Regulation Mechanism of Plant Pigments Biosynthesis: Anthocyanins, Carotenoids, and Betalains

Abstract

Anthocyanins, carotenoids, and betalains are known as the three major pigments in the plant kingdom. Anthocyanins are flavonoids derived from the phenylpropanoid pathway. They undergo acylation and glycosylation in the cytoplasm to produce anthocyanin derivatives and deposits in the cytoplasm. Anthocyanin biosynthesis is regulated by the MBW (comprised by R2R3-MYB, basic helix-loop-helix (bHLH) and WD40) complex. Carotenoids are fat-soluble terpenoids whose synthetic genes also are regulated by the MBW complex. As precursors for the synthesis of hormones and nutrients, carotenoids are not only synthesized in plants, but also synthesized in some fungi and bacteria, and play an important role in photosynthesis. Betalains are special water-soluble pigments that exist only in Caryophyllaceae plants. Compared to anthocyanins and carotenoids, the synthesis and regulation mechanism of betalains is simpler, starting from tyrosine, and is only regulated by MYB (myeloblastosis). Recently, a considerable amount of novel information has been gathered on the regulation of plant pigment biosynthesis, specifically with respect to aspects. In this review, we summarize the knowledge and current gaps in our understanding with a view of highlighting opportunities for the development of pigment-rich plants.

Hydrogen sulfide-mitigated salinity stress impact in sunflower seedlings was associated with improved photosynthesis performance and osmoregulation

“…The distortion of thylakoid membranes may also lead to chlorophyll loss, as Chuartzman et al [ 69 ] reported. NaCl-induced decline in the carotenoid content could be attributed to the inhibition of carotenoid biosynthesis enzymes’ activity and the downregulation of their transcription levels [ 70 ]. Additionally, the decreased value of photosynthetic performance (PI abs ) and the maximal photochemical efficiency of PSII (F v /F m ) in salinity-stressed sunflower leaves are indicative of the photoinhibition caused by NaCl on the donor side of the PSII [ 62 ].…”

“…Similarly, other published works reported H 2 S promotion of chlorophyll contents and photosynthetic capacity in a variety of plants [ 73 – 75 ]. In the same trend, H 2 S-triggered carotenoid concentration can be explained by the contention that H 2 S upregulated the expression levels of the carotenoid-related genes and thus their biosynthesis enzyme activities [ 70 ] as well as enhancing osmoregulators under stress [ 34 ]. It is noteworthy that Zhao et al [ 70 ] showed the carotenoid accumulation increase was associated with improved salinity tolerance in carrots as the carotenoids are essential components of the photosynthetic antenna and reaction center complexes, as precursors in signaling pathways, responsible for antioxidant defense, and other protective roles that help plants cope with abiotic stress.…”

Cloning and functional identification of anthocyanin synthesis-regulating transcription factor AaMYB4 in Aeonium arboreum ‘Halloween’

“…Anthocyanins, water-soluble secondary avonoid metabolites, are branched chain end products of avonoid metabolism. Anthocyanins, typically stored in vesicles after synthesis, red, blue, or purple hues to the leaves, owers, and fruits of plants, enhancing their aesthetic and commercial appeal, particularly in ornamental varieties (Mol et al, 1998;Zhao and Tao, 2015;Zhao et al, 2022). Anthocyanins have the ability to attract pollinating insects and help plants withstand Ultraviolet radiation, cold temperatures, and pathogenic attacks (Oliveira et al, 2020;Alappat and Alappat, 2020;Li et al, 2023).…”

“…The in uence of MYB transcription factors (TFs) on anthocyanin synthesis encompasses both facilitative and inhibitory roles (Yan et al, 2021;Li et al, 2022). Speci cally, proteins within the S6 subgroup of the R2R3-MYB family, such as AtPAP1 (Chhon et al, 2020) and MdMYB10 (Espley et al, 2007) synthesis by inhibiting the formation of the complex responsible for anthocyanin synthesis via interacting with the bHLH protein in the MBW complex (Zhang et al, 2020;Zhao et al, 2022;Xie et al, 2022). In contrast, the mechanism of R2R3-type MYBs inhibition is not uniform; some are inhibited by blocking complex formation through interaction with bHLH proteins (Zhang et al, 2023;Hu et al, 2024), while others are inhibited by inhibiting their expression through direct binding to the promoter regions of anthocyanin synthesis-related enzyme genes (Xu et al, 2017).…”

Transcriptomic and metabolomic analysis of autumn leaf color change in Fraxinus angustifolia

“…Anthocyanins are produced by flavonoid compounds through the shikimic acid synthesis pathway, synthesized in the cytoplasm, and eventually stored in plant cell vacuoles ( Mishio, Takeda & Iwashina, 2015 ). This synthetic pathway is an important branch of the plant flavonoid biosynthesis pathway, and it is also one of the most important pathways for the synthesis of plant secondary metabolites ( Zhao et al, 2022 ). The precursors of anthocyanin synthesis are malonic acid monophthalide-CoA and 4-hydroxybenzoic acid-CoA, and the final product anthocyanin is produced by a series of key enzymes, such as chalcone synthase (CHS), chaleone isomerase (CHI), dihydroflavonol reductase (DFR), and glycosyltransferase (GT) ( Tanaka, Sasaki & Ohmiya, 2008 ).…”