Abstract
Relationship between fluorescent staining reaction and germination in resting spores of Plasmodiophora brassicae Wor. was examined. Blue fluorescence was detected on the cell wall of all spores, whereas red fluorescence was or was not noticeable inside of the spores when observed under fluorescence microscope after staining with two fluorochromes, calcofluor white M2R and ethidium bromide. When the spore suspension accompanied with host roots was incubated at 25°C for 10 days, the percentages of both spores showing red fluorescence and vacant germinated cells significantly increased with the time of incubation. The increase, on the other hand, was not appreciable or slight when the spore suspension incubated without host roots. Quantitative assays showed a close correlation between the fluorescent staining reaction and spore germination when incubated with host roots. The result indicates that the fluorescent staining reaction is available for a criterion of viability, expressed by germination, in resting spores of P. brassicae.
