| Tree peonies, known as 'the king of flowers' in China, are famous for their beautiful flowers. Paeonia section Moutan DC comprises eight species found only in Xizang (Tibet), Sichuan, Yunnan, Hubei, Gansu, Shanxi, Shaanxi, Henan and Anhui provinces of China. Because of the specific position of the genus Paeonia L. in angiosperm system, any information on the interspcific relation of tree peonies, the only woody group in the genus, will be useful for further inferring into the phylogeny and evolution of the genus. China is also the origin pake of cultivated tree peonies. The documented cultivation history of tree peonies in China is more than 2,000 years. During long period of cultivation and domestication, cultivated tree peonies of China have developed into a complex group with more than 1,000 cultivars, which were divided into central China, southwest China, northwest China and southern China cultivar groups in horticulture and were distinguished in color and number of petals, flower and leaf shapes etc morphological characters. Tree peonies are cultivated all over China and the temperate regions of the world. In the past decade, the cultivation of tree peonies has been continuously growing in Japan, France, America, and England, and more and more people become attracted by the beautiful flowers of tree peonies. Therefore, it is of important academic and practical values to investigate into the interspecific relation of Paeonia section Moutan and infer into the relationship between wild and cultivated tree peonies. Since 1980s,scholars both in China and abroad have carried out a systematic study on morphology, classification, new taxon description, palynology, ecology and geographical distribution, pollination biology, reproductive characters and conservation biology of tree peonies, but only few work was done on the interspecific relation of Paeonia section Moutan. Our knowledge on the phytogeny of section Moutan is still quit limited. Although the existing studies showed that alcohol dehydrogenase (ADH) gene sequence is better than those of ITS and matK genes in resolving the interspecific relations among the species in the genus Paeonia, the species in section Moutan were not appropriately represented in previous studies. Therefore, the aim of this study is to analyze molecular phylogenetic relationship among all species of section Moutan using DNA sequences of Adh gene family, with an attempt to have a better understanding of the phylogeny of wild tree peonies.Using the primers AdhF2 (5'-CCTCGCATATTTGGTCACGAAG-3') and AdhR2 (5'-GGGCA-CACCAACAAGTACTG-3') reported in current literature, the author amplified a portion of alcohol dehydrogenase genes (AdhlA, Adh 1B and Adh2) from the total genomic DNA of the tree peony accessions used in the present study. The PCR products were first purified and then ligated to the plasmid vector, which were introduced into JM109 competent cell of E. coli. The positive clones were screened on the LB solid culture medium containing ampicilin and X-gal according to 'blue and white reaction'. The positive clones (in white color) were cultured in LB liquid culture medium at 37癈 for 12 hours (overnight). Plasmid DNAs were extracted using the alkaline procedure. The plasmid DNAs of different clones were screened using EcoR I digestion and PCRs. The selected plasmid DNAs were sequenced on ABI377 automatic sequencer. The sequences were edited using SeqED3.0 computer program and aligned with ClustalX computer program. The gene trees were constructed based on the aligned sequences using PAUP computer program. The gene tree for each member of Adh gene family and a tree for the combined sequences of all three genes were built, respectively. Based on the gene trees, the interspecific relations among these species of section Moutan were analyzed and discussed in details.A portion (five exons and four introns) of alcohol dehydrogenase (ADH) genes (Adh1A, Adh1B, Adh2) from 10 accessions of wild tree peonies collected from ten wild populations representing 7 species of section Mou...
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