Cargando…
Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland
Droughts strongly affect carbon and nitrogen cycling in grasslands, with consequences for ecosystem productivity. Therefore, we investigated how experimental grassland communities interact with groups of soil microorganisms. In particular, we explored the mechanisms of the drought-induced decoupling...
Autores principales: | , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2018
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234839/ https://www.ncbi.nlm.nih.gov/pubmed/30464767 http://dx.doi.org/10.3389/fpls.2018.01593 |
_version_ | 1783370788995334144 |
---|---|
author | Karlowsky, Stefan Augusti, Angela Ingrisch, Johannes Akanda, Mohammad Kamal Uddin Bahn, Michael Gleixner, Gerd |
author_facet | Karlowsky, Stefan Augusti, Angela Ingrisch, Johannes Akanda, Mohammad Kamal Uddin Bahn, Michael Gleixner, Gerd |
author_sort | Karlowsky, Stefan |
collection | PubMed |
description | Droughts strongly affect carbon and nitrogen cycling in grasslands, with consequences for ecosystem productivity. Therefore, we investigated how experimental grassland communities interact with groups of soil microorganisms. In particular, we explored the mechanisms of the drought-induced decoupling of plant photosynthesis and microbial carbon cycling and its recovery after rewetting. Our aim was to better understand how root exudation during drought is linked to pulses of soil microbial activity and changes in plant nitrogen uptake after rewetting. We set up a mesocosm experiment on a meadow site and used shelters to simulate drought. We performed two (13)C-CO(2) pulse labelings, the first at peak drought and the second in the recovery phase, and traced the flow of assimilates into the carbohydrates of plants and the water extractable organic carbon and microorganisms from the soil. Total microbial tracer uptake in the main metabolism was estimated by chloroform fumigation extraction, whereas the lipid biomarkers were used to assess differences between the microbial groups. Drought led to a reduction of aboveground versus belowground plant growth and to an increase of (13)C tracer contents in the carbohydrates, particularly in the roots. Newly assimilated (13)C tracer unexpectedly accumulated in the water-extractable soil organic carbon, indicating that root exudation continued during the drought. In contrast, drought strongly reduced the amount of (13)C tracer assimilated into the soil microorganisms. This reduction was more severe in the growth-related lipid biomarkers than in the metabolic compounds, suggesting a slowdown of microbial processes at peak drought. Shortly after rewetting, the tracer accumulation in the belowground plant carbohydrates and in the water-extractable soil organic carbon disappeared. Interestingly, this disappearance was paralleled by a quick recovery of the carbon uptake into metabolic and growth-related compounds from the rhizospheric microorganisms, which was probably related to the higher nitrogen supply to the plant shoots. We conclude that the decoupling of plant photosynthesis and soil microbial carbon cycling during drought is due to reduced carbon uptake and metabolic turnover of rhizospheric soil microorganisms. Moreover, our study suggests that the maintenance of root exudation during drought is connected to a fast reinitiation of soil microbial activity after rewetting, supporting plant recovery through increased nitrogen availability. |
format | Online Article Text |
id | pubmed-6234839 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-62348392018-11-21 Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland Karlowsky, Stefan Augusti, Angela Ingrisch, Johannes Akanda, Mohammad Kamal Uddin Bahn, Michael Gleixner, Gerd Front Plant Sci Plant Science Droughts strongly affect carbon and nitrogen cycling in grasslands, with consequences for ecosystem productivity. Therefore, we investigated how experimental grassland communities interact with groups of soil microorganisms. In particular, we explored the mechanisms of the drought-induced decoupling of plant photosynthesis and microbial carbon cycling and its recovery after rewetting. Our aim was to better understand how root exudation during drought is linked to pulses of soil microbial activity and changes in plant nitrogen uptake after rewetting. We set up a mesocosm experiment on a meadow site and used shelters to simulate drought. We performed two (13)C-CO(2) pulse labelings, the first at peak drought and the second in the recovery phase, and traced the flow of assimilates into the carbohydrates of plants and the water extractable organic carbon and microorganisms from the soil. Total microbial tracer uptake in the main metabolism was estimated by chloroform fumigation extraction, whereas the lipid biomarkers were used to assess differences between the microbial groups. Drought led to a reduction of aboveground versus belowground plant growth and to an increase of (13)C tracer contents in the carbohydrates, particularly in the roots. Newly assimilated (13)C tracer unexpectedly accumulated in the water-extractable soil organic carbon, indicating that root exudation continued during the drought. In contrast, drought strongly reduced the amount of (13)C tracer assimilated into the soil microorganisms. This reduction was more severe in the growth-related lipid biomarkers than in the metabolic compounds, suggesting a slowdown of microbial processes at peak drought. Shortly after rewetting, the tracer accumulation in the belowground plant carbohydrates and in the water-extractable soil organic carbon disappeared. Interestingly, this disappearance was paralleled by a quick recovery of the carbon uptake into metabolic and growth-related compounds from the rhizospheric microorganisms, which was probably related to the higher nitrogen supply to the plant shoots. We conclude that the decoupling of plant photosynthesis and soil microbial carbon cycling during drought is due to reduced carbon uptake and metabolic turnover of rhizospheric soil microorganisms. Moreover, our study suggests that the maintenance of root exudation during drought is connected to a fast reinitiation of soil microbial activity after rewetting, supporting plant recovery through increased nitrogen availability. Frontiers Media S.A. 2018-11-07 /pmc/articles/PMC6234839/ /pubmed/30464767 http://dx.doi.org/10.3389/fpls.2018.01593 Text en Copyright © 2018 Karlowsky, Augusti, Ingrisch, Akanda, Bahn and Gleixner. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Plant Science Karlowsky, Stefan Augusti, Angela Ingrisch, Johannes Akanda, Mohammad Kamal Uddin Bahn, Michael Gleixner, Gerd Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland |
title | Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland |
title_full | Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland |
title_fullStr | Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland |
title_full_unstemmed | Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland |
title_short | Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland |
title_sort | drought-induced accumulation of root exudates supports post-drought recovery of microbes in mountain grassland |
topic | Plant Science |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234839/ https://www.ncbi.nlm.nih.gov/pubmed/30464767 http://dx.doi.org/10.3389/fpls.2018.01593 |
work_keys_str_mv | AT karlowskystefan droughtinducedaccumulationofrootexudatessupportspostdroughtrecoveryofmicrobesinmountaingrassland AT augustiangela droughtinducedaccumulationofrootexudatessupportspostdroughtrecoveryofmicrobesinmountaingrassland AT ingrischjohannes droughtinducedaccumulationofrootexudatessupportspostdroughtrecoveryofmicrobesinmountaingrassland AT akandamohammadkamaluddin droughtinducedaccumulationofrootexudatessupportspostdroughtrecoveryofmicrobesinmountaingrassland AT bahnmichael droughtinducedaccumulationofrootexudatessupportspostdroughtrecoveryofmicrobesinmountaingrassland AT gleixnergerd droughtinducedaccumulationofrootexudatessupportspostdroughtrecoveryofmicrobesinmountaingrassland |