Abstract
A water soluble inhibitor of bacterial multiplication was produced in rice leaves inoculated with strains of Xanthomonas oryzae. In leaves inoculated with an incompatible strain the inhibitor became detectable within 24hr after inoculation, increased rapidly reaching the maximum amount by 8th day, then gradually decreased. In leaves inoculated with a compatible strain, on the contrary, the production of the inhibitor was not detected until the first lesion became visible, i.e. 5 days after inoculation, the inhibitor then increased gradually until the last stage of lesion enlargement, although the amounts produced were much smaller comparing with those in leaves inoculated with an incompatible strain. When the water extract from leaves responding with a resistant reaction was diluted to 1/2 and 1/4 concentrations with distilled water, inhibitory activity decreased correspondently, and almost disappeared by the dilution to 1/8 concentration. The water extract from the healthy leaves also showed a slight inhibitory action, but it disappeared by 1/2 dilution. Dialysis through cellophane membrane suggested that the inhibitor may be a low molecular substance.
