Activation of phenylalanine ammonia lyase as a key component of the antioxidative system of salt-challenged maize leaves

Differential antioxidative activities were assessed in the leaves of two maize inbreds (A-180 and A-619) under salt stress and the subsequent recovery period. Total antioxidation test revealed that in both inbreds, this ability was sharply increased during stress period, but was slowly reverted back to the normal level during recovery. The enzymatic antioxidative analysis showed differential patterns in the activities of catalase, peroxidase and polyphenol oxidase in both maize inbreeds. Comparative analysis of the activity of phenylalanine ammonia lyase (PAL), a key enzyme at the gateway of propanoid biosynthetic pathway, suggested that propanoid compounds might be antioxidants of pivotal importance to the salt-challenged maize antioxidation system. As for drought-stressed plants, a PAL-dependent antioxidative strategy is proposed as a promising target for maize salt resistance engineering.