Energy metabolism is crucial for heat stress tolerance of Arabidopsis seedlings

Temperature is one of the most important abiotic factors affecting plant growth and development, and in the context of global warming, the frequency and severity of heat waves are likely to intensify. To counteract the impact of heat stress on membrane and protein stability, plants implement acclimation mechanisms known as the ”heat stress response”, which includes the induction of heat shock proteins and antioxidant systems. We aim to decipher the contribution of energy metabolism as a component of heat acclimation mechanisms that allow plants to survive otherwise lethal temperatures. Using a robust system, whereby Arabidopsis seedlings are grown in liquid medium under conditions that cause developmental arrest at the cotyledon stage (Benamaret al., 2013), we have shown that a priming treatment (2h at 38°C) enables seedling survival when, 24h later, they are given a 2h heat shock at 43°C. Respiratory and photosynthetic activities measured right after heat shock were partly protected by the priming treatment. Full recovery was observed one day later in primed seedlings, while damage was irreversible in non-primed seedlings. The preservation of energy transduction thus appears to be essential for heat acclimation. Indeed, based on oxygraphic measurements 2h after heat stress, it is possible to predict long-term survival. By integrating multi-level omics data (transcriptome, proteome and metabolome), we will also discuss the signalling and metabolic pathways which seem to be determinant in deciphering seedlings fate (death orsurvival)