Duek Paula D, Fankhauser Christian
Department of Molecular Biology, 30 quai E Ansermet, 1211 Genève 4, Switzerland.
Plant J. 2003 Jun;34(6):827-36. doi: 10.1046/j.1365-313x.2003.01770.x.
Plants are very sensitive to their light environment. They use cryptochromes and phytochromes to scan the light spectrum. Those two families of photoreceptors mediate a number of similar physiological responses. The putative bHLH (basic Helix Loop Helix) transcription factor long hypocotyl in far-red (HFR1) is important for a subset of phytochrome A (phyA)-mediated light responses. Interestingly, hfr1 alleles also have reduced de-etiolation responses, including hypocotyl growth, cotyledon opening and anthocyanin accumulation, when grown in blue light. This phenotype is particularly apparent under high fluence rates. The analysis of double mutants between hfr1 and different blue light photoreceptor mutants demonstrates that, in addition to its role in phyA signalling, HFR1 is a component of cryptochrome 1 (cry1)-mediated light signalling. Moreover, HFR1 mRNA levels are high both in blue and in far-red light but low in red light. These results identify HFR1 as a positively acting component of cry1 signalling and indicate that HFR1 integrates light signals from both phyA and cry1.
植物对其光照环境非常敏感。它们利用隐花色素和光敏色素来扫描光谱。这两类光感受器介导许多相似的生理反应。假定的bHLH（碱性螺旋-环-螺旋）转录因子远红光下长下胚轴（HFR1）对于光敏色素A（phyA）介导的一部分光反应很重要。有趣的是，当在蓝光下生长时，hfr1等位基因的去黄化反应也会减弱，包括下胚轴生长、子叶张开和花青素积累。这种表型在高光照强度下尤为明显。对hfr1与不同蓝光光感受器突变体之间的双突变体分析表明，除了在phyA信号传导中的作用外，HFR1还是隐花色素1（cry1）介导的光信号传导的一个组成部分。此外，HFR1 mRNA水平在蓝光和远红光下都很高，但在红光下很低。这些结果确定HFR1是cry1信号传导的一个正向作用成分，并表明HFR1整合了来自phyA和cry1的光信号。
