AUTHOR=Chen Changsong , Wei Kang , Wang Liyuan , Ruan Li , Li Hailin , Zhou Xiaogui , Lin Zhenghe , Shan Ruiyang , Cheng Hao 

TITLE=Expression of Key Structural Genes of the Phenylpropanoid Pathway Associated with Catechin Epimerization in Tea Cultivars

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00702

DOI=10.3389/fpls.2017.00702

ISSN=1664-462X

ABSTRACT=<p>Catechin epimerization is an important factor affecting tea catechin compositions and thereby tea quality. However, a lack of tea germplasms with high non-epicatechins limits relative research. Here, a tea cultivar Y510 with high non-epicatechins was firstly reported and used for catechin and RNA sequencing (RNA-Seq) analysis. Results showed that the (-)-gallocatechin gallate and (+)-catechin (C) contents in Y510 were at least 136 and 6 times higher than those in Fudingdabaicha and 0306I, but the epicatechins (-)-epigallocatechin and (-)-epicatechin (EC) were significantly lower. Eleven unigenes potentially involved in catechin epimerization were identified by RNA-Seq analysis. Based on a combination of catechin and gene expression analysis, it was hypothesized that two anthocyanidin reductase genes (<italic>CsANR1</italic>, <italic>CsANR2</italic>) and an anthocyanidin synthase gene (<italic>CsANS</italic>) are the key genes affecting catechin epimerization in tea. Non-epicatechin formations were hypothesized to be mainly influenced by the expression ratio of <italic>CsANR2</italic> to <italic>CsANR1</italic> and the expression of <italic>CsANS</italic>. Overexpression of <italic>CsANS</italic> in an Arabidopsis mutant <italic>tds4-2</italic> led to a significant increase of EC accumulation in seeds, revealing <italic>CsANS</italic> is important for catechin epimerization. These results shed new light on breeding tea cultivars with special catechin compositions.</p>