Light-independent sugar signalling in Arabidopsis

Sugar metabolism is a fundamental biological process providing energy and the molecular building blocks to sustain life on our planet. 'Green organisms', such as plants and algae, use light energy from the sun to convert carbon dioxide into stored energy in the form of sugars while producing the oxygen we breathe. This process, known as photosynthesis, is probably the most important metabolic process on the planet. Photosynthetic organisms living in the 'primordial soup' produced the oxygen which gave rise to the Great Oxidation Event ~2.5 billion years ago, facilitating a massive evolutionary advance. Plants are among the descendants of these organisms, which continue to provide most of the energy necessary to sustain life today. Therefore, investigating how plants sense and respond to sugars is a fundamentally important research question in biology. Through improved understanding of these processes, we can gain valuable insight and develop tools to improve efficiency and total productivity of agriculture to feed the growing population around the world.
Since photosynthesis depends on light, it must be effectively regulated to optimise use of daylight. Sugars must be transported to tissues that cannot photosynthesise to meet their energy needs and stored appropriately to last the night. Furthermore, as daylength and seasons change, plants need to be able to adapt to the changes in environment while maintaining optimal carbohydrate metabolism. Coordination of these processes requires mechanisms for plants to sense and respond to sugar availability. The requirement for light in sugar production in plants adds complexity that is a critical consideration to understand these endogenous sugar signalling pathways in photosynthetic organisms. For example, it is difficult to interpret effects of sugars in the light when photosynthesis is active. There is still much to be learned about the underlying mechanisms in these processes. The main objective of this research is to identify novel components of sugar signalling in the model plant species, Arabidopsis thaliana. A novel, sensitive assay has been developed to investigate sugar responses that act independently of light signalling in plants. This assay will be used to identify genes that contribute to light-independent responses to sugars and determine the function of these genes in the context of various, physiologically relevant growth environments. Ultimately, the goal of this research is gain insight into how plants integrate sugar and light signals to optimise photosynthetic efficiency and growth. This work will use a range of genetic and molecular approaches, utilising state-of-the-art technologies to gain genome-wide information about the impacts of these processes.

Carbohydrate metabolism is a fundamental biological process providing energy and the molecular building blocks for life. In plants, sugars are produced from photosynthesis in a light-dependent manner. Photosynthesis is probably the most important metabolic process on the planet. Understanding how plants sense and respond to sugars is therefore a fundamental research question in biology because, in addition to the role in energy storage, sugars regulate growth, developmental, flowering time, pathogen resistance, cell cycle progression and circadian entrainment. The requirement for light in sugar production in plants adds complexity that is a critical consideration to understand endogenous sugar signalling pathways in photosynthetic organisms.
Sugar signalling pathways in plants have been identified so far either by genetic screens for resistance to very high exogenous sucrose in the light or inferred from animal or yeast systems. While these approaches have been successful in identifying components of plant sugar sensing and signalling, there remains much to be learned about these processes. A more sensitive genetic screen for a physiologically relevant sugar-dependent response would provide a powerful tool to uncover plant-specific sugar signalling components.
A genetic screen, based on a novel sugar response assay, has identified mutants that affect sugar signalling independently of light and photosynthesis. Mutants will be mapped and characterised in the context of various physiologically relevant growth environments. A high quality transcriptome dataset will be generated to define global transcriptional events in wild type and mutant plants in response to sugars in the context of light signalling and photosynthesis. This research will identify molecular components of sugar signalling and advance our understanding of how external light signals and endogenous sugar signals are integrated to optimise plant growth and development.

Who might benefit from this research?
1. The PDRA
2. Industrial and commercial scientists interested in plant energy biology and/or sustainable agriculture
3. The general public
How might they benefit from this research?
1. The research programme provides an exciting opportunity for an early career scientist to acquire a wide range of professional skills that are applicable to either an academic or non-academic career.
Within a research context, the PDRA will gain experience and training in broadly applicable, state-of-the-art technologies for gene and protein expression analysis for biological research. This research will be conducted to world-class standards and is expected to have high academic impact. Therefore, this project has the potential to progress the academic career of the researcher. The publication record of Dr Haydon demonstrates a strong track record of academic impact with a high quality of research output. The PDRA will also have the opportunity to interact with world-class biological scientists at the University of York, collaborating partners of the research lab, and while attending an international conference. These networking opportunities will facilitate the next step in his/her career, if an academic path is desired.
The PDRA will also gain experience and training in a range of broadly relevant, non-academic skills including management of research students and technical staff, oral and written presentation, use of general and specialised software and computing tools and effective time-management and organisation. Training will be provided both informally within the context of the research group and formally from training courses provided by the department and the university.
2. Although the research project is focused on fundamental research into biological processes in plants, there is potential for this research to benefit agriculture and the plant science industry. The research builds on recently published, high impact research and will advance our knowledge of energy sensing and carbon metabolism, which are fundamental to all biological systems. Carbohydrate metabolism in plants not only supplies biomass for plant growth but also provides almost all the fixed carbon and oxygen for life on this planet and so has broad implications not only for agriculture but also the environment. This field of research is highly relevant to urgent problems associated with climate change and resource demands because plant carbohydrate metabolism lies at the foundation of energy storage for bio-fuels and provides a major pathway for carbon sequestration. Therefore, contributions to our understanding of sugar metabolism in plants is relevant to achieving the recognised goals of improving sustainable agricultural yields to support the rapidly growing population around the world, enhancing the potential of biofuels and minimising impact of climate change. The impact could be indirect, through the open-access publication of research outcomes, or could be direct by specific interaction with potential industrial and commercial partners as outlined in the pathways to impact.
3. Breakthrough findings towards understanding fundamental biological questions have high potential to make an impact on the general population through the popular science media. This can be facilitated by publication of research outputs in widely recognised scientific journals, publicity through press releases and through public outreach. Public outreach can be achieved at a number of levels such as interaction through the internet and social media, participation in university open days targeted at students and families and, ultimately, through involvement in science media such as podcasts and radio programmes. Effective use of these means of public engagement will ensure this research contributes to increasing public awareness and understanding of the importance of fundamental questions in the biological sciences.