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Bulletin of the University of Osaka Prefecture. Ser. B, Agriculture and biology >
Vol.23 >

このアイテムの引用には次の識別子を使用してください: http://hdl.handle.net/10466/3003

タイトル: Ecologic and Taxonomic Studies on Pythium as Pathogenic Soil Fungi : XII. The "Macerating Enzyme" Involved in Virulence of Pythium
著者: ICHITANI, Takio
KOTANI, Shinji
TAKAHASHI, Yoshimasa
発行日: 1971年3月31日
出版者: University of Osaka Prefecture
引用: Bulletin of the University of Osaka Prefecture. Ser. B, Agriculture and biology. 1971, 23, p.8-18
抄録: The present paper dealt with the differences in susceptibility of potato tuber to pathogenic capability of Pythium and discussed the "macerating enzyme" which was considered to be involved in virulence. Potato tuber (Norin No. 1) is generally highly susceptible to some Pythium exhibiting soft rot, while it is slightly or non-susceptible to others. Susceptibility of potato tuber may vary with Pythium species. It seemed difficult to interpret the differences in susceptibility of Norin No. 1 against Pythium on the theory of defense mechanism since there was no definite relationship between the formation of fungistatic agents and decay of the tuber. Potato cultivars used showed a similar response to specific Pythium. Susceptibility of all potato cultivars tested was not altered when both incubation temperature and inoculum concentration were respectively changed. These results indicate that Pythium tested could be classified according to pathogenic capability. Some Pythium were generally highly virulent to potato tuber, whereas some others were slightly virulent or avirulent. Moderately or highly virulent Pythium respectively produced considerably almost equal amount of the "macerating enzyme" in culture filtrates, whereas slightly virulent Pythium produced no enzyme under the same cultural conditions. However, some of the slightly virulent Pythium might produce considerable amount of the "macerating enzyme" during or after the phase of autolysis by prolonging the incubation period. There was, however, an isolate which failed to produce the enzyme even after the phase of autolysis. Mycelial growth of slightly virulent Pythium was generally poor in the culture medium used for the macerating enzyme assay. It was presumed that the "macerating enzyme" might be involved in infection process of Pythium. There was a similar "macerating enzyme" activity in culture filtrates of various Pythium species at the range of pH 4-7. No significant effects were found after dialysis of the culture filtrates on their macerating ability. Both thermal inactivation and dilution end-points vary respectively with different Pythium species.
URI: http://hdl.handle.net/10466/3003


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