Reininga Jennifer M, Nielsen Dahlia, Purugganan Michael D
Department of Genetics, Box 7614, North Carolina State University, Raleigh, NC 27695, USA.
Mol Ecol. 2009 Jul;18(13):2844-55. doi: 10.1111/j.1365-294X.2009.04206.x. Epub 2009 Apr 24.
Molecular population genetic analysis of three chromosomal regions in Arabidopsis thaliana suggested that balancing selection might operate to maintain variation at three novel candidate adaptive trait genes, including SOLUBLE STARCH SYNTHASE I (SSI), PLASTID TRANSCRIPTIONALLY ACTIVE 7(PTAC7), and BELL-LIKE HOMEODOMAIN 10 (BLH10). If balanced polymorphisms are indeed maintained at these loci, then we would expect to observe functional variation underlying the previously detected signatures of selection. We observe multiple replacement polymorphisms within and in the 32 amino acids just upstream of the protein-protein interacting BELL domain at the BLH10 locus. While no clear protein sequence differences are found between allele types in SSI and PTAC7, these two genes show evidence for allele-specific variation in expression levels. Geographical patterns of allelic differentiation seem consistent with population stratification in this species and a significant longitudinal cline was observed at all three candidate loci. These data support a hypothesis of balancing selection at all three candidate loci and provide a basis for more detailed functional work by identifying possible functional differences that might be selectively maintained.
对拟南芥三个染色体区域的分子群体遗传分析表明，平衡选择可能在维持三个新的候选适应性状基因的变异，这些基因包括可溶性淀粉合酶I（SSI）、质体转录活性7（PTAC7）和类铃型同源结构域10（BLH10）。如果这些位点确实维持了平衡多态性，那么我们预期会观察到先前检测到的选择特征背后的功能变异。我们在BLH10基因座的蛋白质-蛋白质相互作用的BELL结构域内以及其上游32个氨基酸处观察到多个替换多态性。虽然在SSI和PTAC7的等位基因类型之间未发现明显的蛋白质序列差异，但这两个基因显示出表达水平上的等位基因特异性变异的证据。等位基因分化的地理模式似乎与该物种的群体分层一致，并且在所有三个候选基因座处都观察到了显著的纵向渐变。这些数据支持了在所有三个候选基因座处进行平衡选择的假设，并通过识别可能被选择性维持的功能差异，为更详细的功能研究提供了基础。
