Involved in the gamma-resorcylate (2,6-dihydroxybenzoate) catabolism (PubMed:17158677). Oxygenase component of the resorcinol hydroxylase, which catalyzes the FADH(2)-dependent conversion of resorcinol to hydroxyquinol (PubMed:17158677). FADH2 + O2 + resorcinol = benzene-1,2,4-triol + FAD + H(+) + H2O Aromatic compound metabolism. The FADH(2)-dependent resorcinol hydroxylase is composed of two subunits, GraA (the oxygenase component) and GraD (the reductase component). Both subunits are required for activity. Induced in the presence of gamma-resorcylate. Belongs to the HpaH/HsaA monooxygenase family.