The shoot apical meristem (SAM) orchestrates the balance between stem cell proliferation and organ initiation essential for postembryonic shoot growth. Meristems show a striking diversity in shape and size. How this morphological diversity relates to variation in plant architecture and the molecular circuitries driving it are unclear. By generating a high-resolution gene expression atlas of the vegetative maize shoot apex, we show here that distinct sets of genes govern the regulation and identity of stem cells in maize versus Arabidopsis. Cell identities in the maize SAM reflect the combinatorial activity of transcription factors (TFs) that drive the preferential, differential expression of individual members within gene families functioning in a plethora of cellular processes. Subfunctionalization thus emerges as a fundamental feature underlying cell identity. Moreover, we show that adult plant characters are, to a significant degree, regulated by gene circuitries acting in the SAM, with natural variation modulating agronomically important architectural traits enriched specifically near dynamically expressed SAM genes and the TFs that regulate them. Besides unique mechanisms of maize stem cell regulation, our atlas thus identifies key new targets for crop improvement.

中文翻译：

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高分辨率基因表达图谱将专用的分生组织基因与关键的建筑性状联系起来。

茎尖分生组织（SAM）协调了干细胞增殖与胚胎后芽生长必需的器官萌发之间的平衡。分生组织在形状和大小上表现出惊人的多样性。这种形态多样性如何与植物结构的变化以及驱动它的分子电路如何相关尚不清楚。通过生成营养玉米茎尖的高分辨率基因表达图集，我们在这里显示出不同的基因集控制着玉米与拟南芥干细胞的调控和同一性。玉米SAM中的细胞身份反映了转录因子（TFs）的组合活性，该因子驱动在众多细胞过程中起作用的基因家族中各个成员的优先分化表达。因此，亚功能化成为细胞身份基础的基本特征。此外，我们显示成年植物的性状在很大程度上受作用于SAM的基因回路的调节，自然变化调节着农学上重要的建筑性状，特别是在动态表达的SAM基因和调节它们的TFs附近特别丰富。除了玉米干细胞调控的独特机制外，我们的地图集还确定了作物改良的关键新目标。