The Metabolism of Glycolate in Green and Amitrole-chlorotic Oat Leaves

Abstract

Summary In oat leaves which had become chlorotic after treatment with 10− 3 M amitrole, the activities of catalase and glycolate oxidase are suppressed (17 and 28 % of the control, resp.) ; NADH-glyoxylate reductase remains unchanged. Nevertheless, the remaining catalase activity seems to be sufficient for preventing an accumulation of H2O2. Compared with the control treated plants release more 14CO2 from [l-14C]-glycolate in the light and less in the dark indicating an inhibited refixation of 14CO2. Only traces of 14CO2 are evolved from [2-14C]-glyoxylate. Extracts prepared from oat leaves fed with [1-14C]-glycolate or [2-14C]-glyoxylate were separated into cationic, anionic and neutral fractions, which were further fractionated by chromatographic methods. The light-dependent formation of sucrose from glycolate is strongly inhibited in treated plants probably due to a blocked conversion of serine to hydroxypyruvate. Radioactivity accumulates in serine and decreases in glycine. Some radioactivity was detected in aspartate, glutamate, and alanine. The anionic fraction was separated into at least 8 radioactive compounds. In the amitrole-chlorotic plants incorporation into phosphoglycerate and phosphoglycolate is reduced, other differences are less important.