Chitosan: A novel bioactive compound for mangement of plant diseases: A review

Abstract

Chitosan has received much interest for potential wide application in agriculture due to its excellent biocompatibility, biodegradability and bioactivity. Chitosan is, a linear polysaccharide composed of randomly distributed b-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit) is an environmental friendly product. Chitin can be easily obtained from shellfish waste. The chitosan molecule triggers defense responses within the plant, leading to the formation of physical and chemical barriers against invading pathogens. Chitosan has been used to stimulate the immunity of plants to protect plants against microorganisms. This protection leads stimulation of plant growth. Chitosan affects various physiological responses like plant immunity, defense mechanisms involving various enzymes such as, phenylalanine ammonium lyase, polyphenol oxidase, tyrosine ammonia lyase and antioxidant enzymes viz., activities superoxide dismutase, catalase and peroxide against adverse conditions. Recent studies have shown that chitosan induces mechanisms in plants against various biotic (fungi, bacteria, and insects) and abiotic (salinity, drought, heavy metal and cold) stresses and helps in formation of barriers that enhances plant’s productivity. Chitosan has also used as a promising postharvest treatment for fruits due to its natural character, antimicrobial activity and elicitation of defense responses. It has also been shown that chitosan promotes vegetative growth and enhances various processes in developing flower buds. Chitosan treatment have been reported that chitosan increased shoot length, root length, shoot dry weight and relative water content under salinity stress.