Plant Nutrient Resource Use Strategies Shape Active Rhizosphere Microbiota Through Root Exudation

Abstract

Plant strategies for soil nutrient uptake have the potential to strongly influence plant–microbiota interactions, due to the competition between plants and microorganisms for soil nutrient acquisition and/or conservation. In the present study, we investigate whether these plant strategies could influence rhizosphere microbial activities via root exudation, and contribute to the microbiota diversification of active bacterial communities colonizing the root-adhering soil (RAS) and inhabiting the root tissues. We applied a DNA-based stable isotope probing (DNA-SIP) approach to six grass species distributed along a gradient of plant nutrient resource strategies, from conservative species, characterized by low nitrogen (N) uptake, a long lifespans and low root exudation level, to exploitative species, characterized by high rates of photosynthesis, rapid rates of N uptake and high root exudation level. We analyzed their (i) associated microbiota composition involved in root exudate assimilation and soil organic matter (SOM) degradation by 16S-rRNA-based metabarcoding. (ii) We determine the impact of root exudation level on microbial activities (denitrification and respiration) by gas chromatography. Measurement of microbial activities revealed an increase in denitrification and respiration activities for microbial communities colonizing the RAS of exploitative species. This increase of microbial activities results probably from a higher exudation rate and more diverse metabolites by exploitative plant species. Furthermore, our results demonstrate that plant nutrient resource strategies have a role in shaping active microbiota. We present evidence demonstrating that plant nutrient use strategies shape active microbiota involved in root exudate assimilation and SOM degradation via root exudation.

The diversity of soil microbial communities matters when legumes face drought

“…Positive, negative, or neutral effects of microbial diversity are highlighted by upward arrows, downward arrows, and crossed circle, respectively. Black symbols represent measured effects, whereas grey symbols represent putative effects based on the literature: (1) Maron et al (), (2) Baumann et al (), (3) Bonfante (), (4) Marschner and Dell (), (5) Helliwell et al (), (6) Naveed et al (), (7) Redmile‐Gordon et al (), (8) Guyonnet et al (), and (9) Birch () [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Black symbols represent measured effects while grey symbols represent putative effects based on the literature. (1) Maron et al, ; (2) Baumann et al, ; (5) Hellwell et al, 2014; (6) Naveed et al, ; (7) Redmile‐Gordon et al, ; (8) Guyonnet et al, ; (9) Birch, . Under well‐watered conditions (a), higher soil microbial diversity leads to a stimulation of root biomass but not through root branching.…”

Effects of Sea Animal Activities on Tundra Soil Denitrification and nirS‐ and nirK-Encoding Denitrifier Community in Maritime Antarctica

“…Nir encoded by nirS or nirK is structurally different but functionally equivalent ( Shrewsbury et al, 2016 ). The nirS and nirK have been investigated in a variety of environments, including ocean ( Braker et al, 2000 ; Shi et al, 2019 ), estuarine ( Zheng et al, 2015 ; Gao et al, 2016 ), river and bay ( Huang et al, 2011 ; Lee and Francis, 2017 ), wetland ( Priemé et al, 2002 ), glacier foreland and arctic tundra ( Heylen et al, 2006 ; Palmer et al, 2012 ), and in the rhizosphere ( Guyonnet et al, 2018 ; Achouak et al, 2019 ). The nirK is found to be far less abundant than nirS in many environments ( Mosier and Francis, 2010 ; Francis et al, 2013 ; Smith et al, 2015 ).…”

What drives the assembly of plant-associated protist microbiomes?

“…For rhizosphere bacteria a bottom-up regulation through resource supply from roots is seen as the major driver of community selection (Bakker et al , 2015; Sasse et al , 2018). The composition of root exudates, by providing a crucial energy source for soil microorganisms (Kuzyakov and Blagodatskaya, 2015) and containing secondary metabolites as microbial attractants or chemical deterrents have been suggested to select for the plant species specific microbiomes (Guyonnet et al , 2018; Sasse et al , 2018).…”