Instituto de Ecología, Universidad Nacional Autónoma de México, México D.F., 04510, Mexico Fax: (525) 616-1976 E-mail:
Theor Appl Genet. 1998 Mar;96(3-4):539-44. doi: 10.1007/s001220050771.
In the genus Pinus the internal transcribed spacers (ITS1 and ITS2) and the 5.8s region of the nuclear ribosomal DNA are approximately 3000 bp in length. ITS1 is considerably longer than ITS2 and partial sequences of ITS1 indicate that this region is evolving rapidly and exhibits intraspecific variation. The ITS2 and 5.8s regions are relatively conserved. We surveyed restriction fragment length variability of PCR-amplified fragments (PCR-RFLP) of the ITS region in four populations (86 individuals) of Pinus rzedowskii, a pine endemic to western Michoacán, Mexico. Five of the restriction endonucleases assayed revealed variation, with a total of 13 variants, most of which were length mutations of 300-900 bp. A moderate degree of population differentiation was detected. The average diversity (Shannon's index) of ITS fragment size patterns was 1.19, with 34% of the variation due to differences among populations and 66% due to differences among individuals within populations. The same individuals were assayed for nine polymorphic isozymes, which gave diversity measures similar to those of each restriction endonuclease.
在松属植物中，核核糖体 DNA 的内部转录间隔区（ITS1 和 ITS2）和 5.8s 区大约有 3000bp 长。ITS1 比 ITS2 长得多，ITS1 的部分序列表明该区域进化迅速，表现出种内变异。ITS2 和 5.8s 区相对保守。我们调查了 PCR 扩增片段（PCR-RFLP）ITS 区的限制片段长度多态性，在来自墨西哥米却肯州西部的特有松种 Pinus rzedowskii 的四个种群（86 个个体）中进行了调查。五种检测到的限制内切酶显示出变异，共有 13 种变体，其中大多数是 300-900bp 的长度突变。检测到种群间存在中度分化。ITS 片段大小模式的平均多样性（香农指数）为 1.19，其中 34%的变异是由于种群间的差异，66%是由于种群内个体间的差异。对相同的个体进行了九种多态同工酶的检测，其多样性测量结果与每种限制内切酶的相似。
