Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
On the mechanism of starch accumulation in tissues surrounding spots in leaves of rice plants due to the attack of Cochliobolus miyabeanus
V. Some characteristics of starch-decomposition-inhibiting substances found in culture filtrate of the fungus
Hiroyasu TANAKAShigeyasu AKAI
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1965 Volume 30 Issue 3 Pages 139-144

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Abstract

Some compounds, which have an inhibitory effect on starch decomposition, are produced in the culture filtrate of Cochliobolus miyabeanus, the causal fungus of Helminthosporium leaf spot of rice plants. In this paper results on physico-chemical natures of the compounds were described.
1. These compounds are thermostable, and can not be extracted with ethylether, nor precipitated with 90 percent ethanol. They do not form chelate compounds with EDTA or citric acid, but are adsorbed with cation exchange resins. From these facts, it is evident that they are cations of low molecular weight, being neither protein, organic acid nor heavy metal. Consequently, they seem not to be any kinds of SH-inhibitors.
2. These compounds have only one peak of absorption spectrum at 310mμ.
3. These compounds have no relation with a brown color substance produced in the culture filtrate.
4. From the above results, it is assumed that the starch-decomposition-inhibiting substaces are some alkaline metabolites produced by the causal fungus, and that they are diffused from diseased lesions and inhibit β-amylase activity in the surrounding healthy tissues.

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© The Phytopathological Society of Japan
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