The significance and functions of ethylene in flooding stress tolerance in plants

Climate change has increased the global environmental risks, especially the impacts of abiotic stresses on agriculture productivity. Among the abiotic stresses aggravated by climate change, flooding (complete submergence, stagnant flooding, soil waterlogging) has been identified as a major stress for plant growth and food production worldwide. Improving crop plants adaptation to flooding conditions is important to cope with increasing incidences and intensity of flooding, which could potentially be accomplished through manipulating adaptive physiological and molecular processes. Ethylene is a key plant hormone in plant adaptation to flooding, modulating signaling, and metabolic responses. Significant progress was made in understanding the basic physiological and molecular mechanisms associated with ethylene-mediated plant responses to flooding stress, though our knowledge in this field is still far from complete. This review provided (a) an overview of ethylene biosynthesis, signaling and its perception under flood condition in plants, with emphasis on rice; (b) assess the ethylene functions under flooding stress based on available evidences; (c) cross-talks of ethylene with other phytohormones and signaling molecules associated with ethylene-induced flooding responses; and (d) elucidate the role of ethylene mediated tolerance pathways with an aim of developing flood tolerant plants. The review represents a step forward to develop flood resilient crop plants by exploiting the knowledge of ethylene biology and functions.