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S B Halligudi - One of the best experts on this subject based on the ideXlab platform.
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titania supported silicotungstic acid an efficient solid acid catalyst for Veratrole acylation
Catalysis Communications, 2008Co-Authors: Nilesh G Waghmare, Palraj Kasinathan, Amol P Amrute, Nishita Lucas, S B HalligudiAbstract:Abstract Titania supported silicotungstic acid (STA) with different STA loading (10–25 wt%) and calcination temperature (650–750 °C) were prepared by wet impregnation method. The catalysts have been represented by a general formula x STiO 2 y (where x denotes wt%, S denotes STA and y denotes calcination temperature in °C). These catalysts were characterized by techniques such as X-ray diffraction, surface analysis, FTIR–pyridine and TPD–NH 3 and were used as heterogeneous solid acid catalysts in the liquid phase acylation of Veratrole with acetic anhydride (Ac 2 O). It was found that 20STiO 2 700 gave the highest activity in acylation reaction due to its highest acidity.
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novel three dimensional cubic fm3m mesoporous aluminosilicates with tailored cage type pore structure and high aluminum content
Advanced Functional Materials, 2008Co-Authors: Pavuluri Srinivasu, Dhanashri P Sawant, Sher Alam, Veerappan V Balasubramanian, Sivan Velmathi, Winfred Bohlmann, Subhash P Mirajkar, Katsuhiko Ariga, S B HalligudiAbstract:Novel three dimensional cubic Fm3m mesoporous aluminosilicates (AlKIT-5) with very high structural order and unprecedented loadings of Al in the silica framework have been successfully prepared for the first time by using non ionic surfactant as a template in a highly acidic medium. The obtained materials have been unambiguously characterized in detail by several sophisticated techniques such as XRD, N2 adsorption, HRTEM, HRSEM, EDS, elemental mapping, 27Al MAS NMR, and NH3-TPD. We also demonstrate that the nature, and the amount of Al incorporation in the silica framework can easily be controlled by simply varying the nH2O/nHCl and the nSi/nAl ratios, and the Al sources in the synthesis gel. Among the Al sources examined, the Al isopropoxide (AiPr) is superior over other Al sources. 27Al MAS NMR results reveal that the amount of tetrahedral Al in the framework can be controlled by simply adjusting the nSi/nAl ratio in the synthesis gel, which increases with increasing the Al incorporation. One of the interesting findings in the work is the increase of the specific surface area, specific pore volume and the pore diameter of AlKIT-5 with increasing the Al incorporation in the silica framework (up to nSi/nAl ratio of 10) while retaining the well-ordered three dimensional cage type porous structure, and the mechanism for the unusual behavior has been discussed in detail. Finally, the acidity and the catalytic activity in the acetylation of Veratrole of the AlKIT-5 catalysts have been studied and the results have been compared with the several zeolites catalysts. Among the catalysts examined, AlKIT-5(10) is found to be superior over the zeolites catalysts such as mordenite, zeolite H-Y, zeolite H-β, and ZSM-5.
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tungstophosphoric acid supported over zirconia in mesoporous channels of mcm 41 as catalyst in Veratrole acetylation
Journal of Molecular Catalysis A-chemical, 2007Co-Authors: Dhanashri P Sawant, Ajayan Vinu, Frederic Lefebvre, S B HalligudiAbstract:Abstract Tungstophosphoric acid (TPA) over zirconia dispersed uniformly in mesoporous silica (MS) channels of MCM-41 and MCM-48 were synthesized and tested for their catalytic activity in Veratrole acetylation. Catalysts with different TPA loadings (5–50 wt.%) on 22.4 wt.%ZrO2/MCM-41 and 15 wt.%TPA on different zirconia loadings (10–70 wt.%)/MCM-41 were prepared and calcined at 1123 K. The physico-chemical characterization of the supported catalysts was done by powder X-ray diffraction (XRD), surface area measurement (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed-infrared (FT-IR) spectroscopy, UV–vis diffuse reflectance spectra, Temperature programmed desorption (TPD) of ammonia, FT-IR pyridine adsorption and 31P cross polarization-magic angle spinning (CP-MAS) NMR spectroscopy. The mesoporous silica supports play an important role in stabilizing catalytically active TPA along with tetragonal phase of zirconia. Among the catalysts, 15 wt.%TPA/22.4 wt.%ZrO2/MCM-41 calcined at 1123 K was found to have highest acidity and at least four times more active than neat 15 wt.%TPA/ZrO2 in Veratrole acetylation to acetoveratrone by acetic anhydride. Reaction conditions were evaluated with 15 wt.%TPA/22.4 wt.%ZrO2/MCM-41 calcined at 1123 K to get higher conversion of acetic anhydride to acetoveratrone. The reaction was found to be heterogeneously catalyzed and no contribution from homogeneous (leached) TPA into the medium under the reaction conditions.
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tungstophosphoric acid and zirconia supported on mesoporous silica catalyst in Veratrole acetylation
Studies in Surface Science and Catalysis, 2007Co-Authors: S B HalligudiAbstract:Abstract Tungstophosphoric acid (TPA) over zirconia dispersed uniformly in mesoporous silica (MS) channels of MCM-41 and MCM-48 was synthesised and tested for its catalytic activity in Veratrole acetylation. Catalysts with different TPA loadings (5 to 50 wt.%) on 22.4 wt.%ZrO2/MCM-41 and 15 wt.%TPA on different zirconia loadings (10-70 wt.%)/MCM-41 were prepared and calcined at 1123 K. Catalysts were characterised by known techniques. Mesoporous silica supports play an important role in stabilising catalytically active TPA along with tetragonal phase of zirconia. Among the catalysts, 15 wt.%TPA/22.4 wt.%ZrO2/MCM-41 calcined at 1123 K was found to have the highest acidity and be at least four times more active than neat 15 wt.%TPA/ZrO2 in Veratrole acetylation to acetoveratrone by acetic anhydride.
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liquid phase Veratrole acylation and toluene alkylation over wox zro2 solid acid catalysts
Journal of Molecular Catalysis A-chemical, 2006Co-Authors: Ankur Bordoloi, Nevin Thunduvila Mathew, Biju M Devassy, S P Mirajkar, S B HalligudiAbstract:Abstract The liquid-phase acylation of Veratrole with acetic anhydride and alkylation of toluene with 1-dodecene were carried out over WOx/ZrO2 solid acid catalysts. The catalysts were prepared by wet impregnation method using zirconium oxyhydroxide and ammonium metatungstate. Catalysts with different WO3 loading (5–30 wt.%) were prepared and calcined at 800 °C and catalyst with 15% WO3 was calcined from 650 to 850 °C. All the catalysts were characterized by nitrogen adsorption, XRD and NH3-TPD. The catalyst with 15% WO3 calcined at 800 °C (15 WZ-800) was found to be the most active in acylation and alkylation reactions. The effect of temperature, molar ratio and catalyst weight on the conversions of acetic anhydride and dodecene were studied in detail. The catalyst 15 WZ-800 gave 67% acetic anhydride conversion in Veratrole acylation under the reaction conditions of 70 °C, Veratrole/acetic anhydride molar ratio 2, time 4 h and 99% dodecene conversion with >99% monododecyl toluene selectivity at 100 °C, toluene/1-dodecene molar ratio 10 and time 1 h.
Florian P Schiestl - One of the best experts on this subject based on the ideXlab platform.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
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postpollination changes in floral odor in silene latifolia adaptive mechanisms for seed predator avoidance
Journal of Chemical Ecology, 2006Co-Authors: Joelle K Muhlemann, Alex Widmer, M Waelti, Florian P SchiestlAbstract:Floral odor is a key trait for pollinator attraction in many plants, but may also direct antagonists like herbivores to flowers. In this study, we examined how floral scent changes after pollination in Silene latifolia, which has a specialized relationship with the seed predator Hadena bicruris. We found an overall decrease in total scent emission and considerable changes in relative amounts of scent compounds after pollination. Lilac aldehydes A and B as well as Veratrole contributed most to the decrease in scent emission. These three compounds are known to be key signals for the attraction of H. bicruris to the flowers. A specific downregulation of these compounds may increase the reproductive success of the plant by reducing seed predation after pollination.
Alok Gupta - One of the best experts on this subject based on the ideXlab platform.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
Eran Pichersky - One of the best experts on this subject based on the ideXlab platform.
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Veratrole biosynthesis in white campion
Plant Physiology, 2013Co-Authors: Tariq A Akhtar, Eran PicherskyAbstract:White campion (Silene latifolia) is a dioecious plant that emits 1,2-dimethoxybenzene (Veratrole), a potent pollinator attractant to the nocturnal moth Hadena bicruris. Little is known about Veratrole biosynthesis, although methylation of 2-methoxyphenol (guaiacol), another volatile emitted from white campion flowers, has been proposed. Here, we explore the biosynthetic route to Veratrole. Feeding white campion flowers with [(13)C9]l-phenylalanine increased guaiacol and Veratrole emission, and a significant portion of these volatile molecules contained the stable isotope. When white campion flowers were treated with the phenylalanine ammonia lyase inhibitor 2-aminoindan-2-phosphonic acid, guaiacol and Veratrole levels were reduced by 50% and 63%, respectively. Feeding with benzoic acid (BA) or salicylic acid (SA) increased Veratrole emission 2-fold, while [(2)H5]BA and [(2)H6]SA feeding indicated that the benzene ring of both guaiacol and Veratrole is derived from BA via SA. We further report guaiacol O-methyltransferase (GOMT) activity in the flowers of white campion. The enzyme was purified to apparent homogeneity, and the peptide sequence matched that encoded by a recently identified complementary DNA (SlGOMT1) from a white campion flower expressed sequence tag database. Screening of a small population of North American white campion plants for floral volatile emission revealed that not all plants emitted Veratrole or possessed GOMT activity, and SlGOMT1 expression was only observed in Veratrole emitters. Collectively these data suggest that Veratrole is derived by the methylation of guaiacol, which itself originates from phenylalanine via BA and SA, and therefore implies a novel branch point of the general phenylpropanoid pathway.
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Veratrole biosynthesis in white campion 1 w oa
2013Co-Authors: Tariq A Akhtar, Eran PicherskyAbstract:Veratrole. Feeding white campion flowers with [ 13 C 9 ]L-phenylalanine increased guaiacol and Veratrole emission, and a significant portion of these volatile molecules contained the stable isotope. When white campion flowers were treated with the phenylalanine ammonia lyase inhibitor 2-aminoindan-2-phosphonic acid, guaiacol and Veratrole levels were reduced by 50% and 63%, respectively. Feeding with benzoic acid (BA) or salicylic acid (SA) increased Veratrole emission 2-fold, while [ 2 H 5 ]BA and [ 2 H 6 ]SA feeding indicated that the benzene ring of both guaiacol and Veratrole is derived from BA via SA. We further report guaiacol O-methyltransferase (GOMT) activity in the flowers of white campion. The enzyme was purified to apparent homogeneity, and the peptide sequence matched that encoded by a recently identified complementary DNA (SlGOMT1) from a white campion flower expressed sequence tag database. Screening of a small population of North American white campion plants for floral volatile emission revealed that not all plants emitted Veratrole or possessed GOMT activity, and SlGOMT1 expression was only observed in Veratrole emitters. Collectively these data suggest that Veratrole is derived by the methylation of guaiacol, which itself originates from phenylalanine via BA and SA, and therefore implies a novel branch point of the general phenylpropanoid pathway.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
Tariq A Akhtar - One of the best experts on this subject based on the ideXlab platform.
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Veratrole biosynthesis in white campion
Plant Physiology, 2013Co-Authors: Tariq A Akhtar, Eran PicherskyAbstract:White campion (Silene latifolia) is a dioecious plant that emits 1,2-dimethoxybenzene (Veratrole), a potent pollinator attractant to the nocturnal moth Hadena bicruris. Little is known about Veratrole biosynthesis, although methylation of 2-methoxyphenol (guaiacol), another volatile emitted from white campion flowers, has been proposed. Here, we explore the biosynthetic route to Veratrole. Feeding white campion flowers with [(13)C9]l-phenylalanine increased guaiacol and Veratrole emission, and a significant portion of these volatile molecules contained the stable isotope. When white campion flowers were treated with the phenylalanine ammonia lyase inhibitor 2-aminoindan-2-phosphonic acid, guaiacol and Veratrole levels were reduced by 50% and 63%, respectively. Feeding with benzoic acid (BA) or salicylic acid (SA) increased Veratrole emission 2-fold, while [(2)H5]BA and [(2)H6]SA feeding indicated that the benzene ring of both guaiacol and Veratrole is derived from BA via SA. We further report guaiacol O-methyltransferase (GOMT) activity in the flowers of white campion. The enzyme was purified to apparent homogeneity, and the peptide sequence matched that encoded by a recently identified complementary DNA (SlGOMT1) from a white campion flower expressed sequence tag database. Screening of a small population of North American white campion plants for floral volatile emission revealed that not all plants emitted Veratrole or possessed GOMT activity, and SlGOMT1 expression was only observed in Veratrole emitters. Collectively these data suggest that Veratrole is derived by the methylation of guaiacol, which itself originates from phenylalanine via BA and SA, and therefore implies a novel branch point of the general phenylpropanoid pathway.
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Veratrole biosynthesis in white campion 1 w oa
2013Co-Authors: Tariq A Akhtar, Eran PicherskyAbstract:Veratrole. Feeding white campion flowers with [ 13 C 9 ]L-phenylalanine increased guaiacol and Veratrole emission, and a significant portion of these volatile molecules contained the stable isotope. When white campion flowers were treated with the phenylalanine ammonia lyase inhibitor 2-aminoindan-2-phosphonic acid, guaiacol and Veratrole levels were reduced by 50% and 63%, respectively. Feeding with benzoic acid (BA) or salicylic acid (SA) increased Veratrole emission 2-fold, while [ 2 H 5 ]BA and [ 2 H 6 ]SA feeding indicated that the benzene ring of both guaiacol and Veratrole is derived from BA via SA. We further report guaiacol O-methyltransferase (GOMT) activity in the flowers of white campion. The enzyme was purified to apparent homogeneity, and the peptide sequence matched that encoded by a recently identified complementary DNA (SlGOMT1) from a white campion flower expressed sequence tag database. Screening of a small population of North American white campion plants for floral volatile emission revealed that not all plants emitted Veratrole or possessed GOMT activity, and SlGOMT1 expression was only observed in Veratrole emitters. Collectively these data suggest that Veratrole is derived by the methylation of guaiacol, which itself originates from phenylalanine via BA and SA, and therefore implies a novel branch point of the general phenylpropanoid pathway.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Background: Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. Results: We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1 )& S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Conclusions: Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
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identification of white campion silene latifolia guaiacol o methyltransferase involved in the biosynthesis of Veratrole a key volatile for pollinator attraction
BMC Plant Biology, 2012Co-Authors: Eran Pichersky, Alok Gupta, Tariq A Akhtar, Alex Widmer, Florian P SchiestlAbstract:Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially Veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) & S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form Veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of Veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes Veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for Veratrole synthesis in S. latifolia.
