1982 Volume 48 Issue 3 Pages 267-274
The peroxidase inducers, which have the ability to induce the peroxidase production in leaf tissue of rice plant, were isolated from the homogenate of conidia and mycelia of rice blast fungus (Pyricularia oryzae Cavara). On polyacrylamide gel electrophoregram, the isozyme profile of peroxidases of rice leaf treated with the homogenate of blast fungus was similar to the one of rice leaf inoculated with the pathogen. The augmentation of peroxidase in rice plant by the application of inducers was inhibited in the presence of metabolic inhibitors such as formycin A, cycloheximide and blasticidin S. Three and two inducers were separated respectively from the supernatant of conidial and mycelial homogenates by molecular sieving chromatogram. Molecular weights of the inducers separated from the conidial homogenate were estimated to be approximately 700 (CI), 10, 000 (CII) and 70, 000 (or>70, 000, CIII) daltons by Sephadex G-50 gel-filtration using dextrans and other authentic sugars as standards. Two inducers separated from the mycelial homogenate, MI and MII, were eluted in the similar fractions to CI and CIII respectively. Crude inducers showed the inductive activity when applied at a concentration lower than 312.5ng per injured spot (2mm in diameter). It was suggested from these results that the rice plant might recognize the pathogen by means of the substances such as the peroxidase inducers which were produced by the pathogen. It is also worthwhile to investigate further these peroxidase inducers may act as inducer of disease resistance reaction in host plant or not, because many reports described the positive correlation between the augmentation of peroxidase activity and elevation of disease resistance in host plant.
