The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry
The rhizosphere is a hot spot of soil microbial activity and is largely fed by root exudation. The carbon (C) exudation flux, coupled with plant growth, is considered a strategy of plants to facilitate nutrient uptake. C exudation is accompanied by a release of nutrients. Nitrogen (N) and phosphorus...
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MDPI AG
2021-08-01
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| Series: | Land |
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| Online Access: | https://www.mdpi.com/2073-445X/10/8/840 |
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| author | Julian Cardenas Fernando Santa Eva Kaštovská |
| author_facet | Julian Cardenas Fernando Santa Eva Kaštovská |
| author_sort | Julian Cardenas |
| collection | DOAJ |
| description | The rhizosphere is a hot spot of soil microbial activity and is largely fed by root exudation. The carbon (C) exudation flux, coupled with plant growth, is considered a strategy of plants to facilitate nutrient uptake. C exudation is accompanied by a release of nutrients. Nitrogen (N) and phosphorus (P) co-limit the productivity of the plant-microbial system. Therefore, the C:N:P stoichiometry of exudates should be linked to plant nutrient economies, plant functional traits (PFT) and soil nutrient availability. We aimed to identify the strongest links in C:N:P stoichiometry among all rhizosphere components. A total of eight grass species (from conservative to exploitative) were grown in pots under two different soil C:nutrient conditions for a month. As a result, a wide gradient of plant–microbial–soil interactions were created. A total of 43 variables of plants, exudates, microbial and soil C:N:P stoichiometry, and PFTs were evaluated. The variables were merged into four groups in a network analysis, allowing us to identify the strongest connections among the variables and the biological meaning of these groups. The plant–soil interactions were shaped by soil N availability. Faster-growing plants were associated with lower amounts of mineral N (and P) in the soil solution, inducing a stronger competition for N with microorganisms in the rhizosphere compared to slower-growing plants. The plants responded by enhancing their N use efficiency and root:shoot ratio, and they reduced N losses via exudation. Root growth was supported either by reallocated foliar reserves or by enhanced ammonium uptake, which connected the specific leaf area (SLA) to the mineral N availability in the soil. Rapid plant growth enhanced the exudation flux. The exudates were rich in C and P relative to N compounds and served to release surplus metabolic products. The exudate C:N:P stoichiometry and soil N availability combined to shape the microbial stoichiometry, and N and P mining. In conclusion, the exudate flux and its C:N:P stoichiometry reflected the plant growth rate and nutrient constraints with a high degree of reliability. Furthermore, it mediated the plant–microbial interactions in the rhizosphere. |
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| institution | Directory Open Access Journal |
| issn | 2073-445X |
| language | English |
| last_indexed | 2024-03-10T08:40:29Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Land |
| spelling | doaj.art-e8ee19739974479eb740d9f031d26d032023-11-22T08:21:15ZengMDPI AGLand2073-445X2021-08-0110884010.3390/land10080840The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial StoichiometryJulian Cardenas0Fernando Santa1Eva Kaštovská2Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech RepublicNova Information Management School (NOVA IMS), Universidade Nova de Lisboa, 1070-312 Lisbon, PortugalFaculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech RepublicThe rhizosphere is a hot spot of soil microbial activity and is largely fed by root exudation. The carbon (C) exudation flux, coupled with plant growth, is considered a strategy of plants to facilitate nutrient uptake. C exudation is accompanied by a release of nutrients. Nitrogen (N) and phosphorus (P) co-limit the productivity of the plant-microbial system. Therefore, the C:N:P stoichiometry of exudates should be linked to plant nutrient economies, plant functional traits (PFT) and soil nutrient availability. We aimed to identify the strongest links in C:N:P stoichiometry among all rhizosphere components. A total of eight grass species (from conservative to exploitative) were grown in pots under two different soil C:nutrient conditions for a month. As a result, a wide gradient of plant–microbial–soil interactions were created. A total of 43 variables of plants, exudates, microbial and soil C:N:P stoichiometry, and PFTs were evaluated. The variables were merged into four groups in a network analysis, allowing us to identify the strongest connections among the variables and the biological meaning of these groups. The plant–soil interactions were shaped by soil N availability. Faster-growing plants were associated with lower amounts of mineral N (and P) in the soil solution, inducing a stronger competition for N with microorganisms in the rhizosphere compared to slower-growing plants. The plants responded by enhancing their N use efficiency and root:shoot ratio, and they reduced N losses via exudation. Root growth was supported either by reallocated foliar reserves or by enhanced ammonium uptake, which connected the specific leaf area (SLA) to the mineral N availability in the soil. Rapid plant growth enhanced the exudation flux. The exudates were rich in C and P relative to N compounds and served to release surplus metabolic products. The exudate C:N:P stoichiometry and soil N availability combined to shape the microbial stoichiometry, and N and P mining. In conclusion, the exudate flux and its C:N:P stoichiometry reflected the plant growth rate and nutrient constraints with a high degree of reliability. Furthermore, it mediated the plant–microbial interactions in the rhizosphere.https://www.mdpi.com/2073-445X/10/8/840rhizosphereC:N:P ratiosplant growthmineral Nsoil enzymatic activitymicrobial growth |
| spellingShingle | Julian Cardenas Fernando Santa Eva Kaštovská The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry Land rhizosphere C:N:P ratios plant growth mineral N soil enzymatic activity microbial growth |
| title | The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry |
| title_full | The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry |
| title_fullStr | The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry |
| title_full_unstemmed | The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry |
| title_short | The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry |
| title_sort | exudation of surplus products links plant functional traits and plant microbial stoichiometry |
| topic | rhizosphere C:N:P ratios plant growth mineral N soil enzymatic activity microbial growth |
| url | https://www.mdpi.com/2073-445X/10/8/840 |
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