Dynamic role of aquaporin transport system under drought stress in plants

Abstract Prolonged soil moisture deficit poses major threat to plant survival. Plants have evolved to withstand such condition by maintaining water status through adoptive mechanisms. Such mechanisms include modulation of Aquaporins (AQPs) activity. The AQPs are small integral membrane proteins which facilitate water movement across the cells. This review summarizes the important regulatory mechanisms controlling the dynamics of AQP activity to fine tune the plant water status under the water deficit condition. Numerous studies have shown differential AQP expression under drought stress in plants. Among the known AQP subfamilies, members of plasma membrane intrinsic protein (PIP) and tonoplast intrinsic protein (TIP) showed most significant expression under drought condition. The activity, stability, and membrane targeting of these AQPs are known to be regulated at transcriptional as well as post-translational level. Drought induced transcription factors and hormones are also involved in direct or indirect transcriptional regulation. At post-translational level modifications such as phosphorylation, glycosylation, ubiquitination, gating and tetramerization play a role in regulation of the abundance and activity of AQP proteins. Understanding such regulatory mechanisms will help in exploration of AQPs to improve crop plants for sustainable agriculture under changing environmental conditions.