Research Progress in the Mechanism of Carotenoids Regulating Plant Flower Color and Fruit Color

doi:10.13560/j.cnki.biotech.bull.1985.2025-1235

Abstract

Abstract:

Carotenoids are important pigments that determine the color of floral organs and fruits in horticultural plants, directly influencing their ornamental and economic value. Unlike that in photosynthetic organs such as leaves, the accumulation of carotenoids during the development and coloration of plant flowers and fruits is often accompanied by significant changes in chlorophyll degradation and levels of secondary metabolites such as flavonoids, a process that is coordinately regulated by a multi-level regulatory network. In recent years, research on the molecular regulatory mechanisms of carotenoid-mediated flower and fruit coloration in horticultural plants has developed rapidly. This paper comprehensively summarizes research progress in this field, clarifying the core roles of key enzymes encoded by carotenoid biosynthetic genes such as PSY and the processes of chromoplast differentiation and pigment storage in the diversity of metabolic pathways. This metabolic process is coordinately regulated at the transcriptional, post-transcriptional, and epigenetic levels. At the transcriptional level, transcription factors such as MYB, bHLH, NAC, WRKY, and AP2/ERF form complex regulatory networks, precisely maintaining the dynamic balance between carotenoid biosynthesis and degradation by targeting key genes including PSY, LCYB, and CCD4. At the post-transcriptional level, multiple mechanisms, including the stabilization of PSY by ORANGE proteins, ubiquitination-mediated protein degradation, PPR protein regulation, and miRNA-mediated post-transcriptional silencing, coordinately achieve fine-tuning of metabolic flux. Epigenetically, DNA methylation and histone modifications dynamically regulate the chromatin state of key genes, thereby affecting the spatiotemporal patterns of pigment accumulation. Meanwhile, environmental factors such as light and temperature, as well as phytohormone signals like ethylene and abscisic acid, can be integrated into the above regulatory network to jointly determine flower and fruit color. This paper comprehensively reviews this multi-level coordinated and interactive regulatory system, deeply reveals the balance mechanism of carotenoid biosynthesis and degradation in flower and fruit coloration, and based on this, analyzes key issues and development pathways for color improvement and molecular breeding of horticultural products, providing theoretical support and technical guidance for the precise regulation of color traits and quality improvement of horticultural products.

Key words: carotenoids, flower color, fruit color, transcriptional regulation, epigenetic regulation, post-transcriptional regulation, metabolic pathways

LI Fu-wei, LI Hong-yu. Research Progress in the Mechanism of Carotenoids Regulating Plant Flower Color and Fruit Color[J]. Biotechnology Bulletin, 2026, 42(10): 13-26.

Figures/Tables 3

Fig. 1 Carotenoid biosynthesis pathwaysCarotenoids are synthesized in plastids, where GGPPS catalyzes the formation of the precursor GGPP, which is subsequently converted to lycopene via PSY-mediated condensation and multi-step desaturation and isomerization reactions. The pathway then diverges into two branches: in the β,β-branch, LCYB catalyzes the cyclization of lycopene to β-carotene, which is further hydroxylated and epoxidized to yield zeaxanthin, violaxanthin, neoxanthin, and abscisic acid; in the β,ε-branch, LCYE and LCYB act cooperatively to produce α-carotene, which is ultimately converted to lutein. Arrows indicate the direction of enzymatic metabolic reactions; black arrows represent direct regulation, and blue arrows represent indirect regulation. PSY: phytoene synthase; PDS: phytoene desaturase; Z-ISO: ζ-carotene isomerase; ZDS: ζ-carotene desaturase; CRTISO: carotenoid isomerase; LCYE: lycopene ε-cyclase; LCYB: lycopene β-cyclase; CYP97A/C: cytochrome P450 hydroxylase; BCH: β-carotene hydroxylase; CCS: capsanthin/capsorubin synthase; VDE: violaxanthin de-epoxidase; ZEP: zeaxanthin epoxidase; NXS: neoxanthin synthase; CCD: carotenoid cleavage dioxygenase; NCED: 9-cis-epoxycarotenoid dioxygenase. Blue represents the MEP pathway for carotenoid precursor synthesis; orange indicates the upstream core backbone pathway; green indicates the β,ε-branch; yellow indicates the β,β-branch; the right side shows derivative synthesis from the β,β-branch

Table 1 Key transcription factors affecting carotenoid biosynthesis

转录因子 Transcription factors	物种 Species	作用机制 Regulatory mechanism	对色泽的作用 Impact on color		参考文献 Reference
转录因子 Transcription factors	物种 Species	作用机制 Regulatory mechanism	正向 Positive	负向 Negative	参考文献 Reference
MYB	桂花、辣椒、猴面花、鹅掌楸、柑橘、蒺藜苜蓿	直接结合启动子激活结构基因；少数成员抑制结构基因或招募抑制复合物	促进黄、橙、红色素积累	改变色素组成，导致留绿或褪色	［43-46， 84-85］
NAC	番茄、木瓜、柑橘、辣椒	部分成员直接激活合成基因，部分成员抑制限速步骤，部分成员调控叶绿素降解间接促进着色	促进果实转红或黄色积累	抑制番茄红素合成，导致黄/橙色果	［47-55］
bHLH	番茄、木瓜、柑橘、芒果	响应光照调控代谢流分支，部分成员直接激活/抑制结构基因，部分成员通过负反馈精确控制着色	促进类胡萝卜素合成与着色	淡绿色未成熟果实和黄化成熟果实	［56-58， 61-63， 87］
AP2/ERF	番茄、柑橘、津巴多橘	受乙烯诱导，广泛激活类胡萝卜素合成途径上游前体到下游修饰环节多个关键基因	上调柑橘类胡萝卜素，增强果皮橙红色泽与着色	下调番茄总类胡萝卜素和番茄红素含量，果色偏橙	［64-67］
WRKY	番茄、柑橘	激活MEP途径；激活合成基因；协同调控叶绿素降解	上调类胡萝卜素积累，驱动果实由绿色转为黄色或红色	—	［68-70］
BBX	辣椒、番茄、芒果	光形态建成调控因子，直接激活合成基因；部分成员协同调控花青素与类胡萝卜素通路	上调类胡萝卜素/花青素，促进辣椒、番茄、芒果着色	—	［74-76］
MADS	辣椒、柑橘、榴莲	直接激活合成结构基因启动子；部分成员同时激活叶绿素降解基因，协同调控色素代谢	促进类胡萝卜素积累，调控辣椒、柑橘、榴莲果实着色	—	［77-80］

Table 1 Key transcription factors affecting carotenoid biosynthesis

转录因子 Transcription factors	物种 Species	作用机制 Regulatory mechanism	对色泽的作用 Impact on color		参考文献 Reference
转录因子 Transcription factors	物种 Species	作用机制 Regulatory mechanism	正向 Positive	负向 Negative	参考文献 Reference
MYB	桂花、辣椒、猴面花、鹅掌楸、柑橘、蒺藜苜蓿	直接结合启动子激活结构基因；少数成员抑制结构基因或招募抑制复合物	促进黄、橙、红色素积累	改变色素组成，导致留绿或褪色	［43-46， 84-85］
NAC	番茄、木瓜、柑橘、辣椒	部分成员直接激活合成基因，部分成员抑制限速步骤，部分成员调控叶绿素降解间接促进着色	促进果实转红或黄色积累	抑制番茄红素合成，导致黄/橙色果	［47-55］
bHLH	番茄、木瓜、柑橘、芒果	响应光照调控代谢流分支，部分成员直接激活/抑制结构基因，部分成员通过负反馈精确控制着色	促进类胡萝卜素合成与着色	淡绿色未成熟果实和黄化成熟果实	［56-58， 61-63， 87］
AP2/ERF	番茄、柑橘、津巴多橘	受乙烯诱导，广泛激活类胡萝卜素合成途径上游前体到下游修饰环节多个关键基因	上调柑橘类胡萝卜素，增强果皮橙红色泽与着色	下调番茄总类胡萝卜素和番茄红素含量，果色偏橙	［64-67］
WRKY	番茄、柑橘	激活MEP途径；激活合成基因；协同调控叶绿素降解	上调类胡萝卜素积累，驱动果实由绿色转为黄色或红色	—	［68-70］
BBX	辣椒、番茄、芒果	光形态建成调控因子，直接激活合成基因；部分成员协同调控花青素与类胡萝卜素通路	上调类胡萝卜素/花青素，促进辣椒、番茄、芒果着色	—	［74-76］
MADS	辣椒、柑橘、榴莲	直接激活合成结构基因启动子；部分成员同时激活叶绿素降解基因，协同调控色素代谢	促进类胡萝卜素积累，调控辣椒、柑橘、榴莲果实着色	—	［77-80］

Fig. 2 Multi-level regulatory mechanism of carotenoid metabolism on color formation in plant flowers and fruitsCarotenoid metabolism is coordinately regulated at the transcriptional, post-transcriptional, post-translational, and epigenetic levels. At the transcriptional level, transcription factors such as MYB, NAC, bHLH, WRKY, AP2/ERF, and MADS play key roles; among them, MYB, BBX, and bHLH cooperatively regulate the biosynthesis of both carotenoids and flavonoids. PSY, as the key rate-limiting enzyme, and LCYE/LCYB, as metabolic branch points, are subject to multi-level regulation. At the post-transcriptional level, the stabilizing effect of ORANGE protein on PSY and the degradation mediated by PPSR1 form a complementary bidirectional regulatory network. At the epigenetic level, dynamic changes in DNA methylation and histone acetylation co-regulate the expression of key genes involved in carotenoid metabolism. Orange arrows and fonts indicate positive regulation/promotion; blue arrows and fonts indicate negative regulation/inhibition. Light green module is the transcription factor family; the dark pink module is post-transcriptional/post-translational regulation; the yellow module is epigenetic modification; the blue module is the synergistic regulation of flavonoid and carotenoid synthesis

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