Lithium-induced alterations in soybean nodulation and nitrogen fixation through multifunctional mechanisms.

Area of Science:

• Agroecosystem science
• Environmental chemistry
• Plant biology

Background:

• Increasing lithium (Li) in agroecosystems poses risks to crops.
• The impact of Li on legume symbiosis and biological nitrogen fixation (BNF) is not well understood.

Purpose of the Study:

• To investigate the effects of Li exposure on soybean growth, root-nodule symbiosis, and BNF.
• To elucidate the underlying mechanisms of Li toxicity in soybean.

Main Methods:

• Soybean plants were exposed to varying concentrations of Li (25, 50, and 100 mg kg⁻¹).
• Evaluated soybean growth, nodulation parameters, and BNF potential.
• Analyzed nodule metabolic pathways and the abundance of nodule bacteria (Ensifer).

Main Results:

• Soybean growth and nodulation showed a concentration-dependent response to Li.
• High Li concentrations (100 mg kg⁻¹) significantly reduced nodule number, weight, and BNF.
• Li exposure altered nodule metabolism, particularly pathways for nitrogen uptake and metabolism.
• Reduced nodulation was linked to decreased abundance of the bacterium Ensifer.

Conclusions:

• Lithium contamination negatively impacts soybean's ability to fix nitrogen.
• Altered nodule metabolism and reduced Ensifer abundance contribute to Li-induced nodulation failure.
• Findings provide insights for managing Li challenges in agricultural systems.