Construction Of CDNA Libraries For Panax Ginseng Leaf And Root Tissues And Analysis Of Expressed Sequence Tag

Ginseng (Panax ginseng C.A.Meyer), considered to be one of the most potent medicinal plants, is used in traditional medicine. The reputed medicinal and herbal qualities of Ginseng have led to its popularity, primarily in the Orient, but increasingly worldwide. The various kinds of secondary metabolite, the active components of Ginseng, have an obvious regulatory bioactive effects on central nervous sysytem, cardiovascular system, alimentary system, endocrine system, immune system and so on. Although many reports have been published regarding the pharmacological effects of secondary metabolite, little is known about the genes and biochemical pathways in secondary metabolite biosynthesis. In order to delineate these biosynthesis pathways and their regulation using biochemical and molecular biological technique, and preserve the gene resource information of Ginseng, we constructed full-longth cDNA libraries of ginseng leaf and root tissues, and analyzed partial expressed sequence tags.The total RNA was prepared with Trizol reagent separately from 6-year-old ginseng leaf and 4-year-old ginseng root tissues. The full-longth cDNA expression library was constructed by SMART technology. The primary titer of the cDNA library of leaf was 6.55×105 pfu and the rate of recombinant was 81%, the insert size ranged from 0.3~2.5kb. Correspondingly, that of the root primary cDNA library was separately 4.80×105 pfu, 80% and 0.3~2.0kb.Therefore, cDNA libraries of ginseng leaf and root tissues have been successfully constructed. 124 high-quality expressed sequence tags were obtained by single-pass sequencing of 200 randomly chosen recombinant clones, 79 unique sequences were formed after assembly by Seqman program of DNAStar software. 61sequences exhibited homology to previously known sequences of GenBank in the level protein or nucleotide by analysis of blastx and blastn. Subsequently, 38 ESTs were submitted to dbEST. Open reading frame and putative conserved domains were detected in 12 new Ginseng sequences, and then submitted to GenBank.Successful construction of the full-length cDNA expresssion libraries of Ginseng leaf and root tissues, is essential for cloning of genes known and is also an initial key for screening and cloning of new genes, furthermore, is a key work for building the gene resource information databank of Ginseng.