How plants deal with heat and cold: Molecular mechanisms of auxin transport and signaling in response to temperature stress

Project Information

HOT-AND-COLD

Grant agreement ID: 101042198

DOI

10.3030/101042198

Project terminated on 27 August 2025

EC signature date 22 February 2022

Start date 1 September 2022

End date 31 August 2027

Funded under

• European Research Council (ERC)

Total cost

€ 1 382 689,00

EU contribution

€ 1 382 689,00

Coordinated by

SVERIGES LANTBRUKSUNIVERSITET
Sweden

Periodic Reporting for period 2 - HOT-AND-COLD (How plants deal with heat and cold: Molecular mechanisms of auxin transport and signaling in response to temperature stress)

Reporting period: 2025-03-01 to 2027-08-31

Summary of the context and overall objectives of the project

Our planet is warming, and extreme weather events such as sudden heat waves and cold spells will only become more frequent. This poses significant challenges for plants, which are highly sensitive to temperature. Temperature stress – that is condition when temperature is above or below of an optimal temperature range at which plants grow and perform best – can severely affect plant distribution, health and productivity. While most of the studies to date have focused on big-picture elements of plant responses to climate change (e.g. biomass), future research needs to focus on molecular and cellular responses to improve our mechanistic understanding of, and thus our ability to support, plant adaptation to heat and cold stress. To adjust and adapt, plants rely on hormones such as auxin, which plays an essential role in regulating plant growth and development. Auxin undergoes directional transport from one cell to another, which allows asymmetric distribution of this hormone in different cells and tissues. This system creates local auxin maxima, minima, and gradients that are instrumental in both organ initiation and shape determination. However, the molecular mechanisms by which is auxin transport modulated/regulated at the cellular level upon temperature stress are not well explored. It is also unclear how auxin transport is regulated in different types of cells with various functions to make up the plant’s response to temperature stress. By addressing this knowledge gap, the project aims to provide a mechanistic framework linking temperature perception to hormone-mediated growth responses. The results of this project are expected to significantly advance fundamental understanding of plant temperature adaptation by identifying key regulatory processes controlling auxin transport under stress conditions. This knowledge will contribute to the long-term goal of improving plant resilience to climate variability and extreme temperatures, thereby supporting future efforts in crop improvement and sustainable plant production systems.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The HOT-AND-COLD project aims to elucidate the molecular mechanisms regulating auxin transport in response to temperature stress at tissue- and cell-type-specific resolution. To achieve this, we investigated temperature-dependent regulation of auxin transport components using molecular, genetic, and imaging-based approaches. We identified key auxin transporters that respond rapidly to temperature changes and characterized a set of temperature-responsive kinases implicated in the regulation of transporter activity through phosphorylation. In parallel, we analyzed the impact of temperature stress on root cell membrane properties and demonstrated that membrane remodeling constitutes an additional regulatory layer influencing auxin transport. Using advanced imaging techniques, we showed that temperature stress alters auxin distribution across distinct root cell types, leading to adaptive changes in root developmental patterns associated with enhanced tolerance to temperature extremes. Furthermore, we established and validated a new experimental technique in our laboratory to investigate translational regulation of auxin transport components under temperature stress. In addition, a chemical genomics screen was performed, will result in the identification of small molecules that perturb temperature-responsive pathways and point to previously uncharacterized regulators of auxin transport. Overall, the project has delivered new mechanistic insights into temperature-dependent regulation of auxin transport, identified molecular regulators and membrane-associated processes involved in this response, established novel methodological tools, and generated chemical probes for future dissection of temperature-responsive signaling pathways. These outcomes provide a foundation for strategies aimed at improving plant resilience to temperature fluctuations.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project addresses a critical knowledge gap in understanding how plants regulate auxin distribution in response to environmental stress, a process that is essential for growth, development, and survival under unfavourable temperature conditions. By investigating auxin transport regulation at multiple biological levels, the action generates fundamental insights into how plants reorganise developmental and physiological processes in response to heat and cold stress. The results obtained to date indicate that auxin transport is regulated through a complex, multi-layered network involving cell-type-specific mechanisms and temperature-responsive molecular regulators. The project has generated large-scale, root-specific datasets that are being analysed at tissue and cellular resolution, enabling the identification of candidate genes and pathways involved in temperature-dependent auxin transport. Several previously uncharacterised regulators have already been identified and represent promising targets for further functional characterisation. The potential impact of these results lies in their contribution to a mechanistic framework for plant temperature adaptation, which is essential for predicting plant performance under climate variability. In the longer term, this knowledge can inform strategies aimed at improving crop resilience to temperature extremes, thereby supporting agricultural sustainability and ecosystem stability in the context of climate change. To ensure further uptake and success, additional research will be required to validate candidate regulators in different plant species and environmental contexts. Follow-up studies may include functional characterisation, demonstration in crop systems, and integration with breeding and biotechnology approaches. Access to advanced phenotyping platforms, interdisciplinary collaboration, and supportive funding mechanisms will be key to translating fundamental findings into applied outcomes. Taken together, the project has delivered large-scale, cell- and tissue-resolved datasets, identified novel candidate regulators of temperature-dependent auxin transport, and provided new mechanistic insights into how plants coordinate root development in response to heat and cold stress.

HOT-AND-COLD Summary_Marhava