AUTHOR=He Si-Mei , Liang Yan-Li , Cong Kun , Chen Geng , Zhao Xiu , Zhao Qi-Ming , Zhang Jia-Jin , Wang Xiao , Dong Yang , Yang Jian-Li , Zhang Guang-Hui , Qian Zhi-Long , Fan Wei , Yang Sheng-Chao 

TITLE=Identification and Characterization of Genes Involved in Benzylisoquinoline Alkaloid Biosynthesis in Coptis Species

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00731

DOI=10.3389/fpls.2018.00731

ISSN=1664-462X

ABSTRACT=<p>The dried rhizomes of <italic>Coptis chinensis</italic> have been extensively used in heat clearing, dampness drying, fire draining, and detoxification by virtue of their major bioactive components, benzylisoquinoline alkaloids (BIAs). However, <italic>C. teeta</italic> and <italic>C. chinensis</italic> are occasionally interchanged, and current understanding of the molecular basis of BIA biosynthesis in these two species is limited. Here, berberine, coptisine, jatrorrhizine, and palmatine were detected in two species, and showed the highest contents in the roots, while epiberberine were found only in <italic>C. chinensis</italic>. Comprehensive transcriptome analysis of the roots and leaves of <italic>C. teeta</italic> and <italic>C</italic>. <italic>chinensis</italic>, respectively, identified 53 and 52 unigenes encoding enzymes potentially involved in BIA biosynthesis. By integrating probable biosynthetic pathways for BIAs, the jatrorrhizine biosynthesis ill-informed previously was further characterized. Two genes encoding norcoclaurine/norlaudanosoline 6-<italic>O</italic>-methyltransferases (<italic>Cc6OMT1</italic> and <italic>Cc6OMT2</italic>) and one gene encoding norcoclaurine-7OMT (<italic>Ct7OMT</italic>) catalyzed enzymatically <italic>O-</italic>methylate (<italic>S</italic>)-norcoclaurine at C6 that yield (<italic>S</italic>)-coclaurine, along with a smaller amount of <italic>O</italic>-methylation occurred at C7, thereby forming its isomer (isococlaurine). In addition, scoulerine 9-OMT (CtSOMT) was determined to show strict substrate specificity, targeting (<italic>S</italic>)-scoulerine to yield (<italic>S</italic>)-tetrahydrocolumbamine. Taken together, the integration of the transcriptome and enzyme activity assays further provides new insight into molecular mechanisms underlying BIA biosynthesis in plants and identifies candidate genes for the study of synthetic biology in microorganisms.</p>