Catalyzes the transfer of electrons from NADH and NADPH to several quinones in vitro. May act as detoxification enzyme, and protect against auxin-induced oxidative stress. a quinone + H(+) + NADH = a quinol + NAD(+) a quinone + H(+) + NADPH = a quinol + NADP(+) Binds 1 FMN per monomer. A number of isoforms are produced. According to EST sequences. No visible phenotype under normal growth conditions, but mutant plants have increased resistance to the necrotrophic fungus Botrytis cinerea. Belongs to the WrbA family.