2.1 Observation and staining of different types of chlamydospores under general light microscope
Under an optical microscope, the dormant or non-dormant chlamydospore appears round or oval and yellowish brown in the absence of staining (Figure 1A & 1B), while the staining of artificially killed spores were dark (Figure 1C). The normal mature chlamydospore was double walled, spherical, 11.3~35 μm in diameter, and oval in size 16.3~27.5×27.5~67.5 μm. The average spore wall thickness under oil microscope was 2±0.1 μm. The immature chlamydospore or the spore in liquid medium has a smooth surface and has globular protuberances on the surface when mature. The above three types of spores can be stained blue by lactol cotton orchid staining (Figure 1D, 1E & 1F). The artificially killed spores were pale and dark in color. The three types of spores stained with trypan blue were all black (Figure 1G, 1H & 1I), is difficult to distinguish. In MTT assay, dormant and non-dormant spores were stained black or blue, and no matter the spores died artificially or naturally, they were not stained (Figure 1 J, 1K, 1L & 1M). Their differences were significant, suggesting that this staining method could distinguish dead and dormant spores.