Complex mutational patterns and size homoplasy at maize microsatellite loci
Complex mutational patterns and size homoplasy at maize microsatellite loci
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DOI：
10.1007/s00122-007-0625-y
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发表时间：
2007-11-01
影响因子：
5.4
通讯作者：
Confalonieri, V. A.
中科院分区：
文献类型：
--
作者：
Lia, V. V.;Bracco, M.;Confalonieri, V. A.
微卫星标记已成为种质鉴定、群体遗传学和进化研究中最常用的工具之一。为了研究玉米微卫星的突变机制，我们获得了10个位点的核苷酸序列信息。此外，采用单链构象多态性（Single-Strand构象Polymorphism， SSCP）分析来评估大小同质性的发生。54个等位基因序列分析显示，8/10个位点存在复杂的突变模式，只有2个位点表现出严格符合逐步突变的等位基因变异。总体等位基因多样性是由重复和非重复片段中重复单位、碱基替换和索引数的变化引起的。选取6个玉米地方品种的31个电形态进行SSCP分析。每个电形态的构象数从1到7不等，其中74.2%的电形态具有一个以上的构象。在地方种和群体中，大小同源性很明显。在基因座内部和基因座之间观察到大小同源性数量的变化，但在群体之间没有发现差异。本研究的结果为解释来自微卫星标记的遗传数据提供了有用的信息。还需要进一步努力确定这些发现对估计种群参数和推断玉米系统发育关系的影响。
Microsatellite markers have become one of the most popular tools for germplasm characterization, population genetics and evolutionary studies. To investigate the mutational mechanisms of maize microsatellites, nucleotide sequence information was obtained for ten loci. In addition, Single-Strand Conformation Polymorphism (SSCP) analysis was conducted to assess the occurrence of size homoplasy. Sequence analysis of 54 alleles revealed a complex pattern of mutation at 8/10 loci, with only 2 loci showing allele variation strictly consistent with stepwise mutations. The overall allelic diversity resulted from changes in the number of repeat units, base substitutions, and indels within repetitive and non-repetitive segments. Thirty-one electromorphs sampled from six maize landraces were considered for SSCP analysis. The number of conformers per electromorph ranged from 1 to 7, with 74.2% of the electromorphs showing more than one conformer. Size homoplasy was apparent within landraces and populations. Variation in the amount of size homoplasy was observed within and between loci, although no differences were detected among populations. The results of the present study provide useful information on the interpretation of genetic data derived from microsatellite markers. Further efforts are still needed to determine the impact of these findings on the estimation of population parameters and on the inference of phylogenetic relationships in maize investigations.