Use of calcofluor white to detect β-glucan changes in Phytophthora palmivora oospores by fluorescence microscopy

Calcofluor white is a fluorochrome used for detecting β-glucans in cell walls of plant pathogenic fungi. The aim of this study was to detect β-glucans in oospores of the heterothallic Phytophthora palmivora by crossing two compatible A1 and A2 mating types on carrot agar plates with or without a supplement of aqueous French bean extract. Lack of calcofluor white induced fluorescence, in yellow to deep brown oospores, suggests a change in the type of β-glucans in the outer oospore-oogonium cell wall. This staining method is an easy, quick and visual way to monitor changes in β-glucans during oospore development.