[Characterization and expression analysis of two cotton genes encoding putative UDP-Glycosyltransferases].

UDP-Glycosyltransferases (UGT) are a large family of enzymes, which catalyze the transfer of a sugar from an activated sugar donor to an acceptor molecule. Both in plant and in mammalian, they are important in maintenance of cellular homeostasis. In this study, two genes (designated GhUGT1 and GhUGT2, respectively) encoding putative UGT were isolated from cotton fiber cDNA library. The deduced proteins contain the signature sequences of plant UGTs in the C-terminal region. The GhUGT1 gene encodes a polypeptide of 457 amino acids, and displays homology at amino acid levels with the known glucosyltransferase genes. Sequence analysis revealed that the GhUGT2 merely encodes a small protein, as there is a nucleotide substitution that results in formation of a stop codon in its open-reading frame. Real-time RT-PCR analysis revealed that the expression of GhUGT1 is higher in the fast growth tissues, such as in fibers and roots. GhUGT2 has also higher expression in roots, but with lower expression levels in fibers and other tissues. The result also showed that the expression of GhUGT1 is higher than GhUGT2. Further study showed that GhUGT1 and GhUGT2 expressions are regulated under osmotic stress, suggesting they may be involved in plants responding to osmotic stress.