内蒙古中东部草原贝加尔针茅、大针茅和克氏针茅的染色体核型分析

Chromosome Numbers and Karyotypes of Stipa baicalensis,Stipa grandis and Stipa krylovii in Inner-mongolia Steppe

以内蒙古草原3种针茅属植物为材料,常规压片法制片后观察记录染色体数,并进行核型分析。实验结果表明:贝加尔针茅、大针茅和克氏针茅细胞染色体数均为2n=44,属于2A核型,为二倍体。在3种针茅的染色体中,中部着丝粒染色体占大多数平均为62.1%,其次近中部着丝粒染色体平均为28.9%,近端部着丝粒染色体较少约为9.0%。在3种针茅的第五号染色体上均有随体,表明起源于同一祖先。虽然染色体核型均属于较对称型,但是染色体不对称系数随着3种针茅分布生境的干旱程度的增加而逐渐增加,可能是长期适应与进化的结果。

Using the common （slice-making） method, the chromosome numbers and karyotypes of three Stipa species from Inner-Mongolia steppe were studied. The chromosome numbers of the three species were found to be 2n =2x =44（2A type）. In all species, metacentric chromosomes were the most common （mean value 62.1% ）, followed by sub-metacentrics （mean value 28.9% ）, and sub-telocentrics were rare （ mean value 9. 0% ）. The fifth chromosome had a satellite in the three species. These results indicated that their genome structure and origin were the same. The index of asymmetry of the chromosomes decreased as the habitats became drier from the east to the west, which might be the consequence of adaptation of the three species.