Biosynthesis and emission of terpenoid volatiles from Arabidopsis flowers.
Arabidopsis is believed to be mostly self-pollinated, although several lines of genetic and morphological evidence indicate that insect-mediated outcrossing occurs with at least a low frequency in wild populations. Here, we show that Arabidopsis flowers emit both monoterpenes and sesquiterpenes, potential olfactory cues for pollinating insects. Of the 32 terpene synthase genes in the Arabidopsis genome, 20 were found to be expressed in flowers, 6 of these exclusively or almost exclusively so. Two terpene synthase genes expressed exclusively in the flowers and one terpene synthase gene expressed almost exclusively in the flowers were characterized and found to encode proteins that catalyze the formation of major floral volatiles. A beta-glucuronidase fusion construct with a promoter of one of these genes demonstrated that gene expression was restricted to the sepals, stigmas, anther filaments, and receptacles, reaching a peak when the stigma was receptive to cross pollen. The observation that Arabidopsis flowers synthesize and emit volatiles raises intriguing questions about the reproductive behavior of Arabidopsis in the wild and allows detailed investigations of floral volatile biosynthesis and its regulation to be performed with this model plant system.
Chen
Feng
F
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Tholl
Dorothea
D
D'Auria
John C
JC
Farooq
Afgan
A
Pichersky
Eran
E
Gershenzon
Jonathan
J
D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D039821:Monoterpenes / Q000737:chemistry / Q000378:metabolism; D009822:Oils, Volatile / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism; D013729:Terpenes / Q000737:chemistry / Q000378:metabolism*; D014835:Volatilization
D039821:Monoterpenes; D009822:Oils, Volatile; D012717:Sesquiterpenes; D013729:Terpenes; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase