Comparative study of the effects of red and blue light on 14CO2 uptake and carbon metabolism of maize leaves in air and oxygen

Abstract

The effects of blue or red light and oxygen concentration 21 % and 100 % on the distribution of 14C in the products of 2, 5 and 10 minutes photosynthesis in detached maize leaves were investigated. It has been shown that in an atmosphere of 21%O2 the effect of light quality on the distribution of radioactivity among the fractions of sugars, amino acids and organic acids was small. In an atmosphere of 100 % O2 the distribution of 14C among these fractions was strongly affected by quality of light applied. In high O2 concentration and in blue light bulk of radioactivity was incorporated to the fraction of organic acids even after 10 minutes of photosynthesis. In red light at the same time the bulk of radioactivity was located in sugars. In blue light there was a considerable increase of radioactivity in amino acids compared to red light. In the fraction of organic acids bulk of radioactivity was distributed between malate, glycolate, succinate and citrate in both lights applied. In amino acids fraction in 100 % O2 compared to 21 % O2 there was a strong decrease of radioactivity in alanine and aspartic acid with a small effect of light quality on 14C distribution in these compounds. In red light and in smaller extent in blue light there was an increase in the ratio of the radioactivity of glycine + serine to the sum of radioactivity in amino acids. The data indicated that high oxygen concentration stimulates the incorporation of carbon to more oxidized compounds at the expense of sugars. These changes were promoted by blue light compared to red