Cloning of Aquaporin Gene GhNIP6.1 from the Upland Cotton and Its Expression in Different Cotton Tissues

Primers were designed according to the assembled ESTs of Gossypium hirsutum,and an aquaporin gene GhNIP6.1 was obtained from upland cotton Sumian 18 in this experiment by RT-PCR.The gene contains an ORF comprising of 903 nucleotides which encodes 300 amino acids with a predicted molecular mass of 30.97 kD and theoretical isoelectric point of 8.99.Bioinformatics analysis indicates the GhNIP6.1 exhibited a typical structure with six trans-membrane domains which linked by five loops,loop A,C and E were at outside of membrane,loop B,D,N terminal and C terminal were at inside of membrane.N terminal has 79 amino acids and C terminal has 18 amino acids.The amino acid sequence of GhNIP6.1 has the conserved peptides of MIP family.The result of predicted protein 3D structure of GhNIP6.1 showed that it was highly similitude with that of AtNIP6.1.The subcellular localization of GhNIP6.1 maybe localize at plasma membrane,which is consistent with AtNIP6.1.Phylogenic analysis displays GhNIP6.1 has the highest similarity with Arabidopsis thaliana AtNIP6.1 protein.A genomic DNA sequence with 2021 bp clone containing an aquaporin was isolated from the upland cotton in this experiment,and the GhNIP6.1 gene contains eight introns and seven exons.All exon/intron junctions of the gene contain the gt/ag consensus splicing site.Semi-quantitative analysis of GhNIP6.1 expression showed that the gene expressed extensively in cotton roots,stems,leaves,except cotyledon,and leaf is the most highly expressed tissue.