Nucleotide diversity and molecular evolution of the WAG-2 gene in common wheat (Triticum aestivum L) and its relatives.
Nucleotide diversity and molecular evolution of the WAG-2 gene in common wheat (Triticum aestivum L) and its relatives.
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普通小麦（Triticum aestivum L）及其近缘种WAG-2基因的核苷酸多样性和分子进化
DOI：
10.1590/s1415-47572011000400013
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发表时间：
2011-10
影响因子：
2.1
通讯作者：
Ouyang Z
中科院分区：
文献类型：
--
作者：
Wei S;Peng Z;Zhou Y;Yang Z;Wu K;Ouyang Z
在这项工作中，我们研究了WAG-2基因的遗传多样性和进化的基础上新的WAG-2等位基因分离小麦及其近缘种。不同物种的WAG-2基因外显子序列均为单核苷酸多态性（SNP），未发现插入缺失（indels）。内含子中的SNPs和indel多于外显子。外显子、外显子+内含子和内含子的多态性π从二倍体和四倍体基因型到六倍体基因型逐渐降低。这一发现表明WAG-2在二倍体中的多样性大于在六倍体中的多样性，因为后者受到了强大的选择压力。所有的dn/ds比值均< 1.0，表明WAG-2属于受负选择影响的保守基因。在二倍体物种中检测到57个特定SNPs中的39个和10个indel中的8个。WAG-2基因内含子长度的分化程度和系统发育树拓扑结构表明，在普通小麦的A、B和D基因组中存在3个同源序列。小麦类AG基因可分为WAG-1和WAG-2两个分支。后者含有WAG-2、OsMADS 3和ZMM 2基因，表明它们之间具有功能同源性。
In this work, we examined the genetic diversity and evolution of the WAG-2 gene based on new WAG-2 alleles isolated from wheat and its relatives. Only single nucleotide polymorphisms (SNP) and no insertions and deletions (indels) were found in exon sequences of WAG-2 from different species. More SNPs and indels occurred in introns than in exons. For exons, exons+introns and introns, the nucleotide polymorphism π decreased from diploid and tetraploid genotypes to hexaploid genotypes. This finding indicated that the diversity of WAG-2 in diploids was greater than in hexaploids because of the strong selection pressure on the latter. All dn/ds ratios were < 1.0, indicating that WAG-2 belongs to a conserved gene affected by negative selection. Thirty-nine of the 57 particular SNPs and eight of the 10 indels were detected in diploid species. The degree of divergence in intron length among WAG-2 clones and phylogenetic tree topology suggested the existence of three homoeologs in the A, B or D genome of common wheat. Wheat AG-like genes were divided into WAG-1 and WAG-2 clades. The latter clade contained WAG-2, OsMADS3 and ZMM2 genes, indicating functional homoeology among them.