| Licorice is the root and rhizoma of the leguminous plant of Glycyrrhiza uralensis Fisch,Glycyrrhiza inflata Bat and Glycyrrhiza glabra.L, which is firstly described in the Shennong ben caojing as the high grade crude drug, Licorice is commonly used as a staple crude drug and has the function of coordinating the drug actions of a prescription, disintoxicating, deficiency, stoping coughing and moistening lung and other functions. Licorice is widely used in the world covering medicine,food processing,household chemical and other industries. Licorice rely mainly on wild resources in the market, with the development and use of licorice deepening,Licorice demanding at home and abroad has soared.China's wild licorice resources have been severely damaged and in some places even on the verge of extinction.And the ecological environment has suffered serious deterioration.In order to protect our licorice resources and ecological environment in the region of the three North, State Council in June 2000 issued a ban on digging Herba Ephedrae and licorice.With the scarcity of the wild licorice resources and the increasingly daily demanding of the licorice, artificial cultivation of licorice has gained the people's attention. It is the most fundamental and effective measures for the sustainable use of licorice by artificial cultivation of licorice to replace of the wild licorice. But the low of glycyrrhizin content and pesticide residues of the artificial licorice is seriously affected process of the artificial licorice to replace of wild licorice.The excellent breeding is more important for improving the quality of cultivated licorice and the breeding research of the licorice and other medicinal plants is fell behind the crops. Therefore, it is important to learn the experiences from the crops, to choose the licorice of high glycyrrhizin content, good adaptability, strong disease resistance power.while strengthening research of other types of Glycyrrhiza, it will get the excellent genes by interspecific hybridization technology It is rather time-consuming by crossing hybridization, from sowing of the licorice to flowering needs three years at least. If we can find the molecular markers which can reflect the glycyrrhizin content we will overcome these difficulties. It can also speed up the breeding cycle, therefore, it has important significance to find the molecular markers for evaluation of quality of licorice and selection of excellent cultivar of licorice.Currently the subjects of exploring the correlation between of gene and components include genome and individual genes. Genome can reflect all the differences among the plants not directly reflect the content of the active ingredient variation. And the chemical composition of the difference may be limited by the genetic differences, Genomic Variation of clustering may not reflect the changes; and a single gene such as matK gene,rbcL gene can only indirectly reflect content variation of the active ingredient, because genetic evolution is at the same time, matK gene and rbcL gene evolve and the genes closely relating to the active ingredient are evolutionary.It has been reported that there are sequence variations of matK gene and rbcL gene among licorice individuals. But trnL intron and IGS (trnL-trnF spacer) are NCR( non-coding regions), which evolve fast. So they can be used for intraspecies research. We can choose the rbcL gene and matK gene, trnL intron, IGS (trnL-trnF spacer) as the molecular marker to find the correlation between glycyrrhizin content variations and the rbcL gene , matK gene, trnL intron and IGS (trnL-trnF spacer). In this way we can find the molecular marker closely relating to the active ingredient so as to lay foundation for discussing gene mechanism of the variations of active ingredients.In this research the important conclusions are as follows: 1 We choose the individuals under the same conditions for the content of Glycyrrhizin, statistical analysis and find there are great variations of the content of Glycyrrhizin. We separate them into a group with high levels of glycyrrhizin and a group with low levels of glycyrrhizin. There was a significant difference between two groups on glycyrrhizin content.2 Japanese Professor Yamanasi KondoK analyzes the rbcL gene sequence of the licorice finding there are different genetypes and separate into A-T type and G-A type. Hayashi,H submit the rbcL gene sequence of the licorice to Gengbank successfully. And the experiments showed that there are no differences among the rbcL gene sequence of the 10 individuals, which belong to a same genotype ----G-A type. So the sequence also failed to reflect the variations of the glycyrrhizin content. and we need to increase sample sizes, or to find a new molecular marker in-depth study.But compared to the rbcL gene sequence of the licorice Yamanasi KondoK reported, there is a difference of a base. The 55th is A in the report of Yamanasi KondoK. But mine is T. So there may be variations of the gene sequence, demanding deep exploration.3 Japanese Professor Yamanasi KondoK analyzes the matK gene sequence of the licorice finding there are different genetypes and separate into ST type and DEL type. And the experiments showed that there are no differences among the matK gene sequence of the 10 individuals, which belong to a same genotype ---- ST type. So the sequence also failed to reflect the variations of the glycyrrhizin content. and we need to increase sample sizes, or to find a new molecular marker in-depth study.4.It has not been reported that the research trnL intron of licorice ,we get the complete sequences of the trnL intron firstly and registe it in the Genbank No. EF606870.The trnL intron sequences of the ten different licorice individual are no difference.Therefore trnL intron also do not reflect the content variability of glycyrrhizin and we need to increase sample sizes, or to find a new molecular marker in-depth study . 5.It has not been reported that the research trnL-F intergenic region of licorice ,we get the complete sequences of the trnL-F intergenic region of licorice firstly and registe it in the Genbank No. EF606871.The trnL-F intergenic region sequences of the ten different licorice individual are no difference.Therefore trnL-F intergenic region also do not reflect the content variability of glycyrrhizin and we need to increase sample sizes, or to find a new molecular marker in-depth study... |
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