Free amino acids and ammonia in theAzolla-Anabaenaassociation grown with N2, NH4+, and NO3−

Abstract

Abstract The level and localization of free amino acids and ammonia in the Azolla-Anabaena association grown with N2, NH4 +, and NO3¯ were compared. In the leaves, the levels of ammonia and most of the amino acids except for aspartic acid and glutamic acid decreased in the dark and increased in the light. In the roots, ammonia was most abundant and its level varied in parallel with the level of ammonia in the leaves. When the plants were grown on media containing NH4 +, the level of total amino acids plus ammonia in both the leaves and the roots increased markedly, whereas it decreased when the plants were grown on media containing NO3¯. Glutamine in the leaves and ammonia in the roots were the major components responsible for the variation induced by the addition of NH4 + and NO3¯. The level of total amino acids plus ammonia in Anahaena-free Azolla was comparable to that in Anabaena-containing Azolla when they were fed with NH4 +. However, when fed with NO3¯, the level of total amino acids plus ammonia i...