Aquaporins: A potential weapon in plants for abiotic stress tolerance

Abiotic stresses are the major limiting factors for crop growth and productivity worldwide. Plant aquaporins (AQPs) belong to the major intrinsic protein (MIP) family, facilitate the flux across the membrane, and play a vital role in maintaining the water balance under abiotic stresses. Overexpression of AQPs under stress conditions could reduce oxidative stress by enhancing endogenous proline contents of plants and is also involved in reducing ion leakage, membrane injury, and cellular dehydration. Under elevated salt concentrations, AQPs induce reduction in lipid peroxidation and membrane injury. It induced a decline in the amassing of K+ and Na+ in cells and improved the K+/Na+ ratio thus enhancing the salt stress tolerance. In water-deficit conditions, AQPs provide a helping hand in maintaining the endomembrane integrity and turgor, displayed a decline in MDA levels and ion leakage, and induced enhancement in plants’ resistance response to drought stress. Under high concentration of heavy metals, AQPs enhance water uptake by the roots. Additionally, they can regulate the transmembrane water flow, obstruct the root hydraulic conductivity, display longer hypocotyls, and enhance antioxidant activity. Various experimental studies have revealed the roles of AQPs under various abiotic stresses. Conversely, only a few experimental studies were found on the roles of AQPs under all abiotic stresses at the time. Thus, in the present chapter, we concisely describe the particular roles of AQPs for enhancing abiotic stress tolerance in various crops.