Chrysanthemum ×morifolium has great ornamental and economic value on account of its exquisite capitulum. However, previous studies have mainly focused on the corolla morphology of the capitulum. Such an approach cannot explain the variable inflorescence architecture of the chrysanthemum. Previous research from our group has shown that NO APICAL MERISTEM (ClNAM) is likely to function as a hub gene in capitulum architecture in the early development stage. In the present study, ClNAM was used to investigate the function of these boundary genes in the capitulum architecture of C. lavandulifolium, a closely related species of C. ×morifolium in the genus. Modified of ClNAM in C. lavandulifolium resulted in an advanced initiation of the floral primordium at the capitulum. As a result, the receptacle morphology was altered and the number of florets decreased. The ray floret corolla was shortened, but the disc floret was elongated. The number of capitula increased significantly, arranged in more densely compound corymbose synflorescences. The yeast and luciferase reporter system revealed that ClAP1, ClRCD2 and ClLBD18 target and activate ClNAM. Subsequently, ClNAM targets and activates ClCUC2a/c, which regulates the initiation of floral and inflorescence in C. lavandulifolium. ClNAM was also targeted and cleaved by cla-miR164 in this process. In conclusion, this study established a boundary gene regulatory network with cla-miR164-ClNAM as the hub. This network not only influence the architecture of capitulum, but also affect compound corymbose synflorescences of the C. lavandulifolium. These results provide new insights into the mechanisms regulating inflorescence architecture in chrysanthemum.

中文翻译：

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cla-miR164-NO 顶端分生组织 (ClNAM) 调节菊花花序结构发育

菊花以其精美的头状花序而具有极大的观赏和经济价值。然而，先前的研究主要集中在头状花序的花冠形态上。这种方法无法解释菊花可变的花序结构。我们小组之前的研究表明，NO APICAL MERISTEM (ClNAM) 很可能在早期发育阶段充当头状花序结构的中心基因。在本研究中，ClNAM 用于研究这些边界基因在 C. lavandulifolium 头状花序结构中的功能，C. lavandulifolium 是该属中与 C. × morifolium 密切相关的物种。在薰衣草中对 ClNAM 进行修饰导致头状花序处的花原基提前起始。结果，花托形态发生改变，小花数量减少。舌状花花冠缩短，但花盘小花拉长。头状花序数量显着增加，排列成更密集的复合伞房状花序。酵母和荧光素酶报告系统显示 ClAP1、ClRCD2 和 ClLBD18 靶向并激活 ClNAM。随后，ClNAM 靶向并激活 ClCUC2a/c，后者调节薰衣草花和花序的起始。在此过程中，ClNAM 也被 cla-miR164 靶向和切割。总之，本研究建立了以cla-miR164-ClNAM为枢纽的边界基因调控网络。该网络不仅影响头状花序的结构，还影响薰衣草的复合伞房状花序。这些结果为调节菊花花序结构的机制提供了新的见解。