An information geometric framework reveals size-dominant and context-dependent stomatal perturbations in cacao under pathogen challenge

Authors: Ahn, Ezekiel; LIM, SEUNGHYUN - Orise Fellow; Baek, Insuck; Kim, Moon; Park, Sunchung; Meinhardt, Lyndel

Submitted to: Plant Stress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2026
Publication Date: 7/7/2026
Citation: Ahn, E.J., Lim, S., Baek, I., Kim, M.S., Park, S., Meinhardt, L.W. 2026. An information geometric framework reveals size-dominant and context-dependent stomatal perturbations in cacao under pathogen challenge. Plant Stress. 22. Article e101470. https://doi.org/10.1016/j.stress.2026.101470.
DOI: https://doi.org/10.1016/j.stress.2026.101470

Interpretive Summary: A plant's leaf pores (stomata) must process both long-term changes from growth and short-term stimuli like light or fungi at the same time. Understanding how these two signals operate independently without confusion was the problem this study addressed. By precisely analyzing the shape of over 19,000 cacao leaf stomata, we revealed for the first time that the 'growth' signal and the 'environmental stimulus' signal are processed through two geometrically separate (decoupled) and independent pathways. While growth follows a stable 'A' path, stimuli like light or fungi cause the stomata's shape to 'jump' to a completely different 'B' state. Furthermore, we discovered that different types of fungi use various strategies, such as 'hijacking' the plant's existing response pathways or 'tilting' to forge their own unique infiltration routes. This research clarifies how plants process complex signals and can contribute to developing crops that are more resilient to environmental stress and disease in the future. This information will be used by researchers, plant breeders and plant pathologists to improve this important tropical tree crop (Theobroma cacao).

Technical Abstract: This study analyzed how developmental and environmental stimulus signals are jointly encoded within the cacao stomatal morphospace. By integrating over 19,000 stomata data points, we applied a Joint PCA and an information-geometric pipeline (Free-Energy, Wasserstein distance, KL Surprisal, Mode Vectors). The analysis confirmed that the two signaling systems are clearly decoupled. The developmental gradient (apex-to-base) traced a stable, low-energy 'valley,' whereas all light/dark/pathogen stimulus states 'jumped' to a distinct, high-energy 'basin' that was nearly orthogonal and exhibited a high information surprisal of ˜16–18 bits. Critically, within this stimulus basin, pathogen infection trajectories showed isolate-specific strategies: some isolates 'hijacked' the plant's existing light/dark response axis (3–6° alignment), while another isolate (GH21) 'tilted' to a new, independent angle (43–90°) or adopted context-dependent trajectories. This framework quantifies a multi-scale morphometric code for how development, abiotic cues, and biotic agents partition a shared phenotypic space.