Environmental hormesis of non-specific and specific adaptive mechanisms in plants

Abstract

Adaptive responses of plants are important not only for local processes in populations and communities but also for global processes in the biosphere through the primary production of ecosystems. In recent years, the concept of environmental hormesis has been increasingly used to explain the adaptive responses of living organisms, including plants, to low doses of natural factors, both abiotic and biotic, as well as various anthropogenic impacts. However, the issues of whether plant hormesis is similar/different when it is induced by mild stressors having different specific effects and what is the contribution of hormetic stimulation of non-specific and specific adaptive mechanisms in plant resilience to strong stressors (i.e., preconditioning) remains unclear. This paper analyses hormetic stimulation of non-specific and specific adaptive mechanisms in plants and its significance for preconditioning, the phenomenon of the hormetic trade-off for these mechanisms, and the position of hormetic stimulation of non-specific and specific adaptive mechanisms in the system of plant adaptations to environmental challenges. The analysis has shown that both non-specific and specific adaptive mechanisms of plants can be stimulated hormetically by mild stressors and are important for plant preconditioning. Due to limited plant resources, non-specific and specific adaptive mechanisms have hormetic trades-offs 1 (hormesis accompanied by the deterioration of some plant traits) and 2 (hormesis of some plant traits with the invariability of others). At the same time, hormetic trade-off 2 is observed much more often than hormetic trade-off 1, at least, this was demonstrated here for non-specific adaptive responses of plants. The hormetic stimulation of non-specific and specific adaptive mechanisms is part of the inducible adaptation of plants caused by stress factors and is an adaptation to random (unpredictable) changes in the environment.

Keywords: Adaptation; Environmental factors; Hormetic trade-off; Preconditioning; Stress.