Instantaneous change in hyphal diameter in basidiomycete fungi

Under certain conditions, fungi can rapidly change the size of their cells. For example, it is known that the cells of many yeast species under hyperosmosis instantly and reversibly shrink entirely, without plasmolysis, with a decrease in volume of up to 70%. There is evidence that filamentous fungi can also instantly change the diameter of their unspecialized hyphae. This property is fundamental but requires detailed study. In this large-scale study (involving more than 50,000 cells measured) using light microscopy, the ability of three unrelated basidiomycete species to rapidly change the diameter of their hyphae under various factors was analyzed. It was found that all three fungi respond similarly to moderate hyperosmotic shock or detergent treatment, shrinking by an average of 12-14% in diameter. However, inhibitors of actin assembly can cause either expansion or shrinkage of hyphae or have no effect on a fungus. These results, along with previously established features of the macroinvagination systems of the plasma membrane in basidiomycetes, are important for understanding the complex structural-protective physiological mechanisms responsible for the survival and continuous functioning of fungal cells in unstable environmental conditions.