Paltiel Judith, Amin Revital, Gover Ayala, Ori Naomi, Samach Alon
The Robert H. Smith Institute for Plant Sciences and Genetics, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University, P.O. Box 12, Rehovot, 76100, Israel.
Planta. 2006 Nov;224(6):1255-68. doi: 10.1007/s00425-006-0305-1. Epub 2006 Jun 15.
GIGANTEA (GI) is a large nuclear protein which is involved in circadian-clock function, red-light signaling and photoperiodic flowering. Accumulation of GI transcript displays a strong diurnal pattern, and is under circadian-clock control, as demonstrated in several diverse species. Clock entrainment and compensation, as well as flowering time, are largely responsive to changes in the environment. We asked if part of this response is mediated through modification of GI expression. We identified a strong response of GI expression to changes in temperature and light, in both Arabidopsis and the model legume Medicago truncatula. Extreme temperatures resulted in increased GI trough levels. Light increased GI expression near dawn and the response to light appeared to be gated by the circadian clock. We provide evidence that the GI response to blue and far-red light requires CRYPTOCHROME function in Arabidopsis. Unknown roles for GI in both blue-light deetiolation and precocious flowering under warm short days were revealed. Plants seem to respond to changes in the environment partly through environmentally induced modifications of a basal clock-regulated pattern of GI transcript accumulation.
巨大蛋白（GI）是一种大型核蛋白，参与昼夜节律功能、红光信号传导和光周期开花。GI转录本的积累呈现出强烈的昼夜模式，并受昼夜节律控制，这在多个不同物种中都有体现。生物钟的同步和补偿以及开花时间在很大程度上对环境变化有响应。我们探讨了这种响应的一部分是否通过GI表达的改变来介导。我们发现，在拟南芥和模式豆科植物蒺藜苜蓿中，GI表达对温度和光照变化有强烈响应。极端温度导致GI低谷水平升高。光照在黎明时分增加GI表达，并且对光的响应似乎受昼夜节律调节。我们提供证据表明，在拟南芥中，GI对蓝光和远红光的响应需要隐花色素功能。还揭示了GI在温暖短日条件下蓝光去黄化和早熟开花中的未知作用。植物似乎部分通过环境诱导的基础生物钟调节的GI转录本积累模式的改变来响应环境变化。
