Wavelength effects on photosynthetic carbon metabolism inChlorella1

摘要

To study the wavelength-effect on photosynthetic carbon metabolism,14C-bicarbon-ate was added toChlorella vulgaris1 lh suspension under monochromatic blue (456 nm) and red (660 nm) light. The light intensities were so adjusted that the rates of14CO2fixation under blue and red light were practically equal. Analysis of14C-fixation products revealed that the rates of14CO2incorporation into sucrose and starch were greater under red light than under blue light, while blue light specifically enhanced14CO2incorporation into alanine, aspartate, glutamate, glutamine, malate, citrate, lipid fraction and alcohol-water insoluble non-carbohydrate fraction. Pretreatment of the algal cells in phosphate medium in the dark, which was essential for the blue light enhancement of PEP carboxylase activity, was not necessary to induce the above wavelength effects. Superimposition of monochromatic blue light at low intensity (450 erg.cm−2.sec−1) on the red light at saturating intensity caused a significant decrease in the rate of14CO2incorporation into sucrose and increase in incorporation into alanine, lipid-fraction, aspartate and other related compounds, indicating that the path of carbon in photosynthesis is regulated by short wavelengdi light of very low intensity. Possible effects of wavelength regulation of photosynthetic carbon metabolism in algal cells are discus