In vitro and in vivo production of pectolytic enzymes by some phytopathogenic fungi

Five fungal plant pathogens were investigated for their in vitro and in vivo ability to produce pectolytic enzymes. Only Fusarium solani did not produce any appreciable amount of enzymes in vivo and in vitro. Alternaria solani, Collectotrichum truncatum, Colletotrichum capsici and Curvularia pallescens produced pectolytic enzymes in vitro which were detected after ten‐fold concentration of the cultures by ammonium sulphate precipitation. These same four fungi produced pectolytic enzymes in vivo which were detected after twenty‐fold concentration of blended infected host tissue. The pH values of peak enzyme activity of 3.0 and 5.0 indicate that the enzymes produced were polygalacturanaes. The monogalacturonide end‐product of sodium polypectate and cell wall degradation indicate that exopolygalacturonases were produced by the pathogens. The low concentration of these enzymes in infected host plant tissues and the slow pectate‐splitting action of the exopolygalacturonases produced may account for the slow development and the dry necrotic nature of the disease these fungi cause.