Abstract
The nutation frequency of Arabidopsis inflorescence stems gradually decreased when cultivated under dark or irradiation of weak white light (<5 μmol m-2s-1). Re-irradiation of white, blue, red and far-red light during dark treatment had different effects on the nutation frequency. The nutation frequency of inflorescence stems increased soon after irradiation with a red light. This quick response in the nutation frequency to red light irradiation was observed in wild-type plant and phyB mutant, but not in either phyA or phyAphyB mutants. These results suggest that the light intensity and the red light photoperception via phytochrome A play important roles in the regulation of circumnutation.
