Genome-wide identification and characterization of the aquaporin gene family in Sorghum bicolor (L.)

• A total of 41 AQP genes were identified in Sorghum and grouped into four families.
• Gene expression analysis suggests functional divergence in Sorghum.
• The gene structure, phylogeny and chromosome locations were analyzed.
• SbAQP promoter sequences were investigated using in silico analysis.
• The first report of a genome-wide analysis of AQP genes in Sorghum

The aquaporin (AQP) gene family constitutes the most conserved class of gene families and plays a key role in water transport and conservation in plants. Although Sorghum genome sequencing has been completed, a comprehensive study of AQP genes in Sorghum bicolor is lacking. In the present study, we identified and characterized Sorghum AQP genes using a genome-wide scale, including factors such as their relationship with other species, chromosome distribution, sequence analysis and expression levels. A total of 41 non-redundant AQP genes were identified and classified into four subfamilies (PIPs, TIPs, NIPs and SIPs). Analysis of physical distributions revealed that SbAQP genes are unevenly dispersed in the Sorghum genome. Topological analysis indicated that members of the SbAQP gene family have two to seven transmembrane domains, whereas PIPs have four to six transmembrane domains. SbAQP genes were disrupted by introns, with intron numbers varying from zero to four. In silico promoter analysis of SbAQP genes suggested that it has diverse functions associated with plant development and abiotic stress responsiveness. The transcript analysis of SbAQP genes in different tissues and under abiotic stress conditions revealed that AQPs may play an important role in growth and development during abiotic stress conditions. To our knowledge, this is the first systematic study of the AQP gene family in S. bicolor. This study provides basic insights into the putative role of these genes under different environmental conditions. In summary, our genome-wide analysis of SbAQP genes provides a valuable resource for functional analysis aimed towards understanding their role in stress adaptation.