A critical role for ABA-mediated Ca2+ signaling as an early and overriding process leading to stomatal closure, a beneficial behavior for plants in the face of salt stress

Stomata under salt stress—what can mechanistic modeling tell us?

Thu N. B.A. , Amtmann A. , Blatt M. R., Nguyen T.-H.  (2022)

University of Glasgow – College of Medical Veterinary and Life Sciences > School of Molecular Biosciences

In: Shabala, S. (ed.) Stomata Regulation and Water Use Efficiency in Plants under Saline Soil Conditions – Series: Advances in botanical research (103) – Academic Press: Amsterdam, pp. 139-162 – ISBN 9780323912174 – doi: 10.1016/bs.abr.2022.02.012 –

https://eprints.gla.ac.uk/281348/

Abstract

Stomata are pores that form between pairs of guard cells and are commonly found in the leaf epidermis. The pores allow gaseous exchange between the inner air spaces of the leaf and the atmosphere, opening for CO2 entry to support photosynthesis and closing to reduce transpirational water loss. Guard cell membrane transport and its coordination play a central part in regulating the pore aperture. We know how guard cells respond to light, CO2 and drought with sufficient detail to model with quantitative accuracy their mechanics. By contrast, there is surprisingly little detail about the impact of salt stress on guard cells.

Here we review the topic and introduce Na+ transport within the proven OnGuard3 modeling platform to question the mechanics of stomatal responses to salinity. The analysis indicates a critical role for ABA-mediated Ca2+ signaling as an early and overriding process leading to stomatal closure, a beneficial behavior for plants in the face of salt stress.

The OnGuard model providing a framework for systems analysis of stomatal guard cells

 

 

Systems dynamic modeling of the stomatal guard cell predicts emergent behaviors in transport, signaling, and volume control.

by Chen Z. H., Hills A., Bätz U., Amtmann A., Lew V. L., Blatt M. R. (2012)

in Plant Physiol 159: 1235–1251 – doi:10.1104/pp.112.197350 –

CrossRef | CAS –

http://researchdirect.westernsydney.edu.au/islandora/object/uws:13280

Abstract

The dynamics of stomatal movements and their consequences for photosynthesis and transpirational water loss have long been incorporated into mathematical models, but none have been developed from the bottom up that are widely applicable in predicting stomatal behavior at a cellular level.

We previously established a systems dynamic model incorporating explicitly the wealth of biophysical and kinetic knowledge available for guard cell transport, signaling, and homeostasis.

Here we describe the behavior of the model in response to experimentally documented changes in primary pump activities and malate (Mal) synthesis imposed over a diurnal cycle.

We show that the model successfully recapitulates the cyclic variations in H+, K+, Cl-, and Mal concentrations in the cytosol and vacuole known for guard cells. It also yields a number of unexpected and counterintuitive outputs. Among these, we report a diurnal elevation in cytosolic-free Ca2+ concentration and an exchange of vacuolar Cl- with Mal, both of which find substantiation in the literature but had previously been suggested to require additional and complex levels of regulation.

These findings highlight the true predictive power of the OnGuard model in providing a framework for systems analysis of stomatal guard cells, and they demonstrate the utility of the OnGuard software and HoTSig library in exploring fundamental problems in cellular physiology and homeostasis.