Alleviation of Stress-Induced Ethylene-Mediated Negative Impact on Crop Plants by Bacterial ACC Deaminase: Perspectives and Applications in Stressed Agriculture Management

Abstract

The environmental stresses such as heavy metal toxicity, salinity, water deficit, flooding, extreme temperatures, nutrient deficiency, and pathogenicity, which are considered to be the most important limiting factors for agricultural production, are rising all over the world. The occurrence and magnitude of environmental (abiotic and biotic) stresses might augment in the near future because of global climate change. These stresses lead to a significant reduction in yield and growth of stressed plants. It is well known that a sizable portion of the damage that occurs in stress-sensitive crop varieties as a consequence of abiotic and biotic stresses is due to the deleterious action of “stress ethylene” and not necessarily from the direct effects of the stress. In order to reduce the negative effects of “stress ethylene” on growth and yield of stressed plants, application of ecologically compatible and environmentally friendly methods is needed. An alternative approach to reducing stress-induced ethylene production in growing plants in stress-affected soils involves employing 1-aminocyclopropane-1-carboxylate (ACC) deaminase-generating bacterial endophytes. These bacteria may promote stressed plant’s growth as a consequence of expressing the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase which cleaves 1-aminocyclopropane-1-carboxylate (ACC) (prerequisite of ethylene production) to α-ketobutyrate and ammonia and thereby diminishes ethylene levels in stressed host plants. In this review, the role of bacterial endophytes equipped with the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase in mitigating stress-induced ethylene-mediated negative impact on stressed plants under various environmental stresses (heavy metal toxicity, salinity, water deficit (drought), flooding, extreme temperatures, and nutrient deficiency) is described. In addition, some suggestions that are needed for future research in this context are also presented.