Jonathan Gershenzon

Publications (202)762.6 Total impact

• Article: A common fungal associate of the spruce bark beetle metabolizes the stilbene defenses of Norway spruce.

  Almuth Hammerbacher, Axel Schmidt, Namita Wadke, Louwrance Peter Wright, Bernd Schneider, Joerg Bohlmann, Willi A Brand, Trevor M Fenning, Jonathan Gershenzon, Christian Paetz
  [show abstract] [hide abstract]
  ABSTRACT: Norway spruce (Picea abies) forests suffer periodic fatal attacks by the bark beetle Ips typographus and its fungal associate, Ceratocystis polonica. P. abies protects itself against fungal and bark beetle invasion by production of terpenoid resins, but it is unclear whether resins or other defenses are effective against the fungus. We investigated stilbenes, a group of phenolic compounds found in P. abies bark with a diaryl-ethene skeleton with known antifungal properties. During C. polonica infection, stilbene biosynthesis was up-regulated as evidenced by elevated transcript levels of stilbene synthase genes. However, stilbene concentrations actually declined during infection and this was due to fungal metabolism. C. polonica converted stilbenes to ring-opened, deglycosylated and dimeric products. Chromatographic separation of C. polonica protein extracts confirmed that these metabolites arose from specific fungal enzyme activities. Comparison of C. polonica strains showed that rapid conversion of host phenolics is associated with higher virulence. C. polonica is so well adapted to its host's chemical defenses that it is even able to use host phenolic compounds as its sole carbon source.
  Plant physiology 06/2013; · 6.53 Impact Factor
• Article: Natural variation in maize aphid resistance is associated with DIMBOA-Glc methyltransferase activity

  Lisa Meihls, Vinzenz Handrick, Gaetan Glauser, Hugues Barbier, Harleen Kaur, Meena Haribal, Alexander Lipka, Jonathan Gershenzon, Edward Buckler, Matthias Erb, Tobias Köllner, Georg Jander
  [show abstract] [hide abstract]
  ABSTRACT: Plants differ greatly in their susceptibility to insect herbivory, suggesting both local adaptation and resistance tradeoffs. We used maize recombinant inbred lines to map a quantitative trait locus (QTL) for Rhopalosiphum maidis (corn leaf aphid) susceptibility to maize Chromosome 1. Phytochemical analysis revealed that the same locus was also associated with high levels of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) and low levels of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc). In vitro enzyme assays with candidate genes from the region of the QTL identified three O-methyltransferases (Bx10a-c) that convert DIMBOA-Glc to HDMBOA-Glc. Variation in HDMBOA-Glc production was attributed to a natural CACTA family transposon insertion that inactivates Bx10c in maize lines with low HDMBOA-Glc accumulation. When tested with a population of 26 diverse maize inbred lines, R. maidis produced more progeny on those with high HDMBOA-Glc and low DIMBOA-Glc. Although HDMBOA-Glc was more toxic to R. maidis than DIMBOA-Glc in vitro, BX10c activity and the resulting decline of DIMBOA-Glc upon methylation to HDMBOA-Glc were associated with reduced callose deposition as an aphid defense response in vivo. Thus, a natural transposon insertion appears to mediate an ecologically relevant trade-off between the direct toxicity and defense–inducing properties of maize benzoxazinoids.
  The Plant Cell 06/2013; · 8.99 Impact Factor
• Article: Plants Suppress Their Emission of Volatiles When Growing with Conspecifics.

  Rose N Kigathi, Wolfgang W Weisser, Daniel Veit, Jonathan Gershenzon, Sybille B Unsicker
  [show abstract] [hide abstract]
  ABSTRACT: Plant volatiles mediate interactions with herbivores, herbivore enemies, and abiotic stresses, but these interactions mostly have been studied with individual isolated plants. It is not yet known how intra- and interspecific plant competition influence volatile emission. In a greenhouse experiment, we investigated the volatile emission by red clover (Trifolium pratense) growing alone, with a conspecific, or with an individual of the naturally co-occurring orchard grass, Dactylis glomerata. The individual and combined effects of above- and below ground plant contact were investigated. When T. pratense grew together with a conspecific, both total and herbivore-induced emission of volatiles was significantly reduced as compared to T. pratense growing with D. glomerata or growing alone. This reduction in emission occurred despite the fact that there was a significant reduction in T. pratense biomass due to competition with D. glomerata. The suppression of T. pratense volatile emission growing next to a conspecific was a general pattern observed for all major herbivore-induced volatiles and independent of whether plants were in contact above ground, below ground, or both above- and below ground. The reduction in volatile emission from plants growing with conspecifics may serve to reduce attack by specialist herbivores and minimize exploitation of herbivore attack information by neighbors.
  Journal of Chemical Ecology 03/2013; · 2.66 Impact Factor
• Source

  Available from: Sven Geiselhardt

  Article: Egg Laying of Cabbage White Butterfly (Pieris brassicae) on Arabidopsis thaliana Affects Subsequent Performance of the Larvae

  Sven Geiselhardt, Kinuyo Yoneya, Blenn, Navina Drechsler, Jonathan Gershenzon, Reinhard Kunze, Monika Hilker
  [show abstract] [hide abstract]
  ABSTRACT: Plant resistance to the feeding by herbivorous insects has recently been found to be positively or negatively influenced by prior egg deposition. Here we show how crucial it is to conduct experiments on plant responses to herbivory under conditions that simulate natural insect behaviour. We used a well-studied plant – herbivore system, Arabidopsis thaliana and the cabbage white butterfly Pieris brassicae, testing the effects of naturally laid eggs (rather than egg extracts) and allowing larvae to feed gregariously as they do naturally (rather than placing single larvae on plants). Under natural conditions, newly hatched larvae start feeding on their egg shells before they consume leaf tissue, but access to egg shells had no effect on subsequent larval performance in our experiments. However, young larvae feeding gregariously on leaves previously laden with eggs caused less feeding damage, gained less weight during the first 2 days, and suffered twice as high a mortality until pupation compared to larvae feeding on plants that had never had eggs. The concentration of the major anti-herbivore defences of A. thaliana, the glucosinolates, was not significantly increased by oviposition, but the amount of the most abundant member of this class, 4-methylsulfinylbutyl glucosinolate was 1.8-fold lower in larval-damaged leaves with prior egg deposition compared to damaged leaves that had never had eggs. There were also few significant changes in the transcript levels of glucosinolate metabolic genes, except that egg deposition suppressed the feeding-induced up-regulation of FMO GS-OX2 , a gene encoding a flavin monooxygenase involved in the last step of 4-methylsulfinylbutyl glucosinolate biosynthesis. Hence, our study demonstrates that oviposition does increase A. thaliana resistance to feeding by subsequently hatching larvae, but this cannot be attributed simply to changes in glucosinolate content. Citation: Geiselhardt S, Yoneya K, Blenn B, Drechsler N, Gershenzon J, et al. (2013) Egg Laying of Cabbage White Butterfly (Pieris brassicae) on Arabidopsis thaliana Affects Subsequent Performance of the Larvae. PLoS ONE 8(3): e59661. Copyright: ß 2013 Geiselhardt et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: ND was supported by a grant of the Dahlem Centre of Plant Sciences (DCPS), Freie Universität Berlin (www.dcps.fu-berlin.de). KY was supported by the German Academic Exchange Service (DAAD) (www.daad.de). BB was supported by the German Research Foundation (DFG) (www.dfg.de). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist.
  PLoS ONE 03/2013; 8(3):e59661. · 4.09 Impact Factor
• Article: Metal ions control product specificity of isoprenyl diphosphate synthases in the insect terpenoid pathway.

  Sindy Frick, Raimund Nagel, Axel Schmidt, René R Bodemann, Peter Rahfeld, Gerhard Pauls, Wolfgang Brandt, Jonathan Gershenzon, Wilhelm Boland, Antje Burse
  [show abstract] [hide abstract]
  ABSTRACT: Isoprenyl diphosphate synthases (IDSs) produce the ubiquitous branched-chain diphosphates of different lengths that are precursors of all major classes of terpenes. Typically, individual short-chain IDSs (scIDSs) make the C(10), C(15), and C(20) isoprenyl diphosphates separately. Here, we report that the product length synthesized by a single scIDS shifts depending on the divalent metal cofactor present. This previously undescribed mechanism of carbon chain-length determination was discovered for a scIDS from juvenile horseradish leaf beetles, Phaedon cochleariae. The recombinant enzyme P. cochleariae isoprenyl diphosphate synthase 1 (PcIDS1) yields 96% C(10)-geranyl diphosphate (GDP) and only 4% C(15)-farnesyl diphosphate (FDP) in the presence of Co(2+) or Mn(2+) as a cofactor, whereas it yields only 18% C(10) GDP but 82% C(15) FDP in the presence of Mg(2+). In reaction with Co(2+), PcIDS1 has a K(m) of 11.6 μM for dimethylallyl diphosphate as a cosubstrate and 24.3 μM for GDP. However, with Mg(2+), PcIDS1 has a K(m) of 1.18 μM for GDP, suggesting that this substrate is favored by the enzyme under such conditions. RNAi targeting PcIDS1 revealed the participation of this enzyme in the de novo synthesis of defensive monoterpenoids in the beetle larvae. As an FDP synthase, PcIDS1 could be associated with the formation of sesquiterpenes, such as juvenile hormones. Detection of Co(2+), Mn(2+), or Mg(2+) in the beetle larvae suggests flux control into C(10) vs. C(15) isoprenoids could be accomplished by these ions in vivo. The dependence of product chain length of scIDSs on metal cofactor identity introduces an additional regulation for these branch point enzymes of terpene metabolism.
  Proceedings of the National Academy of Sciences 02/2013; · 9.68 Impact Factor
• Article: Localization of sesquiterpene formation and emission in maize leaves after herbivore damage.

  Tobias G Köllner, Claudia Lenk, Christiane Schnee, Sabrina Köpke, Peter Lindemann, Jonathan Gershenzon, Jörg Degenhardt
  [show abstract] [hide abstract]
  ABSTRACT: BACKGROUND: Maize (Zea mays L.) leaves damaged by lepidopteran herbivores emit a complex volatile blend that can attract natural enemies of the herbivores and may also have roles in direct defense and inter- or intra-plant signaling. The volatile blend is dominated by sesquiterpenes of which the majority is produced by two herbivore-induced terpene synthases, TPS10 and TPS23. However, little is known about the pattern of volatile emission within maize leaves. RESULTS: In this study, we restricted herbivore feeding to small sections of the maize leaf with the aim of determining the patterns of volatile sesquiterpene emission throughout the damaged leaf and in neighboring leaves. Sesquiterpene volatiles were released at high rates from damaged leaves, but at much lower rates from neighboring leaves. Release was restricted to the site of damage or to leaf sections located apical to the damage, but was not seen in sections basal to the damage or on the other side of the midrib. The emission pattern correlated well with the transcript pattern of the respective sesquiterpene synthase genes, tps10 and tps23, implying that biosynthesis likely occurs at the site of emission. The concentrations of jasmonic acid and its leucine derivative were also elevated in terpene-emitting tissues suggesting a role for jasmonates in propagating the damage signal. CONCLUSIONS: In contrast to other defense reactions which often occur systemically throughout the whole plant, herbivore-induced sesquiterpene production in maize is restricted to the wounding site and distal leaf parts. Since the signal mediating this reaction is directed to the leaf tip and cannot propagate parallel to the leaf axis, it is likely connected to the xylem. The increasing gradient of volatiles from the tip of the leaf towards the damage site might aid herbivore enemies in host or prey finding.
  BMC Plant Biology 01/2013; 13(1):15. · 3.45 Impact Factor
• Source

  Available from: Ricarda Jost

  Dataset: Kruse et al 2012 J Plant Phys 169(7)

  Cordula Kruse, Florian H Haas, Ricarda Jost, Bianca Reiser, Michael Reichelt, Markus Wirtz, Jonathan Gershenzon, Ewald Schnug, Rüdiger Hell
• Article: Interaction of glucosinolate content of Arabidopsis thaliana mutant lines and feeding and oviposition by generalist and specialist lepidopterans.

  Francisco R Badenes-Perez, Michael Reichelt, Jonathan Gershenzon, David G Heckel
  [show abstract] [hide abstract]
  ABSTRACT: The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is an insect specialized on glucosinolate-containing Brassicaceae that uses glucosinolates in host-plant recognition. We used wild-type and mutants of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) to investigate the interaction between plant glucosinolate and myrosinase content and herbivory by larvae of the generalist Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) and the specialist P. xylostella. We also measured glucosinolate changes as a result of herbivory by these larvae to investigate whether herbivory and glucosinolate induction had an effect on oviposition preference by P. xylostella. Feeding by H. armigera and P. xylostella larvae was 2.1 and 2.5 times less, respectively, on apk1 apk2 plants (with almost no aliphatic glucosinolates) than on wild-type plants. However, there were no differences in feeding by H. armigera and P. xylostella larvae on wild-type, gsm1 (different concentrations of aliphatic glucosinolates compared to wild-type plants), and tgg1 tgg2 plants (lacking major myrosinases). Glucosinolate induction (up to twofold) as a result of herbivory occurred in some cases, depending on both the plant line and the herbivore. For H. armigera, induction, when observed, was noted mostly for indolic glucosinolates, while for P. xylostella, induction was observed in both aliphatic and indolic glucosinolates, but not in all plant lines. For H. armigera, glucosinolate induction, when observed, resulted in an increase of glucosinolate content, while for P. xylostella, induction resulted in both a decrease and an increase in glucosinolate content. Two-choice tests with wild-type and mutant plants were conducted with larvae and ovipositing moths. There were no significant differences in preference of larvae and ovipositing moths between wild-type and gsm1 mutants and between wild-type and tgg1 tgg2 mutants. However, both larvae and ovipositing moths preferred wild-type over apk1 apk2 mutants. Two-choice oviposition tests were also conducted with P. xylostella moths comparing undamaged plants to plants being attacked by larvae of either P. xylostella or H. armigera. Oviposition preference by P. xylostella was unaffected as a result of larval plant damage, even in the cases where herbivory resulted in glucosinolate induction.
  Phytochemistry 12/2012; · 3.35 Impact Factor
• Article: Localization of Phenolics in Phloem Parenchyma Cells of Norway Spruce (Picea abies).

  Sheng-Hong Li, Nina Elisabeth Nagy, Almuth Hammerbacher, Paal Krokene, Xue-Mei Niu, Jonathan Gershenzon, Bernd Schneider
  [show abstract] [hide abstract]
  ABSTRACT: Norway spruce (Picea abies) bark contains specialized phloem parenchyma cells that swell and change their contents upon attack by the bark beetle Ips typographus and its microbial associate, the blue stain fungus Ceratocystis polonica. These cells exhibit bright autofluorescence after treatment with standard aldehyde fixatives, and so have been postulated to contain phenolic compounds. Laser microdissection of spruce bark sections combined with cryogenic NMR spectroscopy demonstrated significantly higher concentrations of the stilbene glucoside astringin in phloem parenchyma cells than in adjacent sieve cells. After infection by C. polonica, the flavonoid (+)-catechin also appeared in phloem parenchyma cells and there was a decrease in astringin content compared to cells from uninfected trees. Analysis of whole-bark extracts confirmed the results obtained from the cell extracts and revealed a significant increase in dimeric stilbene glucosides, both astringin and isorhapontin derivatives (piceasides A to H), in fungus-infected versus uninfected bark that might explain the reduction in stilbene monomers. Phloem parenchyma cells thus appear to be a principal site of phenolic accumulation in spruce bark.
  ChemBioChem 11/2012; · 3.94 Impact Factor
• Article: The biosynthesis of hydroxycinnamoyl quinate esters and their role in the storage of cocaine in Erythroxylum coca.

  José Carlos Pardo Torre, Gregor W Schmidt, Christian Paetz, Michael Reichelt, Bernd Schneider, Jonathan Gershenzon, John C D'Auria
  [show abstract] [hide abstract]
  ABSTRACT: Complexation of alkaloids is an important strategy plants utilize to facilitate storage in vacuoles and avoid autotoxicity. Previous studies have implicated hydroxycinnamoyl quinate esters in the complexation of purine alkaloids in Coffea arabica. The goal of this study was to determine if Erythroxylum coca uses similar complexation agents to store abundant tropane alkaloids, such as cocaine and cinnamoyl cocaine. Metabolite analysis of various E. coca organs established a close correlation between levels of coca alkaloids and those of two hydroxycinnamoyl esters of quinic acid, chlorogenic acid and 4-coumaroyl quinate. The BAHD acyltransferase catalyzing the final step in hydroxycinnamoyl quinate biosynthesis was isolated and characterized, and its gene expression found to correlate with tropane alkaloid accumulation. A physical interaction between chlorogenic acid and cocaine was observed and quantified in vitro using UV and NMR spectroscopic methods yielding similar values to those reported for a caffeine chlorogenate complex in C. arabica. These results suggest that storage of cocaine and other coca alkaloids in large quantities in E. coca involves hydroxycinnamoyl quinate esters as complexation partners.
  Phytochemistry 10/2012; · 3.35 Impact Factor
• Article: A Gain-of-Function Polymorphism Controlling Complex Traits and Fitness in Nature

  Kasavajhala V. S. K. Prasad, Bao-Hua Song, Carrie Olson-Manning, Jill T. Anderson, Cheng-Ruei Lee, M. Eric Schranz, Aaron J. Windsor, Maria J. Clauss, Antonio J. Manzaneda, Ibtehaj Naqvi, Michael Reichelt, Jonathan Gershenzon, Sanjeewa G. Rupasinghe, Mary A. Schuler, Thomas Mitchell-Olds
  [show abstract] [hide abstract]
  ABSTRACT: Identification of the causal genes that control complex trait variation remains challenging, limiting our appreciation of the evolutionary processes that influence polymorphisms in nature. We cloned a quantitative trait locus that controls plant defensive chemistry, damage by insect herbivores, survival, and reproduction in the natural environments where this polymorphism evolved. These ecological effects are driven by duplications in the BCMA (branched-chain methionine allocation) loci controlling this variation and by two selectively favored amino acid changes in the glucosinolate-biosynthetic cytochrome P450 proteins that they encode. These changes cause a gain of novel enzyme function, modulated by allelic differences in catalytic rate and gene copy number. Ecological interactions in diverse environments likely contribute to the widespread polymorphism of this biochemical function.
  Science 08/2012; 337(6098):1081-1084. · 31.20 Impact Factor
• Article: The organ-specific expression of terpene synthase genes contributes to the terpene hydrocarbon composition of chamomile essential oils.

  Sandra Irmisch, Sandra T Krause, Grit Kunert, Jonathan Gershenzon, Jörg Degenhardt, Tobias G Köllner
  [show abstract] [hide abstract]
  ABSTRACT: The essential oil of chamomile, one of the oldest and agronomically most important medicinal plant species in Europe, has significant antiphlogistic, spasmolytic and antimicrobial activities. It is rich in chamazulene, a pharmaceutically active compound spontaneously formed during steam distillation from the sesquiterpene lactone matricine. Chamomile oil also contains sesquiterpene alcohols and hydrocarbons which are produced by the action of terpene synthases (TPS), the key enzymes in constructing terpene carbon skeletons. Here, we present the identification and characterization of five TPS enzymes contributing to terpene biosynthesis in chamomile (Matricaria recutita). Four of these enzymes were exclusively expressed in above-ground organs and produced the common terpene hydrocarbons (-)-(E)-β-caryophyllene (MrTPS1), (+)-germacrene A (MrTPS3), (E)-β-ocimene (MrTPS4) and (-)-germacrene D (MrTPS5). A fifth TPS, the multiproduct enzyme MrTPS2, was mainly expressed in roots and formed several Asteraceae-specific tricyclic sesquiterpenes with (-)-α-isocomene being the major product. The TPS transcript accumulation patterns in different organs of chamomile were consistent with the abundance of the corresponding TPS products isolated from these organs suggesting that the spatial regulation of TPS gene expression qualitatively contribute to terpene composition. The terpene synthases characterized in this study are involved in the organ-specific formation of essential oils in chamomile. While the products of MrTPS1, MrTPS2, MrTPS4 and MrTPS5 accumulate in the oils without further chemical alterations, (+)-germacrene A produced by MrTPS3 accumulates only in trace amounts, indicating that it is converted into another compound like matricine. Thus, MrTPS3, but also the other TPS genes, are good markers for further breeding of chamomile cultivars rich in pharmaceutically active essential oils.
  BMC Plant Biology 06/2012; 12:84. · 3.45 Impact Factor
• Article: CML42-mediated calcium signaling coordinates responses to Spodoptera herbivory and abiotic stresses in Arabidopsis.

  Jyothilakshmi Vadassery, Michael Reichelt, Bettina Hause, Jonathan Gershenzon, Wilhelm Boland, Axel Mithöfer
  [show abstract] [hide abstract]
  ABSTRACT: In the interaction between Arabidopsis (Arabidopsis thaliana) and the generalist herbivorous insect Spodoptera littoralis, little is known about early events in defense signaling and their link to downstream phytohormone pathways. S. littoralis oral secretions induced both Ca²⁺ and phytohormone elevation in Arabidopsis. Plant gene expression induced by oral secretions revealed up-regulation of a gene encoding a calmodulin-like protein, CML42. Functional analysis of cml42 plants revealed more resistance to herbivory than in the wild type, because caterpillars gain less weight on the mutant, indicating that CML42 negatively regulates plant defense; cml42 also showed increased aliphatic glucosinolate content and hyperactivated transcript accumulation of the jasmonic acid (JA)-responsive genes VSP2 and Thi2.1 upon herbivory, which might contribute to increased resistance. CML42 up-regulation is negatively regulated by the jasmonate receptor Coronatine Insensitive1 (COI1), as loss of functional COI1 resulted in prolonged CML42 activation. CML42 thus acts as a negative regulator of plant defense by decreasing COI1-mediated JA sensitivity and the expression of JA-responsive genes and is independent of herbivory-induced JA biosynthesis. JA-induced Ca²⁺ elevation and root growth inhibition were more sensitive in cml42, also indicating higher JA perception. Our results indicate that CML42 acts as a crucial signaling component connecting Ca²⁺ and JA signaling. CML42 is localized to cytosol and nucleus. CML42 is also involved in abiotic stress responses, as kaempferol glycosides were down-regulated in cml42, and impaired in ultraviolet B resistance. Under drought stress, the level of abscisic acid accumulation was higher in cml42 plants. Thus, CML42 might serve as a Ca²⁺ sensor having multiple functions in insect herbivory defense and abiotic stress responses.
  Plant physiology 05/2012; 159(3):1159-75. · 6.53 Impact Factor
• Article: Molecular Regulation of Induced Terpenoid Biosynthesis in Conifers

  Michael A. Phillips, Jörg Bohlmann, Jonathan Gershenzon
  [show abstract] [hide abstract]
  ABSTRACT: Conifers have evolved elaborate inducible, terpenoid-based defense mechanisms to deter attacks from bark beetles and other herbivore species. Herbivore damage triggers the production of oleoresin containing monoterpene, sesquiterpene and diterpene components that serve as toxins and physical barriers to herbivore invasion. Induced terpene formation appears to be regulated by specific enzymes of terpene metabolism whose activity increases on herbivore damage. Among the best studied of these are terpene synthases, enzymes which convert acyclic prenyl diphosphates to the parent terpene skeletons. Terpene synthase activity in turn is regulated by the transcription of terpene synthase genes. Induced terpene biosynthesis is also often accompanied by extensive cellular differentiation, including the formation of new resin ducts. The signal transduction cascades that initiate these shifts in conifer metabolism and cell differentiation are poorly understood due to the lack of well-developed model systems and appropriate genetic mutants. However, there are strong indications that octadecanoid pathway metabolites and ethylene have roles in this signaling, as they do in defense signaling in angiosperms. There are still large gaps in our knowledge of the signal transduction networks leading to herbivore-induced terpenoid accumulation in conifers. However, the development of new genomic, proteomic and metabolomic tools, as well as the establishment of convenient in vitro systems should facilitate more rapid advances in this field in the near future. The results will have important implications for understanding the evolution of conifer defense mechanisms as well as for the management of commercially important forest tree species, such as spruce, pine, and fir.
  Phytochemistry Reviews 04/2012; 5(1):179-189. · 4.33 Impact Factor
• Article: Evaluation of Candidate Reference Genes for Real-Time Quantitative PCR of Plant Samples Using Purified cDNA as Template

  Michael A. Phillips, John C. D’Auria, Katrin Luck, Jonathan Gershenzon
  [show abstract] [hide abstract]
  ABSTRACT: Quantitative real-time polymerase chain reaction (qRT-PCR) is a precise method to measure changes in gene transcript level. Accurate quantification requires careful RNA quality assessment, determination of primer efficiency, and selection of an appropriate reference gene. While many experimental procedures for these purposes have been described for mammalian samples, the direct application of these methods to plant samples often introduces unexpected experimental errors due to the complex and variable nature of the ribosomal RNA species present in typical plant extracts. In this paper, we report a simple procedure for the purification and quantification of complementary DNA (cDNA) after reverse transcriptase reactions by microcapillary electrophoresis. The use of purified cDNA allows template concentrations to be more accurately standardized for SYBR Green PCR reactions and increases amplification efficiencies so that these closely resemble those determined by the standard curve method. These advantages facilitate a more precise evaluation of the transcript levels of candidate reference genes under various experimental conditions without bias from differences in reverse transcriptase efficiency, template loading, or the presence of PCR inhibitors following reverse transcription. Using samples from Arabidopsis thaliana and Picea abies (Norway spruce), we demonstrate the value of this approach for selecting reference genes.
  Plant Molecular Biology Reporter 04/2012; 27(3):407-416. · 2.45 Impact Factor
• Source

  Available from: mpg.de

  Article: Herbivore induction of the glucosinolate–myrosinase defense system: major trends, biochemical bases and ecological significance

  Susanne Textor, Jonathan Gershenzon
  [show abstract] [hide abstract]
  ABSTRACT: Like many other plant defense compounds, glucosinolates are present constitutively in plant tissues, but are also induced to higher levels by herbivore attack. Of the major glucosinolate types, indolic glucosinolates are most frequently induced regardless of the type of herbivore involved. Over 90% of previous studies found that herbivore damage to glucosinolate-containing plants led to an increased accumulation of indolic glucosinolates at levels ranging up to 20-fold. Aliphatic and aromatic glucosinolates are also commonly induced by herbivores, though usually at much lower magnitudes than indolic glucosinolates, and aliphatic and aromatic glucosinolates may even undergo declines following herbivory. The glucosinolate defense system also requires another partner, the enzyme myrosinase, to hydrolyze the parent glucosinolates into biologically active derivatives. Much less is known about myrosinase induction after herbivory compared to glucosinolate induction, and no general trends are evident. However, it is clear that insect feeding stimulates the formation of various myrosinase associated proteins whose function is not yet understood. The biochemical mechanism of glucosinolate induction involves a jasmonate signaling cascade that leads eventually to increases in the transcript levels of glucosinolate biosynthetic genes. Several recently described transcription factors controlling glucosinolate biosynthesis are activated by herbivory or wounding. Herbivore induction of glucosinolates has sometimes been demonstrated to increase protection against subsequent herbivore attack, but more research is needed to evaluate the costs and benefits of this phenomenon.
  Phytochemistry Reviews 04/2012; 8(1):149-170. · 4.33 Impact Factor
• Article: The specificity of herbivore-induced plant volatiles in attracting herbivore enemies.

  Andrea Clavijo McCormick, Sybille B Unsicker, Jonathan Gershenzon
  [show abstract] [hide abstract]
  ABSTRACT: Plants respond to herbivore attack by emitting complex mixtures of volatile compounds that attract herbivore enemies, both predators and parasitoids. Here, we explore whether these mixtures provide significant value as information cues in herbivore enemy attraction. Our survey indicates that blends of volatiles released from damaged plants are frequently specific depending on the type of herbivore and its age, abundance and feeding guild. The sensory perception of plant volatiles by herbivore enemies is also specific, according to the latest evidence from studies of insect olfaction. Thus, enemies do exploit the detailed information provided by plant volatile mixtures in searching for their prey or hosts, but this varies with the diet breadth of the enemy.
  Trends in Plant Science 04/2012; 17(5):303-10. · 11.05 Impact Factor
• Article: Inducibility of chemical defenses in Norway spruce bark is correlated with unsuccessful mass attacks by the spruce bark beetle.

  Christian Schiebe, Almuth Hammerbacher, Göran Birgersson, Johanna Witzell, Peter E Brodelius, Jonathan Gershenzon, Bill S Hansson, Paal Krokene, Fredrik Schlyter
  [show abstract] [hide abstract]
  ABSTRACT: Secondary attraction to aggregation pheromones plays a central role in the host colonization behavior of the European spruce bark beetle Ips typographus. However, it is largely unknown how the beetles pioneering an attack locate suitable host trees, and eventually accept or reject them. To find possible biomarkers for host choice by I. typographus, we analyzed the chemistry of 58 Norway spruce (Picea abies) trees that were subsequently either (1) successfully attacked and killed, (2) unsuccessfully attacked, or (3) left unattacked. The trees were sampled before the main beetle flight in a natural Norway spruce-dominated forest. No pheromones were used to attract beetles to the experimental trees. To test the trees' defense potential, each tree was treated in a local area with the defense hormone methyl jasmonate (MeJ), and treated and untreated bark were analyzed for 66 different compounds, including terpenes, phenolics and alkaloids. The chemistry of MeJ-treated bark correlated strongly with the success of I. typographus attack, revealing major chemical differences between killed trees and unsuccessfully attacked trees. Surviving trees produced significantly higher amounts of most of the 39 analyzed mono-, sesqui-, and diterpenes and of 4 of 20 phenolics. Alkaloids showed no clear pattern. Differences in untreated bark were less pronounced, where only 1,8-cineole and (-)-limonene were significantly higher in unsuccessfully attacked trees. Our results show that the potential of individual P. abies trees for inducing defense compounds upon I. typographus attack may partly determine tree resistance to this bark beetle by inhibiting its mass attack.
  Oecologia 03/2012; 170(1):183-98. · 3.41 Impact Factor
• Article: A single amino acid determines the site of deprotonation in the active center of sesquiterpene synthases SbTPS1 and SbTPS2 from Sorghum bicolor.

  Stefan Garms, Feng Chen, Wilhelm Boland, Jonathan Gershenzon, Tobias G Köllner
  [show abstract] [hide abstract]
  ABSTRACT: The multitude of terpene carbon skeletons found in nature is formed by enzymes known as terpene synthases (TPSs). These proteins are often multiproduct enzymes converting a single prenyl diphosphate substrate into a mixture of terpene products. The recently identified sesquiterpene synthases SbTPS1 and SbTPS2 from Sorghum bicolor produce terpene blends containing the same products, but in different proportions. A single amino acid in the active site was reported to determine the different product specificities of SbTPS1 and SbTPS2. In this study we examined the reaction mechanism of the Sorghum TPSs. Feeding experiments with deuterium-labeled substrates and chiral analysis of the enzyme products zingiberene, β-sesquiphellandrene and β-bisabolene revealed that the reactions catalyzed by both enzymes proceeded via (S)-nerolidyl diphosphate and the cyclic (6S)-bisabol-7-yl and (6R)-bisabol-1-yl cation intermediates. The site of deprotonation of the final cation was shown to be the only catalytic difference between SbTPS1 and SbTPS2. Docking of the (6R)-bisabol-1-yl cation into structural models of SbTPS1 and SbTPS2 indicated a potential role of initially cleaved pyrophosphate group as a proton acceptor.
  Phytochemistry 03/2012; 75:6-13. · 3.35 Impact Factor
• Article: Nonradioactive assay for detecting isoprenyl diphosphate synthase activity in crude plant extracts using liquid chromatography coupled with tandem mass spectrometry.

  Raimund Nagel, Jonathan Gershenzon, Axel Schmidt
  [show abstract] [hide abstract]
  ABSTRACT: Terpenoids form the largest class of plant metabolites involved in primary and secondary metabolism. Isoprenyl diphosphate synthases (IDSs) catalyze the condensation of the C(5) terpenoid building blocks, isopentenyl diphosphate and dimethylallyl diphosphate, to form geranyl diphosphate (C(10)), farnesyl diphosphate (C(15)), and geranylgeranyl diphosphate (C(20)). These branch point reactions control the flow of metabolites that act as precursors to each of the major terpene classes-monoterpenes, sequiterpenes, and diterpenes, respectively. Thus accurate and easily performed assays of IDS enzyme activity are critical to increase our knowledge about the regulation of terpene biosynthesis. Here we describe a new and sensitive nonradioactive method for carrying out IDS assays using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to detect the short-chain prenyl diphosphate products directly without dephosphorylation. Furthermore, we were able to separate cisoid and transoid isomers of both C(10) enzyme products (geranyl diphosphate and neryl diphosphate) and three C(15) products [(E,E)-, (Z,E)-, and (Z,Z)-farnesyl diphosphate]. By applying the method to crude protein extracts from various organs of Arabidopsis thaliana, Nicotiana attenuata, Populus trichocarpa, and Picea abies, we could determine their IDS activity in a reproducible fashion.
  Analytical Biochemistry 03/2012; 422(1):33-8. · 3.00 Impact Factor