Genome-Wide Identification and Expression Dynamics of Aquaporin Under Biotic and Abiotic Stress Conditions in Brassicaceae Species

Aquaporins (AQPs) are integral membrane proteins of vital importance in the cellular transport system of all living organisms. Plant AQPs are mainly involved in the movement of water and many other small solutes, and, as such, regulate important physiological processes. In this study, genome-wide identification, distribution and characterization of AQPs was performed in seven Brassicaceae species namely Arabidopsis lyrata, Capsella grandiflora, Capsella rubella, Eutrema salsugineum, Brassica rapa, B. oleracea, and B. napus (canola). The AQPs were further classified into subfamilies based on the phylogenetic distribution and characterized using computational approaches for the presence of transmembrane domains, signal peptides, NPA motifs, selectivity filters and other conserved domains. Furthermore, expression analysis of root, leaf and seed tissues-specific AQPs was conducted in canola. Evaluation of available RNA-seq data obtained under biotic and abiotic stresses identified putative AQPs involved in stress tolerance mechanisms in canola. In addition, the effect of ploidy level, and resulting gene dose effect on AQP expression was analyzed with the different combinations of Brassica A and C genomes. Dose-normalization for the pairs of duplicated genes was dominantly observed across all the four AQP subfamilies. This first in-depth characterization of Brassicaceae AQPs will be valuable for the understanding of transport mechanisms and related physiological processes leading to an improved breeding of stress tolerant cultivars.