The Arabidopsis Concert of Metabolic Acclimation to High Light Stress

ABSTRACT:

In plants, exposure to high light irradiation induces various stress responses, which entail complex metabolic rearrangements. To explore these dynamics, we conducted time-course experiments spanning 2 minutes to 72 hours with Arabidopsis thaliana under high and control light. Comparative metabolomics, transcriptomics, redox proteomics, and stable isotope labelling on leaf rosettes identified a series of synchronous and successive responses that provide a deeper insight into well-orchestrated mechanisms contributing to high light acclimation. We observed transient transcriptome downregulation related to light harvesting and electron flow before the profound remodeling of the photosynthetic apparatus. Throughout the entire time course, redox homeostasis is tightly balanced between downregulation of production and enhanced transformation of NADPH accompanied by redistribution of reducing equivalents across several subcellular compartments. In both light conditions, C4 acids such as malate and fumarate are produced via anaplerosis. Their accumulation in vacuoles surpasses plastidic levels and intensifies notably under high light. In parallel, citrate synthesis from pyruvate is significantly hindered diurnally. Isotopic labeling in 2-oxoglutarate and glutamate suggests a moderate de novo synthesis of C5 acids from a vacuolar citrate reservoir during the light phase while they are largely renewed during the night. In the absence of a diurnal clockwise flow through the TCA cycle, increased oxidation of photorespiratory glycine takes over as a source of reductants to fuel mitochondrial ATP production. These findings, along with previous research, contribute to a model integrating redox balance and linking increased carbon assimilation and nitrogen metabolism, especially in the context of an incomplete TCA cycle.

INSTRUMENT(S): Liquid Chromatography MS - negative - reverse phase, Liquid Chromatography MS - positive - reverse phase

PROVIDER: MTBLS3109 | MetaboLights | 2024-08-16

REPOSITORIES: MetaboLights