Accepts electrons from ETF and reduces ubiquinone. May act downstream of IVD and D2HGDH in the degradation of phytol or chlorophyll during dark-induced senescence and sugar starvation. a ubiquinone + reduced [electron-transfer flavoprotein] = a ubiquinol + H(+) + oxidized [electron-transfer flavoprotein] Binds 1 [4Fe-4S] cluster. Up-regulated by KIN10, by S1-bZIP specific dimers, and also by C/S1 bZIP heterodimers. By dark-induced senescence. Accelerated senescence and short siliques with reduced seed number. Belongs to the ETF-QO/FixC family. Sequencing errors.