四川当归属六种植物的核型

从居群水平对四川当归属(AngelicaL.)6种植物的核型进行了研究,其中管鞘当归核型为首次报道。6个种的染色体均为2n=2x=22,多为中部和近中部着丝粒染色体,核型多为2A型,仅疏叶当归石灰窑居群为1A型;峨眉当归核型为2n=22=10m 2sm 10st,茂汶当归核型为2n=22=16m 4sm 2sm(SAT),当归核型为2n=22=14m 8sm,阿坝当归核型为2n=22=14m 8sm,管鞘当归核型为2n=22=12m 8sm 2sm(SAT),而疏叶当归不同居群的核型或多或少发生了不同程度的变异。参照Stebbins的观点,峨眉当归以核型不对称系数最高而在6个种中显示一定的核型进化性,疏叶当归不对称系数较低,且出现1A型核型因而体现出一定的原始性。但是,综合形态解剖、花粉性状以及核型特征可以看出,四川当归属植物各性状间具有进化的不同步性,这也表明,作为当归属分布频度中心之一的四川地区,同时也是当归属的分化中心之一。

Study on Karyotypes of Six Species in Angelica from Sichuan,China

Karyotypes of 6 species in Angelica L.from Sichuan are studied at population level and the karyotype of A.pseudoselinum is firstly reported.3It is found that the number of chromosomes are invariably 2n=2x=22,with most of them are median and submedian centromeric chromosomes,while subterminal centromeric chromosomes exist in A.omeiensis.The majority of karyotypes belong to 2A,and Shihuiyao population of A.laxifoliata has 1A types.As for karyotypic formula,A.omeiensis is 2n=22=10m 2sm 10st,A.maowenensis is 2n=22=16m 4sm 2sm(SAT),A.sinensis is 2n=22=14m 8sm,A.apaensis is 2n=22=14m 8sm,and A.pseudoselinum is 2n=22=12m 8sm 2sm(SAT).However,different populations of A.laxiforliata BFdon'tBFQ have the same karyotypic formulae,and there are some variations between the caryotypes more or less.According to Stebbins,BFA.omeiensis'sBFQ evolution status was showed by the highest index of asymmetry among six species studied in this paper,while A.laxiforliata is a little primitive because of its lower index of asymmetry and its 1A caryotypes.However,the morphological,anatomic,karyotypic characters and that of pollen grains are evolving asynchronously,suggesting that,Sichuan as one of the frequency centers of Angelica L.in China,is also one of the differentiation centers of Angelica L.