Some plant species have a striking capacity for regeneration in nature, including regeneration of the entire individual from explants. However, due to the lack of suitable experimental models, the regulatory mechanisms of spontaneous whole plant regeneration are mostly unknown. In this study, we established a novel model system to study these mechanisms using an amphibious plant within Brassicaceae, Rorippa aquatica, which naturally undergoes vegetative propagation via regeneration from leaf fragments. Morphological and anatomical observation showed that both de novo root and shoot organogenesis occurred from the proximal side of the cut edge transversely with leaf vascular tissue. Time-series RNA-seq analysis revealed that auxin and cytokinin responses were activated after leaf amputation and that regeneration-related genes were upregulated mainly on the proximal side of the leaf explants. Accordingly, we found that both auxin and cytokinin accumulated on the proximal side. Application of a polar auxin transport inhibitor retarded root and shoot regeneration, suggesting that the enhancement of auxin responses caused by polar auxin transport enhanced de novo organogenesis at the proximal wound site. Exogenous phytohormone and inhibitor applications further demonstrated that, in R. aquatica, both auxin and gibberellin are required for root regeneration, whereas cytokinin is important for shoot regeneration. Our results provide a molecular basis for vegetative propagation via de novo organogenesis.

中文翻译：

---

北美水芹（Rorippa aquatica）（十字花科）通过再生进行天然营养繁殖的分子基础。

一些植物物种具有自然再生的惊人能力，包括从外植体再生整个个体。然而，由于缺乏合适的实验模型，自发整株植物再生的调控机制尚不清楚。在这项研究中，我们建立了一个新颖的模型系统来研究这些机制，这些植物使用的是十字花科的两栖植物，该植物通过叶片碎片的再生而自然地进行营养繁殖。形态和解剖学观察显示，从根部和枝条的器官发生均发生在切缘的近侧，横向于叶片维管组织。时间序列RNA-seq分析显示，截肢后植物生长素和细胞分裂素反应被激活，并且与再生相关的基因主要在叶片外植体的近端上调。因此，我们发现生长素和细胞分裂素都在近端积累。极性植物生长素转运抑制剂的应用阻碍了根和茎的再生，这表明由极性植物生长素转运引起的植物生长素应答的增强增强了近端伤口部位的新生器官发生。外源性植物激素和抑制剂的应用进一步证明，在水生罗非鱼中，生长素和赤霉素都需要进行根再生，而细胞分裂素对于枝条再生很重要。我们的结果为通过从头器官发生的营养繁殖提供了分子基础。