A cotton gene encodes a tonoplast aquaporin that is involved in cell tolerance to cold stress

To enhance the survival probability in cold stress, plant cells often increase their cold- and freezing-tolerance in response to low, nonfreezing temperatures by expressing some cold-related genes. In present study, a cotton gene encoding tonoplast intrinsic protein (TIP) was isolated from a cotton seedling cDNA library, and designated as GhTIP1;1. GFP fluorescent microscopy indicated that GhTIP1;1 protein was localized to the vacuolar membrane. Assay on GhTIP1;1 expression in Xenopus laevis oocytes demonstrated that GhTIP1;1 protein displayed water channel activity and facilitated water transport to the cells. At normal conditions, GhTIP1;1 transcripts were predominantly accumulated in roots and hypocotyls, but less abundance in other tissues of cotton. The GhTIP1;1 expression was dramatically up-regulated in cotyledons, but down-regulated in roots within a few hours after cotton seedlings were cold-treated. Overexpression of GhTIP1;1 in yeast (Schizosaccharomyces pombe) significantly enhanced the cell survival probability, suggesting that the GhTIP1;1 protein is involved in cell freezing-tolerance.