Transcriptome-Wide Characterization and Functional Identification of the Aquaporin Gene Family During Drought Stress in Common Vetch

Aquaporins (AQPs) are transmembrane channels that are essential for the movement of water and other small molecules between biofilms in various physiological processes in plants. In this study, based on transcriptome-wide data, we identified and described a total of 21 AQP genes in common vetch (Vicia sativa subsp. sativa), which is an economically important pasture legume worldwide. Based on phylogenetic analyses, the VsAQPs were sorted into four subfamilies, including four plasma membrane intrinsic proteins (PIPs), six tonoplast intrinsic proteins (TIPs), seven NOD26-like intrinsic proteins, and four small basic intrinsic proteins. Furthermore, chemical and physical properties of these VsAQPs, including the isoelectric point and theoretical molecular weight, were analyzed. Analyses of the AQP signature sequences and key residues indicated the substrate specificity of each VsAQP. A set of VsAQPs was selected for gene expression analysis in a number of tissues and after drought stress treatments using real-time quantitative reverse transcription/polymerase chain reaction assays. Most of the PIPs and TIPs were proposed to have critical roles in regulating the flow of water during drought stress. Heterologous expression experiments in yeast indicated that VsPIP1;2 and VsPIP2;2 are key candidate genes for improving drought stress tolerance. The results reported in this study could be a crucial resource for further practical analyses and for genetic improvement of drought stress tolerance in common vetch.