Glycollate oxidase inhibition and its effect on photosynthesis and pigment formation in Hordeum vulgare

Investigations of the effect of 2-hydroxy-3-butynoic acid and its methyl ester on photosynthesis in Hordeum vulgare are reported. In the presence of either of these compounds the assimilation of ¹⁴CO₂ was greatly decreased. The labelling patterns showed massive accumulation of glycollate and greatly reduced incorporation into sucrose and other products of photosynthesis. The inhibition was specific for the S(+) enantiomers. In greening barely the S(+) enantiomers inhibited formation of chloroplast pigments, and this was paralleled by inhibition of glycollate oxidase. This was the only enzyme of the glycollate pathway whose activity was significantly decreased after inhibitor treatments. Of a range of metabolises tested, only supplementations with glycine and glutamate or glycine, serine and succinate fully restored greening.