title: Veratrole biosynthesis in white campion.
abstract: White campion (Silene latifolia) is a dioecious plant that emits 1,2-dimethoxybenzene (veratrole), a potent pollinator attractant to the nocturnal moth Hadena bicruris. Little is known about veratrole biosynthesis, although methylation of 2-methoxyphenol (guaiacol), another volatile emitted from white campion flowers, has been proposed. Here, we explore the biosynthetic route to veratrole. Feeding white campion flowers with [(13)C9]l-phenylalanine increased guaiacol and veratrole emission, and a significant portion of these volatile molecules contained the stable isotope. When white campion flowers were treated with the phenylalanine ammonia lyase inhibitor 2-aminoindan-2-phosphonic acid, guaiacol and veratrole levels were reduced by 50% and 63%, respectively. Feeding with benzoic acid (BA) or salicylic acid (SA) increased veratrole emission 2-fold, while [(2)H5]BA and [(2)H6]SA feeding indicated that the benzene ring of both guaiacol and veratrole is derived from BA via SA. We further report guaiacol O-methyltransferase (GOMT) activity in the flowers of white campion. The enzyme was purified to apparent homogeneity, and the peptide sequence matched that encoded by a recently identified complementary DNA (SlGOMT1) from a white campion flower expressed sequence tag database. Screening of a small population of North American white campion plants for floral volatile emission revealed that not all plants emitted veratrole or possessed GOMT activity, and SlGOMT1 expression was only observed in veratrole emitters. Collectively these data suggest that veratrole is derived by the methylation of guaiacol, which itself originates from phenylalanine via BA and SA, and therefore implies a novel branch point of the general phenylpropanoid pathway.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Tariq A
authors.initials: TA
authors.lastname: Akhtar
authors.forename: Eran
authors.initials: E
authors.lastname: Pichersky
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000840:Anisoles / Q000737:chemistry / Q000378:metabolism*; D019817:Benzoic Acid / Q000494:pharmacology; D053898:Biosynthetic Pathways; D002247:Carbon Isotopes / Q000032:analysis; D018076:DNA, Complementary / Q000235:genetics; D035264:Flowers / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006139:Guaiacol / Q000737:chemistry / Q000378:metabolism; D007189:Indans / Q000494:pharmacology; D008745:Methylation; D009822:Oils, Volatile / Q000378:metabolism; D063065:Organophosphonates / Q000494:pharmacology; D010649:Phenylalanine / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D010938:Plant Oils / Q000378:metabolism*; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D054817:Pollination; D020156:Salicylic Acid / Q000494:pharmacology; D020539:Sequence Analysis, Protein; D029751:Silene / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: C411146:2-aminoindan-2-phosphonic acid; D000840:Anisoles; D002247:Carbon Isotopes; D018076:DNA, Complementary; D007189:Indans; D009822:Oils, Volatile; D063065:Organophosphonates; D010938:Plant Oils; D010940:Plant Proteins; D010649:Phenylalanine; C005299:veratrole; D006139:Guaiacol; D019817:Benzoic Acid; D010650:Phenylalanine Ammonia-Lyase; D020156:Salicylic Acid
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