• The Plant Pathology Journal
• /
• v.23 no.3
• /
• pp.203-209
• /
• 2007

Infection structures were observed using a fluorescence microscope at the penetration sites on the leaves of potato plants pre-inoculated with the bacterial strains Pseudomonas putida TRL2-3, Micrococcus luteus TRK2-2, and Flexibacteraceae bacterium MRL412, which mediated an induced systemic resistance on potato plants against late blight disease caused by Phytophthora infestans. In order to compare the infection structures on the leaves expressing systemic acquired resistance, the leaves of potato plants pre-treated with DL-3-amino butyric acid (BABA) were also observed after challenge inoculation with the same pathogen. The infection structures were investigated. The total number of germination and appressorium formation of P. infestans were counted. Furthermore, the frequencies of fluorescent epidermal cells at the penetration sites, which indicate a defense response of plant cell, were estimated. There were no differences on the germination rates of the fungal cysts among the untreated control, BABA pre-treated, and bacterial strains pre-inoculated plants. However, appressorium formation was slightly decreased on the leaves of BABA pre-treated plants compared to those of untreated as well as bacterial strains pre-inoculated plants. Furthermore, the frequencies of fluorescent cells of BABA pre-treated and bacterial strains pre-inoculated were higher than that of untreated plants, indicating an active defense reaction of the host cells against the fungal attack. On the other hand, the pre-treatment with BABA caused a stronger fluorescent of epidermal cells at the penetration sites compared to the pre-inoculation with the bacterial strains. Interestingly, the frequency of fluorescent cells by BABA, however, was lower than that by the bacterial strains. Based on the results it is suggested that the infection structures showing resistance reaction on the leaves of potato plants were different between by pre-inoculation with bacterial strains and by pre-treatment with BABA against the late blight pathogen.

• Mycobiology
• /
• v.34 no.2
• /
• pp.67-72
• /
• 2006

Efficacy of resistance induction by the bacterial isolates Pseudomonas putida (TRL2-3), Micrococcus luteus (TRK2-2) and Flexibacteraceae bacterium (MRL412), which were isolated from the rhizosphere of plants growing in Jeju Mountain, were tested in a greenhouse. The disease severity caused by Phytophthora infestans was effectively reduced in the potato plants pre-inoculated with bacterial isolates compared with those of the untreated control plants growing in a greenhouse. In order to estimate the level of protection by the bacterial isolates, Mancozeb WP (Diesen $M^{(R)}$, Kyong nong) and DL-3-amino butyric acid (BABA) were pre-treated, whereas Dimethomorph WP ($Forum^{(R)}$, Kyong nong) and phosphonic acid ($H_{3}PO_{3}$) were post-treated the challenge inoculation with the pathogen. Disease severities of chemical pre-treated as well as post-treated plants were reduced compare to those of the untreated. The disease reduction in the plants pre-treated with Mancozeb WP was the highest, whereas that of post-treated with Dimethomorph WP was the lowest. The yields of plants pre-inoculated with three bacterial isolates were greatly increased than those of control plants. These results suggest that biological control by bacterial isolates might be an alternative strategy against late blight disease in potato plants growing in greenhouse.