Effect of chronic β-radiation on long-distance electrical signals in wheat and their role in adaptation to heat stress

Abstract

Plants are unavoidably exposed to ionizing radiation (IR) from natural and anthropogenic sources. Along with the chronic irradiation, plants are influenced by other environmental stress factors, to which they must adapt. We suppose that high background radiation modifies plant response to environmental stressors by influencing the stress signaling which are the crucial players in induction and orchestrating the formation of plant adaptation. Chronic β-radiation (31.3 μGy/h) does not cause pronounced oxidative stress and significant changes in morphometric parameters of wheat seedlings (Triticum aestivum L.). At the same time, chronic IR exposure causes slight activation of transpiration and assimilation, and activates H+-ATPase-dependent transmembrane transport. In irradiated plants, there is an increase in the amplitude, velocity and propagation distance of electrical signals induced by a local stimulus. Accordingly, in irradiated plants, photosynthesis and transpiration responses caused by an electrical signal are significantly enhanced. The opposite effect of the electric signal on heat stress resistance was found: after the signal passing, the resistance of control plants increases, but it decreases for irradiated plants. It is assumed that the inversion of the effect is resulted from the enhanced responses of transpiration due to the electrical signals amplification.