O-Methyltransferases Involved in the Biosynthesis of Volatile Phenolic Derivatives in Rose Petals.

O-Methyltransferases Involved in the Biosynthesis of Volatile Phenolic Derivatives in Rose Petals.

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O -Methyltransferases Involved in the Biosynthesis of Volatile Phenolic Derivatives in Rose Petals 1 Noa Lavid, Jihong Wang, Moshe Shalit, Inna Guterman, Einat Bar, Till Beuerle, Naama Menda, Sharoni Shafir, Dani Zamir, Zach Adam, Alexander Vainstein, David Weiss, Eran Pichersky, and Efraim Lewinsohn* Vegetable Crops, Newe Ya’ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel (N.L., M.S., E.B., E.L.); Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109–1048 (J.W., T.B., E.P.); and Faculty of Agricultural, Food, and Environmental Quality Science, The Hebrew University of Jerusalem, Rehovot, Israel (I.G., N.M., S.S., D.Z., Z.A., A.V., D.W.) Rose ( Rosa hybrida ) flowers produce and emit a diverse array of volatiles, characteristic to their unique scent. One of the most prominent compounds in the floral volatiles of many rose varieties is the methoxylated phenolic derivative 3,5- dimethoxytoluene (orcinol dimethyl ether). Cell-free extracts derived from developing rose petals displayed O -methyltransferase (OMT) activities toward several phenolic substrates, including 3,5-dihydroxytoluene (orcinol), 3-methoxy,5-hydroxytoluene (orcinol monomethyl ether), 1-methoxy, 2-hydroxy benezene (guaiacol), and eugenol. The activity was most prominent in rose cv Golden Gate, a variety that produces relatively high levels of orcinol dimethyl ether, as compared with rose cv Fragrant Cloud, an otherwise scented variety but which emits almost no orcinol dimethyl ether. Using a functional genomics approach, we have identified and characterized two closely related cDNAs from a rose petal library that each encode a protein capable of methylating the penultimate and immediate precursors (orcinol and orcinol monomethyl ether, respectively) to give the final orcinol dimethyl ether product. The enzymes, designated orcinol OMTs (OOMT1 and OOMT2), are closely related to other plant methyltransferases whose substrates range from isoflavones to phenylpropenes. The peak in the levels of OOMT1 and OOMT2 transcripts in the flowers coincides with peak OMT activity and with the emission of orcinol dimethyl ether. Roses ( Rosa hybrida ) are cultivated in nearly all of the countries of the world. They are grown as garden plants, as cut flowers, and as a source of natural fragrances and flavorings (Weiss, 1997). The genus Rosa includes 200 species and more than 18,000 cul- tivars (Haring, 1986; Gudin, 2000). The damask rose ( Rosa damascena ) is the most important species used to produce rose water, attar of rose, and essential oils in the perfumery industry. Modern cut-rose varieties are not notable for their scent (Zuker et al., 1998). It could be that because selection in breeding for the cut flower market is geared toward enhancing vase life and modifying color and form, the loss of fragrance may be coincidental (Barletta, 1995). More than 400 volatile compounds have been iden-
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O-Methyltransferases Involved in the Biosynthesis of Volatile Phenolic Derivatives in Rose Petals.

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