苦豆子不同居群染色体数目及核型分析

为了探讨苦豆子（Sophora alopecuroides）不同居群的染色体核型特征及进化关系，采用染色体常规压片技术分析了分布于内蒙古、甘肃、宁夏等6个自然地理居群的核型特征和进化趋势。结果显示：苦豆子6个居群的染色体数目恒定，均为2n=2x=36；染色体类型有中部着丝粒（m）和近中部着丝粒（sm）2种，除甘肃武威的居群3含有sm型染色体外，其余居群的染色体均为m型；染色体平均臂比为1.19~1.37，长度比介于1.72~2.19，核型不对称系数处于54.30%~57.17%；核型类型有1A、3A和2B三种；苦豆子居群3的核型不对称系数最大，进化程度较高，居群19（内蒙古鄂尔多斯）的核型不对称系数最小，进化程度较低。聚类分析显示，苦豆子6个参试居群聚集成A和B两大分支，分支A又可分为C和D两亚支，其中居群5（甘肃武威）和居群13（内蒙古阿拉善盟）聚为C亚支，亲缘关系较近，居群3单独聚为D亚支，与C亚支两居群的亲缘关系相对较远；分支B又可分为E和F两亚支，居群19和居群43（内蒙古鄂尔多斯）聚为E亚支，亲缘关系较近，居群17（宁夏银川）单独聚为F亚支，与E亚支两居群的亲缘关系相对较远。本研究从居群水平上探讨了苦豆子的染色体数目、核型特征和进化趋势，为今后苦豆子系统进化和种质资源遗传多样性研究提供了细胞学证据。

Chromosome Number and Karyotype Analysis of Different Populations in Sophora alopecuroides (Fabaceae)

In order to explore the karyotype characteristics and evolutionary relationship of different populations of Sophora alopecuroides， the karyotype characteristics and evolutionary of six natural geographic populations distributed in Inner Mongolia， Gansu， Ningxia were analyzed respectively， and chromosome conventional slicing technology was used. The results showed that the number of chromosomes in six populations of S. alopecuroides was constant，2n=2x=36. There were two types of central centromere（m） chromosome and sub-central centromere（sm） chromosome in three populations. Chromosomes of most populations were only central centromere chromosome except for Population 3 in Wuwei， Gansu， with central centromere and sub-central centromere chromosome. The average arm ratio of chromosomes ranged from 1.19 to 1.37， the length ratio was between 1.72 and 2.19， and the karyotype asymmetry coefficient was from 54.30% to 57.17%. There were three types of karyotypes including 1A， 3A and 2B for S. alopecuroides. The karyotype asymmetry coefficient of population 3 of S. alopecuroides was the largest and the evolutionary degree was the highest， while those of population 19（Ordos， Inner Mongolia） was the smallest and the lowest. Cluster analysis showed that the six populations of S. alopecuroides were aggregated into two major branches of A and B. Branch A could be divided into two subclades of C and D. Among them， population 5（Wuwei， Gansu） and population 13（Alxa， Inner Mongolia） were clustered into subclade C， which had the closest relationship， whereas population 3 was clustered into subclade D alone， which was relatively distant with two populations from subclade C. Similarly， branch B could be further divided into subclade E and subclade F respectively. Subclade E was consisted of population 19 and population 43（Ordos， Inner Mongolia）， which had the closer relationship， while Subclade F only contained population 17（Yinchuan， Ningxia）， which had the relatively distant with two populations from subclade E. In this study， the chromosome number， karyotype characteristics and evolutionary trend of S. alopecuroides were discussed at the population level， which provided cytological evidence for further studying the system and evolution， and genetic diversity of germplasm resources of S. alopecuroides.