Cloning And Characterization Of Two Genes Related With Fiber Development In Gossypium Hirsutum L.

Cotton fibers are important textile materials that play important role in national economy and people's lives. Each cotton fiber is a single cell of ovule epidermis that elongates to 2.5-3.0 cm within approximately 16 days post anthesis (DPA). There are a great deal of cellulosic and noncellulosic polysaccharide been synthesized during cotton fiber development to participate in the formation of fiber configuration, and this developmental process consists of myriads of saccharide progressing complicated biochemical reactions. So cloning the developmentally regulated genes from cotton fibers may play an important role not only in improving the quality of cotton fiber, but also in studying plant cell development and cellulose biosynthesis.Two cDNA clones were separated from developmentally different cotton fiber pool of premium material 7235 library:(1) plasma membrane intrinsic protein/aquaqporins.we named it GhAQP.The insert fragment of the cDNA clone was 1207bp,its open reading frame was 837bp,and encoded a polypeptide containing 249 amino acids and the Mw of the deduced amino acid is 29.7kDa, and pI is predicted to be 9.13. Blastx analysis indicated GhAQP had substantive homologies with some reported plasma membrane intrinsic protein/aquaqporins;(2) Vesicle-Associated Membrane Protein, We named it GhVAMP .The insert fragment of the cDNA clone was 1080bp,its open reading frame was 549bp,and encoded a polypeptide containing 183 amino acids ,and the Mw of the deduced amino acid is 20.4kDa, and pI is predicted to be 9.13. Blastx analysis indicated GhVAMP had some identity with some reported VAMP (3)The rest of the seven cDNA clones had little identity with the reported genes.We predicted their signal peptide via signalP process.GhVAMP had typical signal peptide but GhAQP had not. We predicted their phosphorylation sites via NetPhos process ,they had 6 and 12 sites each. We predicted their N-glyoosylation sites via NetNGlyc process ,They had one site both.We also analyzed their conserved domain and phylogenetic tree.Judging from their expression characters,GhAQP and GhVAMP were expressed in fiber cells and in root, leaf and had a preferential expression in stem, while it could be detected in ovules and fiber cells of different developing period, especially in elongating fibers; GhAQP was preferential expressed in fiber cells from 3DPA to 14DPA,and its expression was decreased after 17DPA in fiber developmental stages, GhVAMP was preferential expressed in fiber cells from 3DPA to 11DPA,and its expression was decreased after 17DPA in fiber developmental stages.Sense and antisense expression vector containing 35S promoter e using pBI121 plasmid were constructed for GhAQP; Antisense expression vectors containing 35S promoter using pBI121 plasmid were constructed for GhVAMP.The work of transferring these recombined vectors into Gossypium hirsutum L. by Agrobacterium tumefaciens is ongoing.