Peakall R, Gilmore S, Keys W, Morgante M, Rafalski A
Division of Botany and Zoology, Australian National University, Canberra, Australia.
Mol Biol Evol. 1998 Oct;15(10):1275-87. doi: 10.1093/oxfordjournals.molbev.a025856.
We investigated the transferability of 31 soybean (Glycine max) simple sequence repeat (SSR) loci to wild congeners and to other legume genera. Up to 65% of the soybean primer pairs amplified SSRs within Glycine, but frequently, the SSRs were short and interrupted compared with those of soybeans. Nevertheless, 85% of the loci were polymorphic within G. clandestina. Cross-species amplification outside of the genus was much lower (3%-13%), with polymorphism restricted to one primer pair, AG81. AG81 amplified loci in Glycine, Kennedia, and Vigna (Phaseoleae), Vicia (Vicieae), Trifolium (Trifolieae), and Lupinus (Genisteae) within the Papilionoideae, and in Albizia within the Mimosoideae. The primer conservation at AG81 may be explained by its apparent proximity to the seryl-tRNA synthetase gene. Interspecific differences in allele size at AG81 loci reflected repeat length variation within the SSR region and indels in the flanking region. Alleles of identical size with different underlying sequences (size homoplasy) were observed. Our findings and the emerging patterns in other plant studies suggest that in contrast to animals, successful cross-species amplification of SSRs in plants is largely restricted to congeners or closely related genera. Because mutations in both the SSR region and the flanking region contribute to variation in allele size among species, knowledge of DNA sequence is essential before SSR loci can be meaningfully used to address applied and evolutionary questions.
我们研究了31个大豆（Glycine max）简单序列重复（SSR）位点向野生同属植物及其他豆科属的转移性。高达65%的大豆引物对能在大豆属内扩增出SSR，但与大豆的SSR相比，这些SSR通常较短且有间断。尽管如此，85%的位点在野大豆（G. clandestina）内具有多态性。属外的跨物种扩增率要低得多（3%-13%），多态性仅限于一个引物对AG81。AG81在蝶形花亚科的大豆属、鸡血藤属（Kennedia）和豇豆属（Vigna）（菜豆族）、野豌豆属（Vicia）（野豌豆族）、三叶草属（Trifolium）（三叶草族）和羽扇豆属（Lupinus）（染料木族）以及含羞草亚科的合欢属（Albizia）中扩增出位点。AG81引物的保守性可能是由于其明显靠近丝氨酰 - tRNA合成酶基因。AG81位点等位基因大小的种间差异反映了SSR区域内重复长度的变化以及侧翼区域的插入缺失。观察到具有不同潜在序列但大小相同的等位基因（大小同质性）。我们的研究结果以及其他植物研究中出现的模式表明，与动物不同，植物中SSR的成功跨物种扩增在很大程度上仅限于同属植物或近缘属。由于SSR区域和侧翼区域的突变都导致物种间等位基因大小的变化，因此在SSR位点能够有意义地用于解决应用和进化问题之前，DNA序列知识至关重要。
