中国葱属根茎组植物15种25居群的核型研究

Karyotypes of 25 Populations of 15 Species in Allium Section Rhiziridium from China

采用常规压片法,对15种25居群葱属根茎组植物进行核型研究,首次报道荒漠韭Allium tekesicola、蓝花韭A.beesianum的染色体数目和核型,并增补了一些根茎组植物的细胞学资料。结果表明:供试类群为二倍体或四倍体,核型类型为1A、2A或2B;高山韭A.sikkimense壤塘居群和荒漠韭具短臂随体,宽苞韭A.platyspathum的和布克赛尔居群、奇台居群具居间随体;野黄韭A.rude雅江居群和荒漠韭中各存在1条B染色体。结合前人研究结果,我们讨论了中国根茎组植物的染色体基数、随体染色体的多型性、B染色体的进化意义和该组植物的进化方式,探讨了天蓝韭A.cyaneum、齿丝山韭A.nutans的地理分布成因,得到了如下推论:(1)中国根茎组植物的染色体基数x=8;(2)中国根茎组植物的核型进化趋势为:1A→2A→2B→2C;(3)中国根茎组植物的随体染色体具多型性;(4)多倍化和结构变异是中国根茎组植物进化的两种重要方式;(5)天蓝韭和齿丝山韭以多倍化和无性生殖来克服扩大新的生存空间遇到的困难。

Karyotypes of 25 populations of 15 species in Allium section Rhiziridium from China were analyzed to discuss the evolutionary mechanisms of Allium section Rhiziridium and cytogeography of some species. Root tips for the study of mitotic chromosomes were obtained from potted plants and pretreated with paradichlorobenzene at room temperature for 9 hours. After 12-24 hours fixation in 1∶3 aceticalcohol, the root tips were macerated in 1mol·L-1 HC1 for 9 minutes at 60℃ and then stained and squashed in carbol fuchsin. Karyotype asymmetry was assessed by As.K%. Results showed that taxa investigated were diploid or tetraploid. Furthermore, the karyotype types were 1A, 2A or 2B according to Stebbins’ karyotype classification. Karyotypes of A.tekesicola, A.tianschanicum, A.beesianum and A.spirale were reported for the first time. Combined with previous karyotype studies, we suggested that： （1） The basic chromosome number of Allium section Rhiziridium from China is x=8. （2） The karyotype types evolutionary trend of Allium section Rhiziridium from China is 1A→2A→2B→2C . （3） Satellite chromosomes of Allium section Rhiziridium from China are varied in numbers and shapes. （4） Polyploidy and chromosome structural rearrangement are two important evolution patterns in Allium section Rhiziridium from China. （5） A.cyaneum and A.nutans have exploited new niches through polyploidy and asexual reproduction.