CEITEC - Central European Institute of Technology and Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno 62500, Czech Republic
European Molecular Biology Laboratory, Heidelberg 69117, Germany.
Development. 2018 Jul 20;145(14):dev163907. doi: 10.1242/dev.163907.
Mutual interactions of the phytohormones, cytokinins and auxin determine root or shoot identity during postembryonic organogenesis in plants. However, our understanding of the role of hormonal metabolism and perception during early stages of cell fate reprogramming is still elusive. Here we show that auxin activates root formation, whereas cytokinins mediate early loss of the root identity, primordia disorganisation and initiation of shoot development. Exogenous and endogenous cytokinins influence the initiation of newly formed organs, as well as the pace of organ development. The process of shoot apical meristem establishment is accompanied by accumulation of endogenous cytokinins, differential regulation of genes for individual cytokinin receptors, strong activation of AHK4-mediated signalling and induction of the shoot-specific homeodomain regulator The last is associated with upregulation of isopentenyladenine-type cytokinins, revealing higher shoot-forming potential when compared with -zeatin. Moreover, AHK4-controlled cytokinin signalling negatively regulates the root stem cell organiser in the root quiescent centre. We propose an important role for endogenous cytokinin biosynthesis and AHK4-mediated cytokinin signalling in the control of -induced organ identity.
在植物胚胎后器官发生过程中，植物激素、细胞分裂素和生长素的相互作用决定了根或芽的身份。然而，我们对激素代谢和感知在细胞命运重编程早期阶段的作用仍知之甚少。在这里，我们表明生长素激活根的形成，而细胞分裂素介导根身份的早期丧失、原基组织紊乱和芽发育的开始。外源和内源细胞分裂素影响新形成器官的起始以及器官发育的速度。芽顶端分生组织建立的过程伴随着内源细胞分裂素的积累、个别细胞分裂素受体基因的差异调节、AHK4 介导的信号的强烈激活以及芽特异性同源结构域调节因子的诱导。最后与异戊烯腺嘌呤型细胞分裂素的上调有关，与玉米素相比，显示出更高的芽形成潜力。此外，AHK4 控制的细胞分裂素信号负调节根静止中心中的根干细胞组织者。我们提出内源性细胞分裂素生物合成和 AHK4 介导的细胞分裂素信号在 -诱导的器官身份控制中的重要作用。
