Durotaxis of Physarum polycephalum

The utilization of mechanical cues in guiding the morphological growth of decentralized organisms has remained unexplored. Here, we present experimental evidence demonstrating the mechanical guidance and durotaxis of a unicellular decentralized organism, Physarum polycephalum. We investigate the spatial-temporal dynamics of its plasmodial nodes as it expands over agar substrates with gradients in stiffness. Our findings reveal directional persistence and strong polarization of the plasmodia towards regions of stiffer substrates, indicating a guided migration response. Notably, as supported by simulations, this guided migration is found to be independent of the absolute gradient of substrate stiffness.