Vascular plants have segmented body axes with iterative nodes and internodes. Appropriate node initiation and internode elongation are fundamental to plant fitness and crop yield; however, how these events are spatiotemporally coordinated remains elusive. We show that in barley (Hordeum vulgare L.), selections during domestication have extended the apical meristematic phase to promote node initiation, but constrained subsequent internode elongation. In both vegetative and reproductive phases, internode elongation displays a dynamic proximal – distal gradient, and among subpopulations of domesticated barleys worldwide, node initiation and proximal internode elongation are associated with latitudinal and longitudinal gradients, respectively. Genetic and functional analyses suggest that, in addition to their converging roles in node initiation, flowering-time genes have been repurposed to specify the timing and duration of internode elongation. Our study provides an integrated view of barley node initiation and internode elongation, and suggests that plant architecture should be recognized as a collection of dynamic phytomeric units in the context of crop adaptive evolution.

中文翻译：

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动态植物群生长有助于大麦的局部适应

维管植物具有分段的体轴，具有迭代的节和节间。适当的节起始和节间伸长是植物适应性和作物产量的基础；然而，这些事件如何在时空上协调仍然难以捉摸。我们发现，在大麦（Hordeum vulgare L.）中，驯化过程中的选择延长了顶端分生期以促进节的起始，但限制了随后的节间伸长。在营养和繁殖阶段，节间伸长表现出动态的近端-远端梯度，并且在全世界驯化大麦的亚群中，节起始和近端节间伸长分别与纬度和纵向梯度相关。遗传和功能分析表明，除了在节点起始中发挥聚合作用外，开花时间基因还被重新用于指定节间伸长的时间和持续时间。我们的研究提供了大麦节起始和节间伸长的综合视图，并表明植物结构应被视为作物适应性进化背景下动态植物单元的集合。