title: Heliolactone, a non-sesquiterpene lactone germination stimulant for root parasitic weeds from sunflower.
abstract: Root exudates of sunflower (Helianthus annuus L.) line 2607A induced germination of seeds of root parasitic weeds Striga hermonthica, Orobanche cumana, Orobanche minor, Orobanche crenata, and Phelipanche aegyptiaca. Bioassay-guided purification led to the isolation of a germination stimulant designated as heliolactone. FT-MS analysis indicated a molecular formula of C20H24O6. Detailed NMR spectroscopic studies established a methylfuranone group, a common structural component of strigolactones connected to a methyl ester of a C14 carboxylic acid via an enol ether bridge. The cyclohexenone ring is identical to that of 3-oxo-α-ionol and the other part of the molecule corresponds to an oxidized carlactone at C-19. It is a carlactone-type molecule and functions as a germination stimulant for seeds of root parasitic weeds. Heliolactone induced seed germination of the above mentioned root parasitic weeds, while dehydrocostus lactone and costunolide, sesquiterpene lactones isolated from sunflower root exudates, were effective only on O. cumana and O. minor. Heliolactone production in aquacultures increased when sunflower seedlings were grown hydroponically in tap water and decreased on supplementation of the culture with either phosphorus or nitrogen. Costunolide, on the other hand, was detected at a higher concentration in well-nourished medium as opposed to nutrient-deficient media, thus suggesting a contrasting contribution of heliolactone and the sesquiterpene lactone to the germination of O. cumana under different soil fertility levels.
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Kotomi
authors.initials: K
authors.lastname: Ueno
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Furumoto
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Umeda
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Mizutani
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Hirosato
authors.initials: H
authors.lastname: Takikawa
authors.affiliation: AgroBioInstitute, Dragan Tsankov Blvd., Sofia 1164, Bulgaria.
authors.forename: Rossitza
authors.initials: R
authors.lastname: Batchvarova
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan. Electronic address: yukihiro@kobe-u.ac.jp.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Sugimoto
mesh_terms: D002031:Bulgaria; D003512:Cyclohexanones / Q000737:chemistry; D018525:Germination / Q000187:drug effects; D006368:Helianthus / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D031672:Orobanche / Q000187:drug effects / Q000254:growth & development; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism; D057685:Plant Weeds / Q000187:drug effects / Q000254:growth & development; D012639:Seeds / Q000187:drug effects / Q000254:growth & development
chemical_list: C525367:3-oxo-alpha-ionol; D003512:Cyclohexanones; D007783:Lactones; C571055:carlactone; C000595227:heliolactone
keywords: Asteraceae; Carlactone; Helianthus annuus; Orobanchaceae; Orobanche cumana; Strigolactone; Sunflower