Abstract: Induction of disease resistance is one of the important strategies of biological control on fruit postharvest decay. The mandarin（Citrus reticulata Blancdo‘Shiyueju’）fruit were inoculated with Penicillium digitatum after vacuum infiltration of Benzothiadiazole（BTH）. Results showed that the expression of CR-CT1 and CR-BG3 substantially increased 12 h after BTH treatment. The morbidity and lesion area of green mold in mandarins，and the in vivo disease incidences of the fruit were signicantly reduced by different concentrations of BTH. BTH treatment induced the activities of CT，GUN，PAL，PPO，POD，and evoked the increase of H2O2 content. The results suggested that strong expression of CR-CT1 and CR-BG3，enhanced activities of several defense enzymes and H2O2 content are all involved in the induction of disease resistance by BTH treatment in mandarin fruit.

Key words: Citrus reticulata, BTH, disease resistance, gene expression