Kubalová Monika, Griffiths Jayne, Müller Karel, Levenets Lev, Tylová Edita, Tarkowská Danuše, Jones Alexander M, Fendrych Matyáš
Institute of Experimental Botany of the Czech Academy of Sciences, Prague 16502, Czech Republic.
Department of Experimental Plant Biology, Charles University, Prague 12844, Czech Republic.
Proc Natl Acad Sci U S A. 2025 Jul 29;122(30):e2425574122. doi: 10.1073/pnas.2425574122. Epub 2025 Jul 22.
Plant bodies are built from immobile cells, making the regulation of cell expansion essential for growth, development, and adaptation. In roots, cell elongation executes the movement of the root tips through the soil. This process is tightly controlled by numerous signaling pathways. Among these, gibberellin and auxin signaling stand out for their contrasting effects on root growth, interacting through complex cross talk at multiple regulatory levels. Here, we reveal the molecular basis of the auxin-gibberellin cross talk in the model plant . We show that the auxin signaling pathway steers the expression of , key gibberellin-deactivating enzymes in the root elongation zone (EZ). GA2OXs are negative regulators of root cell elongation; overexpression decreases gibberellin levels and inhibits root cell elongation; in contrast, the mutant roots show elevated gibberellin levels in the EZ and grow longer roots. Intriguingly, shoot-derived auxin can regulate and expression in roots, linking systemic auxin signaling to local gibberellin level modulation. Together, our findings identify GA2OX6 and GA2OX8 enzymes as key mediators of auxin-gibberellin cross talk, providing insights into their roles in root elongation. These results expand our understanding of how auxin integrates with gibberellin signaling to coordinate root development and growth dynamics.
植物体由固定不动的细胞构成,因此细胞扩张的调控对于生长、发育和适应至关重要。在根中,细胞伸长促使根尖在土壤中移动。这一过程受到众多信号通路的严格控制。其中,赤霉素和生长素信号因其对根生长的相反作用而格外突出,它们在多个调控层面通过复杂的相互作用进行交流。在此,我们揭示了模式植物中生长素 - 赤霉素相互作用的分子基础。我们发现,生长素信号通路调控根伸长区(EZ)中关键的赤霉素失活酶GA2OX6和GA2OX8的表达。GA2OXs是根细胞伸长的负调控因子;过表达会降低赤霉素水平并抑制根细胞伸长;相反,GA2OX6和GA2OX8突变体根在EZ中显示出升高的赤霉素水平,且根生长更长。有趣的是,来自地上部的生长素可以调控根中GA2OX6和GA2OX8的表达,将系统性生长素信号与局部赤霉素水平调节联系起来。总之,我们的研究结果确定GA2OX6和GA2OX8酶是生长素 - 赤霉素相互作用的关键介质,为它们在根伸长中的作用提供了见解。这些结果扩展了我们对生长素如何与赤霉素信号整合以协调根发育和生长动态的理解。