Developmental stage-dependent response of Pilobolus crystallinus sporangiophores to gravitative and centrifugal stimulation

Gravitropic response of sporangiophores of Pilobolus crystallinus was studied by successive microscopic observation of the sporangiophores horizontally placed in the dark (red light) and by analysis of sporangiophore response to centrifugal stimulation. Negative tropism against the gravitative and also centrifugal stimulation was found only in mature sporangiophores after development of sporangium and after the resumption of elongation beneath the fully-developed subsporangial vesicle, but there was no response in younger sporangiophores, implying that the gravitative perception system of the sporangiophores is dependent on their developmental stages.