Light-dark modulation of hydroxycinnamate: CoA ligase activity from stems of Salix babylonica cultivated in vitro.

Plantlets of Salix babylonica cultivated in vitro were used to study the regulation of the lignification process. The hydroxycinnamate: CoA ligase activity of the stems was shown to be controlled by light. During photoperiodic cycles, photocontrol also occurred and induced a diurnal oscillation of enzyme activity. The oscillation was maintained in continuous light and to a certain extent in continuous darkness.