Abstract: 【Objective】 The Farnesyl pyrophosphate synthase (FPS) is a key enzyme in the mevalonate biosynthesis pathway of the crude rubber. The FPS was cloned from Taraxacum kok-saghyz Rodinand transformedinto the wild types, this study will lay a foundation for the research of regulating effects of FPS gene on T.kok-saghyz biosynthesis. 【Method】 Homologous cloning was used to clone the full-length cDNA of this gene, bioinformatic analysis was conducted. Multiple sequence alignment and phylogenetic tree analysis were performed using typical sequences of T.kok-saghyz and other 18 plants FPS proteins. The total RNA was extracted from root, petiole, leaf, peduncle, flower and seed to analysis tissue-specific expression of FPS gene in T.kok-saghyz. The comparation of relative expression levels of the FPS from different growth stages of T.kok-saghyz was processed to research the regulating role of TKFPS in different developing periods of T.kok-saghyz. And this gene was overexpressed in T.kok-saghyz, the expression level of TKFPS and rubber content changes were analyzed after the FPS overexpressed. The rubber was extracted from roots of the wild-type and transgenic strains with Alkali cooking method for determining rubber content. 【Result】 The full-length cDNA of the FPS from T.kok-saghyz was obtained (TkFPS, KJ558350.1). The ORF of 1029 bp encodes 342 amino acid residues with the predicted molecular weight of 39.35 kD, isoeletric point value of 5.41 and average hydrophobicity value of -0.242. Amino acid sequence analysis showed that it contains five conserved domains of FPS gene in higher plants. Phylogenetic tree analysis showed that the T.kok-saghyz had the closest evolutionary relationship with Herba Taraxaci. Subcellular localization analysis of TMHMM and TargetP indicated that it might be targeted to the cytoplasm without transmembrane region. TKFPS gene was expressed in the root, petiole, leaf, peduncle, flower and seed of T.kok-saghyz by the tissue-specificity expression. The expressive content of TKFPS gene in different tissues of T.kok-saghyz was different: the highest was leaf, the next was root, and the lowest level was in flower. Six transgenic strains were obtained after recombinant pCAMBIA2300-35S-TkFPS was transformed to wild T.kok-saghyz by Agrobacterium-mediated transformation. The fluorescent quantitative RT-PCR showed that the relative expression levels of the FPS in transgenic lines were significantly higher, with the increases up to 2.8 times over the wild types. On average, rubber assay results showed that rubber content in roots of six transgenic lines was increased by about 3.92% compared to the wild types. 【Conclusion】 The FPS was successfully cloned from T.kok-saghyz and transformed into the wild types. The obtained transgenic lines had much more rubber than the wilds, this result indicated that TKFPS does play an important role in the biosynthetic pathway of the rubber in T.kok-saghyz.

Key words: Taraxacum kok-saghyz Rodin;farnesyl pyrophosphate synthase; bioinformatics, real-time PCR