Anti-oxidant enzymes during trace metal stress in alfalfa stems and their implication in cell wall dynamics

Abstract

The economic importance of plants in agriculture can be summarized in 4 words: food, feed, fiber and fuel. Of tremendous importance to each one of these are biopolymers. Biopolymers of particular interest are the components of lignocellulose, the building block of the plant cell wall. These biopolymers (cellulose, lignin and hemicellulose) have various applications and are most abundant in plant stems. Polymerization of some of these macro-molecules, such as lignin, is dependent on (anti-)oxidative enzymes, the primary role of which is to safeguard the oxidative balance of the cell. The oxidative balance can be disturbed by the excess of metal trace elements such as copper and zinc, which will first encounter the apoplast before being able to damage the protoplast. Presence of these metals might thus modify the composition of the cell wall by influencing various anti-oxidative enzymes, and thus might have agricultural and economic implications. This research aimed to investigate the activity of key enzymes and metabolites, that are involved in both the anti-oxidative defense of the plant and bio-polymerization in the cell wall in the stem tissue of Medicago sativa (alfalfa), exposed to excess copper and zinc.