Plant carotenoids: recent advances and future perspectives

Abstract

Carotenoids are isoprenoid metabolites synthesized de novo in all photosynthetic organisms. Carotenoids are essential for plants with diverse functions in photosynthesis, photoprotection, pigmentation, phytohormone synthesis, and signaling. They are also critically important for humans as precursors of vitamin A synthesis and as dietary antioxidants. The vital roles of carotenoids to plants and humans have prompted significant progress toward our understanding of carotenoid metabolism and regulation. New regulators and novel roles of carotenoid metabolites are continuously revealed. This review focuses on current status of carotenoid metabolism and highlights recent advances in comprehension of the intrinsic and multi-dimensional regulation of carotenoid accumulation. We also discuss the functional evolution of carotenoids, the agricultural and horticultural application, and some key areas for future research.

Phytoene Synthase: The Key Rate-Limiting Enzyme of Carotenoid Biosynthesis in Plants

“…Phytoene synthase is a major rate-limiting enzyme in carotenoid biosynthesis and its activity effectively determines the metabolic flux to carotenoids. It is therefore not surprising that multiple mechanisms at various levels are utilized to regulate the spatiotemporal expression and activity of PSY in plants ( Figure 1 ; Ruiz-Sola and Rodríguez-Concepción, 2012 ; Sun and Li, 2020 ; Sun et al, 2022 ). Transcriptional regulation is central to the control of PSY activity for carotenogenesis.…”

“…Perturbation of carotenoid biosynthesis has also been observed to activate PSY2 activity in tomato and pepper fruits when PSY1 is not functional ( Jang et al, 2020 ; Gupta et al, 2022 ; Karniel et al, 2022 ). Epigenetic regulation such as histone modification as well as DNA methylation and demethylation modifies SlPSY1 mRNA levels during tomato fruit ripening ( Liang et al, 2017 ; Liu et al, 2020 ; Sun et al, 2022 ).…”

“…Additionally, PSY expression and enzymatic activity are also regulated at post-transcriptional and post-translational levels ( Figure 1 ). Mechanisms comprising of alternative splicing, protein-protein interactions, and multi-enzyme complexes constitute efficient, rapid, and dynamic regulation to fine-tune PSY activity and carotenogenesis ( Ruiz-Sola and Rodríguez-Concepción, 2012 ; Nisar et al, 2015 ; Sun and Li, 2020 ; Sun et al, 2022 ).…”

“…Carotenoids are also important to human nutrition and health as dietary precursors of vitamin A and antioxidants in preventing vitamin A deficiency and reducing the risk of various chronic diseases ( Eggersdorfer and Wyss, 2018 ). The critical roles of carotenoids to plants and humans have provoked significant efforts to understand carotenoid metabolism in plants and to generate carotenoid enriched crops ( Nisar et al, 2015 ; Giuliano, 2017 ; Rodriguez-Concepcion et al, 2018 ; Zheng et al, 2020 ; Sun et al, 2022 ).…”

“…β-carotene is the most potent provitamin A carotenoid. Abbreviations for metabolites and pathway enzymes can be found in Sun et al (2022) . Protein structure: A high confident structure prediction of Arabidopsis PSY protein ( https://www.alphafold.ebi.ac.uk/entry/P37271 ) with conserved motifs of enzymatic active site indicated.…”