THE SUSCEPTIBILITY OF TISSUE CELL-WALLS TO ERWINIA ENZYMES DIFFERS AMONG THE POTATO CULTIVARS

In the cell wall matrix of higher plants, cellulose fibrils are embedd ed in a network of pectic substances, hemicelluloses and structural pr oteins. But plant pathogenic Erwinia carotovora bacteria secrete a mix ture of enzymes including pectinases, cellulases and proteases to degr ade the cell walls of host plant tissue. Tuber tissue of 31 potato gen otypes was exposed to a mixture of Erwinia enzymes before the degree o f cell wail lysis was determined by a Neutral-red vital staining metho d. The data indicate that the resistance of cell walls to the action o f Erwinia enzymes differed significantly among the potato cultivars an d clones. The decrease in cell viability caused by the action of enzym es ranged from 7% for cv. Maxilla to >46% for cv. Arnika. An increased rate of N-fertilization coincided with enhanced susceptibility of cel l walls to the action of Erwinia enzymes. There was a correlation betw een the amount of cell wall substances in tuber tissue and the resista nce of cell walls to enzymic degradation.