Table_7_Plant Nutrient Resource Use Strategies Shape Active Rhizosphere Microbiota Through Root Exudation.xlsx

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.

植物对土壤养分摄取的策略对植物-微生物群相互作用具有显著影响，这源于植物与微生物在土壤养分获取与/或保存方面的竞争。在本研究中，我们旨在探究这些植物策略是否能够通过根系分泌物影响根际微生物活动，并促进根际附着土壤（RAS）及根组织中栖息的活性细菌群落的微生物多样性。我们采用基于DNA的稳定同位素探针（DNA-SIP）方法，针对沿植物养分资源策略梯度分布的六种草本植物进行研究，该梯度从以低氮（N）吸收、长寿命和低根系分泌物水平为特征的保守物种，到以高光合速率、快速N吸收和高根系分泌物水平为特征的掠夺性物种。我们通过基于16S-rRNA的元条形码分析了它们参与根系分泌物同化和土壤有机质（SOM）降解的相关微生物群组成。（i）通过气相色谱法确定根系分泌物水平对微生物活动（反硝化和呼吸）的影响。（ii）测量结果显示，掠夺性物种的RAS中栖息的微生物群在反硝化和呼吸活动方面均有所增加。这种微生物活动的增加可能源于掠夺性植物物种更高的分泌物速率和更丰富的代谢产物。此外，我们的研究结果还表明，植物养分资源策略在塑造活性微生物群中发挥着作用。我们提供了证据，证明植物养分利用策略通过根系分泌物塑造了参与根系分泌物同化和SOM降解的活性微生物群。