Ascorbate Biosynthesis and Oxidative Stress Responses in Plants

Ascorbate (vitamin C) is a central antioxidant and enzymatic cofactor in plants, integral to redox homeostasis and defence against environmental stress. Plants synthesise ascorbate predominantly via the Smirnoff–Wheeler pathway, converting sugars into L-galactono-1,4-lactone before its oxidation to ascorbate. This molecule neutralises reactive oxygen species generated during photosynthesis and in response to abiotic stress, while also participating in hormone metabolism, cell-wall biosynthesis and epigenetic regulation. Efficient recycling through the ascorbate–glutathione cycle maintains its pool, enabling rapid turnover under fluctuating redox conditions. Integration of biosynthesis, transport and recycling underpins plant resilience to drought, high light, salinity and temperature extremes, with implications for crop improvement and nutritional quality.

Research from Nature Portfolio

Recent studies have elucidated the final enzymatic steps and transport mechanisms that underpin ascorbate abundance and function. Structural and evolutionary analysis of aldonolactone oxidoreductases has revealed a conserved active-site architecture across eukaryotes, demonstrating how minimal sequence changes modulate oxidase versus dehydrogenase activity and substrate stereoselectivity. Reconstruction of ancestral enzymes highlights adaptive shifts that balance vitamin C synthesis with cellular redox demands. In parallel, identification of a chloroplast-envelope transporter has clarified how mitochondrial synthesis and plastidic requirement are coordinated. Functional characterisation of this protein shows membrane-potential and ionic-driven ascorbate import into chloroplasts, essential for photoprotection and prevention of photoinhibition under intense light stress.

Ascorbate Biosynthesis and Oxidative Stress Responses in Plants publication trend

The graph below shows the total number of articles in ascorbate biosynthesis and oxidative stress responses in plants across all publications each year (not limited to Nature Index journals).

Technical terms

Ascorbate: The reduced form of vitamin C in plants, acting as a primary water-soluble antioxidant and enzyme cofactor.

Reactive oxygen species (ROS): Highly reactive molecules such as superoxide and hydrogen peroxide, generated during metabolism and environmental stress.

Smirnoff–Wheeler pathway: The principal biosynthetic route in plants converting GDP-D-mannose to L-galactono-1,4-lactone for ascorbate production.

Ascorbate–glutathione cycle: A metabolic network comprising ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase that regenerates ascorbate and detoxifies ROS.

Aldonolactone oxidoreductases: Flavin-dependent enzymes catalysing the terminal oxidation of L-galactono-1,4-lactone to ascorbate, with variations in substrate specificity and electron acceptors.

References

1. Structure, mechanism, and evolution of the last step in vitamin C biosynthesis. Nature Communications (2024).
2. AtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis. Nature Communications (2015).
3. The effects of exogenously applied antioxidants on plant growth and resilience. Phytochemistry Reviews (2023).
4. Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress. Antioxidants (2019).
5. Exogenous Ascorbic Acid Induced Chilling Tolerance in Tomato Plants Through Modulating Metabolism, Osmolytes, Antioxidants, and Transcriptional Regulation of Catalase and Heat Shock Proteins. Plants (2020).