The Relationship between Antigenic Compounds Produced by Sweet Potato in Response to Black Rot Infection and the Magnitude of Disease Resistance

Tissue extracts of healthy, sliced and black-rotted sweet potato roots of several Japanese varieties showed immunochemical precipitation lines with antisera toward sliced and diseased tissue extracts prepared from an American resistant variety, Sunnyside. The immunochemical precipitation patterns of healthy and sliced tissue extracts and those of diseased tissue extract of the Japanese varieties respectively were almost the same as those of sliced and diseased tissue extracts of the American Sunnyside. Antigenic components designated as A and Cs were distributed in all tissue extracts of both Japanese and American varieties. Components B and D were produced in response to the infection in root tissues of Japanese varieties as well as of American ones. The amount of component B produced in several Japanese varieties was correlated with the magnitude of resistance action of root tissues to the fungus infection and the order was as follows: Norm No. 10 (highly resistant) >Norin No. 1 and Okimasari (resistant) >Norin No. 4 and Norin No. 5 (susceptible). Components B and D seemed to be present in healthy root tissue in very small amounts, and showed an increase in response to the simple injury or slicing, though the magnitude of this increase was much less than the response to the pathogenic infection.