INFLUENCE OF CALCIUM PRETREATMENT ON PECTIC SUBSTANCE EVOLUTION IN CUCUMBER FRUIT (CUCUMIS-SATIVUS) DURING BOTRYTIS-CINEREA INFECTION

The role of calcium in protecting plant tissue from infection by Botry tis cinerea was studied in cucumber fruit. A self-defense reaction, co nsisting of an increase in cell-wall-bound Ca, occurred in the plant t issue after an injury or an infection. However, it was not sufficient to protect the tissue from the spread of the fungus, which is accompan ied by pectic substance digestion. The degradation induced mainly a de crease in acid- and chelator-soluble pectin levels, and an increase in water-soluble pectin. Ca treatment of the fruit prior to infection co uld amplify the cell-wall-bound Ca and therefore lessen pectin digesti on by fungal pectinolytic enzymes.