Carotenoid Biosynthesis and Metabolism in Plants

Carotenoids constitute a diverse group of isoprenoid pigments synthesised de novo in plastids of all photosynthetic organisms. These tetraterpenoid molecules serve essential roles in light harvesting and photoprotection, quenching excess energy and reactive oxygen species. Beyond these functions, carotenoids act as precursors for phytohormones such as abscisic acid and strigolactones, and yield volatile apocarotenoids that influence aroma, flavour and signalling to pollinators and symbionts. The biosynthetic pathway initiates with the condensation of two geranylgeranyl diphosphate molecules to form phytoene, catalysed by phytoene synthase. This is followed by desaturation and isomerisation steps converting phytoene into all-trans-lycopene. Cyclisation reactions then generate β- and α-carotene, which are further modified by hydroxylases and epoxidases to produce xanthophylls such as lutein, zeaxanthin and violaxanthin. Carotenoid turnover is mediated by carotenoid cleavage dioxygenases that yield apocarotenoids including signalling molecules, pigments and aroma compounds. Metabolic flux is controlled at transcriptional, post-translational and sequestration levels, often involving chromoplast biogenesis, enzyme complex formation and membrane lipid or crystal deposition. Recent advances in genomics, transcriptomics and structural biology have illuminated the regulatory networks coordinating synthesis, storage and degradation, underpinning both fundamental plant physiology and the biofortification of crop species.

Research from Nature Portfolio

A recent population-genomics study on carrot has defined the molecular basis of high-carotene orange root phenotypes. By resequencing hundreds of accessions against an improved reference genome, researchers pinpointed three recessive loci that regulate α- and β-carotene accumulation through coordinated control of biosynthetic enzymes, chloroplast development and circadian pathways. These findings reveal how historical selection during domestication and improvement harnessed both structural and regulatory genes to enhance carotenoid content and nutritional value in a globally important crop.

Carotenoid Biosynthesis and Metabolism in Plants publication trend

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

Technical terms

Geranylgeranyl diphosphate (GGPP): A five-carbon isoprenoid intermediate that serves as the starting substrate for carotenoid synthesis.

Phytoene synthase (PSY): The enzyme catalysing the first committed step of the pathway, condensing two GGPP molecules into phytoene.

Carotenoid cleavage dioxygenase (CCD): A family of enzymes that cleave carotenoids at specific double bonds to generate apocarotenoids, including hormones and volatile compounds.

References

1. Installing the neurospora carotenoid pathway in plants enables cytosolic formation of provitamin A and its sequestration in lipid droplets. Molecular Plant (2023).
2. Population genomics identifies genetic signatures of carrot domestication and improvement and uncovers the origin of high-carotenoid orange carrots. Nature Plants (2023).
3. Plant carotenoids: recent advances and future perspectives. Molecular Horticulture (2022).