Study On Molecular Phylogenetics Of The Genus Syringa In Northeastern China

The phylogenetic relationships of Syringa in Northeastern China were investigated by means of molecular systimatics, which was based on three DNA sequences from genomes,including chloroplast DNA trnL-trnF, nrlTS and nrETS gene.The present study includes classification within the Genus Syringa and relationships of taxa groups.In addition, a cladistic analysis based on the morphology of Syringa was carried on. The results were summarized as follows,1. Cladistic analysis based on the morphologic charactersA cladistic analysis of the genus Syringa from the Northeastern China was carried out through surveying on the morphologic characters and using MP and UPGMA methods by MEGA 3.1 and PHYLIP 3.65. The results showed, 11species of Syringa were divided into four clades and belonged to relevant Series of Sectâ… . Ligustrina and Sectâ…¡. Syringa classified by Rehder (1928). So it is well supported to Rehder's infrageneric system. Through analysis we considered that the genus Syringa would be divided into five series, Ser. Villosae, Ser. Syringa, Ser. Pubescentes, Ser. Pinnatifoliae and Ser. Ligustrina.2. Studied on the cpDNA TrnL-trnF Intergenic Spacer Sequence in the Genus Syringa of Northeastern ChinaThe cpDNA TrnL-trnF intergenic spacer sequence in the genus Syringa were amplified and sequenced successfully, the size of which are about 362-374bp.After alignment the size of sequences are 382bp,including 35 mutations. The contents of G+C are37.2%, which showed the trnL-trnF sequences were AT-rich fragment. Based on TrnL-trnF Intergenic Spacer Sequence, the phylogenetic reconstruction were performed using the parsimonious anlysis (MP), the maximum likelihood (ML),UPGMA and the neighbor-joining(NJ)methods, repectively.The results show that: 11species of Syringa were divided into four groups, Syringa chinensis, S. dilatata, S. oblata and S. vugaris were one group ; S. pubescens ,S. velutina and S. microphylla were one group ; S. villosa and S. wolfii one group; S. pekinensis and S. reticulata var. mandshurica one group. The relationships among groups were different based on different methods, and the phylogenetic trees were different.3. Studied on the nrDNA ITS Sequence in the Genus Syringa of Northeastern ChinaThe average content of A is 30.5%, C 21.5%, G32.0%,T16.0% in 11 species of Syringa and outgroup species. After alignment the size of sequences are 623bp, including 79 mutations, and the rate is 12.7%.The contents of G+C are higher than 50%, and the average is 54.8%. The difference of the contents of G+C is not significant, the smallest one is 53.86%( S. vugaris), the biggest one is 55.86%( S. pekinensis) , and the contents of G+C of Forsythia mandshurica is 54.9%.Based on the ITS sequences the phylogenetic reconstruction showed the similar results with the cpDNA TrnL-trnF Intergenic Spacer Sequence,but based on the different methods the relationships among series below genus were different. 4. Studied on the nrDNA ETS Sequence in the Genus Syringa of Northeastern ChinaThe average content of A is 19.8%,C 24.5%, G24.6%,T31.2% in 11 species of Syringa and outgroup species. After alignment the size of sequences are 380bp, including 57 mutations, and the rate is 15%.The contents of G+C are from 48% to 50%, and the average is 48.99%. The difference of the contents of G+C is not significant, the smallest one is 48.1%(S. pubescen), the biggest one is 50% ( S. dilatata), and the contents of G+C of Ligustrum obtusifolium is 48.94%. Based on the ETS sequences the phylogenetic reconstruction showed the similar results with the cpDNA TrnL-trnF Intergenic Spacer Sequences and ITS sequences, but the relationships among series below genus were different with the results of the cpDNA TrnL-trnF Intergenic Spacer Sequences and ITS sequences.Based on the former literatures and present studies, the main conclusions are presented as follows:1. The cpDNA TrnL-trnF Intergenic Spacer Sequences ,nrDNA ITS and ETS sequences have some mutations among the Genus Syringa and it is feasible using these three sequences to discuss the phylogeny relationship in Syringa.2. Syringa should be divided into five series, including Ser. Villtosae,Ser. Syringa,Ser. Pubescentes ,Ser. Pinnatifoliae and Ser. Ligustrina.3. Based on the different sequences and the different analysical methods The relationships among series were different, but we con conclude that Ser. Syringa is the base clade, Ser. Pubescentes is the mid-type ,and the Ser. Villosae may be one original type.