VIEW ARTICLE

Physiology and Biochemistry

Detection of Polygalacturonase Enzymes in Fruits of Both a Normal Tomato and its Nonripening Nor Mutant Infected with Rhizopus stolonifer. Rivka Barkai- Golan, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel; E. Kopeliovitch(2), and C. J. Brady(3). (2)Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel; (3)Division of Food Research CSIRO, Plant Physiology Unit, North Rhyde N.S.W. 2113, Australia. Phytopathology 76:42-45. Accepted for publication 11 June 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-42.

Rhizopus stolonifer growing on autoclaved tomato fruit homogenate produces at least seven forms of polygalacturonase separable by polyacrylamide gel electrophoresis. Mature-green fruit from normally ripening lines of tomato (Lycopersicon esculentum ‘Rutgers') and also from its nonripening nor mutant line contain no polygalacturonase. After infection with R. stolonifer, the mature-green fruit contain polygalacturonase enzymes that correspond by gel electrophoresis analysis with the fungal enzymes and are not precipitated by antiserum to tomato polygalacturonase. Infected ripe fruit contains both fruit and fungal enzymes; rocket immunoelectrophoresis showed that the infected ripe fruit contained more tomato enzyme than the uninfected fruit of similar maturity. In mature nor fruit, there was no enhancement of plant enzyme by fungal infection. It is concluded that infection by R. stolonifer advanced the ripening process in genetically and developmentally competent tissue but did not induce ripening in the mutant fruits which lack an active ripening system.