不同产地荆芥核型及核型似近系数聚类分析

Cluster Analysis of Karyotype and Resemblance-Near Coefficients of Schizonepeta tenuifolia Briq. from Different Producing Origins

目的探明荆芥核型特征及不同产地来源种质间的亲缘关系。方法以11份不同产地荆芥为材料,采用根尖压片法分析染色体特征,并进行核型似近系数聚类分析。结果 11个产地荆芥的染色体数目均为12,共4种核型公式:2 n=2 x=12=4 m+8 sm、2 n=2 x=12=8 m+4 sm、2 n=2 x=12=6 m+6 sm和2 n=2 x=12=4 m+6 sm+2 st,玉田春和山西荆芥核型属2B型,其他均为2A型。核型不对称系数在61%~67%之间,其中四川荆芥核型最原始,安国夏荆芥进化程度最高。江苏与四川荆芥核型似近系数最高(0.989),核型进化距离最小(0.011),亲缘关系最近;萧山与玉田春荆芥核型似近系数最小(0.792 5),核型进化距离最大(0.232 6),亲缘关系最远。结论核型具有物种稳定性,核型似近系数的聚类分析得出了不同物种间的遗传距离,为荆芥植物资源种质鉴定、亲缘关系和系统演化等研究提供了细胞学基础。

OBJECTIVE To explore the karyotype features and genetic relationship among Schizonepeta tenuifolia Briq. from different producing origins. METHODS The chromosome features of Schizonepeta tenuifolia Briq. from 11 different producing origins were analyzed by using root-tip squashing method and clustered by the karyotype resemblance-near coefficients. RESULTS The Schizonepeta tenuifolia Briq. from 11 different producing origins all had 12 chromosomes. There were four types of karyotype formula： 2n =2x = 12 =4m ＋ 8sm, 2n = 2x = 12 = 8m ＋4sin, 2n = 2x = 12 = 6m ＋ 6sm and 2n = 2x = 12 =4m ＋ 6sm ＋ 2st. The karyotypes of Yutianchun and Shanxi Schizonepeta tenuifolia Briq. were 2B type, and those of the other Schizonep- eta tenuifolia Briq. were 2A type. The asymmetrical karyotype coefficients were not distinctively different, which ranged from 61% to 67 % , and the karyotype of Sichuan Schizonepeta tenuifolia Briq. was the most primitive among all the samples, and the highest degree of evolution belonged to Anguoxia Schizonepeta tenuifolia Briq. The karyotype clustering analysis showed that Jiang- su and Sichuan Schizonepeta tenuifolia Briq had the highest karyotype resemblance-near coefficient （0. 989 ） and the smallest evo- lutionary distance （0.011 ）. The farthest genetic relationship existed between Zhejiang and Yutianchun Schizonepeta tenuifolia Briq. , as shown by the minimum karyotype resemblance-near coefficient （0. 792 5 ） and the maximum evolution distance （0. 232 6）. CONCLUSION Karyotype is an important parameter for identification of medicinal plants. The genetic distances between 11 species of Schizonepeta tenuifolia Briq. are obtained by karyotype clustering analysis of karyotype resemblance-near coefficient. The results provide cytological information for the study of germplasms identification, genetic relationship and system evolution of Schizonepeta tenuifolia Briq.