Potential Action of Defence Enzyme in Biotic Stress: A Review

Abstract

Plants are the ecosystem's primary source of energy and have a direct or indirect influence on human life. Pathogens and insects’ interference with the plants contributes to enormous losses in yield and productivity. Pathogens that can invade plants are capable of recognising and responding to their attack by activating security systems. Controls plant defence responses to the net pathogen attacks. Defense enzyme include that Catalase (CAT), superoxide dismutase (SOD), glutathione and other that helps protect the defense enzyme such as Beta-1,3 glucanase phenylalanise ammonia – lyase, peroxide, chitinase, chitosanase, and polyphenol oxidase. Beta-1,3 glucan and chitin are major polysaccharides in many fungal cell walls. As chitinase and Beta-1,3 glucanase are capable of attacking the fungal pathogen on the cell wall, they are suggested to participate in plant resistance against fungal pathogens. Some important examples of defence enzymes are chitinase, Beta 1,3 Glucanases, Superoxide dismutase, Catalase, Phenylalanine ammonia-lyase (PAL), Peroxide, Glutathione-S-transferase (GST), chitinases- breakdown chitin, a major component of fungal cell walls, helping to protect against fungal infections. Beta-1,3-glucanases – Degrade Beta-glucans found in the cell walls of various pathogens, including fungi, enhancing the plants' defence against infections. Peroxides – Involved in the production of reactive oxygen species to strengthen the cell walls, making it harder the pathogens to penetrate and cause damage to the pathogen cells. Polyphenol oxidases (PPOS)- catalyse the oxidation of phenolic compounds to quinones and can reinforce the cell wall by cross-linking with proteins. Lipoxygenases – Involved in the Synthesis of Jasmonic acid, a signalling molecule that activates defence response in plants. PAL – Involved in the synthesis of Phenolic compounds that contribute to plant defence by forming physical and chemical barriers against the pathogen.