Gene Locus Specificity of the Glucose Effect in the Thiamine Pathway of the Angiosperm, Arabidopsis

All mutants at 3 loci in Arabidopsis thaliana (L.) Heynh., a higher plant, that are associated with the synthesis or coupling of the thiazole moiety of thiamine are susceptible to reversible glucose inhibition. In contrast, several different alleles involved in the synthesis of the pyrimidine moiety of the vitamin are insensitive to glucose. Glucose and maltose are equally effective inhibitors while fructose, lactose, ribose, and xylose are toxic. This toxicity is not released by added thiamine.