Publications

• Characterization of the monoterpene synthase gene tps26, the ortholog of a gene induced by insect herbivory in maize.

  Lin C., Shen B., Xu Z., Koellner T.G., Degenhardt J., Dooner H.K.

  Plants damaged by insects can synthesize and release volatile chemicals that attract natural enemies of the herbivore. The maize (Zea mays subsp. mays) terpene synthase gene stc1 is part of that indirect defense response, being induced in seedling blades in response to herbivory by beet army worm. ... >> More

  Plants damaged by insects can synthesize and release volatile chemicals that attract natural enemies of the herbivore. The maize (Zea mays subsp. mays) terpene synthase gene stc1 is part of that indirect defense response, being induced in seedling blades in response to herbivory by beet army worm. Many genes in maize are duplicated because of a past whole-genome duplication event, and several of these orthologs display different expression patterns. We report here the isolation and characterization of tps26 and confirm by homology and synteny criteria that it is the ortholog of stc1. Prior genetic analysis revealed that the stc1 function is not duplicated, raising the interesting question of how the two orthologs have become differentiated in their expression. tps26 encodes a 633-amino acid protein that is highly conserved with STC1. Like stc1, tps26 is induced by wounding, but in the roots and leaf sheath, instead of the blade, and not in response to beet army worm feeding. tps26 maps near a quantitative trait locus for Southwestern corn borer resistance, making it a plausible candidate gene for that quantitative trait locus. However, while possessing highly polymorphic tps26 alleles, the resistant and susceptible parents of the mapping population do not differ in levels of tps26 expression. Moreover, tps26 is not induced specifically by Southwestern corn borer feeding. Therefore, although they share a wounding response, the stc1 and tps26 maize orthologs differ in their tissue specificity and their induction by insect herbivores. The N termini of STC1 and TPS26 are predicted to encode plastid transit peptides; fusion proteins of green fluorescent protein to either N terminus localized to the plastid, confirming that prediction. The mature proteins, but not the respective complete proteins, were active and synthesized a blend of monoterpenes, indicating that they are monoterpene synthases. A gene closely related to stc1/tps26 is found in the sorghum (Sorghum spp.) genome at a location that is not orthologous with stc1. The possible origin of stc1-like genes is discussed. << Less

  Plant Physiol. 146:940-951(2008) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Vitis vinifera terpenoid cyclases: functional identification of two sesquiterpene synthase cDNAs encoding (+)-valencene synthase and (-)-germacrene D synthase and expression of mono- and sesquiterpene synthases in grapevine flowers and berries.

  Lucker J., Bowen P., Bohlmann J.

  Valencene is a volatile sesquiterpene emitted from flowers of grapevine, Vitis vinifera L. A full-length cDNA from the cultivar Gewürztraminer was functionally expressed in Escherichia coli and found to encode valencene synthase (VvVal). The two major products formed by recombinant VvVal enzyme ac ... >> More

  Valencene is a volatile sesquiterpene emitted from flowers of grapevine, Vitis vinifera L. A full-length cDNA from the cultivar Gewürztraminer was functionally expressed in Escherichia coli and found to encode valencene synthase (VvVal). The two major products formed by recombinant VvVal enzyme activity with farnesyl diphosphate (FPP) as substrate are (+)-valencene and (-)-7-epi-alpha-selinene. Grapevine valencene synthase is closely related to a second sesquiterpene synthase from this species, (-)-germacrene D synthase (VvGerD). VvVal and VvGerD cDNA probes revealed strong signals in Northern hybridizations with RNA isolated from grapevine flower buds. Transcript levels were lower in open pre-anthesis flowers, flowers after anthesis, or at early onset of fruit development. Similar results were obtained using a third probe, (-)-alpha-terpineol synthase, a monoterpenol synthase. Sesquiterpene synthase and monoterpene synthase transcripts were not detected in the mesocarp and exocarp during early stages of fruit development, but transcripts hybridizing with VvVal appeared during late ripening of the berries. Sesquiterpene synthase transcripts were also detected in young seeds. << Less

  Phytochemistry 65:2649-2659(2004) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Identification of Vitis vinifera (-)-alpha-terpineol synthase by in silico screening of full-length cDNA ESTs and functional characterization of recombinant terpene synthase.

  Martin D.M., Bohlmann J.

  The flavour and aroma of certain Vitis vinifera grape varieties is dominated by volatile terpenes and small volatile aldehydes. Monoterpenes contribute to the final grape and wine aroma and flavour in form of free volatiles and as glycoside conjugates of monoterpene alcohols. Typical monoterpenol ... >> More

  The flavour and aroma of certain Vitis vinifera grape varieties is dominated by volatile terpenes and small volatile aldehydes. Monoterpenes contribute to the final grape and wine aroma and flavour in form of free volatiles and as glycoside conjugates of monoterpene alcohols. Typical monoterpenol components of the cultivar Gewürztraminer and other aroma-rich grape varieties are linalool, geraniol, nerol, citronellol, and alpha-terpineol. In a functional genomics effort to identify genes for the formation of monoterpene alcohols in V. vinifera, a database of full-length cDNA sequences was screened in silico and yielded two clones for putative monoterpene synthases. The gene products were functionally characterized by expression in Escherichia coli, in vitro enzyme assay and gas chromatography-mass spectrometry (GC-MS) product identification as multi-product (-)-alpha-terpineol synthases. << Less

  Phytochemistry 65:1223-1229(2004) [PubMed] [EuropePMC]

• Biochemical and genomic characterization of terpene synthases in Magnolia grandiflora.

  Lee S., Chappell J.

  Magnolia grandiflora (Southern Magnolia) is a primitive evergreen tree that has attracted attention because of its horticultural distinctiveness, the wealth of natural products associated with it, and its evolutionary position as a basal angiosperm. Three cDNAs corresponding to terpene synthase (T ... >> More

  Magnolia grandiflora (Southern Magnolia) is a primitive evergreen tree that has attracted attention because of its horticultural distinctiveness, the wealth of natural products associated with it, and its evolutionary position as a basal angiosperm. Three cDNAs corresponding to terpene synthase (TPS) genes expressed in young leaves were isolated, and the corresponding enzymes were functionally characterized in vitro. Recombinant Mg25 converted farnesyl diphosphate (C(15)) predominantly to beta-cubebene, while Mg17 converted geranyl diphosphate (C(5)) to alpha-terpineol. Efforts to functionally characterize Mg11 were unsuccessful. Transcript levels for all three genes were prominent in young leaf tissue and significantly elevated for Mg25 and Mg11 messenger RNAs in stamens. A putative amino-terminal signal peptide of Mg17 targeted the reporter green fluorescent protein to both chloroplasts and mitochondria when transiently expressed in epidermal cells of Nicotiana tabacum leaves. Phylogenetic analyses indicated that Mg25 and Mg11 belonged to the angiosperm sesquiterpene synthase subclass TPS-a, while Mg17 aligned more closely to the angiosperm monoterpene synthase subclass TPS-b. Unexpectedly, the intron-exon organizations for the three Magnolia TPS genes were different from one another and from other well-characterized TPS gene sets. The Mg17 gene consists of six introns arranged in a manner similar to many other angiosperm sesquiterpene synthases, but Mg11 contains only four introns, and Mg25 has only a single intron located near the 5' terminus of the gene. Our results suggest that the structural diversity observed in the Magnolia TPS genes could have occurred either by a rapid loss of introns from a common ancestor TPS gene or by a gain of introns into an intron-deficient progenote TPS gene. << Less

  Plant Physiol. 147:1017-1033(2008) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• cDNA isolation, functional expression, and characterization of (+)-alpha-pinene synthase and (-)-alpha-pinene synthase from loblolly pine (Pinus taeda): stereocontrol in pinene biosynthesis.

  Phillips M.A., Wildung M.R., Williams D.C., Hyatt D.C., Croteau R.

  The complex mixture of monoterpenes, sesquiterpenes, and diterpenes that comprises oleoresin provides the primary defense of conifers against bark beetles and their associated fungal pathogens. Monoterpene synthases produce the turpentine fraction of oleoresin, which allows mobilization of the dit ... >> More

  The complex mixture of monoterpenes, sesquiterpenes, and diterpenes that comprises oleoresin provides the primary defense of conifers against bark beetles and their associated fungal pathogens. Monoterpene synthases produce the turpentine fraction of oleoresin, which allows mobilization of the diterpene resin acid component (rosin) and is also toxic toward invading insects; this is particularly the case for alpha-pinene, a prominent bicyclic monoterpene of pine turpentine. The stereochemistry of alpha-pinene is a critical determinant of host defense capability and has implications for host selection, insect pheromone biosynthesis, and tritrophic-level interactions. Pines produce both enantiomers of alpha-pinene, which appear to arise through antipodal reaction mechanisms by distinct enzymes. Using a cDNA library constructed with mRNA from flushing needles of loblolly pine (Pinus taeda), we employed a homology-based cloning strategy to isolate, and confirm by functional expression, the genes encoding (+)-(3R:5R)-alpha-pinene synthase, (-)-(3S:5S)-alpha-pinene synthase, and several other terpene synthases. The pinene synthases, which produce mirror-image products, share only 66% amino acid identity (72% similarity) but are similar in general properties to other monoterpene synthases of gymnosperms. The stereochemical control of monoterpene cyclization reactions, the evolution of "antipodal" enzymes, and the implications of turpentine composition in ecological interactions are discussed. << Less

  Arch. Biochem. Biophys. 411:267-276(2003) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.