[Cloning of GhAQP1 gene and its specific expression during Ovule development in cotton]

Plant aquaporins, belonging to the MIP superfamily, are a series of transmembrane proteins that facilitate water transport through cell membranes. In this study, a cDNA clone encoding the PIP1-like protein was isolated from cotton (Gossypium hirsutum) cDNA libraries, and designated as GhAQP1 (Fig.1). We also isolated the GhAQP1 gene from cotton genome by PCR. The gene is 2,096 bp in length, including an open reading frame (ORF) and 5'-/3'-untranslated regions (UTR). It contains two introns in its ORF. The first intron is inserted between codons 209 and 210 in the fifth transmembrane helix, and another is located between codons 256 and 257 in the sixth transmembrane helix of GhAQP1, respectively (Figs.2 and 3). Northern blot analysis showed that GhAQP1 gene is expressed specifically in 6-15 DPA ovule, and reaches a peak in 9 DPA ovule (Figs.4 and 5), suggesting that its expression is ovule-specific and developmentally regulated in cotton.