Exopolysaccharides from Rhizobium tropici mitigate Al phytotoxicity in Triticum aestivum

Abstract

Aims

This study aims to investigate the impact of exopolysaccharides (EPS) from Rhizobium tropici on the growth of wheat (Triticum aestivum) seedlings under varying aluminum (Al) concentrations. We explored EPS mitigation of Al toxicity, a major growth-limiting factor in global acidic soils.

Methods

The effects of EPS on wheat were assessed by measuring shoot and root growth, photosynthesis, and lipid peroxidation under different Al concentrations. The study also examined Al uptake and transport within the plant as affected by EPS.

Results

Al exposure was found to substantially decrease shoot and root growth, impede photosynthesis, and cause intense lipid peroxidation in wheat. Application of EPS notably enhanced wheat growth, increasing shoot and root lengths by 86% and 244%, respectively, and dry biomasses of both shoots and roots by 100% and 104%, respectively, compared to the non-EPS treated group. EPS also limited Al absorption and transport in wheat, bolstering antioxidant defense against the oxidative stress. Subcellular analysis revealed that EPS promoted Al accumulation in cell walls and cytosol compartmentalization. Additionally, EPS appeared to regulate phosphorus (P) distribution within subcellular components, mitigating membrane lipid peroxidation and thereby enhancing plant’s Al resistance.

Conclusions

EPS effectively mitigates Al toxicity in wheat seedlings, suggesting its potential application for alleviating Al stress in plants. The study offers new perspectives for potential using EPS in agricultural practices, particularly in acidic soils. Future research should focus on field trials to validate these findings.