A banana aquaporin gene, MaPIP1;1, is involved in tolerance to drought and salt stresses

Background: Aquaporin (AQP) proteins function in transporting water and other small molecules through the biological membranes, which is crucial for plants to survive in drought or salt stress conditions. However, the precise role of AQPs in drought and salt stresses is not completely understood in plants. Results: In this study, we have identified a PIP1 subfamily AQP (MaPIP1; 1) gene from banana and characterized it by overexpression in transgenic Arabidopsis plants. Transient expression of MaPIP1; 1-GFP fusion protein indicated its localization at plasma membrane. The expression of MaPIP1; 1 was induced by NaCl and water deficient treatment. Overexpression of MaPIP1; 1 in Arabidopsis resulted in an increased primary root elongation, root hair numbers and survival rates compared to WT under salt or drought conditions. Physiological indices demonstrated that the increased salt tolerance conferred by MaPIP1; 1 is related to reduced membrane injury and high cytosolic K+/Na+ ratio. Additionally, the improved drought tolerance conferred by MaPIP1; 1 is associated with decreased membrane injury and improved osmotic adjustment. Finally, reduced expression of ABA-responsive genes in MaPIP1; 1-overexpressing plants reflects their improved physiological status. Conclusions: Our results demonstrated that heterologous expression of banana MaPIP1; 1 in Arabidopsis confers salt and drought stress tolerances by reducing membrane injury, improving ion distribution and maintaining osmotic balance.