Localization of the Biosynthesis and Accumulation of Monoterpenoids in Glandular Trichomes of Thyme

Yamaura, Takao; Tanaka, Shigeo; Tabata, Minoru

doi:10.1055/s-2006-961418

Cited by 44 publications

(15 citation statements)

References 2 publications

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“…Likewise, an opposite trend was observed in relative abundances of GARD B and pebrellin, a potential precursor of GARD B lacking only the 6-O-methyl group, which was attributed to changes in the expression of a F6OMT (Voirin and Bayet, 1992). This observation is in line with previous studies on terpene composition in basil (Johnson et al, 1999), peppermint (Brun et al, 1991), and thyme (Thymus vulgare; Yamaura et al, 1992) but contrasts with recent findings (Fischer et al, 2011) that the relative concentrations of several essential oil components in basil are strongly predetermined by the leaf position and vary little throughout leaf development.…”

Section: Line-specific Profiles Of External Flavones Are Conserved Thsupporting

confidence: 89%

A Set of Regioselective O-Methyltransferases Gives Rise to the Complex Pattern of Methoxylated Flavones in Sweet Basil

2012

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Polymethoxylated flavonoids occur in a number of plant families, including the Lamiaceae. To date, the metabolic pathways giving rise to the diversity of these compounds have not been studied. Analysis of our expressed sequence tag database for four sweet basil (Ocimum basilicum) lines afforded identification of candidate flavonoid O-methyltransferase genes. Recombinant proteins displayed distinct substrate preferences and product specificities that can account for all detected 7-/6-/49-methylated, 8-unsubstituted flavones. Their biochemical specialization revealed only certain metabolic routes to be highly favorable and therefore likely in vivo. Flavonoid O-methyltransferases catalyzing 49-and 6-O-methylations shared high identity (approximately 90%), indicating that subtle sequence changes led to functional differentiation. Structure homology modeling suggested the involvement of several amino acid residues in defining the proteins' stringent regioselectivities. The roles of these individual residues were confirmed by site-directed mutagenesis, revealing two discrete mechanisms as a basis for the switch between 6-and 49-O-methylation of two different substrates. These findings delineate major pathways in a large segment of the flavone metabolic network and provide a foundation for its further elucidation.

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Section: Line-specific Profiles Of External Flavones Are Conserved Thsupporting

confidence: 89%

A Set of Regioselective O-Methyltransferases Gives Rise to the Complex Pattern of Methoxylated Flavones in Sweet Basil

2012

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“…The results obtained with trichomes isolated from thyme cotyledons indicate that the biosynthesis and accumulation of monoterpenes take place primarily in the peltate glandular trichomes (Yamaura et al 1992). Isolated secretory cells from several species of mint were shown to be very active in monoterpene biosynthesis .…”

Section: Discussionmentioning

confidence: 93%

Phenylalanine ammonia-lyase and chalcone synthase in glands of Primula kewensis (W. Wats): immunofluorescence and immunogold localization

Sch�pker¹,

Kneisel²,

Beerhues³

et al. 1995

Planta

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Abstract. Phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) were localized by indirect immunofluorescence and immunogold labeling in glands of Primula kewensis. Both enzymes were exclusively present in the head cells of the glands. Phenylalanine ammonialyase was located in the regions of the dense tubular endoplasmic reticulum and occasionally found in more or less spherical organelles that have not yet been identified. Furthermore, an appreciable proportion of the enzyme protein was associated with the plasmalemma and the cell wall of the head cell. In contrast, the occurrence of CHS was restricted to the spherical, unidentified cell compartments. Our findings indicate that the gland cells have the potential for flavonoid biosynthesis. When a mutant of P. kewensis forming structurally intact glands but incapable of farina excretion was studied, neither PAL nor CHS were found in the head cells.

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“…Also, we have found a high correlation between p-cymene and thymol content in T. daenensis essential oil (Table 6). Mikio and Taeko, 31 and Yamaura et al, 32 proposed that thymol biosynthesis pathway includes, δ-terpinene is the component involved in the aromatization process which results in the formation of p-cymene, the precursor of possible oxygenated derivatives, thymol or carvacrol (Fig.1). It may be assumed that the sequence in this process is as follows δ-terpinene, p-cymene, thymol or carvacrol.…”

Section: Essential Oil Compositionmentioning

confidence: 99%

Essential Oil Composition, Total Phenolic Content, Antioxidant Activity and Antifungal Properties of IranianThymus daenensissubsp.daenensisCelak. as in Influenced by Ontogenetical Variation

Alizadeh

Amari

et al. 2013

Journal of Essential Oil Bearing Plants

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Abstract:The chemical composition of essential oil isolated by hydro distillation from the aerial parts of Thymus daenensis subsp. daenensis Celak., at different harvest times were determined using Gas Chromatography (GC) and Gas Chromatography/Mass Spectrometry (GC-MS). Twenty six components were identified in Thymus daenensis essential oils. The main components of the oil were thymol (66.62-71.49 %), p-cymene (5.52-7.12 %), β-caryophyllene (3.91-4.09 %), δ-terpinene (3.22-4.3 %) and carvacrol (2.64-2.77 %). The total phenolic content and the antioxidant activity of plant extract was determined by Folin-Ciocalteau and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays and ferric reducing antioxidant power (FRAP) assay respectively. Total phenols varied from 18.82 to 18.97 (mg GAE/g dw) and the IC 50 in the radical scavenging assay ranged from 8.23 to 8.46 mg/ml and FRAP values ranged form 24.23 to 26.45 μM Quercetin E/g dw. The highest thymol content and radical scavenging effect was found in flowering stage.The essential oil showed 47.89-90.34 % inhibitory properties on Alternaria solani, Fusarium solani and Rhizoctonia solani. The results showed that Flowering stage of harvesting times increased in dry plant weight, and antioxidant activity, and thymol content. Also the oil of T. daenensis has a high antifungal activities against three phathogenic fungi.

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Localization of the Biosynthesis and Accumulation of Monoterpenoids in Glandular Trichomes of Thyme

Cited by 44 publications

References 2 publications

A Set of Regioselective O-Methyltransferases Gives Rise to the Complex Pattern of Methoxylated Flavones in Sweet Basil

A Set of Regioselective O-Methyltransferases Gives Rise to the Complex Pattern of Methoxylated Flavones in Sweet Basil

Phenylalanine ammonia-lyase and chalcone synthase in glands of Primula kewensis (W. Wats): immunofluorescence and immunogold localization

Essential Oil Composition, Total Phenolic Content, Antioxidant Activity and Antifungal Properties of IranianThymus daenensissubsp.daenensisCelak. as in Influenced by Ontogenetical Variation

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