Measurement of Phototropism of the Sporangiophore of Phycomyces blakesleeanus.

The giant sporangiophore, fruiting body, of the fungus Phycomyces blakesleeanus is a single cell that grows guided by several environmental signals, including light. The phototropic response has been investigated in detail. Three proteins, the components of a photoreceptor and transcription factor complex and a regulator of the signal transduction protein Ras, participate in the signal transduction pathway. We describe the basic methods for characterizing phototropic bending and the correlated elongation and rotation responses of the sporangiophore.