A Theoretical Analysis of Relations between Pressure Changes along Xylem Vessels and Propagation of Variation Potential in Higher Plants.

Ekaterina Sukhova,Vladimir Sukhov,Roman Y Pishchalnikov,Sergey V Gudkov,Elena Akinchits,Vladimir Vodeneev

doi:10.3390/plants10020372

Abstract

Variation potential (VP) is an important long-distance electrical signal in higher plants that is induced by local damages, influences numerous physiological processes, and participates in plant adaptation to stressors. The transmission of increased hydraulic pressure through xylem vessels is the probable mechanism of VP propagation in plants; however, the rates of the pressure transmission and VP propagation can strongly vary. We analyzed this problem on the basis of a simple mathematical model of the pressure distribution along a xylem vessel, which was approximated by a tube with a pressure gradient. It is assumed that the VP is initiated if the integral over pressure is more than a threshold one, taking into account that the pressure is transiently increased in the initial point of the tube and is kept constant in the terminal point. It was shown that this simple model can well describe the parameters of VP propagation in higher plants, including the increase in time before VP initiation and the decrease in the rate of VP propagation with an increase in the distance from the zone of damage. Considering three types of the pressure dynamics, our model predicts that the velocity of VP propagation can be stimulated by an increase in the length of a plant shoot and also depends on pressure dynamics in the damaged zone. Our results theoretically support the hypothesis about the impact of pressure variations in xylem vessels on VP propagation.

Highlights

IntroductionElectrical signals are important long-distance signals that are likely to participate in the induction of a systemic response in plants after the local action of stressors [1]
Our model was based on three parameters: the length of the xylem vessel (L), the duration of hydraulic changes in the damaged zone, and the ratio (N) of the integral of pressure increase (P’), which was necessary for induction of variation potential, to the total integral of the pressure increase in the zone of damage (P0 ’)
Variation potential is an important electrical signal in plants that is generated after the local action of dangerous stressors, regulates numerous physiological processes, and is likely to participate in plant adaptation to the action of stressors [1,2,3,4,5,6,7,8]

Summary

Introduction

Electrical signals are important long-distance signals that are likely to participate in the induction of a systemic response in plants after the local action of stressors [1]. It is known that action potential is a short-term impulse signal (depolarization followed by repolarization) that is induced by non-damage stressors; it is related to the transient activation of ion channels (Ca2+ , K+ , and anion channels) and inactivation of H+ -ATPase in the plasma membrane [7]. It is mainly related to the activation of Ca2+ channels and the inactivation of H+ -ATPase [3,5,11]; the transient activation of other anion channels can participate in VP generation [5,7]

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