Periodic Reporting for period 1 - HOT-AND-COLD (How plants deal with heat and cold: Molecular mechanisms of auxin transport and signaling in response to temperature stress)
Reporting period: 2022-09-01 to 2025-02-28
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. This research aims to dissect the molecular mechanisms that control auxin transport at the cellular level under temperature stress across various cell types.
The overarching goal of HOT-AND-COLD project is to uncover the molecular mechanisms that regulate auxin transport in response to temperature stress at both the tissue- and cell-type-specific levels. To date, we have identified key auxin transporters that respond rapidly to temperature changes, as well as kinases—proteins that can regulate e.g. transporter activity through phosphorylation—within a temperature-responsive network. In another major achievement, we examined how temperature stress impacts the fluidity of root cell membranes, which in turn regulates auxin transport. Using specialized probes and advanced imaging techniques, we found that shifts in membrane fluidity affect auxin distribution among different cell types, resulting in adaptive changes in root development that enhance resilience to temperature extremes. Finally, we have established a new technique in our lab that will help us understand how auxin transport is regulated at the translational level. Moreover, through our chemical genomic screen, we've identified chemical compounds that could reveal new components of temperature-responsive pathways in plants. Taken together, our discoveries thus far reveal potential regulatory points in auxin pathways that could be crucial for improving plant resilience to temperature fluctuations.
Tightly controlled auxin distribution throughout the plant body is essential for plant growth and development, pointing towards the urgent need for detailed insights into the regulation of auxin transport in response to environmental stimuli, when plants need to “reorganize” their biological functions to survive unfavourable conditions. Given our progress so far, we anticipate that by the end of the project, we will have significantly advanced our understanding not only of auxin transport regulation at multiple levels but also of how plants generally respond to heat and cold stress. We have been generating large-scale, root-specific datasets, which are being carefully analyzed and will continue to be examined at both the tissue and cellular levels. Currently, very few genes are recognized as pivotal for auxin transport regulation and root responses to temperature stress, but we have already identified multiple potential new regulators for in-depth characterization. Taken together, the fundamental knowledge obtained through my research will contribute to the mechanistic understanding of plant responses to temperature fluctuations that are likely to accompany climate change, knowledge that is critical for anticipating impacts on agricultural and natural ecosystems.