Evolutionary and functional characterization of leucoanthocyanidin reductases from Camellia sinensis
 
作者: 文章来源: 点击数: 更新日期:2017-09-11

Title


Evolutionary and functional characterization of leucoanthocyanidin reductases from Camellia sinensis


Authors


Peiqiang Wang, Lingjie Zhang, Xiaolan Jiang, Xinlong Dai, Lijuan Xu, Tong Li, Dawei Xing, Yanzhi Li, Mingzhuo Li, Liping Gao*, Tao Xia*


Journal


Planta  DOI 10.1007/s00425-017-2771-z


Abstract


Tea is rich in polyphenolic compounds, and catechins are the major polyphenols in tea. The biosynthesis of polyphenols is closely related to the expression of the leucoanthocyanidin reductase (
LAR) and anthocyanidin reductase (ANR) genes. In this paper, an evolutionary analysis and functional characterization of three CsLARs were performed. The phylogenetic tree showed that plant LARs could be grouped into three, including gymnosperms, monocotyledons and dicotyledons (clusters I and II). The eighth amino acid residue in a conserved LAR-specific motif is changeable due to a transversion (G T) and transition (G C) that occur in the corresponding codon. Therefore, plant LARs can be classified as G-type, A-type and S-type LARs due to this variable amino acid residue. Although (2R, 3S)-trans-flavan-3-ols were the products of recombinant CsLARs proteins expressed in Escherichia coli, both (2R, 3S)-trans and (2R, 3R)-cis-flavan-3-ols were detected in tobacco overexpressing CsLARs. However, a butanol/HCl hydrolysis assay indicated that overexpression of the CsLARs caused a decrease in polymerized catechins. A hybridization experiment with CsLARc + AtPAP1 also showed that no polymers other than epicatechin, catechin and glycoside were detected, although the accumulation of anthocyanins was markedly decreased.CsMYB5b promoted the biosynthesis of both flavan-3-ols and proanthocyanidins (PAs). Therefore, LARs promoted the biosynthesis of catechin monomers and inhibited their polymerization. The accumulation of catechin monomers and polymers was increased by up-regulating the expression of the NtLAR and NtANRs in CsMYB5b transgenic tobacco.




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  • evolutionary and functional characterization of leucoanthocyanidin reductases from camellia sinensis(王培强、高丽萍、夏涛,2017).pdf
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