Background: Increasing food security for a growing global population is a major challenge facing humanity. Modulation of root system architecture is a key feature of plant responses to drought, potentially leading to yield benefits. Understanding the mechanisms regulating root development under drought conditions is therefore an important question for plant biology and world agriculture.
Previously, by combining molecular biology (our experimental data and the data in the literature) with systems biology (network construction and spatiotemporal modelling), we have constructed a network describing the interactions between auxin, ethylene, cytokinin and the POLARIS peptide (required for correct auxin, ethylene and cytokinin signalling in Arabidopsis), revealing a hormonal crosstalk circuit that regulates root growth. This model has been expanded to include auxin transport via the PIN-FORMED (PIN) efflux transporters and has been implemented into a spatiotemporal model, which can reproduce the patterning of various hormones and response genes. In addition, we examined the effect of osmotic stress on ABA, cytokinin and ethylene responses and how they mediate auxin transport, distribution and root growth through effects on PIN proteins. We showed that under osmotic stress, Arabidopsis plants display increased ABA responses, and demonstrated the effects on auxin transport to the primary root meristem through altered PIN1 levels. We then used this information to construct a new network to integrate the effects of osmotic stress and ABA with auxin, ethylene and cytokinin. This network developed novel insights into how an integrated system of ABA, auxin, ethylene and cytokinin is formed due to the repression of ethylene effects by ABA to limit auxin accumulation in the meristem, and brought new understanding to the control of root development under osmotic stress. The current programme builds on our success in applying combined molecular and systems biology study and further explores the regulation of root development under osmotic stress conditions.
Aims: Depending on the student’s interest, the student can choose to focus on either or all of the following two aspects. i) acquisition of novel experimental data for elucidating the regulation of root development under osmotic stress conditions; ii) construction of hormonal crosstalk network and development of a predictive in silico model for elucidating regulation of root growth under osmotic stress conditions. Iterative combination of i) and ii) is able to develop novel insights into the effects of osmotic stress on root development at systems level.
Methodology: Experimental data will be acquired using our established methodology. The student will develop skills in molecular biology including RNA extraction and cDNA synthesis; quantitative real-time polymerase chain reaction (qPCR); compound light microscopy; confocal laser scanning microscopy; living imaging system; image analysis. Construction of hormonal crosstalk and model development will be based on our published methodology. The student will develop skills in systems biology including computer software, computer programming, network construction and spatiotemporal modelling. We have already demonstrated that a combined study using both molecular biology and systems biology techniques is a powerful tool for exploring the complexity in regulation of root growth under osmotic stress conditions.
This project is in competition with others for funding. Success will depend on the quality of applications received, relative to those for competing projects. If you are interested in applying, in the first instance contact the supervisor, with a CV and covering letter, detailing your reasons for applying for the project
•Moore S, Zhang X, Mudge A, Rowe JH, Topping JF, Liu J and Lindsey K (2015). Spatiotemporal modelling of hormonal crosstalk explains the level and patterning of hormones and gene expression in Arabidopsis thaliana wildtype and mutant roots. New Phytologist 207: 1110-1122.
• Moore S, Zhang X, Liu J and Lindsey K (2015). Some fundamental aspects of modelling auxin patterning in the context of auxin-ethylene-cytokinin crosstalk. Plant Signaling & Behavior, DOI:10.1080/15592324.2015.1056424.
•Moore S, Zhang X, Liu J and Lindsey K (2015). Modelling Plant Hormone Gradients. In: eLS. John Wiley & Sons, Ltd: Chichester. DOI: 10.1002/9780470015902.a0023733733.
•Rowe, J. H., Topping, J. F., Liu, J. and Lindsey, K. (2016). Abscisic acid regulates root growth under osmotic stress conditions via an interacting hormonal network with cytokinin, ethylene and auxin. New Phytologist 211(1):225-239.
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