제주에서 분리한 길항근권세균의 토마토 역병에 대한 전신적 저항성 유도

Abstract

Plant growth promoting rhizobacteria (PGPR) has been known as a biological inducer of resistance against various plant pathogens in many crops. The efficacy of resistance induction against late blight disease by bacterial strains, which were isolated from Halla mountain, was tested in tomato plants. Furthermore, the resistance mechanism on the leaf surfaces of the plants expressing induced systemic resistance (ISR) was investigated using a fluorescence microscopy. Pre-inoculation with the bacterial strains TRH423-3, TRH427-2, KRY505-3 and KRJ502-1 among the isolated bacterial strains in rhizosphere to tomato plants caused systemic resistance against late blight disease by Phytophthora infestans. DL-3-amino butyric acid, which was used as a positive control in this experiment, also mediated systemic resistance against same disease. All selected bacterial strains did not show direct antifungal effect to Phytophthora infestans in vitro test, indicating non correlation between the efficacy of resistance induction and expressing antifungal activity of bacterial strains. As other effective bacterial strains showing efficacy of resistance induction, all selected bacterial strains promoted the growth of tomato plants. The fluorescence microscopical study revealed that there were no differences in germination rate and in appressorium formation of the fungal cysts on the leaf surfaces between untreated plants and bacterial strains pre-inoculated plants. However, the callose was more frequently formed at the penetration sites on the leaf surfaces of the plants either pre-inoculated with bacterial strains or pre-treated with BABA. The frequency of callose formation on BABA pre-treated plants was slightly lower compared with those on bacterial strains pre-inoculated. But the brightness of fluorescence at the penetration sites was higher in BABA pre-treated plants, indicating more active defense response of host cells. Conclusionally, the bacterial strains isolated from rhizosphere showed efficacy of resistance induction against late blight disease and their resistance mechanism may be difference to that of BABA mediated resistance.