| Different kinds of Chinese medicinal plants have their characteristic features such as morphology, taste, and smell. However, some medicinal plants can have similar appearance that may cause confusion when they are differentiated. Hence, it is necessary to devise methods for rapid and correct identification of Chinese medicinal plants. In this thesis, both conventional and novel molecular biological methods were used for the characterization of selected Chinese medicinal plants.;Sequence of 18S rRNA gene was highly conserved among the plants in the same genus. The difference between any two plants of the same genus was only about 0.5% and this difference increased to about 3--5% when the plants are more distantly related. On the other hand, sequences of Internal Transcribed Spacer (ITS) were highly variable. Difference of about 15% and 40--50% could be found for closely and distantly related plants respectively. It appeared that the sequence analysis of 18S rRNA gene and ITS region was useful for the characterization of the Chinese medicinal plants at the genus and species level respectively. Sequences of rRNA gene were completely conserved among cultivars. Therefore, DNA fingerprints generated from Arbitrary Primed-Polymerase Chain Reaction (AP-PCR) were used to study the Chinese medicinal plants at the cultivar level.;Phylogenetic analysis of Ilex was also carried out using sequences of ITS1, ITS2, rbcL gene, and atpB-rbcL spacer. The degree of divergence of the four DNA regions appeared to be ranked as ITS1 > ITS2 > atpB-rbcL sapcer > rbcL, therefore they can be use to resolve phylogenetic relationship at different taxonomic levels.;DNA dot blot hybridization analyses were carried out for the identification of Chinese medicinal plants for the first time. Different DNA regions including ITS1, ITS2, atpB-rbcL spacer, rbcL gene, intron of tRNA gene LUAA, and the spacer between tRNA L UAA and tRNA FGAA were amplified by PCR and used as probes for the identification of Chinese medicinal plants. |
