Studies On The Germplasm Resources Of Dendrobium In China And Their Genetic Relationships

Dendrobium species are epiphytic plants of orchidaceae. Many wild species ofDendrobium are traditional precious Chinese medical herbals and precious ornamentalplants.Dendrobium orchid cultivers which are cultivated diffusely are artifical hybrids ofDendrobium species.There are rich Dendrobium resources in China, but Densrobium orchidbreeding in China drop behind other countries. Aim at this problem, this research studies on thegermplasm resources of Dendrobiun in China and their genetic relationships, in order toestablish the base of Dendrobium orchid breeding in China.The status quo of Dendrobium resources in China and their conservation measures wereinvestigated and studied. 31 Dendrobium species and 1 variety were collected from Simao andJinghong, Yunnan province and Shenzhen, Guangdong province. The ornamentalcharacteristics of the 32 spcimen were evaluated. Marking by the chloroplast DNA (cpDNA)trnL-trnF sequence and the inter-simple sequence repeat (ISSR) markers, their geneticrelationships were conducted. The main results were as follows.31 Dendrobium species and 1 variety were introduced and cultivated in the greenhouse forscience research in Chinese academy of forestry.It is the first time to evaluate the ornamental characteristics of the Dendrobium resourcesin China by fuzzy mathematics. 32 Dendrobium spp. samples were classified into 4 groups bytheir ornamental characteristics. GroupⅠ,7 species, which are best; GroupⅡ, 14 species and 1variety, which are better; GroupⅢ,8 species, which are medium; GroupⅣ,2 species, whichare disqualification.Ameliorated the DNA extraction method by CTAB from the young foliages of someDendrobium species, such as D. officinale, D. nobile, D. moniliforme, D. devonianum, D.christyanum, D. williamsonii, D. trigonopus.And it is also the first time to study on the genetic relationships inter the Dendrobiumspecies in China by chloroplast DNA (cpDNA) trnL-trnF sequence. 30 cpDNA trnL-trnFsequences of the Dendrobium resource samples had been accepted by GenBank of NCBI.The genetic relationships of 30 samples were analyzed by using software CLUSTALbased on the chloroplast DNA (cpDNA) trnL-trnF sequence.The results showed that 30 samples were classified into 4 groups. The geneticrelationships of 30 Dendrobium samples are as follow. D. primulinum is close with D. aphyllum; D..falconeri is close with D. wardianum; D. williamsonii is close with D. longicornuand D. christyanum; D. terminale is close with D. acinaciforme. These are according to withthe morphological taxonomy of Dendrobium of Chinese flora sinica. But D. trigonopus is closewith D. jenkinsi; D. chrysotoxum is close with D. capillipes; D. nobile is close with D.hercoglossum. The results are not support the Chinese flora sinica classification which isclassified the Dendrobium with the morphological taxonomy.The genetic relationships of Dendrobium resource in China were studied by ISSR marker.5 primers, which produced clear and rich polymorphism bands were chosen from 60ISSR-PCR primers. 103 bands were amplified from 32 samples, and 93 bands of them werepolymorphic (percentage of polymorphic bands was 90.2%). The length of the amplified bandswere between 200～2000bp. The stable and reproducible optimum reaction system ofISSR-PCR and PCR amplification parameter were established. The results provided astandardizing program for the analysis of inter species genetic relationships of Dendrobiumresources.According to the results of ISSR amplified, similarity coefficient and genetic distancewere calculated by using Ntsys(2.0) software.A dendrogram was constructed based onUPGMA cluster analysis. 32 Dendrobium spp. samples were classified into 4 major groups.The genetic relationships of Dendrobium species in China were as fallow: D. moniliforme isclose with D. officinale and D. guangxiense; D. fimbriatum is close with D. denneanum; D.christyanum is close with D. williamsonii and D. longicornu; D. terminale is close with D.acinaciforme. The result is coherency with the Chinese flora sinica. But D. trigonopus is closewith D. jenkinsii; D. chrysanthum is close with D. lohohense. It is incoherecy with theChinese flora sinica.Based on the results of two molecular markers, the genetic relationships of Dendrobiumspecies in China were as follow: D. williamsonii is close with D. longicornu and D.christyanum; D. terminale is close with D. acinaciforme. It is coherency with the Chinese florasinica. But D. trigonopus is close with D. jenkinsii; D. chrysotoxum is close with D. capillipes.It is incoherecy with the Chinese flora sinica.