Effects of light and temperature on sporangiophore initiation in Pilobolus crystallinus (Wiggers) Tode.

Sporangiophore initiation in Pilobolus crystallinus grown in white light was induced by either a dark or a low-temperature treatment. The period of darkness necessary to induce sporangiophore initiation was shortened by lowering the temperature. Arrhenius plots for the sporangiophore-suppressing reaction in both light and darkness consisted of two straight lines with a Q10 of about 2 at lower temperatures and 8-11 at higher temperatures. The temperature at which the Q10 changed was the lower, the higher the fluence rate: 14° C at 8 W/m(2), 19.5° C at 0.24 W/m(2) and 24.5° C in darkness. Possible interpretations of these results are briefly presented.