The oxidized cellooligosaccharides confer thermotolerance in Arabidopsis by priming ethylene via heat shock factor A2

Global climate change, especially heatwaves and aridity, is a major threat to agricultural production and food security. This requires common efforts from the scientific community to find effective solutions to better understand and protect the plant's vulnerabilities to high temperatures. The current study demonstrates the potential of cellooligosaccharides (COS), which are native and oxidized signaling molecules released by lytic polysaccharide monooxygenases (LPMO) enzymes during cell wall degradation by microbial pathogens. The extracellular perception of COS leads to the activation of damage-triggered immunity, often protecting the plant against biotic stress. However, how these signaling molecules affect abiotic stress tolerance is poorly understood. Here, we show that native COS and oxidized COS (oxiCOS) perception increase the transcript levels of several HEAT SHOCK FACTORS (HSFs) and HEAT SHOCK PROTEINS (HSPs) genes in Arabidopsis plants. However, only oxiCOS treatment triggers ethylene priming and increases thermotolerance. Furthermore, the function of the transcription factor HSFA2 is required for these processes. Altogether, our results indicate that the perception of Damage-Associated Molecular Patterns (DAMPs) may improve tolerance to adverse abiotic conditions, like exposure to high temperatures.