基于ITS序列分析仲彬草属植物的亲缘关系

The Phylogenetic Relationships of Kengyilia Species Based on Evidences from ITS Sequences

以旱雀麦为外类群,用PAUP 4.0b10软件并采用最大简约法和邻接法对11份仲彬草属物种的ITS区序列进行系统发育分析,两种方法得到的系统发育树基本一致.结果表明：（1）整个ITS序列长度变异范围为596～601 bp;G＋C含量在所有ITS中的变化范围为61.20%～62.44%;序列间的遗传分化距离为0.003～0.033,平均值为0.015;（2）疏花仲彬草和塔克拉干仲彬草2个物种聚为一支,位于系统发育树的底部,在最大简约法和邻接法分析中分别获得78%和82%的自展支持率,它们之间的亲缘关系较近;（3）形态相似、地理分布一致的物种有聚在一起的倾向,表现出较近的亲缘关系;（4）ITS区序列分析的结果与细胞学、形态学的研究结果基本一致,因此ITS区序列分析能反映仲彬草属种间关系.

The entire sequences of ITS region of nuclear rDNA were analysed in 11 Kengyilia species. Phylogenetic relationships among 11 species in Kengyilia and Bromus tectorum L. as outgroup were estimated by maximum parsimony and neighbor-joining methods with PAUP4.0bl0 software,and similar ITS trees were obtained with the two methods. The results showed： （1） the sequence of ITS in 11 species ranged from 596 bp to 601 bp in length. The G＋C content varied from 61.20% to 62.44%. The genetic distances varied from 0. 003 to 0. 033, with an average of 0. 015; （2） K. laxiflora and K. tahelacana were clustered together,located at the basal position of the tree with a bootstrap value 78% by maximum parsimony and 82 % by neighbor-joining method;（3） The species with similar morphological characters and from the same areas or neighboring geographical regions were clustered together, respectively. It suggested that they had higher genetic similarities and closer relations; （4） The results based on ITS sequence analysis are basically comparable with those obtained from studies on morphology and cytology. It is an effective method to assess relationships among the species of Kengyilia.