Identifying climate-proof mechanisms of plant acclimation to freezing temperatures

About the Project

Climate change brings many challenges for the planet’s plants and one of these is the vulnerability caused by erratic temperatures. Many plants, including major crops, prepare for winter through a process called cold acclimation. In this process, plants respond to the cooler temperatures that prevail in the autumn, by making changes that equip them with resilience against subsequent freezing conditions in winter. This powerful mechanism is now under threat, as harsh frosts often occur without warning, after very warm days. This is particularly prevalent in the spring and is responsible for significant crop losses in temperate countries. This project follows on from our recent discovery that plants can use high levels of light to bring about increased freezing tolerance. The successful candidate will perform a wide range of genetic, metabolic and physiological analyses to identify the steps in cold acclimation that can be brought about by high light levels and will determine whether high light has this effect through increasing levels of photosynthesis or by upregulating the classical cold acclimation pathway. Genes encoding key proteins that are important to the high light-dependent pathway will be identified. The student will then engage in evolutionary analysis of these proteins. This will help us understand whether the ability to use high light as a cold acclimation signal, in the absence of cool autumn temperatures, varies across plant species depending on their habitat. The long-term goal of this research is to produce crop plants that are more resilient to spring frosts and are able to use information other than temperatures to trigger increased freezing tolerance.

Understanding this mechanism could help farmers protect crops from climate change-related frost damage, improving food security. You will gain expertise in plant physiology, molecular biology, bioinformatics, and gene editing.

Project structure:

We have recently demonstrated that 5-day high-light treatment acclimates photosynthetic electron transport (PET, operating efficiency of PSII Fq'/Fm') and enhances freezing tolerance in the absence of cold acclimation. Whether high light acclimation facilitates acclimation to freezing by activating recognised and/or novel cold-responsive signalling or by increasing energy production remains unknown. This project will investigate the basis for this phenomenon.

Objective 1: Determine how PET acclimation under high light conditions augments freezing tolerance. (a) Using inhibitors for specific PET components and dark treatment to fully inhibit light reactions, the role of PET acclimation will be addressed. (b) PET measurements, infrared gas analysis (IRGA) for CO₂ assimilation, metabolite quantification, and marker gene expression will be compared during CA and HLA. This will identify mechanistic differences to reveal high light pathway-specific steps. (c) Testing Arabidopsis mutants of light signalling components for CA response will reveal CA dependency on light-responsive proteins.

Objective 2: Identify ecotypic variation in high light acclimation response with increased freezing tolerance. Natural Arabidopsis ecotypes from diverse environments will be assessed by measuring parameters from 1a and measurement of freezing tolerance. This will reveal whether the ability to use HLA as a proxy for CA might vary with natural habitat. Genomes of accessions showing contrasting behaviours will be analysed for variation at candidate gene loci identified above. This part of the work will be undertaken with our collaborator Dr Maxim Kapralov, University of Newcastle, who will co-supervise the student.

Objective 3: In vivo and in silico analysis of candidate genes. Candidate genes will be investigated using reverse genetics. The student will perform complementary evolutionary analysis of candidate gene homologues from diverse angiosperms in different climates (available in GenBank) within phylogenetic analyses frameworks for positive selection (with MK, Newcastle). This will pinpoint potential amino acid switches within proteins responsible for increased HL-mediated cold acclimation. SNPs encoding such switches will be queried empirically by complementing complete loss-of-function mutants with modified sequences and testing CRISPR-Cas modified plants for freezing tolerance.

Funding Notes

If you are interested in applying, in the first instance contact the supervisor Prof Heather Knight, p.h.knight@durham.ac.uk, with a CV and covering letter, detailing your reasons for applying for the project.