Tuning Photosynthesis to a Changing Environment

The introduction of chemical fertilisers in the 20th century helped revolutionise agriculture and prevent mass famine. At the same time, nitrogen-based fertilisers require huge amounts of energy, via the Haber-Bosch process, and are an important contributor to climate change, undermining agriculture. There is an urgent need therefore to develop N-efficient crops and farming methods.

The most important N sink in plants is photosynthesis. Rubisco, the carbon fixing enzyme of photosynthesis, alone accounts for over 30% of leaf protein, making it the most abundant protein on earth. Depending on the conditions in which plants grow, leaf Rubisco content can vary as much as 50%, making it a vital part of the plants overall N economy.

When plants are exposed to environmental fluctuations, they remobilise N, optimising its distribution within the photosynthetic apparatus, or reallocating it to different processes across the plant, to help maintain productivity and minimise the effects of stress. This process is called photosynthetic acclimation and can occur in response to factors such as light, temperature and CO2 availability.

New results in our lab show that acclimation in the model plant Arabidopsis thaliana is directed by N availability. When plants in a high-N soil are acclimated to low temperature, they increase photosynthetic capacity and Rubisco content, to compensate for the lower temperature. Plants in N-poor soils do the opposite, decreasing photosynthetic capacity, to prioritise defence against stress.

The aim of this project is to understand the molecular processes underlying these contrasting responses.

Building on previous results, you will examine the responses of plants to changes in temperature, across different nutrient conditions. You will examine how carbon and nitrogen resources are redistributed through the plant, using a combination of metabolomics and proteomics, combined with physiological and morphological measurements. Initial work on the model Arabidopsis will be extended to incorporate crop species, to provide a basis for development of nutrient efficient crop varieties.