Effect of Abscisic Acid on Pool Sizes of Free Amino Acids in Lemna minor L. Cultures

Abstract

Summary The effect of ABA on the concentrations of free amino acids within Lemna minor fronds and in the culture medium were determined. Treatment with ABA resulted in a general increase in amino acids, with the exception of arginine. In ABA-treated fronds the amino acids which showed a most marked increase were aspartic acid, threonine, serine, glutamic acid, glutamine, alanine, valine, and γ-aminobutyric acid. ABA also increased amino acid leakage to the culture medium. At 24 h of treatment the amino acids which appeared in the medium in concentrations were serine, alanine, glycine, and ornithine while in control cultures only ornithine was detected. The absence of arginine in the medium of ABA-treated cultures during all phases of the experiment suggests that ABA may specifically affect this amino acid, possibly involving the γ-aminobutyric acid accumulation in the fronds.