Leaf margins of indeterminate Arabidopsis leaves

Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly to suppress activity of a leaf margin meristem in Arabidopsis thaliana, and that their absence confers persistent marginal growth of leaves, cotyledons and floral organs. The marginal meristem is activated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, but other margin elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic from an ancestral shoot system from which seed plant leaves evolved. 2 Biological replicates were collected

叶片是源自无限性茎尖分生组织（indeterminate shoot apical meristems）的扁平有限性器官。特定叶缘分生组织的存在性尚存争议，因叶片中并不具备分生组织典型的解剖学特征。本研究证实，在拟南芥（Arabidopsis thaliana）中，多个NGATHA（NGA）与CINCINNATA类TCP（CIN-TCP）转录因子通过冗余作用抑制叶缘分生组织的活性；当这些因子缺失时，叶片、子叶及花器官会出现持续性的边缘生长。该叶缘分生组织由近轴域与远轴域的并置所激活，并由WOX同源盒转录因子（WOX homeobox transcription factors）维持其活性，但其他叶缘形态建成相关基因对其维持并非必需。这一遗传框架与茎尖分生组织的形态发生程序高度相似，或可代表种子植物叶片演化所源自的祖先茎系统遗迹。本研究共收集2份生物学重复样本。