Looking for a systemic concept and physiological diagnosis of a plant stress state

Abstract

Plant stress state is defined here as an endogenous physiological condition associated with homeostasis disruption involving irreversible or reversible modifications. Plant biologists are facing two important problems: establishing a suitable and dynamic stress concept and devising tools to make a suitable physiological diagnosis to characterize plant stress states. We are proposing here a new concept on stress essentially focused on plant organization as self-organized and emergent systems concentrated in homeostasis disruption as impacted by endogenous and environmental feedbacks. In addition, we are proposing a simplified physiological diagnosis system to evaluate two contrasting stress states in comparison with a non-stressed condition based on progressive alterations in plant homeostasis. This proposal is focused on specific crops, presenting rice as an example. The diagnosis system assumes that homeostasis in plants is dynamic, flexible, spatio-temporal, and organized in multi-modules. The reference state involves a ground homeostasis representing a non-stress state, prior to environmental perturbations and alarm phase. The second stage of homeostatic alterations is characterized by reversible changes in plant organization induced by external factors, characterizing a slightly changed homeostasis or moderate stress state. The third stress state is characterized by strong and irreversible alterations in homeostasis, characterizing collapse in most plant modules leading to a chronic stress. The alterations in the homeostasis induced by mild stressful conditions (eustress) could also trigger different plant memory processes. We believe this systemic stress concept and diagnosis system will shed light on the improvement of stress plant physiology and their respective applications in agriculture.