Bacterial ACC-deaminase: An Eco-friendly Strategy to Cope Abiotic Stresses for Sustainable Agriculture

Abstract

Ethylene is the simplest unsaturated two-carbon gaseous plant hormone which regulates many physiological and developmental processes during plant growth at molecular level. High ethylene concentration, produced by virtually all higher plants under abiotic stresses such as drought, salinity, etc., acts as stress hormone which detrimentally affects the plant root growth, seed germination, and the whole plant growth. Under abiotic stresses like salinity and drought, the endogenous level of ethylene is enhanced substantially due to increased production of its immediate biochemical precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), and it shows major contribution in stress ethylene production under such type of stress conditions. Plant growth-promoting bacteria (PGPB) around the plant root surface or in the roots having a potent enzyme ACC-deaminase maintain ethylene level in plants under adverse environmental conditions (severe drought and high salinity) by the enzymatic degradation of ACC into α-ketobutyrate and ammonia as a carbon and nitrogen source. The use of PGPB containing ACC-deaminase as a bio-inoculant is a most powerful technique in agricultural biotechnology for sustainable crop production in terms of decreasing the detrimental effect of high ethylene concentration and improving growth and development of plants under extreme environmental conditions. In this chapter we endeavor to explore current research on maintaining the physiological and molecular changes in the plants under diverse environmental conditions (drought and high salinity) by the use of PGPB having ACC-deaminase, mode of ACC-deaminase enzyme action, and severe effects of salinity and drought on growth of plant special due to ethylene evolution.