UV-B signaling in plants is mediated by UVR8, which interacts with transcriptional factors to induce root morphogenesis. However, research on the downstream molecules of UVR8 signaling in roots is still scarce. As a wide range of functional cytoskeletons, how actin filaments respond to UV-B-induced root morphogenesis has not been reported. The aim of this study was to investigate the effect of actin filaments on root morphogenesis under UV-B and hydrogen peroxide exposure in Arabidopsis. A Lifeact-Venus fusion protein was used to stain actin filaments in Arabidopsis. The results showed that UV-B inhibited hypocotyl and root elongation and caused an increase in H2O2 content only in the root but not in the hypocotyl. Additionally, the actin filaments in hypocotyls diffused under UV-B exposure but were gathered in a bundle under the control conditions in either Lifeact-Venus or uvr8 plants. Exogenous H2O2 inhibited root elongation in a dose-dependent manner. The actin filaments changed their distribution from filamentous to punctate in the root tips and mature regions at a lower concentration of H2O2 but aggregated into thick bundles with an abnormal orientation at H2O2 concentrations up to 2 mM. In the root elongation zone, the actin filament arrangement changed from lateral to longitudinal after exposure to H2O2. Actin filaments in the root tip and elongation zone were depolymerized into puncta under UV-B exposure, which showed the same tendency as the low-concentration treatments. The actin filaments were hardly filamentous in the maturation zone. The dynamics of actin filaments in the uvr8 group under UV-B exposure were close to those of the control group. The results indicate that UV-B inhibited Arabidopsis hypocotyl elongation by reorganizing actin filaments from bundles to a loose arrangement, which was not related to H2O2. UV-B disrupted the dynamics of actin filaments by changing the H2O2 level in Arabidopsis roots. All these results provide an experimental basis for investigating the interaction of UV-B signaling with the cytoskeleton.

中文翻译：

---

肌动蛋白丝通过改变拟南芥中UV-B和过氧化氢暴露下的分布来调节根系生长

植物中的UV-B信号是由UVR8介导的，它与转录因子相互作用以诱导根形态发生。然而，对根中UVR8信号下游分子的研究仍然很少。作为广泛的功能性细胞骨架，尚未报道肌动蛋白丝如何响应UV-B诱导的根形态发生。这项研究的目的是研究肌动蛋白丝对拟南芥中UV-B和过氧化氢暴露下根系形态发生的影响。Lifeact-Venus融合蛋白用于染色拟南芥中的肌动蛋白丝。结果表明，UV-B抑制了下胚轴和根的伸长，仅导致了根中而不是下胚轴中H2O2含量的增加。另外，下胚轴中的肌动蛋白丝在UV-B照射下扩散，但在控制条件下在Lifeact-Venus或uvr8植物中成束聚集。外源H 2 O 2以剂量依赖性方式抑制根伸长。在较低的H2O2浓度下，肌动蛋白丝在根尖和成熟区域的分布从丝状变为点状，但在最高2 mM的H2O2浓度下聚集为粗束，方向异常。在根部伸长区，肌动蛋白丝的排列在暴露于H2O2后从横向变为纵向。在紫外线-B照射下，根尖和延伸区的肌动蛋白丝解聚成点状，这与低浓度处理的趋势相同。肌动蛋白丝在成熟区几乎没有丝状。在紫外线-B照射下，uvr8组中的肌动蛋白丝动力学接近于对照组。结果表明，UV-B通过将肌动蛋白丝从束中重组为松散排列来抑制拟南芥下胚轴伸长，这与H2O2无关。UV-B通过改变拟南芥根中的H2O2水平来破坏肌动蛋白丝的动力学。所有这些结果为研究UV-B信号与细胞骨架的相互作用提供了实验基础。UV-B通过改变拟南芥根中的H2O2水平来破坏肌动蛋白丝的动力学。所有这些结果为研究UV-B信号与细胞骨架的相互作用提供了实验基础。UV-B通过改变拟南芥根中的H2O2水平来破坏肌动蛋白丝的动力学。所有这些结果为研究UV-B信号与细胞骨架的相互作用提供了实验基础。