ACC Deaminase containing PGPR for potential exploitation in agriculture

Abstract

The beneficial free-living bacteria present in the plant rhizosphere are usually referred to as plant growth promoting rhizobacteria (PGPR). Among the various mechanisms of plant growth promotion, certain PGPR possess the enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase that cleaves plant-produced ACC, the immediate precursor of the stress hormone ethylene. ACC deaminase containing PGPR act as a sink for ACC and protects the developing seedlings from deleterious effects of stress ethylene that is synthesized during various environmental stresses like phytopathogens, flooding, drought, salt, heavy metals, organic contaminants, and high and low temperatures. ACC deaminase is a pyridoxyl 5′ phosphate-dependent enzyme and genes expressing this particular trait have been isolated and characterized from a number of PGPRs of different genera. Some of the rhizobacterial ACC deaminase genes have been already utilized in PGPR strain improvement as well as transgenic crop development. Several studies have reported the potential exploitation of ACC deaminase containing PGPR in improving the crop yields; improving self life and quality of vegetables and ornamental flowers; protecting crop plants against a range of abiotic and biotic stresses; and phytoremediation of organic pollutants and heavy metal contamination in soils.