Drought and Plant Community Composition Affect the Metabolic and Genotypic Diversity of Pseudomonas Strains in Grassland Soils

Abstract

Climate and plant community composition (PCC) modulate the structure and function of microbial communities. In order to characterize how the functional traits of bacteria are affected, important plant growth-promoting rhizobacteria of grassland soil communities, pseudomonads, were isolated from a grassland experiment and phylogenetically and functionally characterized. The Miniplot experiment was implemented to examine the mechanisms underlying grassland ecosystem changes due to climate change, and it investigates the sole or combined impact of drought and PCC (plant species with their main distribution either in SW or NE Europe, and a mixture of these species). We observed that the proportion and phylogenetic composition of nutrient-releasing populations of the Pseudomonas community are affected by prolonged drought periods, and to a minor extent by changes in plant community composition, and that these changes underlie seasonality effects. Our data also partly showed concordance between the metabolic activities and 16S phylogeny. The drought-induced shifts in functional Pseudomonas community traits, phosphate and potassium solubilization and siderophore production did not follow a unique pattern. Whereas decreased soil moisture induced a highly active phosphate-solubilizing community, the siderophore-producing community showed the opposite response. In spite of this, no effect on potassium solubilization was detected. These results suggest that the Pseudomonas community quickly responds to drought in terms of structure and function, the direction of the functional response is trait-specific, and the extent of the response is affected by plant community composition.

Geographically Disperse, Culturable Seed-Associated Microbiota in Forage Plants of Alfalfa (Medicago sativa L.) and Pitch Clover (Bituminaria bituminosa L.): Characterization of Beneficial Inherited Strains as Plant Stress-Tolerance Enhancers

“…Some authors even defend that the use of siderophore-producing rhizobacteria can improve plant growth in such environments [ 110 ]. However, some authors have described, for Pseudomonas species, that as soil moisture decreased, phosphate solubilizers increased, but siderophore producers decreased [ 111 ]. Thus, it seems that phosphate solubilization is more relevant, but the seedborne strains we isolated appear to be able to assemble even more desirable capacities to improve plant tolerance in arid environments.…”

Mechanistic Insights and Potential Use of Siderophores Producing Microbes in Rhizosphere for Mitigation of Stress in Plants Grown in Degraded Land

“…Siderophore-producing microbes can produce plant growth-promoting attributes such as plant hormones, phosphate solubilization, secondary metabolites, etc., and provide suitable environments in stressed soil that enhances plant growth such as drought (Vivas et al, 2003 ; Breitkreuz et al, 2021 ). B. subtilis produce iron-chelating compounds that enhance the nutrient level in soil resulting in the growth of wheat plants under drought conditions (Lastochkina et al, 2020 ).…”

“…in lettuce increases the nitrogen, phosphorous, and potassium nutrients under drought stress conditions (Vivas et al, 2003 ). Siderophore-producing microbe Pseudomonas strains enhance the soil nutrients and other activities, including phosphate solubilization, potassium solubilization, and siderophore production under drought conditions (Breitkreuz et al, 2021 ).…”

Biodiversity and Ecosystem Function under Simulated Gradient Warming and Grazing

“…Moreover, it is well known that ecosystem biodiversity should include the diversity of organisms at multiple trophic levels, and there are several interactions among these biodiversity indexes that affect ecosystem function (productivity) [ 14 , 15 ]. For example, plant biodiversity affects microbial diversity by influencing the state of substrates (soil organic matter) decomposed by microorganisms [ 16 , 17 ], and microorganisms exert feedback on plant community composition by altering soil nutrients [ 18 ]. Finally, the interaction of plants and microorganisms can collaboratively influence ecosystem function (vegetation productivity, soil carbon and soil nitrogen stocks, etc.)…”