X-Gluc is used to detect β-glucuronidase (GUS) activity in genetically modified plant tissue. β-glucuronidase is encoded by the gusA (uidA) gene found in Escherichia coli. In transformed cells, β-glucuronidase cleaves X-gluc, and forms an insoluble blue dimer, 5-bromo-4-chloro-3-indolyl-β-D-glucuronic Acid; Monocyclohexyl Ammonium Salt
