• Arabidopsis Flowers
    The Arabidopsis genome was the first plant genome
    to be fully sequenced. This knowledge, together
    with a large body of mutational data, tools for
    genetic manipulation and access to closerelatives
    with varied physiological traits, greatly speeds
    fundamental research in the plant sciences.
  • Cyanobacteria
    Cyanobacteria, also known as blue-green algae,
    obtain their energy through photosynthesis,
    making use of much the same pathways as plants.
    It is thought that modern plants arose through
    a symbiotic association with cyanobacteria,
    which have since evolved to form the chloroplasts
    of higher plants thus providing energy to the
    host. For these reasons, cyanobacteria have long
    been used as a model with which to study the
    process of photosynthesis.
  • Begonia
    Begonias represent one of the largest and most
    diverse genera among the angiosperms. Several
    Begonia species exhibit complex stomatal
    patterning and variable stomatal clustering,
    which may be important for their physiological
    adaptation to extremewet environments such as
    around waterfalls, and is a focus of research
    in the Laboratory.
  • Broad Bean
    Vicia faba is familiar to us as the broad bean
    or butterbean. It is a robust, upright annual
    that grows well in cooler environments. It’s
    rounded, segmented leaves are easy to dissect
    by hand and have long been a favourite for
    research on stomatal guard cells and their
    control of gas exchange in plants. Data that
    comes from studies of Vicia remains the gold
    standard in the field of membrane transport
    and its control.
  • Jungle Night
    Amorphophallus Paeoniifolius is one of a number
    of giant arums found in tropical central
    Americas. Its close relative, Amorphophallus
    titanium, produces the largest flower in the
    world, which can grow to over 2 meters in
    height. Like many giant arums, A. paeoniifolius
    grows from an elongated tuber. The leaf
    structure, stomatal organisation and venation,
    visible here, are well-adapted for highly humid
  • Water Scarcity
    Water scarcity and changes in the global
    environment are the most serious threats to
    global food security. Many parts of the USA,
    Australia and Asia as well as the mediterranean
    countries have seen substantial increases in
    water deficits over the past decade. Even in the
    UK, the demand for irrigation water has risen
    almost 10-fold in the past 20 years. Recurrence
    of the Dust Bowl phenomenon that devastated the
    American wheat belt is a real concern.
  • Oilseed rape
    Brassica napus is a major focus
    for translational research building on work
    from Arabidopsis. The leaves and stems are
    commonly eaten in Southeast Asia and are often
    found in asian groceries sold as tender greens.
    Over 60% of its cultivation in the EU currently
    goes into biodiesel production. Rapeseed demands
    substantial water and N fertilization, although
    newer varieties grown in Canada have been
    reported to be more drought-tolerant.

Guard Cell Modelling Software - On-Guard

The OnGuard software package was constructed for quantitative systems dynamic modelling of the stomatal guard cell. It incorporates explicitly all of the fundamental properties for transporters at the plasma membrane and tonoplast, the salient features of osmolite metabolism, and the major controls of cytosolic-free Ca2+ concentration and pH. OnGuard takes a structured approach to tier and interrelate elements, and gives ready access to parameters and equations ‘on the fly’ while enabling the network of components within each model to interact computationally.

The latest release (Version, Winter 2017) includes all new features described in the latest publication, including the ability to model guard cell responses to humidity changes.


Download Installer for 32-Bit Windows



Download Installer for 64-Bit Windows



Download our introductory video


Key Notes

Hardware Requirements


Pentium V or better CPU, running Microsoft Windows Vista or Windows 7; Administrator rights to install the package. We recommend a quad processor system for best results.


Included Features


* Direct and easy access to all model parameters, and facility to define solute compositions, transporter populations, biophyical and kinetic parameters.

* Automatic ‘smart’ time base that accelerates computational speed with minimum and maximum limits.

* A Reference State Wizard that aids establishing stable models.

* Simulation-time graphical display of current-voltage relations for transporters at both membranes.

* Simulation-time tabular display of all ionic and other solute contents for each compartment and fluxes between compartments, tabular display of related variables.

* Simulation-time graphical chart recorder of key variable outputs.

* Logging of all variables in spreadsheet-readable (*.csv) format.

*OnGuard is supplied with model parameter (*.obg) files for Vicia and Arabidopsis guard cells.


Terms of Use


On-Guard is freely available, but is an expert system. Effective use requires a good working knowledge of guard cells, transport physiology, and an interpretive understanding of current-voltage curves. When publishing simulations and analysis using the software, please cite the following two articles:

Adrian Hills, Zhonghua Chen, Anna Amtmann, Michael R. Blatt and Virgilio L. Lew: “On-Guard: A Computational Platform for Quantitative Kinetic Modeling of Guard Cell Physiology.” Plant Physiology, 2012, 159:1026–1042.

Zhonghua Chen, Adrian Hills, Ulrike Bӓtz, Anna Amtmann, Virgilio L. Lew and Michael R. Blatt: “Systems Dynamic Modeling of the Stomatal Guard Cell Predicts Emergent Behaviors in Transport, Signaling and Volume Control.” Plant Physiology, 2012, 159:1235–1251.