Advances in Genetic Transformation of Panax Ginseng / 中国生物工程杂志

Genetic engineering is a powerful tool in Panax ginseng breeding.Genetic transformation and plant regeneration are the premise and foundation involved in genetic engineering of Panax ginseng.Ginseng can be regenerated through organogenesis or somatic embryogenesis and indirect somatic embryogenesis is mainly used for its regeneration.Summurized the factors influencing plant regeneration such as different explants,different carbohydrates,somatic embryo optimization and hormone-free approach.Ginseng transformation has been achieved by Agrobacterium tumefaciens and Agrobacterium rhizogenes and transgenic ginseng with good characters was obtained by introducing genes associated with biosynthesis of ginsenosides or herbicide gene.Hairy root culture system can supply large scale of ginsenosides,thus effect of rolC genes on ginseng hairy root induction,regeneration and bioreactor culture of hairy root were discussed.Additionally,problems that are present in genetic engineering of Panax ginseng were also discussed in this review.

Cloning of Ginseng ? AS Gene and the Construction of Its Antisense Plant Expression Vector / 中国生物工程杂志

RT-PCR amplification of ginseng ?-amyrin synthase gene was successfully performed based on the total RNAs extracted from ginseng hairy roots induced by Agrobacterium rhizogenes A4 using a modified guanidine isothiocyanate-method. Sequence analysis of this gene revealed that its sequence was consistent with the sequence of a previously reported ginseng ?-amyrin synthase gene (GenBank No. AB009030). This gene was inserted into pMD-119T simple vector and transformed into E.coli DH5?. Furthermore antisense plant expression vector of this gene was constructed using the pBI121 vector, laying foundation for studies on antisense regulation of ginseng ?-amyrin synthase gene.

Induction of hairy roots of Panax ginseng and studies on suitable culture condition of ginseng hairy roots / 生物工程学报

Ginseng is a valuable medicinal plant with ginsenosides as its mian effective components. Because ginseng is a perennial plant and has a very strict demand for soil conditions, the way of cultivating ginseng by cutting woods is still used in China at present and thus forest resources has been extremely destroyed. Increasing attention has been paid to the hairy roots induced by the infection of Agrobacterium rhizogenes in the production of plant secondary metabolic products for the hairy roots are characterized by rapid growth and stable hereditary and biochemical traits. That has opened a new way for the industrial production of ginseosides. However, there is little report for such studies from China. In this paper, hairy roots of ginseng were induced from the root explants of two-year-old ginseng by Agrobacterium rhizogenes A4 with directly inoculating. The transformed hairy roots could grow rapidly on MS medium and 1/2 MS medium without hormones. The cultured clones of the hairy roots were established on a solid 1/2 MS medium. After 4 - 5 subcultures the hairy roots still maintained a vigorous growth. A pair of primers were designed and synthesized according to the analytical results of RiA4TL-DNA sequence by Slightom et al . 0.8kb rolC was obtained by PCR using the genome DNA of hairy root of ginseng. Transformation was confirmed by PCR amplification of rolC genes from the hairy roots of P. ginseng. Growth rate of hairy roots on liquid medium increased by 2 times then that of the solid medium. The growth of the hairy roots can be divided into three stages: high speed in the first two weeks, middle speed in the 3 - 4 weeks and low speed hereafter. Changing the culture solution at 2 weeks regular intervals is conductive to maintaining the rapid growth of the hairy roots. By means of determination for specific growth rate and ginsenosides content, the high-yield hairy root clone R9923 was selected. The content of monomer gisenoside of Rg1, Re, Rf, Rbl, Rc, Rb2 and Rd in hairy root clone R9923 was determined by the HPLC. The total ginsenosides content in the hairy toot clone R9923 came up to 15.2 mg/g. The suitable culture conditions for ginseng hairy roots growing were 1/2 MS liquid medium (30 g/L glucose), in a shaker at 110 r/min, changing the culture solution at 2 weeks and subculture time 4 weeks. In the liquid fermented culture of 2L medium, the yield of the hairy roots could amount to 270.10 g in 4 weeks. The industrial production of ginsenosides has been preliminarily realized. Effect factors on biomass and ginsenosides content such as culture volume, inoculation, in steps cultural technology at the scale-up process of hairy roots culture were also explorated. Our results have laid a foundation for defining optimum culture manner for large-scale cultivation and large-scale production of ginsenosides.