Determination of flavonoid level variation in onion (Allium cepa L.) infected by Fusarium oxysporum using liquid chromatography-tandem mass spectrometry

► Onion (Allium cepa L.) bulbs were analysed flavonoid level variation by HPLC-MS/MS. ► The individual characterised components were quantified by HPLC-UV. ► Flavonoids as the defense materials against Fusarium oxysporum have been discussed.