IMMUNOCYTOCHEMICAL LOCALIZATION OF TOMATO PECTINESTERASE IN ROOT-CELLS OF TOMATO PLANTS INFECTED BY FUSARIUM-OXYSPORUM F-SP RADICIS-LYCOPERSICI

Polyclonal antibodies produced against a purified commercial pectinesterase obtained from tomato plants permitted ultrastructural localization of this enzyme in the roots of young tomato plants infected by Fusarium oxysporum f.sp. radicis-lycopersici Jarvis & Shoemaker. In inoculated susceptible cultivars, gold labeling for pectinesterase was intense over electron-dense material in the cortex intercellular spaces, in altered pit membranes in the vascular cylinder, and in the dense coating material deposited along vessel walls. Contrarily, in resistant or uninoculated susceptible plants, which lacked coating material in vessels, labelling was present but nonabundant in the intercellular spaces. The enzyme was not found in the hyphae, indicating that the labelled pectinesterase was probably of host origin. This study suggests the involvement of the tomato pectinesterase in the host reaction against infection by F. oxysporum f.sp. radicis-lycopersici.