铁线莲属21个类群的染色体核型分析

Chromosome karyotype analysis of 21 Clematis taxa

铁线莲属(Clematis L.)为毛茛科大属之一,具有重要的园艺与药用价值。为探讨铁线莲属植物染色体组演化规律,揭示属下组间及种间的亲缘关系,该研究采用常规压片法对铁线莲属21个类群的根尖进行处理、压片,对染色体的形态特征进行观察及核型分析,同时利用Ward联接法进行聚类分析研究。狭裂太行铁线莲、毛果扬子铁线莲、卷萼铁线莲、中印铁线莲、钝萼铁线莲的染色体形态为首次报道。结果表明:铁线莲属21个类群均为二倍体,染色体数均为16(2n=2x=16),除中印铁线莲外其他类群均具随体;长瓣铁线莲、钝萼铁线莲、芹叶铁线莲、褐毛铁线莲、C.flammula、毛果扬子铁线莲的染色体为“2B”型,其他类群染色体为“2A”型;铁线莲属核型不对称系数在60.29%~63.79%之间;铁线莲属植物染色体组表现的较为原始,种间核型存在广泛变异。综上结果表明,铁线莲属植物染色体数目应由二倍体向多倍体演化后通过多倍体的二倍化过程产生非整倍体方向演化。铁线莲属染色体的演化主要在二倍体水平上进行,通过产生染色体结构变异的方式实现,通过产生杂合染色体、加强核型不对称性、染色体类型改变以及随体染色体的变化四种途径进化。同时,核型特征在分组水平与物种水平上的划分与传统分类基本一致,说明核型分析可为铁线莲属下组一级分类提供一定的线索。该研究结果为铁线莲属植物系统分类、遗传演化与资源利用等研究领域提供了新的参考资料。

Clematis L.is one of the major genera of Ranunculaceae,and has important horticultural and medicinal values.In order to discuss the chromosome evolution law of Clematis plants,reveal the genetic relationship among sections and species,karyotype analysis in 21 Clematis taxa were observed.In this study,the root tips of 21 groups of Clematis were treated and pressed by conventional pressing method,the morphological characteristics of chromosomes were observed,karyotype was analyzed,and cluster analysis was carried out by Ward connection method.C.kirilowii var.chanetii,C.puberula var.tenuisepala,C.tubulosa,C.tibetana and C.peterae were reported for the first time.The results were as follows:All the 21 taxa of Clematis were diploid with x=8(2n=2x=16),the genome of each taxon had at least one pair of satellites except of C.tibetana.The chromosome of C.fusca,C.peterae,C.macropetala,C.aethusifolia,C.puberula var.tenuisepala,C.flammula were‘2B’type,C.acerifolia,C.fruticose,C.heracleifolia,C.intricate,C.grandidentata,C.brevicaudata,C.puberula var.tenuisepala,C.glauca,C.hexapetala,Clematis kirilowii,C.kirilowii var.chanetii,C.alpina var.ochotensis,C.tangutica,C.tibetana,C.tubulosa,C.vitalba were‘2A’type.The karyotype asymmetry coefficient ranged from 60.29%to 63.79%.The chromosomes of Clematis were primitive,and the karyotypes varied widely among species.Through the above research,we can draw the following conclusions:The chromosome number of Clematis should evolve from diploid to polyploid,and then aneuploidy be produced through the polyploid diploidization process.The chromosome evolution of Clematis is mainly carried out at the diploid level,which is realized by generating chromosome structural variation,and evolve through four ways:generating heterozygous chromosomes,strengthening karyotype asymmetry,chromosome type change and satellite chromosome change.At the same time,the karyotype characteristics of Clematis are basically consistent with the traditional classification at the section level and species level,which indicates that karyotype analysis can provide new reference basis for the classification of Clematis.The results of the present study have significant scientific values in the further studies on the taxonomy,phylogenetics and resources utilization in genus Clematis.