Yanovsky M J, Mazzella M A, Casal J J
IFEVA, Facultad de Agronomía-UBA, Buenos Aires, Argentina.
Curr Biol. 2000 Aug 24;10(16):1013-5. doi: 10.1016/s0960-9822(00)00651-5.
Time measurement and light detection are inextricably linked. Cryptochromes, the blue-light photoreceptors shared between plants and animals, are critical for circadian rhythms in flies and mice [1-3]. WC-1, a putative blue-light photoreceptor, is also essential for the maintenance of circadian rhythms in Neurospora [4]. In contrast, we report here that in Arabidopsis thaliana the double mutant lacking the cryptochromes cry1 and cry2, and even a quadruple mutant lacking the red/ far-red photoreceptor phytochromes phyA and phyB as well as cry1 and cry2, retain robust circadian rhythmicity. Interestingly, the quadruple mutant was nearly blind for developmental responses but perceived a light cue for entraining the circadian clock. These results indicate that cryptochromes and phytochromes are not essential components of the central oscillator in Arabidopsis and suggest that plants could possess specific photosensory mechanisms for temporal orientation, in addition to cryptochromes and phytochromes, which are used for both spatial and temporal adaptation.
时间测量与光探测紧密相连。隐花色素是植物和动物共有的蓝光感光受体，对果蝇和小鼠的昼夜节律至关重要[1 - 3]。WC - 1是一种假定的蓝光感光受体，对粗糙脉孢菌中昼夜节律的维持也必不可少[4]。相比之下，我们在此报告，在拟南芥中，缺乏隐花色素cry1和cry2的双突变体，甚至缺乏红光/远红光感光受体phyA和phyB以及cry1和cry2的四突变体，仍保持强大的昼夜节律性。有趣的是，四突变体对发育反应几乎无感知能力，但能感知用于调节生物钟的光信号。这些结果表明，隐花色素和光敏色素并非拟南芥中央振荡器的必需成分，并表明除了用于空间和时间适应的隐花色素和光敏色素外，植物可能还拥有用于时间定向的特定光感机制。
