A morphogen for the sporulation of Physarum polycephalum detected by cell fusion experiments

Area of Science:

• Cellular Biology
• Developmental Biology
• Mycology

Background:

• The slime mold Physarum polycephalum exhibits induced sporangia development upon light stimulus under starvation.
• Plasma circulation within the plasmodium facilitates the transfer of stimuli.
• Premorphogenetic phase precedes visible sporulation.

Purpose of the Study:

• To investigate the transferability of light-induced morphogenetic signals in Physarum polycephalum.
• To determine if protoplasm transfer can induce sporulation in incompetent plasmodia.
• To analyze the effect of fusion with sporulating plasmodia on non-sporulating or growing plasmodia.

Main Methods:

• Transfer of protoplasm from a sporulating donor plasmodium (post-premorphogenetic phase) to a starved, light-induction-incompetent acceptor plasmodium via short-period fusion.
• Observation and quantification of sporulation and premorphogenetic phase duration in acceptor plasmodia.
• Fusion of sporulating plasmodia with highly starved non-sporogenic or growing plasmodia.

Main Results:

• Protoplasm transfer successfully induced sporulation in the acceptor plasmodium.
• The premorphogenetic phase in the acceptor plasmodium was significantly reduced from 9 to 3 hours.
• Fusion with sporulating plasmodia inhibited further sporangia morphogenesis in the sporulating partner when fused with highly starved or growing plasmodia.

Conclusions:

• The light-induced morphogenetic stimulus for sporangia development in Physarum polycephalum is transferable via plasma circulation.
• Protoplasm transfer can accelerate and induce the sporulation process, even in plasmodia initially incompetent to light stimulus.
• Interactions between plasmodia of different physiological states (sporulating, starved, growing) can modulate developmental pathways.