HOT-AND-COLD · How plants deal with heat and cold: Molecular mechanisms of auxin transport and signaling in response to temperature stress

Ambient temperature above or below a threshold can adversely affect plant growth and development, and even lead to death. The tightly regulated distribution of the hormone auxin throughout the plant body controls an impressive variety of developmental processes that tailor plant growth and morphology to environmental conditions. Although non-optimal ambient temperature can alter auxin transport, the precise nature of this alteration and the underlying molecular mechanisms remain enigmatic. Hence, the aim of HOT-AND-COLD is to dissect the molecular mechanisms involved in auxin transport and its downstream signaling upon temperature stress, down to the tissue and cell-type-specific level, focusing on the root of the model organism Arabidopsis thaliana. To achieve this aim, I will combine high-resolution imaging techniques integrated with a temperature-controlled stage system, mass-spectrometry-based phosphoproteomics, TRAP-seq and chemical screens in a multifaceted approach that has never been used for such a study in plant root systems. Using this approach, I expect to reveal: (i) the temperature-responsive phosphoproteome of membrane proteins; (ii) the link between changes in membrane fluidity and the dynamics of auxin transport components within the plasma membrane; (iii) cell-type-specific translatomes that orchestrate auxin transport upon temperature shock as well as in the gradual temperature stress response; and (iv) sensors and components of the signaling pathways controlling plant acclimation to temperature stress. Taken together, the fundamental knowledge obtained through this research will contribute to the mechanistic understanding of plant responses to the temperature variability that will accompany climate change. Such understanding is key for anticipating the impacts of climate variability on agricultural and natural ecosystems.