Lanthanum (a rare earth element)-induced abscisic acid responses to modulate stomatal dynamics, nitrogen-carbon assimilation, metabolomic fingerprinting and yield traits in wheat

Abstract

Lanthanum (La), being one of the crucial rare earth elements (REEs), plays an explicit role in agriculture as fertilizer. Due to its hormetic response, it exhibits dualistic behaviour in Triticum aestivum (wheat) plants. Abscisic acid (ABA) is a key plant hormone regulating various physiological and metabolomic responses in plants, but the interaction between La and ABA remains unclear. The present study investigated the role of La at beneficial (60 µM) and toxic (80 µM) levels with ABA (10 µM) through carbon-nitrogen assimilation, metabolic, growth and yield responses. The study also shows that ABA plays a critical modulatory role at optimal concentrations in wheat, coordinating with La60 to confer beneficial physiological and yield effects and acting as a key regulator in reducing La-induced toxic responses. Further, together La60 and ABA significantly enhanced the stomatal dynamics and defense systems. The results also revealed that the nitrogenous compounds, lipids and their derivatives, and secondary metabolites are involved as a secondary defense through gas chromatography- mass spectrometry (GCMS) analysis. This study highlights finely tuned interactions between La doses and ABA to modulate growth and development in wheat plants and, therefore, ensuring their global food security. These findings suggest that managing La exposure at toxic levels could help mitigate potential toxicity in crops and reduces the risk of environmental accumulation and associated ecological impacts.