Cloning And Functional Analysis Of The Fiber Growing Gene Ghkob In Upland Cotton(Gossypium Hirsutum)

Cotton is an important industrial crop worldwide, occupying important position in national economy. In order to improve the quality of raw cotton in our country and competitiveness in the international market of fabrics, it is necessary to develop varieties of fine cotton that combine different quality characters, such as length, strength and slender to meet domestic and international market demand.The Kob gene encodes a kind of protein, which the cellulose synthesis needs. It relates to cellulose array, and affects the cell elongation subsequently, especially in the fast elongating cell. When the cellulose synthesis is blocked in mutant, the cellulose suddenly reduction will cause the micro-fiber to arrange random. As a result, the phenotype of plant is dwarfish. In this research, the upland cotton variety SHIYUAN321 was used as a material and RACE technology applied in obtaining the whole cDNA sequence of the gene. Ghkob, totally 2001bp, has a biggest open reading frame (ORF) 1620 bp. Its 5'untranslation areas (5'UTR) has 64 bp, and its 3'untranslation areas (3'UTR) has 317 bp. The ORF encodes a protein of 539 amino acids, and the molecular weight of the protein is 60.8 kD. The deduced nucleotide sequence and the amino acid sequence of Ghkob are highly homologous to the other plant's kob.The RNAi vector pAR8 contains the fragment of phytoene desaturase gene was constructed and transferred into tobacco to evaluate the effectiveness of the RNAi vector. After induction with ethanol, the young leaves of transgenic tobacco showed albino.Then, the RNAi vector Bar2, which harboring the cDNA fragment of Ghkob, was constructed and transferred into cotton. We got 43 transformants and validated them through PCR. The ovules of transgenic cotton were cultured in vitro and induced with ethanol. The development of fiber was inhibited after the silencing of Ghkob, which means Ghkob is essential in fiber development.The over-expressed vector pG0229-kob which harboring the Ghkob gene droved by 35S promoter was constructed and transferred into cotton. Selections for transgenic plants are carrying out.In order to understand the function of this gene within short time, we also constructed yeast ((Schizosaccharomyces pombe) vector to analyze the gene function, but the result investigated that over expression of this gene could not increase the length of yeast cell. It suggested that expression of the gene is not a direct reason in cell elongation.