Articles
Genetic regulation of flavonoids biosynthesis in citrus
Article number
1448_48
Pages
375 – 386
Language
English
Abstract
Flavonoids are integral to numerous biological processes and responses to both biotic and abiotic factors in plants.
They are also prevalent in human diets, offering antioxidant effects and other bioactivities that are beneficial to human health.
Citrus is rich in various flavonoids, which are differentially distributed in most parts of the plant.
In particular, fruits are an important diet source of flavonoids.
The flavonoids biosynthesis pathway is a branch of the phenylpropanoid biosynthesis pathway. 4-Coumarate: CoA ligase (4CL) is the terminal enzyme in the phenylpropanoid biosynthesis pathway.
It directs carbon flow toward diverse subbranches, including the biosynthesis of flavonoids and lignin.
In citrus, there are at least three members of the 4CL gene family.
Through a comprehensive analysis of the gene expression and relationship with flavonoid production, this study suggested that in citrus, 4CL1 (Ciclev10019532m) is a key gene in flavonoid biosynthesis.
The other two members of the 4CL family are involved in lignin biosynthesis.
Chalcone synthase (CHS) is the initial enzyme in flavonoid biosynthesis.
The CHS gene family comprises multiple members, with 10 identified in citrus.
The CHS1, CHS2, and CHS3 are major active genes of the CHS family.
They exhibit distinct expression patterns in different tissues and developmental stages, with different levels of effects on flavonoids biosynthesis.
Our study also revealed that a citrus R2R3-MYB family gene, CitMYB21, could be a key regulatory gene differentiating the flavonoids biosynthesis in different tissues.
The expression of CitMYB21 is highly tissue-specific, with high expression in roots and low expression in stems, leaves and peels, which is significantly negatively correlated with the flavonoid contents in those tissues.
Moreover, the expression of CitMYB21 is inversely correlated to that of CHS2, suggesting that CitMYB21 may suppress the expression of CHS2 to affect the flavonoids biosynthesis.
Silence of CitMYB21 with VIGS also resulted in downregulated gene expression, but an increased content of flavonoids in sweet orange leaves.
Transient overexpression of CitMYB21 led to an upregulated gene expression, but a decreased content of flavonoids in the peels of sweet orange.
Our findings provide molecular evidence for tissue-specific biosynthesis of flavonoids, and lay a foundation for studying the molecular mechanism of regulating flavonoids biosynthesis in citrus.
They are also prevalent in human diets, offering antioxidant effects and other bioactivities that are beneficial to human health.
Citrus is rich in various flavonoids, which are differentially distributed in most parts of the plant.
In particular, fruits are an important diet source of flavonoids.
The flavonoids biosynthesis pathway is a branch of the phenylpropanoid biosynthesis pathway. 4-Coumarate: CoA ligase (4CL) is the terminal enzyme in the phenylpropanoid biosynthesis pathway.
It directs carbon flow toward diverse subbranches, including the biosynthesis of flavonoids and lignin.
In citrus, there are at least three members of the 4CL gene family.
Through a comprehensive analysis of the gene expression and relationship with flavonoid production, this study suggested that in citrus, 4CL1 (Ciclev10019532m) is a key gene in flavonoid biosynthesis.
The other two members of the 4CL family are involved in lignin biosynthesis.
Chalcone synthase (CHS) is the initial enzyme in flavonoid biosynthesis.
The CHS gene family comprises multiple members, with 10 identified in citrus.
The CHS1, CHS2, and CHS3 are major active genes of the CHS family.
They exhibit distinct expression patterns in different tissues and developmental stages, with different levels of effects on flavonoids biosynthesis.
Our study also revealed that a citrus R2R3-MYB family gene, CitMYB21, could be a key regulatory gene differentiating the flavonoids biosynthesis in different tissues.
The expression of CitMYB21 is highly tissue-specific, with high expression in roots and low expression in stems, leaves and peels, which is significantly negatively correlated with the flavonoid contents in those tissues.
Moreover, the expression of CitMYB21 is inversely correlated to that of CHS2, suggesting that CitMYB21 may suppress the expression of CHS2 to affect the flavonoids biosynthesis.
Silence of CitMYB21 with VIGS also resulted in downregulated gene expression, but an increased content of flavonoids in sweet orange leaves.
Transient overexpression of CitMYB21 led to an upregulated gene expression, but a decreased content of flavonoids in the peels of sweet orange.
Our findings provide molecular evidence for tissue-specific biosynthesis of flavonoids, and lay a foundation for studying the molecular mechanism of regulating flavonoids biosynthesis in citrus.
Publication
Authors
Wanxia Shen, Zimao Ye, Mengyu Liu, Xiaochun Zhao
Keywords
citrus, flavonoids, 4CL, CHS, MYB21
Groups involved
Online Articles (103)