青藏高原菊科特有属绢毛菊属核型的补充报道

Abstract

菊科(Asteraceae)绢毛菊属( Soroseris )是青藏高原地区的特有类群，本文对采自青藏高原及其邻近地区的6种绢毛菊属植物的种子进行核型研究。利用常规压片法通过实验可以确定：绢毛菊属植物染色体基数都为8，除皱叶绢毛菊( S.hookeriana )为四倍体外其余5种都为二倍体，结果如下：金沙绢毛菊( S. gillii )：2n = 2x = 16 = 14 m + 2 sm。；绢毛菊( S. glomerata ) 2n = 2x = 16 = 14 m + 2 sm；空桶参( S. erysimoides ) 2n = 2x = 16 = 14 m + 2 sm；肉菊( S. umbrella )：2n = 2x = 16 = 16 m；羽裂绢毛菊(S. hirsuta)：2n = 2x = 16 = 14 m + 2 sm；皱叶绢毛菊( S.hookeriana )：2n = 4x = 32 = 32 m。核型分析结果表明，除绢毛菊( S. glomerata )和皱叶绢毛菊( S.hookeriana )为1A型外其余都为2A型。以上结果表明，绢毛菊属植染色体基数非常一致(x = 8)，该属植物物种分化的主要途径可能是二倍体水平的染色体结构变异及多倍化。 The genus Soroseris is a small genus of Asteraceae distributing primarily in the Qinghai-Tibet Pla-teau and adjacent regions. In this study, we report the chromosome numbers and karyotypes of 6 species originally assigned to Soroseris . By using the plant root tip cytology research method, the results showed that the chromosome base number is x = 8; the karyotype formulas respectively was: S. gillii with 2n = 2x = 16 = 14 m + 2 sm; S. glomerata with 2n = 2x = 16 = 14 m + 2 sm; S. erysimoides with 2n = 2x = 16 = 14 m + 2 sm; S. umbrella with 2n = 2x = 16 = 16 m; S. hirsute with 2n = 2x = 16 = 14 m + 2 sm; S.hookeriana with 2n = 4x = 32 = 32 m; Karyotypes of all the species ex-amined are relatively asymmetrical, and are classified as Stebbins’ types 1A and 2A. These findings suggest that all of the chromosome base number of Soroseris were x = 8, the variation of chromosome’s structure and polyploidization events played a major role in species diversification in this alpine genus.