AUTHOR=Chen Ruibing , Li Qing , Tan Hexin , Chen Junfeng , Xiao Ying , Ma Ruifang , Gao Shouhong , Zerbe Philipp , Chen Wansheng , Zhang Lei 

TITLE=Gene-to-metabolite network for biosynthesis of lignans in MeJA-elicited Isatis indigotica hairy root cultures

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00952

DOI=10.3389/fpls.2015.00952

ISSN=1664-462X

ABSTRACT=<p>Root and leaf tissue of <italic>Isatis indigotica</italic> shows notable anti-viral efficacy, and are widely used as “Banlangen” and “Daqingye” in traditional Chinese medicine. The plants' pharmacological activity is attributed to phenylpropanoids, especially a group of lignan metabolites. However, the biosynthesis of lignans in <italic>I. indigotica</italic> remains opaque. This study describes the discovery and analysis of biosynthetic genes and AP2/ERF-type transcription factors involved in lignan biosynthesis in <italic>I. indigotica</italic>. MeJA treatment revealed differential expression of three genes involved in phenylpropanoid backbone biosynthesis (<italic>IiPAL, IiC4H, Ii4CL</italic>), five genes involved in lignan biosynthesis (<italic>IiCAD, IiC3H, IiCCR, IiDIR</italic>, and <italic>IiPLR</italic>), and 112 putative AP2/ERF transcription factors. In addition, four intermediates of lariciresinol biosynthesis were found to be induced. Based on these results, a canonical correlation analysis using Pearson's correlation coefficient was performed to construct gene-to-metabolite networks and identify putative key genes and rate-limiting reactions in lignan biosynthesis. Over-expression of <italic>IiC3H</italic>, identified as a key pathway gene, was used for metabolic engineering of <italic>I. indigotica</italic> hairy roots, and resulted in an increase in lariciresinol production. These findings illustrate the utility of canonical correlation analysis for the discovery and metabolic engineering of key metabolic genes in plants.</p>