title: Signal transduction and metabolic flux of beta-thujaplicin and monoterpene biosynthesis in elicited Cupressus lusitanica cell cultures.
abstract: beta-Thujaplicin is an antimicrobial tropolone derived from geranyl pyrophosphate(GPP) and monoterpene intermediate. Yeast elicitor-treated Cupressus lusitanica cell cultures accumulate high levels of beta-thujaplicin at early stages and other monoterpenes at later stages post-elicitation. The different regulation of beta-thujaplicin and monoterpene biosynthesis and signal transduction directing metabolic flux to beta-thujaplicin firstly and then shifting metabolic flow from beta-thujaplicin to other monoterpene biosynthesis were investigated. The earlier rapid induction of beta-thujaplicin accumulation and a later stimulation of monoterpene biosynthesis by yeast elicitor are in well agreement with elicitor-induced changes in activity of three monoterpene biosynthetic enzymes including isopentenyl pyrophosphate isomerase, GPP synthase, and monoterpene synthase. Yeast elicitor induces an earlier and stronger beta-thujaplicin production and monoterpene biosynthetic enzyme activity than methyl jasmonate (MeJA) does. Profiling all monoterpenes produced by C. lusitanica cell cultures under different conditions reveals that beta-thujaplicin biosynthesis parallels with other monoterpenes and competes for common precursor pools. Yet beta-thujaplicin is produced pre-dominantly at early stage of elicitation whereas other monoterpenes are mainly accumulated at late stage while beta-thujaplicin is metabolized. It is suggested that yeast elicitor-treated C. lusitanica cells preferentially accumulate beta-thujaplicin as a primary defense and other monoterpenes as a secondary defense. Inhibitor treatments suggest that immediate production of beta-thujaplicin post-elicitation largely depends on pre-existing enzymes and translation of pre-existing transcripts as well as recruitment of precursor pools from both the cytosol and plastids. The later beta-thujaplicin and other monoterpene accumulation strictly depends on active transcription and translation. Induction of beta-thujaplicin production and activation of monoterpene biosynthetic enzymes by elicitor involves similar signaling pathways, which may activate early beta-thujaplicin production and later monoterpene biosynthesis and induce a metabolic flux shift from beta-thujaplicin to monoterpene accumulation.
authors.affiliation: Laboratory of Forest Chemistry and Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan. jzhao1@bcm.tmc.edu
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Yoko
authors.initials: Y
authors.lastname: Matsunaga
authors.forename: Koki
authors.initials: K
authors.lastname: Fujita
authors.forename: Kokki
authors.initials: K
authors.lastname: Sakai
mesh_terms: D039821:Monoterpenes / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D064028:Tracheophyta / Q000378:metabolism*; D014334:Tropolone / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D039821:Monoterpenes; D014334:Tropolone; C009479:beta-thujaplicin