Boron Increases Synthesis of Glutathione in Sunflower Plants Subjected to Aluminum Stress

Ionic stress caused by high aluminum (Al) concentrations is one of the most widespread phytotoxicity problems globally in agricultural regions, greatly limiting crop yield in affected areas. The objective of this work was to examine a possible involvement of boron (B) in the detoxification of Al by stimulating glutathione (GSH) metabolism, a mechanism essential for the resistance of plants under stress conditions. Our results clearly demonstrate that increased application of B in the presence of high Al concentrations in the growth medium stimulates GSH biosynthesis, suggesting it could be an effective strategy to combat stress associated with the formation of active-oxygen species (AOS). In the specific case of Al toxicity, B reduces phytotoxicity by stimulating leaf biosynthesis of GSH and an increase in its concentration in the roots. Therefore, in this work, we also identify GSH metabolism as one of the key processes in Al detoxification. Finally, our results imply that greater B application leads to a greater resistance to Al toxicity, a fact that might be significant for higher productivity of agricultural plants grown in acid soils.