Effect of foliar nutrients, fungicides, temperature and metal ions on pectate lyase and endopolygalacturonase from Alternaria alternata found in association with sooty molds on Citrus trees

Abstract

The properties of pectate lyase and endopolygalacturonase, produced by Alternaria alternata isolated from sooty mold infected Citrus trees were studied. These enzymes, related to plant pathogenesis, were obtained from supernatants from liquid Mandels medium inoculated with fungal conidia which contained Citrus pectin as the sole carbon source. The behavior of the enzymes towards metal ions, foliar fertilizer and fungicides, was analyzed. Also, the effect of temperature was tested. Results show that at the suggested concentrations to be used at the field level for foliar nutrients and fungicides, these enzymes maintain enough activity to produce damage on the plant tissues. Also, the high levels of enzymes activities found in the presence of high concentrations of metal ions or at different temperatures could relate to the behavior of these enzymes in the infection process of plant tissues in field conditions.