PROHEXADIONE

This plant growth regulator (FWfree-acid = 178.19 g/mol), also named 3- hydroxy-5-oxo-4-propionylcyclohex-3-ene-1-carboxylic acid, inhibits the biosynthesis of growth active gibberellins (GAs), thereby reducing longitudinal shoot growth. Prohexadione resembles 2-oxoglutaric acid, the co-substrate the dioxygenases that catalyze hydroxylation steps in late stages of GA biosynthesis. Its primary target of is 3b hydroxylation, thereby reducing levels of GA1 (the highly active form) and bringing about theaccumulation of its immediate precursor (inactive). Targets: flavanone 3-dioxygenase flavonol synthase; and gibberellin biosynthesis.