水曲柳核微卫星的长度同塑现象

Size Homoplasy in Nuclear Microsatellites for Fraxinus mandshurica (Oleaceae)

用核微卫星的长度多态性刻画物种的种群遗传结构,推测其进化历史是现时景观遗传学、亲缘地理学的重要研究手段之一。选择具有合适多态性且突变机制相对明确的核微卫星对研究结果的准确性至关重要。通过收集15个已被广泛使用的梣属(Fraxinus)核微卫星,研究其在水曲柳(Fraxinus mandshurica)中的扩增稳定性,同时应用FIASCO方法针对水曲柳新开发了9对微卫星引物,并用克隆方法抽样检测能成功扩增的核微卫星序列,分析其长度变异的突变机制。研究结果表明,有66.7%的梣属核微卫星引物可以在水曲柳中稳定扩增,但其中有70%的引物在微卫星翼区普遍存在插入缺失,从而导致长度同塑。在新开发的9对引物中,仅33.3%的引物在翼区存在插入缺失。研究结果显示微卫星的长度同塑现象较为普遍,尤其是根据近缘物种开发的引物,这种现象应在利用微卫星的研究中得到重视。

The length polymorphism of nuclear microsatellite is one of the important molecular markers for landscape genetics and phylogeography studies. Microsatellites with proper polymorphism and an explicit mutation mechanism are critical for the accuracy of research results. We adopted 15 widely used nuclear microsatellites for Fraxinus to F. mand- shurica to investigate whether the primers could stably work in these species. By using FIASCO, we developed 9 nuclear microsatellite primers for F. mandshurica. To analyze the mutation mechanism of length variation, also we sequenced the PCR products. We found that only 66.7% of primers for Fraxinus could work in F. mandshurica. Among these, 70% were reported to have an insert/deletion in flanking regions. For the 9 newly developed nuclear microsatellites, 33.3% closely size homoplasy. Our study revealed that size homoplasy is common in microsatellites, especially for those closely related species.