Polygalacturonase isozymes produced during infection of the grape berry by Botrytis cinerea

This paper focuses on polygalacturonase activity during the early stages of infection of the grape berry by the fungus Botrytis cinerea. While a weak polygalacturonase activity was measured in healthy, ripe Semillon grape berries, in infected berries the activity increased rapidly with infection. Liquid isoelectrofocalisation was used to separate polygalacturonase isozymes in healthy and infected berries. In healthy berries, we found 4 isozymes of polygalacturonase with pI values of 4.2, 4.9, 6.0 and 8.0. In infected berries, we have separated up to 7 isozymes of polygalacturonase in infected berries. The first isozymes detected had acidic pIs; basic isozymes of polygalacturonase with considerable activity were separated. The most active isozyme had a pI of 8.8. At the onset of infection by B. cinerea, polygalacturonase activity consists of a large number of isozymes, most of which are identical with the isozymes previously described.