Electrotonic signal transduction between <em>Aloe vera</em> plants using underground pathways in soil: Experimental and analytical study

Abstract

Plants communicate with other plants using different pathways: (1) volatile organic compounds’ (VOC) emission and sensing; (2) mycorrhizal networks in the soil; (3) the plants’ rhizosphere; (4) electrostatic or electromagnetic interactions; (5) roots of the same species can sometimes naturally graft. Here we show that there is an additional pathway for electrical signal transduction between neighboring plants: fast underground electrical signal propagation between roots through the soil. The mathematical model of electrical signal transduction between plants and the analytical study are supported by experimental data. The pulse train, sinusoidal and a triangular saw-shape voltage profiles were used for electrostimulation of plants and underground electrotonic signal transmission between plants. Electrostimulation of a leaf in Aloe vera by 1.5 V D-batteries or by a function generator induces electrotonic potentials propagation in the electrostimulated plants and the neighboring plants. The amplitude and sign of electrotonic potentials in both electrostimulated and neighboring Aloe vera plants depend on the amplitude, rise and fall of the applied voltage. Electrostimulation by a sinusoidal wave from a function generator induces an electrical response in leaves with a phase shift. Experimental results show cell-to-cell electrical coupling and existence of electrical differentiators in the leaves of Aloe vera. Electrostimulation is an important tool for the evaluation of mechanisms of communication between plants.