Signaling Molecule Methylglyoxal Remits the Toxicity of Plumbum by Modifying Antioxidant Enzyme and Osmoregulation Systems in Wheat (Triticum aestivum L.) Seedlings

Abstract

Methylglyoxal (MG) has traditionally been known as a toxic byproduct of cellular metabolism in plants, which now has been found to function as a novel signaling molecule, participating in overall life cycle of plants from seed germination to senescence. However, wheat (Triticum aestivum L.) as the second crop in China, whether MG can remit the toxicity of plumbum (Pb) in plant is unknown. In this study, Pb stress showed a visible damage symptom, as reflected in a growth inhibition of wheat seedlings. The growth inhibition by Pb was mitigated by exogenous application of MG, implying that MG could alleviate Pb toxicity in wheat seedlings. To further understand the possible mechanisms of the MG-alleviated Pb toxicity, the activities of antioxidant enzymes (ascorbate peroxidase: APX, guaiacol peroxidase: GPX, catalase: CAT, and superoxide dismutase: SOD) and the contents of osmolytes, proline (Pro), trehalose (Tre), and total soluble sugar (TSS), were determined. The data exhibited that Pb stress activated APX, GPX, and CAT, as well as increased Pro, Tre, and TSS levels to varying degrees in both leaves and roots of wheat seedlings. This activation and increase was further intensified by the exogenous administration of MG, hinting that antioxidant enzyme and osmoregulation systems played a synergistic effect in MG-ameliorated the tolerance of wheat seedlings to Pb stress. The present study indicated that signaling molecule MG could remit the toxicity of Pb in wheat seedlings by modifying antioxidant enzyme and osmoregulation systems.