Devlin P F, Kay S A
Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA.
Plant Cell. 2000 Dec;12(12):2499-2510. doi: 10.1105/tpc.12.12.2499.
The circadian clock is entrained to the daily cycle of day and night by light signals at dawn and dusk. Plants make use of both the phytochrome (phy) and cryptochrome (cry) families of photoreceptors in gathering information about the light environment for setting the clock. We demonstrate that the phytochromes phyA, phyB, phyD, and phyE act as photoreceptors in red light input to the clock and that phyA and the cryptochromes cry1 and cry2 act as photoreceptors in blue light input. phyA and phyB act additively in red light input to the clock, whereas cry1 and cry2 act redundantly in blue light input. In addition to the action of cry1 as a photoreceptor that mediates blue light input into the clock, we demonstrate a requirement of cry1 for phyA signaling to the clock in both red and blue light. Importantly, Arabidopsis cry1 cry2 double mutants still show robust rhythmicity, indicating that cryptochromes do not form a part of the central circadian oscillator in plants as they do in mammals.
昼夜节律钟通过黎明和黄昏时的光信号与昼夜的日常循环同步。植物利用光敏色素（phy）和隐花色素（cry）这两类光感受器来收集有关光环境的信息，从而设定生物钟。我们证明，光敏色素phyA、phyB、phyD和phyE作为光感受器参与生物钟的红光输入，而phyA以及隐花色素cry1和cry2作为光感受器参与蓝光输入。phyA和phyB在生物钟的红光输入中起累加作用，而cry1和cry2在蓝光输入中起冗余作用。除了cry1作为介导蓝光输入生物钟的光感受器的作用外，我们还证明了cry1在红光和蓝光中对phyA向生物钟的信号传导都是必需的。重要的是，拟南芥cry1 cry2双突变体仍表现出强劲的节律性，这表明隐花色素在植物中并不像在哺乳动物中那样构成中央昼夜节律振荡器的一部分。
