The relation between peroxidase activity and the morphological expression of the hooded gene in barley.

Reproductive meristems of the hooded (KK) genotype of barley at the stage of young lemma primordia were injected with the inhibitors sodium azide, hydrazine, and hydroxylamine at concentrations of 10(-3), 10(-4), and 10(-5)M, as well as with phenylboric acid. These treatments all brought about an altered expression of the adult phenotype in the direction of awned (kk) genotype. Analysis of tissues treated with the same reagents revealed a reduction in peroxidase activity which was proportional to the effect of each inhibitor in modifying the phenotypic expression of the gene. Exogenous IAA injected in the same manner brought about a similar modification of the phenotype and parallel reduction of peroxidase activity, but to a lesser degree. These results are believed to be caused by modifications of the action of the IAA oxidase system in the developing meristems.