A circadian clock regulates transcription of the wheat <i>Cab-1</i> gene

Abstract

In wheat plants grown under 12-hr light (L)/12-hr dark (D) cycles, the expression of a single member of the Cab family, designated the Cab-1 gene, cycles in plants that have been transferred to continuous light or darkness, indicating control by an endogenous circadian clock. The plant photoreceptor, phytochrome, interacts with the clock to govern the level of Cab-I RNA. Furthermore, when the wheat Cab-1 gene is transferred to tobacco, the circadian regulation is maintained. Fusion of the upstream region of the Cab-1 gene to the bacterial chloramphenicol acetyltransferase (CAT) gene results in the circadian fluctuation of CAT mRNA in transgenic plants. Not only does this indicate that the circadian clock is acting at the transcriptional level, but it also identifies the cis-acting element that mediates this response.