万寿竹六个居群的核型研究

本文研究了在云南境内的万寿竹Disporum cantoniense (Lour．)Merr．从滇东南经滇中到滇西 北不同居群间的核型变异。该种的染色体数目较为稳定，2n=14，没有观察到不同数目的变异。六个 居群的不对称性均属于3B型，但各个居群的核型结构表现出一定的差异，核型间随体位置和数目的不 同以及同源染色体的杂合性是居群间变异的主要特征，这种种内不同居群间核型的变异或许与该种的地理分布及生境有一定的相关性。

A Cytological Study of Six Populations of Disporum cantoniense (Liliaceae)

 Disporum cantoniense (Lour.) Merr. is widely distributed in the area from the Himalayas to Indonesia, via south China, Indo-China and Taiwan, es- pecially in the various parts of Yunnan Province. In this paper, the karyotype vari- ation  of  six  populations  of  the  apecies  from  southeastern,  middle  and northwestern part of Yunnan are studied. The result shows that the chromosome number of all the populations are 2n= 14.      The species was reported to have 2n= 16, 30 (Hasegawa 1932, Mehra and Pathamia 1960, Kurosawa 1966, 1971, Tang et al. 1984) and 2n= 14 (Kurosawa 1971, Mehra and Sachdeva 1976a). 2n= 14, 2n= 16 and 2n=32 were observed in the material from Taiwan (Chuang, et al. 1962, Chao, 1963, Hsu, 1971, 1972, Chang, 1974). Based on the cytological study of D. megalanthum Wang et Tang and seven other species in this genus reported by other authors,  Hong and Zhu (1990) consider that the basic number of this genus is x= 8, because species with 2n= 16 was more than those with 2n= 14, despite some number variation of chromosomes in this genus. Based on the results of the present paper, we consider that x= 7 might be one of the basic numbers of this genus.      In the karyotypes studied here, the relative chromosome lengths and the ratio of the longest/the shortest chromosomes of the six populations are rather approxi- mate.  Moreover, all the karyotypes belong to Stebbins’3B type.  However, karyotype variation was detected in these populations. The homologues of the 2nd, 3rd and 6th pair of chromosomes are different from each other, the numbers and popsition of satellites are found very different, among the populations except for the Lijiang population, the 1st, 2nd, 3rd or 4th pair of all the populations ex- hibited heterozygosity. Although all the karyotypes belong to Stebbins ‘3B type, the homologues were more regular in the Lijiang population than in the other populations, and the most irregular in the Wenshan population, because it hadfour pairs of heterozygous chromosomes.