Signalling the way forward: Understanding plant adaption to environmental change

Plants respond to abiotic stress with a wide range of effective protective responses. Key signalling events and transcriptional responses to environmental perturbation have been widely reported. However, responses at the metabolic level are less well understood. One clear example is the metabolic stress response involving lipid remodelling. Plants regulate pathways of fatty acid synthesis, lipid assembly and trafficking for remodelling of membranes in response to stress. For instance, temperature stress triggers lipid-dependent signalling cascades (e.g. phosphoinositides, sphingolipids, diacylglycerol), which control gene clusters and activate adaption. Levels of fatty acid synthesis and desaturation are regulated to maintain membrane function and plants undertake complex remodelling of plasma phospholipids (phosphocholine) and thylakoid galactolipids (e.g. monogalactosyl diacylglycerol) via a network of induced lipase and acyltransferase activities. Some metabolic changes associated with adaption produce toxic metabolites (e.g. free fatty acids), which can be dealt with by incorporation into triacylglycerol. Collectively these changes to the cellular lipidome (the totality of lipids in cells) enable plants to adapt and survive in variable climates. Although all plants share the ability to remodel their cellular lipidome in response to abiotic stress, the capacity in different species and cultivars often varies. Currently, our understanding of lipid responses to abiotic stress largely comes from model species such as Arabidopsis, but there is now interest in using extremophile species, adapted to challenging climates, to dissect the mechanisms of plant lipid signalling and remodelling. Eutrema salsugineum ('salt cress') is highly resilient to abiotic stress (temperature and salinity). Moreover, as a member of the Brassica family and closely related to Arabidopsis it is a platform for understanding stress tolerance. The genome of Eutrema is fully sequenced and transformation methods have been established. The similarity between genomes of Eutrema and Arabidopsis allows a direct comparison between genes and their function, rendering most of the experimental procedures developed for Arabidopsis highly adaptable. The central aim of the proposed project is to clarify the biochemical processes and functional significance of stress induced lipid metabolism. Using both Arabidopsis and Eutrema, we will focus on the mechanistic response to temperature stress. Current and predicated climate variability has critical effects on food production, therefore the fundamental understanding developed in the proposed work will establish knowledge-based strategies to address crop temperature resilience.