Localization of phenolics in phloem parenchyma cells of Norway spruce (Picea abies).

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.

Learning from nature: new approaches to the metabolic engineering of plant defense pathways.

Biotechnological manipulation of plant defense pathways can increase crop resistance to herbivores and pathogens while also increasing yields of medicinal, industrial, flavor and fragrance compounds. The most successful achievements in engineering defense pathways can be attributed to researchers striving to imitate natural plant regulatory mechanisms. For example, the introduction of transcription factors that control several genes in one pathway is often a valuable strategy to increase flux in that pathway.

The biosynthesis of hydroxycinnamoyl quinate esters and their role in the storage of cocaine in Erythroxylum coca.

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.

A gain-of-function polymorphism controlling complex traits and fitness in nature.

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.

Nonseed plant Selaginella moellendorffi [corrected] has both seed plant and microbial types of terpene synthases.

Terpene synthases (TPSs) are pivotal enzymes for the biosynthesis of terpenoids, the largest class of secondary metabolites made by plants and other organisms. To understand the basis of the vast diversification of these enzymes in plants, we investigated Selaginella moellendorffi, [corrected] a nonseed vascular plant. The genome of this species was found to contain two distinct types of TPS genes.

Unique proline-benzoquinone pigment from the colored nectar of "bird's Coca cola tree" functions in bird attractions.

The major pigment responsible for the dark brown nectar of the "bird's Coca cola tree", Leucosceptrum canum (Labiatae), was isolated and identified as a unique symmetric proline-quinone conjugate, 2,5-di-(N-(-)-prolyl)-para-benzoquinone (DPBQ). Behavioral experiments with both isolated and synthetic authentic samples indicated that DPBQ functions mainly as a color attractant to bird pollinators.

An elm EST database for identifying leaf beetle egg-induced defense genes.

Background: Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor), egg laying by the elm leaf beetle ( Xanthogaleruca luteola) activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes.

The organ-specific expression of terpene synthase genes contributes to the terpene hydrocarbon composition of chamomile essential oils.

Background: 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.

Plant tropane alkaloid biosynthesis evolved independently in the Solanaceae and Erythroxylaceae.

The pharmacologically important tropane alkaloids have a scattered distribution among angiosperm families, like many other groups of secondary metabolites. To determine whether tropane alkaloids have evolved repeatedly in different lineages or arise from an ancestral pathway that has been lost in most lines, we investigated the tropinone-reduction step of their biosynthesis. In species of the Solanaceae, which produce compounds such as atropine and scopolamine, this reaction is known to be catalyzed by enzymes of the short-chain dehydrogenase/reductase family.

CML42-mediated calcium signaling coordinates responses to Spodoptera herbivory and abiotic stresses in Arabidopsis.

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.

The specificity of herbivore-induced plant volatiles in attracting herbivore enemies.

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.

Inducibility of chemical defenses in Norway spruce bark is correlated with unsuccessful mass attacks by the spruce bark beetle.

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.

Improved sulfur nutrition provides the basis for enhanced production of sulfur-containing defense compounds in Arabidopsis thaliana upon inoculation with Alternaria brassicicola.

The antifungal activities of many sulfur-containing defense compounds suggest a connection between pathogen infection, primary sulfur metabolism and sulfate nutritional status of plants. This relationship was investigated using Arabidopsis thaliana plants that were cultivated under different sulfur regimes and challenged by Alternaria brassicicola. Plants grown with 500 μM sulfate were significantly less infected compared to plants grown on 50 μM sulfate.

Expression pattern of the glucosinolate side chain biosynthetic genes MAM1 and MAM3 of Arabidopsis thaliana in different organs and developmental stages.

Aliphatic glucosinolates, secondary metabolites known to be involved in plant defence, make up the majority of the glucosinolate content of Arabidopsis thaliana, and their structural diversity arises in part from chain elongations of methionine before the formation of the glucosinolate core structure. The key enzymatic step in determining the length of the chain is the condensation of acetyl-coenzyme A with a series of ω-methylthio-2-oxoalkanoic acids, catalyzed by methylthioalkylmalate (MAM) synthases. The existence of two MAM synthases has been previously reported in A.

The first step in the biosynthesis of cocaine in Erythroxylum coca: the characterization of arginine and ornithine decarboxylases.

Despite the long history of cocaine use among humans and its social and economic significance today, little information is available about the biochemical and molecular aspects of cocaine biosynthesis in coca (Erythroxylum coca) in comparison to what is known about the formation of other pharmacologically-important tropane alkaloids in species of the Solanaceae. In this work, we investigated the site of cocaine biosynthesis in E. coca and the nature of the first step.

Nonradioactive assay for detecting isoprenyl diphosphate synthase activity in crude plant extracts using liquid chromatography coupled with tandem mass spectrometry.

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.

A single amino acid determines the site of deprotonation in the active center of sesquiterpene synthases SbTPS1 and SbTPS2 from Sorghum bicolor.

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.

Metabolism of glucosinolate-derived isothiocyanates to glutathione conjugates in generalist lepidopteran herbivores.

The defensive properties of the glucosinolate-myrosinase system in plants of the order Brassicales have been attributed to the formation of toxic isothiocyanates generated upon tissue damage. Lepidopteran herbivores specialised on brassicaceous plants have been shown to possess biochemical mechanisms preventing the formation of isothiocyanates. Yet, no such mechanisms are known for generalist lepidopterans which also occasionally but successfully feed on plants of the Brassicales.

The major volatile organic compound emitted from Arabidopsis thaliana flowers, the sesquiterpene (E)-β-caryophyllene, is a defense against a bacterial pathogen.

Flowers have a high risk of pathogen attack because of their rich nutrient and moisture content, and high frequency of insect visitors. We investigated the role of (E)-β-caryophyllene in floral defense against a microbial pathogen. This sesquiterpene is a common volatile compound emitted from flowers, and is a major volatile released from the stigma of Arabidopsis thaliana flowers.

Plant community diversity influences allocation to direct chemical defence in Plantago lanceolata.

Background: Forecasting the consequences of accelerating rates of changes in biodiversity for ecosystem functioning requires a mechanistic understanding of the relationships between the structure of biological communities and variation in plant functional characteristics. So far, experimental data of how plant species diversity influences the investment of individual plants in direct chemical defences against herbivores and pathogens is lacking.

Methodology/principal Findings: We used Plantago lanceolata as a model species in experimental grasslands differing in species richness and composition (Jena Experiment) to investigate foliar concentrations of the iridoid glycosides (IG), catalpol and its biosynthetic precursor aucubin.

Floral odor bouquet loses its ant repellent properties after inhibition of terpene biosynthesis.

In their natural environment, plants are synchronously confronted with mutualists and antagonists, and thus benefit from signals that contain messages for both functional groups of interaction partners. Floral scents are complex blends of volatiles of different chemical classes, including benzenoids and terpenoids. It has been hypothesized that benzenoids have evolved as pollinator attracting signals, while monoterpenoids serve as defensive compounds against antagonists.

Genetic evidence for natural product-mediated plant-plant allelopathy in rice (Oryza sativa).

• There is controversy as to whether specific natural products play a role in directly mediating antagonistic plant-plant interactions - that is, allelopathy. If proved to exist, such phenomena would hold considerable promise for agronomic improvement of staple food crops such as rice (Oryza sativa). • However, while substantiated by the presence of phytotoxic compounds at potentially relevant concentrations, demonstrating a direct role for specific natural products in allelopathy has been difficult because of the chemical complexity of root and plant litter exudates.

Induction of isoprenyl diphosphate synthases, plant hormones and defense signalling genes correlates with traumatic resin duct formation in Norway spruce (Picea abies).

Norway spruce (Picea abies) defends itself against herbivores and pathogens by formation of traumatic resin ducts filled with terpenoid-based oleoresin. An important group of enzymes in terpenoid biosynthesis are the short-chain isoprenyl diphosphate synthases which produce geranyl diphosphate (C(10)), farnesyl diphosphate (C(15)), and geranylgeranyl diphosphate (C(20)) as precursors of monoterpenes, sesquiterpenes, and diterpene resin acids, respectively. After treatment with methyl jasmonate (MJ) we investigated the expression of all isoprenyl diphosphate synthase genes characterized to date from Norway spruce and correlated this with formation of traumatic resin ducts and terpene accumulation.

Metabolic detoxification of capsaicin by UDP-glycosyltransferase in three Helicoverpa species.

Capsaicin β-glucoside was isolated from the feces of Helicoverpa armigera, Helicoverpa assulta, and Helicoverpa zea that fed on capsaicin-supplemented artificial diet. The chemical structure was identified by NMR spectroscopic analysis as well as by enzymatic hydrolysis. The excretion rates of the glucoside were different among the three species; those in the two generalists, H.

The MAP kinase MpkA controls cell wall integrity, oxidative stress response, gliotoxin production and iron adaptation in Aspergillus fumigatus.

The saprophytic fungus Aspergillus fumigatus is the most important air-borne fungal pathogen. The cell wall of A. fumigatus has been studied intensively as a potential target for development of effective antifungal agents.