Fluorescent microscopy of sunflower glandular trichomes from anther appendages showed a strong autofluorescence, caused by flavonoids. Chemical analysis with NMR and HRMS lead to the identification of 7-hydroxy-6,8,4′-trimethoxyflavone, a novel 5-deoxyflavone, exclusively found in capitate glandular trichomes. 5-Deoxy flavones are rarely found in Asteraceae and this is the first report for the genus Helianthus. Semiquantitative RT-PCR showed the presence of transcripts for phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) in all biosynthetically active trichome stages. PAL and CHS are key steps in flavonoid biosynthesis indicating that flavonoid production occurs directly within the trichomes. This offers the possibility for examination of 5-deoxyflavone biosynthesis within Asteraceae.
SpringO. (2000) Chemotaxonomy Based on Metabolites from Glandular Trichomes. In Advances in Botanical Research. HellahanDL, GrayJC, CallowJA (Eds), Academic Press, London, UK, 31, 153–174
2.
BurnettWC, JonesSB, MabryTJ, PadolinaWG. (1974) Sesquiterpene Lactones – Insect Feeding Deterrents in Veronia. Biochemical Systematics and Ecology, 2, 25–29
3.
MullinCA, AlfataftaAA, HarmanJL, EverettSL, SerinoAA. (1991) Feeding and Toxic Effects of Floral Sesquiterpene Lactones, Diterpenes, and Phenolics from Sunflower (Helianthus annuus L.) on Western Corn Rootworm. Journal of Agricultural and Food Chemistry, 39, 2293–2299
4.
SchillingEE. (1983) Flavonoids of Helianthus series Angustifolii. Biochemical Systematics and Ecology, 11, 341–344
5.
SpringO, HeilN, EliassonU. (1999) Chemosystematic studies on the genus Scalesia (Asteraceae). Biochemical Systematics and Ecology, 27, 277–288
6.
HeinrichG, PfeiferhoferHW, StabenstheinerE, SawidisT. (2002) Glandular Hairs of Sigesbeckia jorullensis Kunth (Asteraceae): Morphology, Histochemistry and Composition of Essential Oil. Annals of Botany, 89, 459–469
7.
AscensãoL, MatquesN, PaisSM. (1997) Peltate Glandular Trichomes of Leonotis leonurus Leaves: Ultrastructure and Histochemical Characterization of Secretions. International Journal of Plant Sciences, 158, 249–258
8.
AscensãoL, MotaL, CastroMDM. (1999) Glandular Trichomes on the Leaves and Flowers of Plectranthus ornatus: Morphology, Distribution and Histochemistry. Annals of Botany, 84, 437–447
9.
BisioA, CoralloA, GastaldoP, RomussiG, CiarolloG, FontanaN, De TommasiN, ProfumoP. (1999) Glandular Hairs and Secreted Material in Salvia blepharophylla Brandegee ex Epling Grown in Italy. Annals of Botany, 83, 441–452
10.
TattiniM, GravanoE, PinelliP, MulinacciN, RomaniaA. (2000) Flavonoids Accumulate in Leaves and Glandular Trichomes of Phillyrea latifolia Exposed to Excess Solar Radiation. New Phytologist, 148, 69–77
11.
LiakopoulosG, StavrianakouS, KarabourniotisG. (2006) Trichome Layers Versus Dehaired Lamina of Olea europaea Leaves: Differences in Flavonoid Distribution, UV-Absorbing Capacity, and Wax Yield. Environmental and Experimental Botany, 55, 294–304
12.
BohmBA, StuessyTF. (2001) Flavonoids of the Sunflower Family (Asteraceae). Springer, Wien, Austria, 1–830
13.
AlfataftaAA, MullinCA. (1992) Epicuticular Terpenoids and an Aurone from Flowers of Helianthus annuus. Phytochemistry, 31, 4109–4113
14.
GershenzonJ. (1984) The terpenoid chemistry of Helianthus series Corona Solis and its ecological and systematic application. Dissertation, University of Texas, Austin, USA
15.
GaoF, WangH, MabryTJ. (1987) Sesquiterpene Lactones and Flavonoids from Helianthus Species. Journal of Natural Products, 50, 23–29
16.
RiesebergLH, SoltisDE, ArnoldD. (1987) Variation and Localization of Flavonoid Aglycones in Helianthus annuus (Compositae). American Journal of Botany, 74, 224–233
17.
SchillingEE, PaneroJL, StorbeckTA. (1987) Flavonoids of Helianthus Series Microcephali. Biochemical Systematics and Ecology, 15, 671–672
18.
GöpfertJC, HeilN, ConradJ, SpringO. (2005) Cytological Development and Sesquiterpene Lactone Secretion in Capitate Glandular Trichomes of Sunflower. Plant Biology, 7, 148–155
19.
SpringO. (1991) Trichome Microsampling of Sesquiterpene Lactones for the Use of Systematic Studies. In Modern Phytochemical Methods. FischerNH, IsmanMB, StaffordHA (Eds), Plenum Press, New York, USA, 319–345
20.
ChumbalovTK, FadeevaOV. (1969) Flavonoids of Artemisia transiliensis. Chemistry of Natural Products, 5, 439
21.
AhmadVU, IsmailN, KhanMA, BaqaiFT, TareenRB. (1995) Santoflavone, a 5-deoxyflavonoid from Achillea santolina. Phytochemistry, 38, 1305–1307
22.
WollenweberE. (1984) The Systematic Implication of Flavonoids Secreted by Plants. In Biology and Chemistry of Plant Trichomes. RodriguezE, HealeyPL, MehtaI (Eds.), Plenum Press, New York, USA, 53–69
23.
BerteaCM, VosterA, VerstappenFWA, MaffeiM, BeekwilderJ, BouwmeesterHJ. (2006) Isoprenoid Biosynthesis in Artemisia annua: Cloning and Heterologous Expression of a Germacrene A Synthase from a Glandular Trichome cDNA Library. Archives of Biochemistry and Biophysics, 448, 3–12
24.
ElomaaP, HelariuttaY, KotilainenM, TeeriTH. (1996) Transformation of Antisense Constructs of the Chalcone Synthase Gene Superfamily into Gerbera hybrida: Differential Effect on the Expression of Family Members. Molecular Breeding, 2, 41–50
25.
HelariuttaY, KotilainenM, ElomaaP, KalkkinenN, BremerK, TeeriTH, AlbertVA. (1996) Duplication and Functional Divergence in the Chalcone Synthase Gene Family of Asteraceae: Evolution with Substrate Change and Catalytic Simplification. Proceedings of the National Academy of Sciences of the United States of America, 93, 9033–9038
26.
BinetMN, SteinmetzA, TessierLH. (1989) The Primary Structure of Sunflower (Helianthus annuus) Ubiquitin. Nucleic Acids Research, 17, 2119
27.
WaksmannG, LebrunM, FreyssinetG. (1987) Nucleotide Sequence of a Gene Encoding Sunflower Ribulose-1,5-bisphosphate Carboxylase/Oxygenase Small Subunit (rbcs). Nucleic Acids Research, 15, 7181
28.
MazeyratF, SallesS, DrevetJ, Roeckel-DrevetP, TourvieilleD, LedoigtG. (1998) Isolation of a complete PAL cDNA from sunflower (Accession No. Y12461). Plant Physiology, 117, 719
