Glucose activation of Pilobolus longipes sporangiospores

Abstract

Pilobolus longipes sporangiospore activation, as measured by spherical growth, was assayed with an electronic particle counter. Glucose caused spores to grow to the diameter of germinated spores (ca. 18–20 μm) but only when applied in conjunction with a heat treatment. Although spores were activated by glucose its continued presence prevented germ tube formation. Germ tube formation required the early removal of glucose and the addition of exogenous iron. The non-metabolizable glucose analogue, 3-0-methyl-d-glucose (3-OMDG), also activated spores, and these spores produced germ tubes when supplied with exogenous iron. An effect of the heat treatment was to cause glucose (and 3-OMDG) transport, which in turn resulted in activation. These results indicate that germination of P. longipes spores may be triggered by specific effectors (e. g. glucose or 3-OMDG) but metabolism of the effector is not required.