Selenium is involved in the detoxification of methylglyoxal in Arabidopsis seedlings

摘要

Methylglyoxal (MG) is a highly cytotoxic metabolite produced primarily as a byproduct of glycolysis, against which plants intrinsically possess protective systems. On the other hand, selenium (Se) has become an element of interest to many plant scientists owing to its vast array of beneficial roles in plant physiology. In this study, I have addressed MG-associated cellular response to Se supplementation in Arabidopsis thaliana . While the content of intracellular MG along with that of malondialdehyde, a molecular readout of cellular damage, was increased with the increase in exogenous MG, the dose-dependent increase of these unwanted compounds was significantly moderated in Se-supplemented seedlings as compared with plants without Se uptake. Assay of MG detoxifying enzymes revealed that activities of glyoxalase II and aldo-keto reductase were enhanced in the seedlings when supplemented with Se, with the induction being advanced in association with increasing MG dosage. Another assay was conducted for antioxidant enzyme; inhibition of the activity of ascorbate peroxidase by MG was alleviated on Se supplementation to the seedlings, and this favorable effect of Se intervention appeared more remarkablely for its chloroplast stromal isozyme than for its cytosolic isozyme, indicative of stroma-biased protective functions of Se in Arabidopsis seedlings. The present results show that a trace amount of Se contributes to MG detoxification in Arabidopsis thaliana , which presumably results at least in part from its positive regulation of the enzyme activities for MG metabolism and radical scavenging.