青藏高原4种无心菜属植物的细胞学研究

Cytological study on four species of Arenaria from Qinghai-Tibet Plateau

以四川康定和稻城两个居群的无心菜属(Arenaria)雪灵芝亚属(A.subgen.Eremogoneastrum)的雪灵芝(A.brevipetala Y.W.Tsui et L.H.Zhou)、西藏八宿业拉山和安久拉山两个居群的八宿雪灵芝(A.baxoiensis L.H.Zhou)、西藏当雄和工布江达两个居群的瘦叶雪灵芝(A.ischnophylla Williams)以及西藏拉萨居群的藓状雪灵芝(A.bryophylla Fernald)为研究材料,采用植物根尖常规压片法,对它们的细胞分类学特征进行研究。结果显示:7个居群中,4种植物的染色体数目均为2n=22,为二倍体,核型公式为2n=2x=22=22 m,核型不对称性属于Stebbins’s-1A型,AI值在1.75~0.32范围内变化。结合无心菜属已有细胞学资料,推断雪灵芝亚属核型特征原始,染色体数目及倍性稳定。本研究中4种植物的染色体数目和核型资料均为首次报道,补充了青藏高原无心菜属的细胞学资料。

To determine the cytotaxonomic characteristics of Arenaria in China,A.subgen.Eremogoneastrum A.brevipetala Y.W.Tsui et L.H.Zhou(two populations from Kangding and Daocheng in Sichuan),A.baxoiensis L.H.Zhou(two populations from Yela and Anjula mountains,Baxoi,Tibet),A.ischnophylla Williams(two populations from Damxung and Gongbo’gyamda in Tibet),and A.bryophylla Fernald(Lhasa,Tibet)were studied.Root tips were used in combination with KaryoType 2.0 analysis for karyotype research.Results showed that the chromosome number in all seven populations of the four species was 2n=22,i.e.,diploid evolution.The karyotype formula was 2n=2x=22=22 m and karyotype asymmetry belonged to Stebbins’s-1A type,with an AI value in the range of 1.75-0.32.Thus,combined with existing cytological data for Arenaria,the karyotype of A.subgen.Eremogoneastrum is primitive,and its chromosome number(ploidy)is stable.The chromosome number and karyotype data of the four studied species are reported here for the first time.These results will supplement current cytological information for Arenaria in the Qinghai-Tibet Plateau and provide insight into the taxonomy,phylogeny,and floristic geography of Arenaria and Caryophyllaceae.