Carotenoid metabolism: New insights and synthetic approaches

Abstract

Carotenoids are well-known isoprenoid pigments naturally produced by plants, algae, photosynthetic bacteria as well as by several heterotrophic microorganisms. In plants, they are synthesized in plastids where they play essential roles in light-harvesting and in protecting the photosynthetic apparatus from reactive oxygen species (ROS). Carotenoids are also precursors of bioactive metabolites called apocarotenoids, including vitamin A and the phytohormones abscisic acid (ABA) and strigolactones (SLs). Genetic engineering of carotenogenesis made possible the enhancement of the nutritional value of many crops. New metabolic engineering approaches have recently been developed to modulate carotenoid content, including the employment of CRISPR technologies for single-base editing and the integration of exogenous genes into specific “safe harbors” in the genome. In addition, recent studies revealed the option of synthetic conversion of leaf chloroplasts into chromoplasts, thus increasing carotenoid storage capacity and boosting the nutritional value of green plant tissues. Moreover, transient gene expression through viral vectors allowed the accumulation of carotenoids outside the plastid. Furthermore, the utilization of engineered microorganisms allowed efficient mass production of carotenoids, making it convenient for industrial practices. Interestingly, manipulation of carotenoid biosynthesis can also influence plant architecture, and positively impact growth and yield, making it an important target for crop improvements beyond biofortification. Here, we briefly describe carotenoid biosynthesis and highlight the latest advances and discoveries related to synthetic carotenoid metabolism in plants and microorganisms.

The Impact of 2-Ketones Released from Solid Lipid Nanoparticles on Growth Modulation and Antioxidant System of Lactuca sativa

“…In this study, chlorophyll content only was increased in seedlings of L. sativa exposed to 500 µL L −1 of 2-nonanone encapsulated into SLNs and decreased in plants exposed to high concentrations of 2-tridecanone, suggesting a possible stress induced by it. Furthermore, carotenoids are isoprenoid pigments produced by plants with an important role in protecting the photosynthetic system from ROS and light harvesting as auxiliary pigment [40]. Curiously, the concentration of carotenoids is maintained or strongly decreased at all encapsulated doses of 2-tridecanone, which can be influenced by the formulation of SLNs.…”

Zinc-Fortified Rice: Approach to Improve Dietary Zinc Consumption and Effect on Human Health

“…To increase production of the branched-chain amino acids alanine, leucine, and isoleucine, the genes ZmALS1 and ZmALS2 have been modified to produce acetolactate synthases. 77 CRISPR-Cas9 type II was used to make changes to the phytoene synthase gene (ZmPSY1), and a stable transformation was shown in offspring. The gene in question is found in the carotenoid biosynthesis pathway Through the use of genome editing, wheat's zinc content was boosted by adding a mutation to the TaVIT2 gene.…”

“…Several regulatory processes in maize were altered via the application of genome editing, enabling the plant to be biofortified. To increase production of the branched-chain amino acids alanine, leucine, and isoleucine, the genes ZmALS1 and ZmALS2 have been modified to produce acetolactate synthases . CRISPR-Cas9 type II was used to make changes to the phytoene synthase gene (ZmPSY1), and a stable transformation was shown in offspring.…”

Editorial: Ion homeostasis in plant stress and development, volume II

“…Breeding for high carotenoid-containing plants is a strategy to provide healthier food. Carotenoid biosynthesis is dependent on phosphate availability as glyceraldehyde-3-phosphate is a precursor for its biosynthesis (Stra et al, 2023). The review of Hao et al, included in the Research Topic summarizes the knowledge on all the phosphate transporters localized in plastids, and focuses on their relation to carotenoid accumulation, summarizing the published information.…”