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Chloroplastic ascorbate modifies plant metabolism and may act as a metabolite signal regardless of oxidative stress.

Dávid TóthRoland TengölicsFayezeh AarabiAnna KarlssonAndré Vidal-MeirelesLászló KovácsSoujanya KuntamTímea KörmöcziAlisdair Robert FernieElton Paul HudsonBalázs PappSzilvia Z Tóth
Published in: Plant physiology (2024)
Ascorbate is a major plant metabolite that plays crucial roles in various processes, from reactive oxygen scavenging to epigenetic regulation. However, to what extent and how ascorbate modulates metabolism is largely unknown. We investigated the consequences of chloroplastic and total cellular ascorbate-deficiencies by studying chloroplastic ascorbate-transporter mutant lines lacking PHOSPHATE TRANSPORTER 4; 4 (PHT4; 4) , and the ascorbate-deficient vtc2-4 mutant of Arabidopsis (Arabidopsis thaliana). Under regular growth conditions, both ascorbate deficiencies caused minor alterations in photosynthesis, with no apparent signs of oxidative damage. In contrast, metabolomics analysis revealed global and largely overlapping alterations in the metabolome profiles of both ascorbate-deficiency mutants, suggesting that chloroplastic ascorbate modulates plant metabolism. We observed significant alterations in amino acid metabolism, particularly in arginine metabolism, activation of nucleotide salvage pathways, and changes in secondary metabolism. In addition, proteome-wide analysis of thermostability revealed that ascorbate may interact with enzymes involved in arginine metabolism, the Calvin-Benson cycle, and several photosynthetic electron transport components. Overall, our results suggest that, independently of oxidative stress, chloroplastic ascorbate modulates the activity of diverse metabolic pathways in vascular plants and may act as an internal metabolic signal.
Keyphrases
  • oxidative stress
  • amino acid
  • arabidopsis thaliana
  • mass spectrometry
  • computed tomography
  • dna damage
  • signaling pathway
  • wild type
  • ischemia reperfusion injury
  • cell wall