Dynamic and thermodynamic aspects of water in plants, and its relationship with metabolic and redox state changes caused by stress conditions

CABADAS, MANUEL; OTAIZA GONZÁLEZ SN; LASCANO HR; AMBROGGIO, ERNESTO ESTEBAN; BAGATOLLI, LUIS

Rosario

Congreso; L Reunión Anual SAB; 2022

Sociedad Argentina de Biofísica

BackgroundThe classical cellular model assigns a role to water as a (passive) biological solvent where biochemical reactions occur. This view has been challenged by studies which indicate that the properties of interfacial water in crowded media are very different from those of this compound in dilute systems. In contrast to this classical model, the “Association-Induction Hypothesis” considers cells as dynamic colloidal systems capable of responding to endogenous (metabolic) or environmental fluctuations in a cooperative manner, thus modulating their emergent properties during cell function. As its name makes explicit, this hypothesis contains two important parts: i) Association: given by the behavior of ionizable species in crowded environments, which contemplates the existence of a system of charges with one of the ions showing limited mobility; ii) Induction: based on the structural dynamics of proteins, their characteristics as partially resonant polymers and their nature as polyelectrolytes.Our WorkWe aim to study how intracellular water polarization is affected in different experimental plant systems of Arabidopsis thaliana in response to various stress conditions. For this purpose, we employ fluorescent probes (ACDAN and PRODAN) sensitive to the changes in the dipolar orientation of water molecules surround coupled to different techniques of fluorescence spectroscopy (steady state and lifetime measurement) and confocal microscopy (FLIM- spectral phasor analysis and fluorescence spectral imaging). Changes in the fluorescence properties of the dyes upon stress induction allow us to infer on the degree of dipolar relaxation in plant cells and tissue(s).Preliminar resultsAs a proof of concept, we evaluated how the intracellular water dipolar relaxation is modified in Arabidopsis occlusive cells under conditions where the stomatal pore is closed or open. Preliminary data suggest that the degree of dipolar relaxation decreases when the pore is closed.