【摘要】 对中国云南西部和西北部分布的腋花扭柄花Streptopussimplex的4个居群进行了细胞学研究。生长在云南西北香格里拉县(原中甸县)碧塔海和小中甸冷杉林中的腋花扭柄花两个居群的体细胞染色体数目为2n=2x=18,而生长在高黎贡山的福贡县片马和贡山县的灌丛中的植物体细胞染色体数目则为2n=2x=14。2n=14为腋花扭柄花一个新的染色体数目,x=7为扭柄花属一个新的染色体基数。香格里拉碧塔海和小中甸两个居群的核型公式分别为2n=4m+8sm+4st和2n=8m+2sm+6st,染色体逐渐变小;贡山和福贡片马两个居群的核型公式分别为2n=14=4m+10sm和2n=14=7m+7sm,其中第一对中部着丝粒的染色体显著大于其余染色体。由于x=8是扭柄花属最常见的染色体基数,因此可认为x=8是腋花扭柄花的染色体原始基数,x=7的数目是衍生的;x=7居群染色体的一条大染色体可能是由x=8的染色体的两条st型染色体的着丝粒发生了罗伯逊易位而来。更多还原

【Abstract】 Four populations of Streptopus simplex (Liliaceae) from western and northwestern Yunnan Province, China, were investigated cytologically. The chromosome count of the two populations growing in spruce forests from Bitahai and Xiaozhongdian, Shangri-La County (formerly Zhongdian County), northwestern Yunnan, was 2n=16 with x=8, confirming the previous counts for this species, but the count of the two populations growing in alpine scrubs, one from Pianma, Fugong County, and the other from Gongshan County, both of western Yunnan, was 2n=14 with x=7, which represents a new count for the species and a new basic number for the genus. The karyotypes of the two populations from Shangri-La were formulated as 2n=4m+8sm+4st and 2n=8m+2sm+6st, respectively, with the chromosomes changing in size gradually from the largest to the smallest one, and those of the other two populations were formulated as 2n=14=4m+10sm, and 2n=14=7m+7sm, respectively, with the first pair of chromosomes being median-centromeric (m) and markedly larger than the remaining ones. As the basic chromosome number of x=8 is the commonest one in the genus Streptopus, this might be considered as the original number whereas the number of x=7 the advanced one. The presence of one pair of much larger chromosomes yet one less pair of smaller subterminal-centromeric (st) ones in the chromosome complement of the x=7 populations suggest that this number may have been derived from x=8 through the Robertsonian fusion of centromeres.更多还原