Histological Change in Cucumber Tissue and Cellulase Activity of <i>Plectosphaerella melonis</i> Strain 502

Abstract

In the last ten years, many countries around the world recorded a new disease of the Cucurbitaceae, the agent of which was P. melonis. The ability of P. melonis 502 to form intracellular mycelium in the epidermal and parenchymal tissues of roots was shown. Leading tissues (xylem and phloem) did not colonize, which indicates the impossibility of plant vessel clogging and shows the fungus’s biochemical effects on plants, which causes the process of pathogenesis. P. melonis 502 is able to develop in a wide range of pH values, while the pH-optimum is 8.5. P. melonis 502 is able to adjust the pH of the medium to the optimal value—8.5. We also showed that cellulase enzyme synthesis depends on pH. We studied the exo-, endo- and β-glucasidase activity of P. melonis 502 and found that the highest activity of cellulase enzymes was on a medium whose pH was 8.5. In the process, the total cellulolytic activity was 0.326 U mL−1, exoglucanase activity—0.539 U mL−1, endoglucanase activity—0.950 U mL−1 and β-glucosidase activity—0.795 U mL−1.

Keywords

• cellulase activity
• cucumber
• pathogen
• pH-optimum
• <i>Plectosphaerella melonis</i>
• secondary metabolites