O-methyltransferases involved in the biosynthesis of volatile phenolic derivatives in rose petals.
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.
Lavid
Noa
N
Vegetable Crops, Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, 30095, Israel.
Wang
Jihong
J
Shalit
Moshe
M
Guterman
Inna
I
Bar
Einat
E
Beuerle
Till
T
Menda
Naama
N
Shafir
Sharoni
S
Zamir
Dani
D
Adam
Zach
Z
Vainstein
Alexander
A
Weiss
David
D
Pichersky
Eran
E
Lewinsohn
Efraim
E
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010636:Phenols / Q000378:metabolism*; D010696:Phloroglucinol / Q000378:metabolism; D010802:Phylogeny; D010936:Plant Extracts / Q000378:metabolism; D018547:Plant Stems / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012118:Resorcinols / Q000378:metabolism; D027826:Rosa / Q000201:enzymology* / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D010636:Phenols; D010936:Plant Extracts; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012118:Resorcinols; C005282:orcinol; D010696:Phloroglucinol; D008780:Methyltransferases