In Vivo Spectroscopy

Abstract

In vivo spectroscopy is used to directly assay phytochromes in intact plant material. The method is depending on the photoreversibility of phytochromes displaying light induced absorbance changes in response to actinic irradiation. Dual-wavelength ratio spectrophotometers (ratiospects) are the instruments successfully used for assaying phytochromes in highly scattering plant material. In the present chapter I describe the general instrument setup of an automated ratiospect and explain the measuring procedure and data calculation required to determine the total amount of photoreversible phytochromes in a sample as well as the proportion of phytochrome present in the Pfr conformation.