Some Observations on the Hypersensitivity of Late Blight Infected Potato Epidermis Cells by Using Fluorescent Whitening Dye

Abstract

The cell wall of midrib epidermis of potato leaves was labeled with the fluorescent dye, Calcofluor white M2, for 3 hours, and the zoospores of Phytophthora infestans were inoculated on the epidermis. After 3 and 18 hours, the fluorescence was observed under fluorescence microsope (Olympus HLS) with 320-400mμ U.V. through DV-1 and BG-12 filters. Just after labeling the cell wall with the dye, equally intense fluorescence was recognized around the healthy cell wail both in resistant and susceptible varieties. No fluorescence was observed on hypersensitive flecks in the resistant variety caused by the invasion of an incompatible race nor on susceptible lesions caused by the invasion of a compatible race of Phytophthora infestans. Sometimes, strong and clear fluorescence appeared in the cell wall around hypersensitive flecks in the resistant variety.