Positional differentiation for development along the sporangiophore in Phycomyces blakesleeanus

 Small segments of Phycomyces sporangiophores regenerate various structures on incubation in a moist chamber. We tested the regeneration capacities of middle sporangiophore segments whose protoplasm had been totally or partially removed and replaced with protoplasm from various segments of a genetically different strain. The structures that were regenerated depended on the source of the injected protoplasm (sporangia of various sizes and segments from middle and basal parts of the sporangiophores), implying a positional differentiation of protoplasm along the sporangiophore axis. Protoplasm from various sources showed a high affinity; that is, they mixed successfully and led, in most cases, to the formation of heterokaryotic regenerating structures. The highest affinity was seen when mixing protoplasm from the middle segments of two different strains. Received: November 29, 2000 / Accepted: March 19, 2002