Identification of aquaporin members in Acacia auriculiformis and functional characterization of AaPIP1-2 involved in drought stress

Aquaporins (AQPs), which serve as water channel proteins, are linked to a plethora of processes related to plant growth and development, such as water transport and the acquisition of carbon, nitrogen, or micronutrients. However, little is known about Acacia auriculiformis AQPs. In this study, we present the first transcriptome-wide identification of the AQP gene family in A. auriculiformis. The total of 21 AQP genes that were identified were divided into four sub-families (NIPs, PIPs, SIPs, and TIPs) based on a phylogenetic analysis. Functional prediction based on NPA motifs, the ar/R selectivity filter, and Froger's positions, suggested substrate specificity for these A. auriculiformis proteins. AQPs, which were globally expressed in all organs (roots, stems, nascent and mature leaves), as shown by gene expression profiles, were responsive to three environmental cues: elevated CO2, salt, and drought. Heterologous expression of AaPIP1-2 in Arabidopsis thaliana played a positive role in the response to PEG-treated drought stress by maintaining relative water content and enhancing the activities of enzymes that scavenge reactive oxygen species (ROS). Reduced ROS was likely associated with an increase in the activities of ROS-scavenging enzymes, and might be linked with the up-regulated expression of AaAQP genes. This study provides comprehensive bio-information on A. auriculiformis AQPs which would be helpful for additional gene function analyses.

Automated summary

This study provides comprehensive information on A. auriculiformis AQPs, identifying 21 AQP genes divided into four sub-families based on phylogenetic analysis. Functional prediction and gene expression profiles suggest that AQPs are responsive to environmental cues such as elevated CO2, salt, and drought, playing a role in maintaining water content and scavenging ROS. Heterologous expression of AaPIP1-2 in Arabidopsis thaliana showed positive responses to drought stress, potentially linked with up-regulated expression of AaAQP genes.