The effect of cadmium stress on phytochelatin, thiol and polyamine content in maize

Introduction Cadmium was found to generate oxidative stress via activated oxygen radicals, and to cause membrane damage due to lipid peroxidation. Plants synthesize antioxidant enzymes and molecules, such as glutathione, or phytochelatins (PCs), that may prevent the cellular damage induced by heavy metals (Sanita di Toppi and Gabbrielli 1999). During the last few years polyamines (Pas) have also been reported as efficient antioxidants and suggested to function as metal chelators (Lovaas 1996). Glutathione (GSH), as an important component of the ascorbate-glutathione cycle, plays a role in protecting plants from oxidative stress. In the biosynthesis of GSH, the first reaction forms y-glutamylcysteine (y-EC) from glutamate and cysteine, and then GSH is synthesized