A light‐ and temperature‐entrained circadian clock controls expression of transcripts encoding nuclear proteins with homology to RNA‐binding proteins in meristematic tissue

作者：Christian Heintzen, Siegbert Melzer, Ruth M. Fischer, Stefan R. Kappeler, Klaus Apel, Dorothee Staiger · 发表于：The Plant Journal · 年份：1994 · DOI：10.1046/j.1365-313x.1994.5060799.x · 被引用次数：158 · 研究领域：Plant Molecular Biology Research、Light effects on plants、Photosynthetic Processes and Mechanisms

To investigate physiological processes generated by endogenous circadian rhythms on the molecular level, we have identified clock-controlled genes in the long-day plant Sinapis alba L. A cDNA library was differentially screened using cDNA probes representing transcripts expressed at either the middle of the light period or the middle of the dark period. Two closely related groups of transcripts, Sagrp1 and Sagrp2, controlled by a circadian rhythm have been isolated. RNA blot analysis verified that transcript levels oscillate in plants grown in light/dark cycles with maxima between 'Zeitgeber' time (zt)8 and zt12 (8-12 h after onset of illumination) and minima around zt20. Steady-state mRNA levels continue to oscillate in plants shifted from light/dark cycles to constant light. No synchronous mRNA oscillations are found in plants grown from seed in constant light at constant temperature, suggesting that the clock has to be entrained initially. In contrast, when plants grown in constant light are exposed to rhythmic temperature shifts oscillations of steady-state Sagrp mRNA levels are induced, indicating that temperature acts as an alternative external stimulus (zeitgeber) other than light to entrain the oscillator. In situ hybridization reveals that both transcript groups are expressed predominantly in meristematic and growing tissue. Strong expression is observed in the leaf primordia of the shoot apex, the procambial strands, cambium and in all cell layers of young leaves ar...