Effects of Light on Chlorophyll Formation in Cultured Tobacco Cells I. Chlorophyll Accumulation and Phototransformation of Protochlorophyll(ide) in Callus Cells under Blue and Red light

摘要

A marked accumulation of chlorophyll was observed in callus cells ofNicotiana glutinosawhen they were grown under blue light, while under strong red light no chlorophyll accumulated. This blue light effect saturated at an intensity of about 500 mW.m−2.The effects of white, blue and red light on the transformation of protochlorophyll (ide) (Pchl) accumulated in dark-grown callus cells were studied by following the changes in the intensity of fluorescence emitted by Pchl and different forms of chlorophyll (ide) (Chi). Pchl with a fluorescence maximum at 633 nm (absorption maximum: 630 nm) decreased slowly, concomitant with an increase in Chl having a fluorescence maximum at 677 nm (absorption maximum: 675 nm), which was subsequently transformed, independently of light, to Chi with a fluorescence maximum at 683 nm (absorption maximum: 680 nm). Both blue and red light of low intensities were effective for the phototransformation, while red light, but not blue light, of high intensities caused significant destruction of Pchl. An action spectrum for this photodestruction showed that the maximum destruction took place at 630 nm. White light of high intensities was effective for the photoreduction with only slight destruction of Pchl, suggesting that blue light counteracts the destructive effect of red light. At low temperatures, however, blue light as well as red light of low intensities caused photodestruction of Pchl. It was inferred that blue light enhances a certain step or steps involved in the production of a reductant required for the photoreduction of Pchl to Ch