With global food demand rising alongside accelerating climate change, agriculture faces the twin challenge of increasing yields while safeguarding crop health under more frequent drought, heat, salinity, and pathogen pressure. Unlike animals, plants cannot escape unfavourable environments. Instead, they depend on rapid long-distance signalling to detect threat, coordinate defence, and reprogram physiology at the scale of the whole organism.

Plants orchestrate these responses through tightly coupled electrical and chemical signalling networks. Electrophysiological events can propagate rapidly across tissues and are intertwined with ionic fluxes that shape downstream responses. Despite their importance for systemic communication, stress adaptation, and growth regulation, the mechanisms governing signal initiation, propagation, and coupling to ionic dynamics remain poorly understood. A key limitation has been the lack of plant tissue interface technology that can resolve fast, spatially distributed signals across heterogeneous plant tissues while simultaneously reporting the associated biochemical processes.

This thesis develops and applies an integrated bioelectronic platform to map plant electrical activity and its ionic basis in intact leaves. First, a conformable, multielectrode array (MEA) is introduced that inter-faces reliably with the full leaf architecture and enables high-resolution, multi-site electrophysiological recording. Using this inter-face, electrical signal propagation across leaves is quantified, including stress-dependent changes in spatiotemporal dynamics.

Next, the platform is extended to a multimodal framework by integrating MEA recording technology with genetically encoded fluorescent indicators of key signalling species, including calcium (GCaMP3: genetically encoded calcium indicator) and glutamate (iGluSnFR: intensity-based glutamate-sensing fluorescent reporter). This enables simultaneous electrophysiology and optical biosensing on a shared time axis, allowing direct correlation between electrical transients and the accompanying ionic dynamics. Combined with measurements in mutant lines, this approach benchmarks how dis-tinct signalling pathways contribute to systemic signal initiation, amplification, and self-propagation.

To enable causal interrogation of pathway contributions, the trans-parent MEAs are further integrated with optogenetic actuation, allowing selective activation of defined membrane conductances and direct testing of how specific ionic mechanisms shape the observed electrical responses. Finally, organic electrochemical transistors (OECTs) are incorporated to provide local, on-site amplification and improve sensitivity to low-amplitude plant signals.

Together, these approaches reveal spatiotemporally distinct propagation patterns and highlight how tissue architecture, cellular microenvironment, and intrinsic feedback regulation jointly govern signal onset, amplitude, speed, and coordination. Overall, this work establishes a robust experimental and analytical framework for studying plant systemic signalling in real time, bridging electrical recordings with molecular readouts. Beyond advancing fundamental understanding of communication within a plant, the methodology provides a foundation for future bioelectronic interfaces and sensing technologies that could support precision agriculture, sustainable biohybrid systems, and broader biological diagnostics.