Deciphering acclimation strategies to combined abiotic stresses in Arabidopsis thaliana

Abstract

Plants grown in natural or agricultural environments are frequently exposed to abiotic stress and their combinations. Research on plant stress resilience usually focusses on single environmental stressors mostly imposed at a lethal severity. However, plant responses to sublethal abiotic stress combinations are often distinct from either stress applied in isolation. Investigating acclimation strategies mediating relevant stress combinations is therefore essential. In this thesis we studied the morphological, physiological, and molecular mechanisms underlying the acclimation responses of the model plant Arabidopsis thaliana to combined or sequential abiotic stresses. We focused on i) combined high temperature and drought and ii) flooding followed by drought, both of which are relevant in natural and agricultural settings and have already - and will further - increase in frequency due to climate change. We uncovered the unique phenotypic and molecular signatures of plant responses to combinatorial stresses in comparison with the corresponding single stresses and identified key molecular processes and putative candidate regulators mediating the acclimation responses. These putative regulators were further validated for their functions in plant growth, development, and physiology under combined or sequential stresses. Additionally, we described a novel role for the transcription factor GOLDEN2-LIKE 2 in thermomorphogenesis. The results presented in this thesis provide a comprehensive understanding of plant acclimation mechanisms to complex environmental challenges, which can potentially contribute to the development of climate change-resilient field crops.