Gardner Kyle M, Latta Robert G
Department of Biology, Dalhousie University, 1355 Oxford St., Halifax, NS, Canada B3H 4J1.
Mol Ecol. 2006 Apr;15(5):1321-33. doi: 10.1111/j.1365-294X.2005.02835.x.
We constructed recombinant inbred lines of a cross between naturally occurring ecotypes of Avena barbata (Pott ex Link), Poaceae, associated with contrasting moisture environments. These lines were assessed for fitness in common garden reciprocal transplant experiments in two contrasting field sites in each of two years, as well as a novel, benign greenhouse environment. An AFLP (amplified fragment length polymorphism) linkage map of 129 markers spanned 644 cM in 19 linkage groups, which is smaller, with more linkage groups, than expected. Therefore parts of the A. barbata genome remain unmapped, possibly because they lack variation between the ecotypes. Nevertheless, we identified QTL (quantitative trait loci) under selection in both native environments and in the greenhouse. Across years at the same site, the same loci remain under selection, for the same alleles. Across sites, an overlapping set of loci are under selection with either (i) the same alleles favoured at both sites or (ii) loci under selection at one site and neutral at the other. QTL under selection in the greenhouse were generally unlinked to those under selection in the field because selection acted on a different trait. We found little evidence that selection favours alternate alleles in alternate environments, which would be necessary if genotype by environment interaction were to maintain genetic variation in A. barbata. Additive effect QTL were best able to explain the genetic variation among recombinant inbred lines for the greenhouse environment where heritability was highest, and past selection had not eliminated variation.
我们构建了来自燕麦草（禾本科，学名：Avena barbata (Pott ex Link)）自然生态型杂交的重组自交系，这些生态型与不同的水分环境相关。在两年中，每年在两个截然不同的田间试验点以及一个全新的、良性的温室环境中，通过共同园圃互作移植试验对这些品系的适合度进行评估。一个由129个标记组成的AFLP（扩增片段长度多态性）连锁图谱，在19个连锁群中跨度为644厘摩，比预期的要小且连锁群更多。因此，燕麦草基因组的部分区域仍未定位，可能是因为这些区域在生态型之间缺乏变异。尽管如此，我们还是在原生环境和温室中都鉴定出了受选择的QTL（数量性状位点）。在同一试验点跨年度，相同的位点仍因相同的等位基因而受到选择。在不同试验点之间，有一组重叠的位点受到选择，要么（i）两个试验点都青睐相同的等位基因，要么（ii）一个试验点的位点受到选择而另一个试验点的位点为中性。温室中受选择的QTL通常与田间受选择的QTL不连锁，因为选择作用于不同的性状。我们几乎没有发现证据表明选择在不同环境中青睐交替的等位基因，而如果基因型与环境互作要维持燕麦草的遗传变异，这将是必要的。加性效应QTL最能解释重组自交系在温室环境中的遗传变异，在该环境中遗传力最高，且过去的选择尚未消除变异。
