The ascorbate biosynthesis pathway in plants is known, but there is a way to go with understanding control and functions

Smirnoff, N and Wheeler, G 2024 The ascorbate biosynthesis pathway in plants is known, but there is a way to go with understanding control and functions. Journal of Experimental Botany, erad505. 27, pp. https://doi.org/10.1093/jxb/erad505

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Abstract/Summary

Ascorbate (vitamin C) is one of the most abundant primary metabolites in plants. Its complex chemistry enables it to function as an antioxidant, as a free radical scavenger, and as a reductant for iron and copper. Ascorbate biosynthesis occurs via the mannose/L-galactose pathway in green plants, and the evidence for this pathway being the major route is reviewed. Ascorbate accumulation is leaves is responsive to light, reflecting various roles in photoprotection. GDP-L-galactose phosphorylase (GGP) is the first dedicated step in the pathway and is important in controlling ascorbate synthesis. Its expression is determined by a combination of transcription and translation. Translation is controlled by an upstream open reading frame (uORF) which blocks translation of the main GGP-coding sequence, possibly in an ascorbate-dependent manner. GGP associates with a PAS-LOV protein, inhibiting its activity, and dissociation is induced by blue light. While low ascorbate mutants are susceptible to oxidative stress, they grow nearly normally. In contrast, mutants lacking ascorbate do not grow unless rescued by supplementation. Further research should investigate possible basal functions of ascorbate in severely deficient plants involving prevention of iron overoxidation in 2-oxoglutarate-dependent dioxygenases and iron mobilization during seed development and germination

Item Type:	Publication - Article
Additional Keywords:	GDP-mannose, iron, light response, oxidative stress, 2-oxoglutarate-dependent dioxygenases, upstream open reading frame, vitamin C, vtc mutants
Subjects:	Botany Chemistry
Divisions:	Marine Biological Association of the UK > Marine Microbiome
Depositing User:	Ms Kristina Hixon
Date made live:	22 Mar 2024 09:36
Last Modified:	22 Mar 2024 09:36
URI:	https://plymsea.ac.uk/id/eprint/10145

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