Genetic C Diversity Analysis Of Orchidacece Plant Based On Dendrobium Officinale EST-SSRs Development

The Orchidaceae family has many Chinese traditional precious medical herbals and valuable ornamental plants,.The orchid industry has become an important part of international flower industry. Our country has some wild orchid resources with very high ornamental value and extremely high medicinal value. Due to excessive mining, this species is on the verge of extinction. The study and protection of the plants is urgently needed. Phylogenetic studies of Orchidaceae is not only directly related to the effective evaluation and rational use of existing resources but also more conducive to the cultivation of high-quality new varieties and the development of the orchid industry.In order to conduct a more comprehensive phylogenetic study of orchids at molecular level, this study developed SSR markers from Dendrobium officinale, which is the representative species of the genus Dendrobium of orchids. The EST-SSR markers used to verify the transferability and polymorphism of Dendrobium, can be applied to the orchid plants to lay foundation for genetic diversity study of orchids.(1)The study analyzed cDNA library of Dendrobium qfficinale established by Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants.4075EST sequences were screened and706EST sequences cont aining838microsatellite loci were obtained. Finally,110primer pairs for EST-SSRswere designed.Di-nucleotide repeats and Tri-nucleotide repeats were more t han other types(37.83%and42.96%respectively), followed by the type of Tetr a-nucleotide repeats(12.53%) and the Hexa-nucleotide types just accounting for2.98%of all the primers.(2)110primer pairs fromthe Dendrobium officinale cDNA library are in108EST sequences.And among the108EST sequences, the gene functions of99sequences have been annotated in GenBank Database.110primer pairs were used to test the genomic DNA of31species of Dendrobiumto assess the transferability and polymorphism of the Dendrobium.The results showed that, the Dendrobium EST-SSR in the Dendrobium has high transferability and polymorphism of47.82%and88.56%, respectively.(3)We took all the EST-SSR primers from Dendrobium nobile and Dendrobium officinale cDNA library constructed by our laboratory, which have high transferability and polymorphism to test genomic DNA of44individuals from15genera of orchid. Result from genera of orchid other than Dendrobium showed low transferability of25.05%and high polymorphism of55.38%. Then the polymorphism loci of10representative pairs of primers were sequenced,and a total of223sequences were received. Differences among the genera orchid were analyzed at sequence level.Finally intergeneric relationships of orchid were studied through clustering.These results prove that EST-SSR markers are effective to reveal genetic diversity and relationship across Orchidaceae.