Genome-wide comparative analysis of tonoplast intrinsic protein (TIP) genes in plants

Tonoplast intrinsic proteins (TIPs) play a vital role in water transport across membranes. In the present study, we performed a comparative analysis of TIP genes in ten plant species including both monocots and dicots. A total of 100 TIP aquaporin genes were identified, and their relationships among the plant species were analyzed. Phylogenetic analysis was performed to evaluate the relationship of these genes within the plant species. Based on the phylogenetic analysis results, TIPs were classified into five distinct arbitrary groups (group I to group V), which represented TIP2, TIP5, TIP4, TIP1, and TIP3, respectively. Group I represented the largest arbitrary group, followed by group IV, in the phylogenetic tree. The result clearly indicates that TIP2 and TIP1 are abundant aquaporins and highly related among the species. In the present review, a comparative study of gene structure analysis between dicots and monocots has been performed to analyze their structural variation. Most of the predicted motifs are conserved among the species, signifying an evolutionary relationship. The gene expression analysis indicated that the expression of TIP genes varies during different developmental stages and also during stressed conditions. The results indicated a great degree of evolutionary relationship and variation in the expression levels of TIPs in plants.