试论沙冬青属的染色体地理*

沙冬青属是我国西北干旱地区及中亚东部荒漠的一个特有属,是我国荒漠中唯一的旱生常绿阔叶灌木,本文采用细胞学的方法,研究沙冬青属2种植物及其近缘属──黄花木属和黄华属在青藏高原的代表种(黄花木、紫花黄华)的核型、酯酶同工酶,进而探讨沙冬青属的演化趋势、地理分布及与环境的关系。本文是植物染色体地理的试验研究。

A STUDY ON THE CHROMOSOMAL GEOGRAPHY OF AMMOPIPTANTHUS GENUS

This paper mainly discusses the comparison and analysis of the chromosomal karyotype, esterase isozymes and geographical distribution of the two species in Ammopiptanthus genus (A. mongolicus and A. nanus). At the sametime, the chromosomal karyotype, esterase isozymes of the kindred genus-the representative species in Qinghai-Xizang Plateau (Piptanthus nepalensis, Thermopsis barbata) were studied in order to further approach the evolutional trend, geographical distribution and the relations between the environment and the Ammopiptanthus genus.Cytological observation shows that the karyotype formulas of the four species are: A. mongolicus-2n=2x=18=6m (2SAT) + 10sm (2SAT) + 2st; A. nanus-2n=2x=18= 8m(4SAT) +8sm+2st ; T. barbaa-2n=2x=18=6m (2SAT) + 10sm+2st; and P. nepalensis-2n=2x=18=14m(2SAT) +4sm. The karyotypes of the four species belong to 3A; 2A; 2A and 1A respectively. The results of the research on esterase isozymes were: The A. mongolicus has 6 first grade dark and wide bands and the A. nanus has 5 first grade bands. The activity of the enzyme of the A.nanus is lower than the A. monglocus. It shows that the karyotype and esterase of the A. mongolicus are more evolved than the A. nanus. In the desert, A. nanus only distributes in the narrow areas with good hydrologic conditions, but the A. mongolicus can form the endemic vegelation in the desert in the east part of Central-Asia. About the chromosomal number and the karyotype, there are many reports both in and out of China, but our research is quite different from all of the reports.All of the appraisal results of the esterase isozymes are firstly reported.