Abstract
Ascorbic acid (AA) is a major redox buffer in plant cells. The role of ethylene in the redox signaling pathways that influence photosynthesis and growth was explored in two independent AA deficient Arabidopsis thaliana mutants (vtc2-1 and vtc2-4). Both mutants, which are defective in the AA biosynthesis gene GDP-L-galactose phosphorylase, produce higher amounts of ethylene than wt plants. In contrast to the wt, the inhibition of ethylene signaling increased leaf conductance, photosynthesis and dry weight in both vtc2 mutant lines. The AA-deficient mutants showed altered expression of genes encoding proteins involved in the synthesis/responses to phytohormones that control growth, particularly auxin, cytokinins, abscisic acid, brassinosterioids, ethylene and salicylic acid. These results demonstrate that AA deficiency modifies hormone signaling in plants, redox-ethylene interactions providing a regulatory node controlling shoot biomass accumulation.
Highlights
Ascorbic acid (AA) participates of many physiological processes in plants
We investigated how low redox buffering capacity in two independent vtc2 mutant lines that have very low AA contents interacts with ethylene signaling to regulate photosynthesis and rosette development
The synthesis of ethylene is an autocatalytic process occurring at the last stages of plant growth in order to accelerate plant senescence [15]
Summary
Ascorbic acid (AA) participates of many physiological processes in plants. It has a central function in plant antioxidant defenses, in the elongation and cell division and in the optimization of photosynthesis [1]. Since Homo sapiens like other primates has lost the capacity to synthesize AA, the accumulation of this antioxidant to high levels in edible plant organs is of paramount interest to human nutrition [3]. The reduced activity of VTC5 leads to a small contribution to this pathway and vtc plants have very low concentration of AA [6]. Mutants with low activity of VTC2/VTC5 are very useful to study the specific role of AA in plant biology
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