Perceptual Distortions in Plants: Decoding the Physics of Decentralized Sensing

Phototropism, the directional growth of plants in response to light, has long been understood as a straightforward optimization process to maximize light capture. However, a new study led by Prof. Yasmine Meroz, PhD student Ahron Kempinski, and lab alumnus Dr. Amir Porat (currently at the University of Cambridge) from the School of Plant Sciences and Food Security, alongside Dr. Mathieu Rivière from Aix-Marseille Université, demonstrates that spatial light integration in plants follows a far more intricate sensory logic.

Published in PNAS, the research examines how sunflower seedlings (Helianthus annuus) evaluate conflicting light vectors. The team established that light transmission across the stem tissue involves nonlinear transduction. Because plants lack a central processor, sensory computation occurs locally across the tissue circumference, causing the organism to align its growth according to the vectorial sum of internally processed signals rather than the absolute physical flux of external light.

This localized processing strategy can generate systemic perceptual distortions analogous to optical illusions. Under specific spatial configurations, opposing light cues cancel each other out within the plant's internal signal representation, prompting the stem to orient toward a secondary, significantly weaker light source. Beyond plant biophysics, the study introduces a broadly applicable geometric framework that models how extended biological systems without a central brain (ranging from navigating immune cells to developing neuronal axons) integrate multi-directional sensory inputs to guide directional movement.