基于ITS和matK基因对牡丹组序列分析及其亲缘关系的研究

以芍药属牡丹组全部9个野生种、5个紫斑牡丹栽培品种及3个中原牡丹品种为试材，进行核糖体内转录间隔区（ITS）和叶绿体成熟酶K （matK）基因片段测序分析，探讨ITS和matK序列为牡丹组所有野生种种间关系提供分子证据。从GeneBank中选取了1个牡丹及3个外类群芍药、川赤芍和草芍药的ITS及matK序列。对试验样品进行DNA提取、PCR扩增并双向测序得到44条序列，人工校正后将所得44条序列进行比对；计算碱基组成频率、变异位点、简约信息位点数、转换/颠换比率、种内及种间遗传距离，以邻接法进行系统发育分析。结果表明，牡丹组所有个体ITS序列长度在750~800 bp，含有86个多态位点，74个简约信息位点，转换/颠换比率（R）为1.2；而matK序列含有20个简约信息位点，转换/颠换比率（R）为1.7。ITS序列分析将牡丹组野生种分为两大枝，稷山牡丹、紫斑牡丹、卵叶牡丹和杨山牡丹聚为一枝，狭叶牡丹、滇牡丹、黄牡丹和大花黄牡丹聚为另一枝，这两枝分别与革质花盘亚组和肉质花盘亚组相对应，而四川牡丹位于革质花盘亚组最底端，支持前人研究将四川牡丹归为革质花盘亚组。matK序列分析的牡丹组野生种间遗传距离结果不理想，未能清晰的表明野生种之间的亲缘关系。由此说明，ITS序列更适合牡丹组野生种间亲缘关系的研究分析。

Interspecific Relationship among the Wild Species of Paeonia Sect. Moutan DC with ITS and matK Sequence

Revealing the interspecific relationship between wild species of Paeonia Sect. Moutan DC at molecular evidences would provide theoretical basis for preserving and utilizing wild peony resources. The sequence of ribosomal DNA internal transcribed spacer(ITS) and the coding region of the matK gene sequenced from 9 Paeonia Sect. Moutan DC, 5 cultivars of P.rockii, and 3 accessions of P.suffriticosa. Sequences of ITS and matK of one P.suffruticosa, one P.delavayi and three outgroups of P.lactiflora,P.veitchii and P.obovata were retrieved from GeneBank. The 44 sequences were obtained and corrected, and the divergences, variable sites, parsim-informative sites, the ratio of transition to transversion(R) and pairwise distances were analyzed. The phylogenetic analysis was conducted by Neighbor-joining(NJ) method. The size of ITS sequences of Paeonia Sect. Moutan DC wild species and cultivars ranged from 750 to 800 bp containing 86 polymorphic sites and 74 parsim-informative sites with R of 1.2, whereas, their matK sequences encompassing 20 parsim-informative sites with R of 1.7. From the phylogenetic trees of ITS, P.jishanensis, P.rockii, P.qiui and P.ostii fell into a large clade. The similarity coefficients between P.ludlowii, and the species of P.lutea, P.potaninii and P.delavayi were clustered in another clade. These two clades corresponded well to Subsect. P.decomposita were at the bottom of Subsect. Vaginatae, which showed the classification of P.decomposita into Subsect Vaginatae. By matK sequences analysis, there is closely genetic distance between wild species from Paeonia Sec. Moutan DC; however, there was no clear genetic relationships between wild species. As a result, ITS sequence can be better used to study interspecific relationship among wild species of Paeonia Sect. Moutan DC.