Kondo Yuki
Department of Biology, Graduate School of Science, Kobe University, Kobe, Hyogo 657-8501, Japan.
Plant Biotechnol (Tokyo). 2022 Mar 25;39(1):59-64. doi: 10.5511/plantbiotechnology.21.1109a.
For permanent secondary growth in plants, cell proliferation and differentiation should be strictly controlled in the vascular meristem consisting of (pro)cambial cells. A peptide hormone tracheary element differentiation inhibitory factor (TDIF) functions to inhibit xylem differentiation, while a plant hormone brassinosteroid (BR) promotes xylem differentiation in (pro)cambial cells. However, it remains unclear how TDIF and BR cooperate to regulate xylem differentiation for the proper maintenance of the vascular meristem. In this study, I developed an easy evaluation method for xylem differentiation frequency in a vascular induction system Vascular cell Induction culture System Using Arabidopsis Leaves (VISUAL) by utilizing a xylem-specific luciferase reporter line. In this quantitative system, TDIF suppressed and BR promoted xylem differentiation in a dose-dependent manner, respectively. Moreover, simultaneous treatment of TDIF and BR with (pro)cambial cells revealed that they can cancel their each other's effect on xylem differentiation, suggesting a competitive relationship between TDIF and BR. Thus, mutual inhibition of "ON" and "OFF" signal enables the fine-tuned regulation of xylem differentiation in the vascular meristem.
对于植物的永久性次生生长，细胞增殖和分化应在由（原）形成层细胞组成的维管分生组织中受到严格控制。一种肽激素——管状分子分化抑制因子（TDIF）的作用是抑制木质部分化，而一种植物激素——油菜素内酯（BR）则促进（原）形成层细胞中的木质部分化。然而，TDIF和BR如何协同调节木质部分化以维持维管分生组织的正常功能仍不清楚。在本研究中，我利用木质部特异性荧光素酶报告系，开发了一种在维管诱导系统——拟南芥叶片维管细胞诱导培养系统（VISUAL）中评估木质部分化频率的简易方法。在这个定量系统中，TDIF分别以剂量依赖的方式抑制木质部分化，而BR则促进木质部分化。此外，将TDIF和BR同时与（原）形成层细胞处理表明，它们可以相互抵消对方对木质部分化的影响，这表明TDIF和BR之间存在竞争关系。因此，“开”信号和“关”信号的相互抑制能够对维管分生组织中的木质部分化进行微调。
