microbes away from natives or harbor novel microbes harmful to native forbs.…”