Center for Plant Molecular Biology, University of Tuebingen, 72076 Tuebingen, Germany.
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
Genome Res. 2019 Dec;29(12):1962-1973. doi: 10.1101/gr.250878.119. Epub 2019 Nov 19.
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 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.
茎尖分生组织（SAM）协调干细胞增殖和器官起始之间的平衡，这对于胚胎后茎生长至关重要。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相关尚不清楚。通过生成拟南芥营养茎尖的高分辨率基因表达图谱，我们在这里表明，不同的基因集在玉米和拟南芥 SAM 中调节干细胞的调控和身份。细胞身份反映了转录因子（TFs）的组合活性，这些转录因子驱动在众多细胞过程中发挥作用的基因家族的单个成员的优先、差异表达。因此，亚功能化成为细胞身份的一个基本特征。此外，我们还表明，植物的成年特征在很大程度上受到 SAM 中作用的基因电路的调节，自然变异调节了在 SAM 中高度表达的基因和调节它们的 TF 附近的特定农业上重要的结构特征。除了玉米干细胞调控的独特机制外，我们的图谱还确定了作物改良的关键新目标。
