不同生境梯度下差不嘎蒿(Artemisia halodendron)种群ITS基因的序列分析

以科尔沁沙地差不嘎蒿(Artemisia halodendron)为研究对象,以中亚草原蒿(Artemisia depauperata)为外类群,研究不同生境梯度下差不嘎蒿种群核糖体DNA的ITS序列间差异.结果表明:排序后的差不嘎蒿ITS序列总长度为696 bp,ITS-1和ITS-2长度分别为253～256 bp和264～269 bp、G+C含量的变化范围分别为54.02％～54.77％和56.75％～58.64％,这表明ITS-2在序列长度和序列组成方面均比ITS-1变异大.差不嘎蒿9个种群序列间的一致度为85.7％～99.7％,这表明序列间存在一定的遗传分化.ITS最大简约树说明,CladeⅡ较Clade Ⅰ原始,顺序依次为subp4→subp1→subp2→subp3→subp8→subp6→subp7→subp9→subp5,与其相对应的生境次序大致为丘间低地→半流动沙丘→流动沙丘→半固定沙丘→固定沙丘,这表明差不嘎蒿的进化过程与科尔沁沙地沙漠化的形成过程以及生态恢复过程紧密相关.

ITS Sequence Analysis of Artemisia halodendron in Different Habitats Gradients

The aim of the present study is to investigate the difference between ITS sequences of Artemisia halodendron from different habitats gradients in Horqin Sandy Land, and the Artemisia depauperata is selected as outgroup. The results indicate that the total length of A. halodendron ITS is 696 bp, the lengths of the unaligned ITS-1 and ITS-2 sequences varied from 253 bp to 256 bp and 264 bp to 269 bp, respectively, the GC content of the ITS-1 and ITS-2 sequences ranged from 54.02% to 54.77% and 56.75% to 58.64%, respectively. It indicates that there is a high difference of the length and composition of sequence in ITS-1 than ITS-2. The genetic identities between ITS sequences of A. halodendron from 9 populations ranged from 85.7% to 99.7%. It indicates that there are some genetic differentiations between sequences. In the most parsimonious tree, most ITS sequences from A. halodendron showed two major clades: Clade Ⅰ and Clade Ⅱ, and Clade Ⅱ older than Clade Ⅰ, the order were subp4→subp1→subp2→subp3→subp8→subp6→subp7→subp9→subp5,and corresponding habitats orders were Inter-dune lowland→Semi-mobile dune→mobile dune→semi-fixed dune→fixed dune. It indicates that there is a closely related between the evolutionary processes of A. halodendron and desertification forming processes and ecological restoration processes of Horqin Sandy Land.