葱属Anguinum亚属4种19居群的核型研究

Karyotypes of nineteen populations of four species in Allium subgenus Anguinum

关键词:  葱属, Anguinum亚属, 核型, 进化, 细胞地理

Key words:  Allium, subgenus Anguinum, karyotype, evolution, cytogeography

摘要:

石蒜科(Amaryllidaceae)葱亚科(Allioideae)葱族(Allieae)葱属(Allium)的Anguinum亚属在中国分布有6种2变种,该亚属植物具有重要的药用价值。该研究在扩大样本量和覆盖范围的基础上,采用常规压片法对葱属Anguinum亚属4种植物19居群的染色体核型进行了研究,首次报道了心叶韭(Allium ovalifolium var. cordifolium)的核型。结果表明:供试类群中茖葱都为四倍体,对叶韭和心叶韭都为二倍体,太白韭具有二倍体和四倍体,染色体基数均为x=8,核型类型都为2A型,每个居群都具有随体染色体,随体染色体多为st染色体,随体均位于短臂末端,并且对叶韭眉县居群和太白韭聂拉木居群存在B染色体。结合前人研究结果讨论了Anguinum亚属植物的染色体特征、随体染色体的多态性和该亚属植物的进化方式,探讨了茖葱(Allium victorialis)和对叶韭(A. listera)的细胞地理学问题。得到如下推论:(1)染色体加倍和结构变异是Anguinum亚属进化的两种重要机制,环境异质性使得Anguinum亚属植物随体染色体具较高的多态性;(2)茖葱通过多倍化和无性繁殖并存来扩大居群;(3)染色体形态变异是对叶韭适应环境变异的重要方式。

Abstract:

Subgenus Anguinum belongs to genus Allium L., tribe Allieae Dumort,subfamily Allioideae Herb., family Amaryllidaceae J. St.-Hil. Six speices and two variety species in this subgenus occur in East Asian. They are important medicinal plant, having great economic value. Allium victorialis has been traditionally widely used to treat various conditions such as kaempferol, acid, diallydisulfide, furostanol glycosides. Bioactivity experiments have demonstrated that the plant is effective in lowering lipids and obesity, resisting oxidation, diabetes, cancer, and protecting the liver. Karyotypes of nienteen populations of four species in Allium subgenus Anguinum from China were analyzed to discuss the evolutionary mechanisms of Allium subgenus Anguinum and cytogeography of Allium victorialis, A. listera and A. prattii. Karyotypes of A. ovalifolium var. cordifolium was reported for the first time. Root tips for the study of mitotic chromosomes were obtained from potted plants and pretreated with paradichlorobenzene at room temperature for 9 h.After 12-24 h fixation in 1:3 acetic-alcohol, the root tips were macerated in 1 mol·L^-1 HCL for 9 min at 60 ℃, then stained and squashed in carbol fuchsin, and then Karyotype asymmetry was assessed by As.K%. The results showed that the karyotypes of all the species investigated were 2A according to Stebbins' karyotype classification, and the basic chromosome number is x = 8. All the populations had satellite chromosomes, and most of the satellite chromosomes were subterminal chromosomes and satellites were located in the short arm. Combined with previous studies, our inferences are as follows:(1)Polyploidy and chromosome structural rearrangement are two important evolution patterns in Allium subgenus Anguinum, and environmental heterogeneity promotes the variation in satellite chromosomes.(2)Polyploidy and asexual reproduction are important strategies for Allium victorialis to disperse and exploit new niches.(3)A. listera expands population by chromosome structural rearrangement.