ISOPEROXIDASE INVOLVEMENT IN THE RESISTANCE OF CAPSICUM-ANNUUM TO INFECTION BY CUCUMBER MOSAIC-VIRUS

Cucumber mosaic virus (CMV) infection of Capsicum annuum leaves provok es a strong increase in soluble peroxidase activity. Isoelectrofocusin g of the peroxidase activity in polyacrylamide gel patterns, after sta ining the soluble protein fractions from both healthy and infected lea ves with benzidine/H2O2, revealed the presence of two acidic and one b asic isoperoxidases, the increase in peroxidase activity being mainly due to the former. Staining of peroxidase activity in the gels with co niferyl alcohol/H2O2 showed that acidic isoenzymes were more capable o f catalyzing coniferyl alcohol oxidation than basic isoenzymes. Native polyacrylamide gel electrophoresis of the soluble fraction showed tha t the increase in peroxidase isoenzymes. CMV elicitation of the acidic isoperoxidase through its involvement in the lignification process mi ght be considered as a part of the defense mechanism of Capsicum annuu m against viral infection, and lignin deposition on plasmodesmata coul d act as a physical barrier against the cell-to-cell advance of viral particles.