Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Department of Biology, Southern University of Science and Technology (SUSTech), Shenzhen, China.
The State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Joint Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China.
PLoS Genet. 2021 Feb 18;17(2):e1009384. doi: 10.1371/journal.pgen.1009384. eCollection 2021 Feb.
The exogenous light signal and endogenous auxin are two critical factors that antagonistically regulate hypocotyl growth. However, the regulatory mechanisms integrating light and auxin signaling pathways need further investigation. In this study, we identified a direct link between the light and auxin signaling pathways mediated by the auxin transcriptional repressor IAA3 and light-controlled PIF transcription factors in Arabidopsis. The gain-of-function mutation in IAA3 caused hyposensitivity to light, whereas disruption of IAA3 led to an elongated hypocotyl under different light intensity conditions, indicating that IAA3 is required in light regulated hypocotyl growth. Genetic studies showed that the function of IAA3 in hypocotyl elongation is dependent on PIFs. Our data further demonstrated that IAA3 interacts with PIFs in vitro and in vivo, and it attenuates the DNA binding activities of PIFs to the target genes. Moreover, IAA3 negatively regulates the expression of PIFs-dependent genes. Collectively, our study reveals an interplay mechanism of light and auxin on the regulation of hypocotyl growth, coordinated by the IAA3 and PIFs transcriptional regulatory module.
外源性光信号和内源性生长素是拮抗调节下胚轴生长的两个关键因素。然而，整合光和生长素信号通路的调节机制需要进一步研究。在这项研究中，我们在拟南芥中鉴定了生长素转录阻遏物 IAA3 和光控 PIF 转录因子介导的光和生长素信号通路之间的直接联系。IAA3 的功能获得性突变导致对光的低敏感性，而 IAA3 的破坏导致在不同光照强度条件下下胚轴伸长，表明 IAA3 是光调节下胚轴生长所必需的。遗传研究表明，IAA3 在伸长下胚轴中的功能依赖于 PIFs。我们的数据进一步表明，IAA3 在体外和体内与 PIFs 相互作用，并减弱 PIFs 对靶基因的 DNA 结合活性。此外，IAA3 负调控 PIFs 依赖基因的表达。综上所述，我们的研究揭示了光和生长素在调节下胚轴生长中的相互作用机制，由 IAA3 和 PIFs 转录调控模块协调。
