Sandhya Samarasinghe

Title : Structural properties of the ABA signaling network defines the evolutionary success of the system

Abstract:

Stomatal closure, the most rapid physiological response in plant leaves to drought stress, is the means by which plants prevent water loss and avoid desiccation of their cells. Guard cell signalling network is a complex and an evolutionarily well conserved system organized to control the stomatal aperture in response to drought stress. This system comprises of interconnected proteins, lipids, small molecules and various other conditions of the guard cell to facilitate the communication flow in the whole system in response to environmental signals to achieve stomatal closure. Network topology, which defines the connectivity of elements in a system, can reveal the influence of network structure on the functional and dynamical properties of a system. Therefore, it is of interest to find out how the structural properties of guard cell signalling network have defined its evolutionary success through a study of its topological properties. We assembled the guard cell signalling network by expanding the existing network in literature with new knowledge and conducted a systematic study of its topological properties. The study revealed modularity of the ABA signalling network as a system of subsystems identified by topological distance measures and centrality measures. Network was decomposed into three interconnected subsystems comprising seven self-organised functional modules along with a number of hub elements that provided an easy to understand view of ABA signalling system. These interconnected subsystems with functional modules elicit an appropriate and timely response to environmental signals by means of a collection of feedback processes with shifting dominance in time and space. The study also revealed that the ABA signalling network shows characteristics of a scale-free network pointing to its evolutionarily success. Further, the network is sensitive to hub element removal but robust to removal of sparsely connected elements. This system of subsystems view enabled by modularity revealed a meaningful and coherent organization of the structure and function of the complex ABA network. In systems thinking, this defined hierarchy, coupled with a tight binding by feedback loops with shifting dominance in time and space, provides the ABA network with resilience to function in a variable environment with minimum time delay thereby enabling its evolutionary success. The systems view presented here can contribute to improving plant stress tolerance in a changing climate.

Audience Takeaway Notes:

• The audience will gain a high-level functional view of the ABA signaling system involved in guard cell stomatal  closure.
• It will provide an improved understanding of stomatal closure from a holistic perspective.
• It can contribute towards advancing biotechnology approaches to improving plant stress tolerance.
• It can be used to expand research and teaching on ABA signaling and plant stomatal closure.
• It can invite new experiments to test some of the findings

Biography:

Dr Sandhya Samarasinghe is a Professor of AI and Complex Systems at Lincoln University, New Zealand, where she is also the Head of Complex Systems, Big Data and Informatics Initiative (CSBII). She graduated with MS and PhD (Engineering) from Virginia Tech, USA. Her current research involves Computational Systems Biology where she uses AI, Neural Networks and Complex Systems Modelling to address complex intractable problems in biology from a holistic systems view. Her research covers modelling cell signaling networks, cell cycle and self-repair and regeneration of biological organisms. She has published books, book chapters and over 160 peer-reviewed publications on modelling and biology and produced many AI models for industrial applications. She is a Fellow of the Modelling and Simulation Society of Australia and New Zealand and Senior Member of Institute of Electrical and Electronics Engineers (IEEE).