Changes in soil microbiota alter root exudation and rhizosphere pH of the gypsum endemic Ononis tridentata L.
de la Puente, L., Echevarría, L., Igual, J.M., Ferrio, J.P., Palacio, S. (2024) Changes in soil microbiota alter root exudation and rhizosphere pH of the gypsum endemic Ononis tridentata L.. Plant Soil (2024). https://doi.org/10.1007/s11104-024-06691-x
Background and aims
Plants living on gypsum are adapted to uptake nutrients in extremely poor alkaline soils. Under such extreme conditions, processes affecting the chemical conditions of the rhizosphere may be crucial for plant survival and growth. Rhizosphere acidification in plants living on gypsum soils has never been reported before and the effect of root exudation and microbes on the rhizosphere pH remains undescribed.
Methods
In this study we cultivated seeds of the gypsum specialist Ononis tridentata in rhizoboxes with natural gypsum soil and with gypsum soil with reduced microbiota, and monitored changes in the rhizosphere pH with planar optodes coupled to a calibrated image recording system. Soil microbial life was estimated with PLFAs analyses and root exudation was characterised.
Results
The reduced microbiota treatment decreased both fungal and microbial presence. Plants grown in natural soil, with unaltered presence of soil microbiota, had lower rhizosphere pH. However, in the microbial-reduced treatment we found higher root exudation of several organic acids and alcohols such as malonic and isocitric acids and sorbitol-mannitol. Interestingly, plant biomass was not significantly altered by treatments.
Conclusion
The natural soil microbiota contributed to acidify alkaline gypsum soils, likely improving nutrient availability. However, O. tridentata seedlings grown in microbial-reduced soils seemed to compensate the effects of microbes through increased root exudation, attaining similar growth both in natural and microbial-reduced soils. These seedlings seemed to be adapted to soil where microbial abundance fluctuates.
Background and aims
Plants living on gypsum are adapted to uptake nutrients in extremely poor alkaline soils. Under such extreme conditions, processes affecting the chemical conditions of the rhizosphere may be crucial for plant survival and growth. Rhizosphere acidification in plants living on gypsum soils has never been reported before and the effect of root exudation and microbes on the rhizosphere pH remains undescribed.
Methods
In this study we cultivated seeds of the gypsum specialist Ononis tridentata in rhizoboxes with natural gypsum soil and with gypsum soil with reduced microbiota, and monitored changes in the rhizosphere pH with planar optodes coupled to a calibrated image recording system. Soil microbial life was estimated with PLFAs analyses and root exudation was characterised.
Results
The reduced microbiota treatment decreased both fungal and microbial presence. Plants grown in natural soil, with unaltered presence of soil microbiota, had lower rhizosphere pH. However, in the microbial-reduced treatment we found higher root exudation of several organic acids and alcohols such as malonic and isocitric acids and sorbitol-mannitol. Interestingly, plant biomass was not significantly altered by treatments.
Conclusion
The natural soil microbiota contributed to acidify alkaline gypsum soils, likely improving nutrient availability. However, O. tridentata seedlings grown in microbial-reduced soils seemed to compensate the effects of microbes through increased root exudation, attaining similar growth both in natural and microbial-reduced soils. These seedlings seemed to be adapted to soil where microbial abundance fluctuates.