POLYGALACTURONASE PRODUCED IN APPLE TISSUE DECAYED BY BOTRYTIS-CINEREA

An exo-polygalacturonase with an isoelectric point of 4.6 and an appar ent molecular weight of 45 kDa was isolated from apple tissue decayed by Botrytis cinerea. This isozyme had a similar isoelectric point, opt imum pH, and mode of action as an isozyme produced in liquid culture b y B. cinerea. The enzyme produced in the decayed tissue was less sensi tive to lower pH and less inhibited by CaCl2, MgCl2, or NaCl than the enzyme produced in culture. Such changes in the properties of the enzy me produced in infected tissue could have been essential for the patho gen's successful colonization of the host tissue. Among the cations st udied, calcium was the best inhibitor of PG activity.