AUTHOR=Gurkok Tugba , Ozhuner Esma , Parmaksiz Iskender , Özcan Sebahattin , Turktas Mine , İpek Arif , Demirtas Ibrahim , Okay Sezer , Unver Turgay 

TITLE=Functional Characterization of 4′OMT and 7OMT Genes in BIA Biosynthesis

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00098

DOI=10.3389/fpls.2016.00098

ISSN=1664-462X

ABSTRACT=<p>Alkaloids are diverse group of secondary metabolites generally found in plants. Opium poppy (<italic>Papaver somniferum</italic> L.), the only commercial source of morphinan alkaloids, has been used as a medicinal plant since ancient times. It produces benzylisoquinoline alkaloids (BIA) including the narcotic analgesic morphine, the muscle relaxant papaverine, and the anti-cancer agent noscapine. Though BIAs play crucial roles in many biological mechanisms their steps in biosynthesis and the responsible genes remain to be revealed. In this study, expressions of <italic>3-hydroxy-N-methylcoclaurine 4</italic>′–<italic>methyltransferase</italic> (<italic>4</italic>′<italic>OMT</italic>) and <italic>reticuline 7-O-methyltransferase</italic> (<italic>7OMT</italic>) genes were subjected to manipulation to functionally characterize their roles in BIA biosynthesis. Measurements of alkaloid accumulation were performed in leaf, stem, and capsule tissues accordingly. Suppression of <italic>4</italic>′<italic>OMT</italic> expression caused reduction in the total alkaloid content in stem tissue whereas total alkaloid content was significantly induced in the capsule. Silencing of the <italic>7OMT</italic> gene also caused repression in total alkaloid content in the stem. On the other hand, over-expression of <italic>4</italic>′<italic>OMT</italic> and <italic>7OMT</italic> resulted in higher morphine accumulation in the stem but suppressed amount in the capsule. Moreover, differential expression in several BIA synthesis genes (<italic>CNMT, TYDC, 6OMT, SAT, COR, 4</italic>′<italic>OMT</italic>, and <italic>7OMT</italic>) were observed upon manipulation of <italic>4</italic>′<italic>OMT</italic> and <italic>7OMT</italic> expression. Upon silencing and overexpression applications, tissue specific effects of these genes were identified. Manipulation of <italic>4</italic>′<italic>OMT</italic> and <italic>7OMT</italic> genes caused differentiated accumulation of BIAs including morphine and noscapine in capsule and stem tissues.</p>