| Project/Area Number |
63440010
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物保護
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| Research Institution | Tottori University |
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Principal Investigator |
KOHMOTO Keisuke Tottori University, Faculty of Agriculture, Professor, 農学部, 教授 (80032093)
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| Co-Investigator(Kenkyū-buntansha) |
KIMURA Yasuo Tottori University, Faculty of Agriculture, Professor, 農学部, 教授 (10011983)
HAMAZAKI Takashi Tottori University, Faculty of Agriculture, Professor, 農学部, 教授 (40032081)
KODAMA Motoichiro Tottori University, Faculty of Agriculture, Assistant, 農学部, 助手 (00183343)
OTANI Hiroshi Tottori University, Faculty of Agliculture, Professor, 農学部, 教授 (50032305)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Host-Specific Toxin / Host Recognition / Toxin Receptor / Mode of Toxin Action / Infection-Inhibiting Factor / Inducer for Defense Reaction / Accessibility Induction / Alternaria |
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| Research Abstract |
The basic concept of the host recognition and initial colonization in host cells by Alternaria pathogens that produce host-specific toxin (s) (HST) on spore germination have been established as follows :
1) Release of a signal HST from germinating spores of the pathogen, 2) recognition of pathogen's signal by putative receptors in host cells, and 3) foment of accessibility to attempted fungal penetration in host cells through transduction of the signal. Lines of evidence for supporting this hypothesis have been collected. New host-specific toxins, ACT-toxins I and II, were isolated from spore germination fluids of the tangerine pathotype of Alternaria alternata and elucidated in structure as poly-hydroxyoctenoylvalyl esters of epoxy-decatrienoic acid. This trienoic acid is the common moiety of AK- and AF- toxins. In addition, ACT-toxin II is 5"-deoxy derivative of toxin I ; hence, a structure-activity correlation study was possible. A candidate protein for HST receptor was detected. Toxin action processes were comparatively analyzed, and the results showed that cell death itself is not necessary for conditioning the accessible state of host cells to fungal invasion. Rather, HST suppresses general defense reactions such as production and/or accumulation of infectionーinhibiting factors or lignification in infection sites that was elicited by "Inducer", 40000 daltons sugars released by fungal spores. Our experiments suggest that HST-depending Alternaria infection definitely differs from the mechanism of necrotrophic parasitism.
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