异叶苣苔属(苦苣苔科)的核型研究

KARYOTYPES OF WHYTOCKIA(GESNERIACEAE )

本文首次报道了中国特有异叶苣苔属的染色体数目及核型。该属所研究种类的染色体数目均为２ｎ＝１８，染色体长度在２．０μｍ以上，在尖舌苣苔族所报道的染色体中显示出较原始的性状。尖舌苣苔族的染色体基数可能是ｘ＝９。异叶苣苔属的间期核均为复杂型；前期染色体呈渐变型。核型从对称型向不对称型的演化主要表现在近中部着丝粒，尤其是近端部着丝粒染色体比例的增大。毕节异叶苣苔Ｗ．ｂｉｊｉｅｎｓｉｓ和峨眉异叶苣苔Ｗ．ｔｓｉａｎｇｉａｎａｖａｒ．ｗｉｌｓｏｎｉ的核型分别为２ｎ＝２Ｍ＋８ｍ＋８ｓｍ（１ｓａｔ）和２ｎ＝２Ｍ＋８ｍ（１ｓａｔ）＋８ｓｍ（２ｓａｔ），较为对称。紫红异叶苣苔Ｗ．ｐｕｒｐｕｒａｓｃｅｎｓ和白花异叶苣苔Ｗ．ｔｓｉａｎｇｉａｎａｖａｒ．ｔｓｉａｎｇｉａｎａ的核型分别为２ｎ＝４ｍ＋６ｓｍ＋８ｓｔ（１ｓａｔ）和２ｎ＝４ｍ＋８ｓｍ（２ｓａｔ）＋６ｓｔ，比较特化。河口异叶苣苔Ｗ．ｈｅｋｏｕｅｎｓｉｓ的核型是２ｎ＝４ｍ＋１０ｓｍ（１ｓａｔ）＋４ｓｔ，处于二者之间。峨眉异叶苣苔和原变种白花异叶苣苔的核型差异较大，在外部形态方面二者之间的性状变异也间断较大。本文建议将该变种从白花异叶苣苔Ｗ．ｔｓｉａｎｇｉａｎａ中移出自成一种，并和?

The karyotypes of the genus Whytockia was investigated in order to reveal its systematic position in the tribe Klugieae and the evolution of karyotypes within this genus. The chromosome numbers are 2n=18 with their length over 2.0 μm in all the investigated species of Whytockia, which represents the most primitive characteristics in the tribe Klugieae. This paper suggests that x=9 be the primitive basic number of chromosomes in the Klugieae. The morphology of the resting nuclei in Whytockia belongs to the complex chromocenter type. The chromosomes at mitotic prophase are classified into the gradient type. The evolution of karyotypes in Whytockia is toward increase of the chromosomes with submedian centromeres and especially those with subterminal centromeres. The karyotype of the variety W. tsiangiana (Hand. Mazz.)A. Weber var. wilsonii A. Weber is distinctly different from that of W. tsiangiana var. tsiangiana, which conforms well with the gross morphology. This paper suggests that this variety be separated from W. tsiangiana as an independent species with affinity to W. bijieensis.