The Functions of Chloroplastic Ascorbate in Vascular Plants and Algae

Ascorbate (Asc) is a multifunctional metabolite essential for various cellular processes in plants and animals. The best-known property of Asc is to scavenge reactive oxygen species (ROS), in a highly regulated manner. Besides being an effective antioxidant, Asc also acts as a chaperone for 2-oxoglutarate-dependent dioxygenases that are involved in the hormone metabolism of plants and the synthesis of various secondary metabolites. Asc also essential for the epigenetic regulation of gene expression, signaling and iron transport. Thus, Asc affects plant growth, development, and stress resistance via various mechanisms. In this review, the intricate relationship between Asc and photosynthesis in plants and algae is summarized in the following major points: (i) regulation of Asc biosynthesis by light, (ii) interaction between photosynthetic and mitochondrial electron transport in relation to Asc biosynthesis, (iii) Asc acting as an alternative electron donor of photosystem II, (iv) Asc inactivating the oxygen-evolving complex, (v) the role of Asc in non-photochemical quenching, and (vi) the role of Asc in ROS management in the chloroplast. The review also discusses differences in the regulation of Asc biosynthesis and the effects of Asc on photosynthesis in algae and vascular plants.

Automated summary

Ascorbate (Asc) is a multifunctional metabolite that plays critical roles in various cellular processes. It acts as an antioxidant, regulates hormone metabolism and gene expression, and impacts photosynthesis through different mechanisms. This review provides an overview of the intricate relationship between Asc and photosynthesis, covering topics such as Asc biosynthesis regulation, interaction with electron transport, involvement in oxygen-evolving complex inactivation, role in non-photochemical quenching, and management of reactive oxygen species in the chloroplast. It also discusses the differences in Asc regulation and effects on photosynthesis in algae and vascular plants.