The biogenesis of anthocyanins: X. The action spectrum for anthocyanin formation in Spirodela oligorrhiza

Abstract

Anthocyanin formation by Spirodela oligorrhiza has been determined as a function of irradiance. The highest yields resulted when the plants were incubated for 40 hours in the dark after irradiation. Saturation was reached in the red at about 20 k.ergs (1.3 × 10 −8 Einsteins) per square millimeter. The irradiance response curve for white fluorescent light, however, did not reach saturation at the highest values applied, namely 600 kiloergs per square millimeter, and possible explanations for this behavior are discussed. Using irradiances within the proportionality range, and calibrated intensities of monochromatic light from a high energy arc in a grating spectrograph, the action spectrum for anthocyanin synthesis was determined. The band widths for each point were less than 4 mμ. The resulting spectrum shows sharp peaks at 705 and (when number of fronds is used as parameter) at 300 mμ. The latter band in the ultraviolet has not yet been reported in other plants. Both blue and green light were relatively ineffective. In spite of many attempts, no evidence for control of anthocyanin formation by a red: far-red reversible system could be obtained.