Abstract
Activities of cellulase, polygalacturonase (PG) and polymethylgalacturonase (PMG) in potato tuber discs treated with coronatine, an extracellular toxin produced by Pseudomonas syringae pv. atropurpurea (Reddy and Godkin) Young et al., were determined as an approach to the mechanism of hypertrophy induced by the toxin. The optimum pHs of cellulase, PG and PMG were around 5.0, 4.0 and 5.0, respectively. All these enzyme activities were considerably increased by coronatine treatment. Cellulase, PG or PMG was little altered, partially inhibited or slightly enhanced, respectively, by the addition of Ca++. The hypertrophy induced by coronatine can be partly explained in terms of the loosening of cell wall due to the increased activities of cellulase, PG and PMG.
