College of Horticulture, Northwest A&F University, Yangling, Shaanxi, ChinaSection of Evolutionary Biology, Department of Biology II, University of Munich (LMU), Planegg-Martinsried, GermanyResearch Unit 'Genetic Diversity and Breeding of Forest Tree Species', Cirad Biological System Department, TA A-39/C, Campus International de Baillarguet, 34398 Montpellier Cedex, France.
Mol Ecol. 2010 Oct;19(19):4144-54. doi: 10.1111/j.1365-294X.2010.04762.x. Epub 2010 Sep 11.
We surveyed nucleotide diversity at two candidate genes LeNCED1 and pLC30-15, involved in an ABA (abscisic acid) signalling pathway, in two closely related tomato species Solanum peruvianum and Solanum chilense. Our six population samples (three for each species) cover a range of mesic to very dry habitats. The ABA pathway plays an important role in the plants' response to drought stress. LeNCED1 is an upstream gene involved in ABA biosynthesis, and pLC30-15 is a dehydrin gene positioned downstream in the pathway. The two genes show very different patterns of nucleotide variation. LeNCED1 exhibits very low nucleotide diversity relative to the eight neutral reference loci that were previously surveyed in these populations. This suggests that strong purifying selection has been acting on this gene. In contrast, pLC30-15 exhibits higher levels of nucleotide diversity and, in particular in S. chilense, higher genetic differentiation between populations than the reference loci, which is indicative of local adaptation. In the more drought-tolerant species S. chilense, one population (from Quicacha) shows a significant haplotype structure, which appears to be the result of positive (diversifying) selection.
我们调查了两个候选基因 LeNCED1 和 pLC30-15 的核苷酸多样性，这两个基因参与了 ABA（脱落酸）信号通路，这两个基因存在于两个密切相关的番茄物种秘鲁番茄和智利番茄中。我们的六个群体样本（每个物种三个）涵盖了从湿润到非常干燥的栖息地。ABA 途径在植物对干旱胁迫的反应中起着重要作用。LeNCED1 是参与 ABA 生物合成的上游基因，而 pLC30-15 是该途径下游的脱水素基因。这两个基因显示出非常不同的核苷酸变异模式。LeNCED1 的核苷酸多样性相对较低，与之前在这些群体中调查的八个中性参考基因相比。这表明该基因受到了强烈的纯化选择。相比之下，pLC30-15 表现出更高水平的核苷酸多样性，特别是在 S. chilense 中，与参考基因相比，群体间的遗传分化更高，这表明存在局部适应。在更耐旱的物种 S. chilense 中，一个来自 Quicacha 的种群显示出显著的单倍型结构，这似乎是正选择（多样化选择）的结果。
