Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, Univ Paris Diderot, INRA, Univ Paris Sud, Univ d'Evry, Université Paris-Saclay, Rue de Noetzlin, 91190, Gif-sur-Yvette, France.
Sci Rep. 2019 Feb 20;9(1):2335. doi: 10.1038/s41598-019-38876-1.
The root system displays a remarkable plasticity that enables plants to adapt to changing environmental conditions. This plasticity is tightly linked to the activity of root apical meristems (RAMs) and to the formation of lateral roots, both controlled by related hormonal crosstalks. In Arabidopsis thaliana, gibberellins (GAs) were shown to positively control RAM growth and the formation of lateral roots. However, we showed in Medicago truncatula that GAs negatively regulate root growth and RAM size as well as the number of lateral roots depending at least on the MtDELLA1 protein. By using confocal microscopy and molecular analyses, we showed that GAs primarily regulate RAM size by affecting cortical cell expansion and additionally negatively regulate a subset of cytokinin-induced root expansin encoding genes. Moreover, GAs reduce the number of cortical cell layers, resulting in the formation of both shorter and thinner roots. These results suggest contrasting effects of GA regulations on the root system architecture depending on plant species.
根系表现出显著的可塑性，使植物能够适应不断变化的环境条件。这种可塑性与根顶端分生组织（RAM）的活性以及侧根的形成密切相关，这两者都受到相关激素相互作用的控制。在拟南芥中，赤霉素（GAs）被证明可以正向调控 RAM 的生长和侧根的形成。然而，我们在蒺藜苜蓿中表明，赤霉素负调控根生长和 RAM 大小以及侧根的数量，至少依赖于 MtDELLA1 蛋白。通过使用共聚焦显微镜和分子分析，我们表明，赤霉素主要通过影响皮层细胞的扩张来调节 RAM 的大小，并且还负调控一组由细胞分裂素诱导的根扩展蛋白编码基因。此外，赤霉素减少了皮层细胞层的数量，导致形成更短、更细的根。这些结果表明，GA 调节对不同植物物种的根系结构具有相反的影响。
