FLOW CYTOMETRIC ANALYSIS OF CONIDIA OF FUNGI ISOLATED FROM SOYBEAN VASCULAR TISSUE

Flow cytometry was used to characterize isolates of Phialophora gregat a using the fluorescence intensity of propidium iodide-stained conidia . The isolates differed in their mean fluorescence intensity, ranging from 100.0 to 129.7 arbitrary units (AU). When the number of fluoresce nt events was plotted against intensity of fluorescence, a single peak was observed. Fluorescent patterns of Acremonium isolates from soybea n vascular tissue were compared with those of P. gregata. Their mean f luorescence intensity ranged from 76.4 to 88.0 AU. With some of these isolates, multiple peak histograms were observed, corresponding to mul tiple spore sizes as well as single and double nucleated conidia. Usin g flow cytometry, we were able to distinguish P. gregata isolates from those of Acremonium, based on mean fluorescence intensity and/or the presence of multiple peaks. Flow cytometric analysis of propidium-iodi de stained conidia of Phialophora isolates should prove to be useful f or determining the relative DNA content of different isolates collecte d from different geographic areas.