O PAPEL DAS ENZIMAS ANTIOXIDANTES NA DEFESA DAS PLANTAS CONTRA INSETOS HERBÍVOROS E FITOPATÓGENOS

Abstract

Many plants suffer significant biochemical changes in response the attack of biotic stressors, such as phytopathogens or herbivorous insects. When any of these biotic stressors attack plants, this causes quick responses via an "oxidative burst”, which constitutes the production of reactive oxygen species (ROS), particularly superoxide anion (O2 •-) and hydrogen peroxide (H2O2). The accumulation of these substances in vegetal cells can be toxic to both the biotic stressors and plants. These ROS will trigger molecules for the induction of defense genes and polymerization of proteins that makes up the cell walls, as well as stimulate the production of antioxidant enzymes or scavenging. There are a variety of these enzymes that will decompose the reactive oxygen species; the superoxide dismutase (SOD), peroxidase (POX), catalase (CAT) and polyphenol oxidase (PPO) are some examples. This review will describe how herbivory and pathogenic triggers cause an oxidative burst stimulating the defense system of the plants with the actions of antioxidant enzymes.