Doust Andrew N, Kellogg Elizabeth A
University of Missouri-St Louis, Department of Biology, One University Boulevard, St Louis, MO 63121, USA.
Mol Ecol. 2006 Apr;15(5):1335-49. doi: 10.1111/j.1365-294X.2005.02791.x.
Many domesticated crops are derived from species whose life history includes weedy characteristics, such as the ability to vary branching patterns in response to environmental conditions. However, domesticated crop plants are characterized by less variable plant architecture, as well as by a general reduction in vegetative branching compared to their progenitor species. Here we examine weedy green millet and its domesticate foxtail millet that differ in the number of tillers (basal branches) and axillary branches along each tiller. Branch number in F(2:3) progeny of a cross between the two species varies with genotype, planting density, and other environmental variables, with significant genotype-environment interactions (GEI). This is shown by a complex pattern of reaction norms and by variation in the pattern of significant quantitative trait loci (QTL) amongst trials. Individual and joint analyses of high and low density trials indicate that most QTL have significant GEI. Dominance and epistasis also explain some variation in branching. Likely candidate genes underlying the QTL (based on map position and phenotypic effect) include teosinte branched1 and barren stalk1. Phytochrome B, which has been found to affect response to shading in other plants, explains little or no variation. Much variation in branching is explained by QTL that do not have obvious candidate genes from maize or rice.
许多驯化作物源自其生活史具有杂草特性的物种，比如能够根据环境条件改变分枝模式。然而，驯化作物的特点是植株结构变化较小，与它们的祖先物种相比，营养分枝总体上也有所减少。在此，我们研究了杂草型青狗尾草及其驯化种谷子，它们在分蘖（基部枝条）数量以及每个分蘖上的腋生枝条数量方面存在差异。这两个物种杂交产生的F(2:3)子代的枝条数量随基因型、种植密度和其他环境变量而变化，存在显著的基因型 - 环境互作（GEI）。这通过反应规范的复杂模式以及不同试验间显著数量性状位点（QTL）模式的变化得以体现。高密度和低密度试验的个体分析与联合分析表明，大多数QTL具有显著的GEI。显性和上位性也解释了分枝的一些变异。基于图谱位置和表型效应，QTL潜在的可能候选基因包括玉米分枝1基因和无穗轴1基因。在其他植物中已发现会影响对遮荫反应的光敏色素B基因，对分枝变异的解释很少或没有解释作用。分枝的许多变异是由在玉米或水稻中没有明显候选基因的QTL所解释的。
