Understanding Ice Formation in Plants: Finding new Routes to Freezing Tolerance

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

The aim of this proposal is to understand the role of plant cell wall constituents, particularly pectins, in mediating and/or preventing extracellular ice formation, which plays a key role in determining the freezing tolerance of plants.

The two main objectives of this project are: (1) to discover the impact of cell wall pectin cross-linking on ice nucleation and growth in plant tissues (WP1) and (2) to reveal the mechanism whereby pectin cross-linking influences plant freezing tolerance (WP2).

To this end, we will use molecular dynamics simulations to investigate the atomistic details of how modified and cross-linked pectins affect ice nucleation and growth and high-speed cryo microscopy to visualise how ice forms and spreads between particular cell types and under different conditions. Then, we will use cryo microscopy and infra-red thermal imaging of Arabidopsis genetic mutants to reveal how specific changes to the cell wall mediated by single genes influence ice growth within and between tissues. The structural properties of cell walls in the mutants examined will be characterised with respect to their mechanical strength and porosity, via a confocal micro-extensometer as well as by a fluorescence quenching method relying on the ability of less porous cell walls to exclude large molecules. Under all conditions, the sensitivity of wild type and mutant plant tissues to freezing and thawing will be assessed by measuring ion conductivity in electrolyte leakage assays. The ability of plants to survive freezing events will be monitored through visual assessment of re-growth after the freezing event and subsequent return to normal temperatures.

As a whole, this ambitious programme of work will enable the rational design of genetic modifications specifically tailored to enhance freezing tolerance in plants, building on the novel microscopic insight that we will deliver by our complementary methodologies, bringing together experiments and simulations.