Stimulating the plant-microorganism-mineral continuum to store carbon in soils: focus on the stabilization of root exudates

Wagon Sarah, Basile-Doelsch Isabelle, Doelsch Emmanuel, Achouak Wafa, Heulin Thierry. 2023. Stimulating the plant-microorganism-mineral continuum to store carbon in soils: focus on the stabilization of root exudates. In : 16th Plant Bacteria Meeting. Abstract Booklet. INRAE. Aussois : INRAE, Résumé, 166. Rencontres plantes-bactéries. 16, Aussois, France, 20 Mars 2023/24 Mars 2023.

Résumé : Soil carbon storage can both mitigate climate change and contribute to food security. A recent study identified that pearl millet lines with large rhizosheath contribute significantly to increased carbon supply into soil compared to millet lines with small rhizosheath. The objective of this work is to evaluate the stabilization of these carbon inputs by the formation of organo-mineral associations in the plant-microorganism-mineral continuum. Different lines or pearl millet were selected and grown on a Mediterranean arenosol sampled under two different soil uses: vineyard and forest. The rhizosheath of these lines were compared by measuring the dry mass of root-adhering soil per dry mass of root tissue (RAS/RT). Soil organic carbon was measured (elemental analysis) in different compartments: root-adhering soil, bulk soil and control unplanted soil. Moreover, an analysis of the microbiota by metabarcoding was performed on the three compartments (roots, root-adhering soil and bulk soil). First, we verified that the ranking of millet lines according to the RAS/RT ratio was identical to that obtained on another arenosol in a previous work. Then, we highlighted that the lines with higher aggregation capacity were characterized by a higher carbon content in the root-adhering soil. The analysis of the microbiota is ongoing. Alpha diversity is expected to be lower in vineyard soil due to the fungicide treatments. We also hypothesize that pearl millet lines with high aggregation capacity recruit exopolysaccharide-producing bacteria and that these molecules promote carbon storage thanks to interactions with weathered mineral surfaces.

Auteurs et affiliations

• Wagon Sarah, CIRAD-PERSYST-UPR Recyclage et risque (FRA)
• Basile-Doelsch Isabelle, CEREGE (FRA)
• Doelsch Emmanuel, CIRAD-PERSYST-UPR Recyclage et risque (FRA) ORCID: 0000-0002-7478-4296
• Achouak Wafa, CEA (FRA)
• Heulin Thierry, CNRS (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/606525/)

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