Repression of cystathionine gamma-synthase in Arabidopsis thaliana produces partial methionine auxotrophy and developmental abnormalities

Cystathionine gamma-synthase (CGS), a key enzyme in methionine biosynthesis , was repressed in transgenic Arabidopsis thaliana by antisense expression of CGS RNA. CGS activity was reduced by 5-9-fold in the antisense plants re sulting in severe growth stunting, morphological abnormalities and an inabi lity to flower. Feeding the plants methionine (Met) or Met metabolites reve rsed the morphological effects of CGS repression. There was little change i n the content of free Met and S-methylmethionine despite the need for exoge nously applied Met for growth. The overall amino acid content was significa ntly increased. The CGS antisense transgene is inherited as a single recess ive locus. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.