Evaluating the explosive spore discharge mechanism of Pilobolus Crystallinus using mechanical measurements and mathematical modeling

The coprophilous Zygomycete Pilobolus uses osmotic turgor pressure as a means of explosive spore discharge, shooting its sporangium up to several meters away from the sporangiophore. This study attempts to clarify the sporangial discharge model by offering the first mechanical measurements of the internal turgor pressure of Pilobolus. In order to account for the forces included within the hypothesized shooting mechanism, a mathematical model is used to model the sporangial projectile trajectory. Measurements of subsporangial turgor pressure using a miniature strain gauge were partially successful, showing a pressure of 0.11 MPa. The mathematical model found that a pressure of 0.474 MPa would be needed to propel the projectile over the average measured distance, 1.14 m. The difference between the measured and the predicted results is attributed to error within the mechanical measurements. These results emphasize the importance of using innovative and rigorous methods for measuring internal turgor pressure, and encourage further examination of the Pilobolus spore discharge apparatus.