Herranz Raúl, Valbuena Miguel A, Youssef Khaled, Medina Francisco-Javier
Centro de Investigaciones Biológicas (CSIC); Madrid, Spain.
Plant Signal Behav. 2014;9(4):e28289. doi: 10.4161/psb.28289. Epub 2014 Mar 10.
Experiments performed in actively proliferating plant cells both in space and simulated microgravity have evidenced a common effect: cell proliferation appears enhanced whereas cell growth is depleted. Coordination of cell growth and proliferation, called meristematic competence, is a major feature of meristematic cells and its disruption may lead to important alterations in the developmental pattern of the plant. Auxin is known to be a mediator of the transduction of the gravitropic signal and a regulator of the rates of growth and proliferation in meristematic cells, as well as of their further differentiation. Therefore, gravity sensing, gravitropism, auxin levels, and meristematic competence are mutually interrelated. However, our experiments in simulated microgravity, using both mechanical and magnetic levitation technologies, have revealed that this interdependence is neither strict nor univocal and may include additional factors and mechanisms. Available data indicate that altered gravity may affect cell growth and proliferation by mechanisms alternative to the transduction of the gravitropic signal perceived by columella cells in the root tip. These mechanisms would include gravity sensing independent from statolith displacement and transduction mediators other than polar auxin transport.
细胞增殖似乎增强，而细胞生长则受到抑制。细胞生长与增殖的协调，即分生组织能力，是分生组织细胞的一个主要特征，其破坏可能导致植物发育模式的重要改变。已知生长素是重力信号转导的介质，也是分生组织细胞生长和增殖速率及其进一步分化的调节因子。因此，重力感知、向重力性、生长素水平和分生组织能力相互关联。然而，我们利用机械和磁悬浮技术在模拟微重力环境下进行的实验表明，这种相互依存关系既不严格也不单一，可能还包括其他因素和机制。现有数据表明，重力改变可能通过与根尖中柱细胞所感知的重力信号转导不同的机制影响细胞生长和增殖。这些机制将包括独立于平衡石位移的重力感知以及除极性生长素运输之外的转导介质。
