Different circadian oscillators control Ca~2+ fluxes and Lhcb gene expression

摘要

Circadian biological clocks control many biological events, but the pathways by which these events are controlled are largely unknown. Based on a model suggesting that cytosolic-free calcium levels control the expression of the Lhcb gene in plants, we tested whether the circadian oscilla- tion of free calcium is responsible for driving tbe rhythm of Lhcb expression. We found that these rhythms free-run with different periods in tobacco seedlings in constant conditions. Moreover, robust oscillations of Lhcb promoter activity con- tinued in undifferentiated tobacco calli in the absence of Ca~2+ oscillations. Therefore, these two circadian rhythms are not linked hierarchically. These data provide evidence for sepa- rate circadian pacemakers controlling molecular events in plants.