Cortico-cortical transfer of socially derived information gates emotion recognition.

Emotion recognition and the resulting responses are important for survival and social functioning. However, how socially derived information is processed for reliable emotion recognition is incompletely understood. Here, we reveal an evolutionarily conserved long-range inhibitory/excitatory brain network mediating these socio-cognitive processes. Anatomical tracing in mice revealed the existence of a subpopulation of somatostatin (SOM) GABAergic neurons projecting from the medial prefrontal cortex (mPFC) to the retrosplenial cortex (RSC). Through optogenetic manipulations and Ca2+ imaging fiber photometry in mice and functional imaging in humans, we demonstrate the specific participation of these long-range SOM projections from the mPFC to the RSC, and an excitatory feedback loop from the RSC to the mPFC, in emotion recognition. Notably, we show that mPFC-to-RSC SOM projections are dysfunctional in mouse models relevant to psychiatric vulnerability and can be targeted to rescue emotion recognition deficits in these mice. Our findings demonstrate a cortico-cortical circuit underlying emotion recognition.

Shank3 deficits in the anteromedial bed nucleus of the stria terminalis trigger an anxiety phenotype in mice.

Anxiety disorders are the most prevalent co-morbidity factor associated with the core domains of autism spectrum disorders (ASD). Investigations on potential common neuronal mechanisms that may explain the co-occurrence of ASD and anxiety disorders are still poorly explored. One of the key questions that remained unsolved is the role of Shank3 protein in anxiety behaviours. Firstly, we characterize the developmental trajectories of locomotor, social behaviour and anxiety traits in a mouse model of ASD. We highlight that the anxiety phenotype is a late-onset emerging phenotype in mice with a Shank3Δe4-22 mutation. Consequently, we used an shRNA strategy to model Shank3 insufficiency in the bed nucleus of the stria terminalis (BNST), a brain region exerting a powerful control on anxiety level. We found that Shank3 downregulation in the anteromedial BNST (amBNST) induced anxiogenic effects and enhanced social avoidance after aversive social defeat. Associated with these behavioural defects, we showed alteration of glutamatergic synaptic functions in the amBNST induced by Shank3 insufficiency during adolescence. Our data strongly support the role of Shank3 in the maturation of amBNST, and its key role in anxiety control. Our results may further help to pave the road on a better understanding of the neuronal mechanisms underlying anxiety disorders implicated in ASDs.

Reciprocal cortico-amygdala connections regulate prosocial and selfish choices in mice.

Decisions that favor one's own interest versus the interest of another individual depend on context and the relationships between individuals. The neurobiology underlying selfish choices or choices that benefit others is not understood. We developed a two-choice social decision-making task in which mice can decide whether to share a reward with their conspecifics. Preference for altruistic choices was modulated by familiarity, sex, social contact, hunger, hierarchical status and emotional state matching. Fiber photometry recordings and chemogenetic manipulations demonstrated that basolateral amygdala (BLA) neurons are involved in the establishment of prosocial decisions. In particular, BLA neurons projecting to the prelimbic (PL) region of the prefrontal cortex mediated the development of a preference for altruistic choices, whereas PL projections to the BLA modulated self-interest motives for decision-making. This provides a neurobiological model of altruistic and selfish choices with relevance to pathologies associated with dysfunctions in social decision-making.

Dysbindin-1A modulation of astrocytic dopamine and basal ganglia dependent behaviors relevant to schizophrenia.

The mechanisms underlying the dichotomic cortical/basal ganglia dopaminergic abnormalities in schizophrenia are unclear. Astrocytes are important non-neuronal modulators of brain circuits, but their role in dopaminergic system remains poorly explored. Microarray analyses, immunohistochemistry, and two-photon laser scanning microscopy revealed that Dys1 hypofunction increases the reactivity of astrocytes, which express only the Dys1A isoform. Notably, behavioral and electrochemical assessments in mice selectively lacking the Dys1A isoform unraveled a more prominent impact of Dys1A in behavioral and dopaminergic/D2 alterations related to basal ganglia, but not cortical functioning. Ex vivo electron microscopy and protein expression analyses indicated that selective Dys1A disruption might alter intracellular trafficking in astrocytes, but not in neurons. In agreement, Dys1A disruption only in astrocytes resulted in decreased motivation and sensorimotor gating deficits, increased astrocytic dopamine D2 receptors and decreased dopaminergic tone within basal ganglia. These processes might have clinical relevance because the caudate, but not the cortex, of patients with schizophrenia shows a reduction of the Dys1A isoform. Therefore, we started to show a hitherto unknown role for the Dys1A isoform in astrocytic-related modulation of basal ganglia behavioral and dopaminergic phenotypes, with relevance to schizophrenia.

Basolateral amygdala activation enhances object recognition memory by inhibiting anterior insular cortex activity.

Noradrenergic activation of the basolateral amygdala (BLA) by emotional arousal enhances different forms of recognition memory via functional interactions with the insular cortex (IC). Human neuroimaging studies have revealed that the anterior IC (aIC), as part of the salience network, is dynamically regulated during arousing situations. Emotional stimulation first rapidly increases aIC activity but suppresses it in a delayed fashion. Here, we investigated in male Sprague-Dawley rats whether the BLA influence on recognition memory is associated with an increase or suppression of aIC activity during the postlearning consolidation period. We first employed anterograde and retrograde viral tracing and found that the BLA sends dense monosynaptic projections to the aIC. Memory-enhancing norepinephrine administration into the BLA following an object training experience suppressed aIC activity 1 h later, as determined by a reduced expression of the phosphorylated form of the transcription factor cAMP response element-binding (pCREB) protein and neuronal activity marker c-Fos. In contrast, the number of perisomatic γ-aminobutyric acid (GABA)ergic inhibitory synapses per pCREB-positive neuron was significantly increased, suggesting a dynamic up-regulation of GABAergic tone. In support of this possibility, pharmacological inhibition of aIC activity with a GABAergic agonist during consolidation enhanced object recognition memory. Norepinephrine administration into the BLA did not affect neuronal activity within the posterior IC, which receives sparse innervation from the BLA. The evidence that noradrenergic activation of the BLA enhances the consolidation of object recognition memory via a mechanism involving a suppression of aIC activity provides insight into the broader brain network dynamics underlying emotional regulation of memory.

Oxytocin Discrepancies in Social Dynamics.

Social group dynamics are highly complex. In this issue of Neuron, Anpilov et al. use a novel wireless optogenetic device to demonstrate that the repeated stimulation of oxytocin neurons modulates pro-social and agonistic behaviors in a time- and context-dependent manner.

Somatostatin interneurons in the prefrontal cortex control affective state discrimination in mice.

The prefrontal cortex (PFC) is implicated in processing of the affective state of others through non-verbal communication. This social cognitive function is thought to rely on an intact cortical neuronal excitatory and inhibitory balance. Here combining in vivo electrophysiology with a behavioral task for affective state discrimination in mice, we show a differential activation of medial PFC (mPFC) neurons during social exploration that depends on the affective state of the conspecific. Optogenetic manipulations revealed a double dissociation between the role of interneurons in social cognition. Specifically, inhibition of mPFC somatostatin (SOM+), but not of parvalbumin (PV+) interneurons, abolishes affective state discrimination. Accordingly, synchronized activation of mPFC SOM+ interneurons selectively induces social discrimination. As visualized by in vivo single-cell microendoscopic Ca2+ imaging, an increased synchronous activity of mPFC SOM+ interneurons, guiding inhibition of pyramidal neurons, is associated with affective state discrimination. Our findings provide new insights into the neurobiological mechanisms of affective state discrimination.

Oxytocin Signaling in the Central Amygdala Modulates Emotion Discrimination in Mice.

Recognition of other's emotions influences the way social animals interact and adapt to the environment. The neuropeptide oxytocin (OXT) has been implicated in different aspects of emotion processing. However, the role of endogenous OXT brain pathways in the social response to different emotional states in conspecifics remains elusive. Here, using a combination of anatomical, genetic, and chemogenetic approaches, we investigated the contribution of endogenous OXT signaling in the ability of mice to discriminate unfamiliar conspecifics based on their emotional states. We found that OXTergic projections from the paraventricular nucleus of the hypothalamus (PVN) to the central amygdala (CeA) are crucial for the discrimination of both positively and negatively valenced emotional states. In contrast, blocking PVN OXT release into the nucleus accumbens, prefrontal cortex, and hippocampal CA2 did not alter this emotion discrimination. Furthermore, silencing each of these PVN OXT pathways did not influence basic social interaction. These findings were further supported by the demonstration that virally mediated enhancement of OXT signaling within the CeA was sufficient to rescue emotion discrimination deficits in a genetic mouse model of cognitive liability. Our results indicate that CeA OXT signaling plays a key role in emotion discrimination both in physiological and pathological conditions.

The Dopamine D5 Receptor Is Involved in Working Memory.

Pharmacological studies indicate that dopamine D1-like receptors (D1 and D5) are critically involved in cognitive function. However, the lack of pharmacological ligands selective for either the D1 or D5 receptors has made it difficult to determine the unique contributions of the D1-like family members. To circumvent these pharmacological limitations, we used D5 receptor homozygous (-/-) and heterozygous (+/-) knockout mice, to identify the specific role of this receptor in higher order cognitive functions. We identified a novel role for D5 receptors in the regulation of spatial working memory and temporal order memory function. The D5 mutant mice acquired a discrete paired-trial variable-delay T-maze task at normal rates. However, both [Formula: see text] and [Formula: see text] mice exhibited impaired performance compared to [Formula: see text] littermates when a higher burden on working memory faculties was imposed. In a temporal order object recognition task, [Formula: see text] exhibited significant memory deficits. No D5-dependent differences in locomotor functions and interest in exploring objects were evident. Molecular biomarkers of dopaminergic functions within the prefrontal cortex (PFC) revealed a selective gene-dose effect on Akt phosphorylation at Ser473 with increased levels in [Formula: see text] knockout mice. A trend toward reduced levels in CaMKKbeta brain-specific band (64 kDa) in [Formula: see text] compared to [Formula: see text] was also evident. These findings highlight a previously unidentified role for D5 receptors in working memory function and associated molecular signatures within the PFC.

Progression of motor deficits in glioma-bearing mice: impact of CNF1 therapy at symptomatic stages.

Glioblastoma (GBM) is the most aggressive type of brain tumor. In this context, animal models represent excellent tools for the early detection and longitudinal mapping of neuronal dysfunction, that are critical in the preclinical validation of new therapeutic strategies. In a mouse glioma model, we developed sensitive behavioral readouts that allow early recognizing and following neurological symptoms. We injected GL261 cells into the primary motor cortex of syngenic mice and we used a battery of behavioral tests to longitudinally monitor the dysfunction induced by tumor growth. Grip strength test revealed an early onset of functional deficit associated to the glioma growth, with a significant forelimb weakness appearing 9 days after tumor inoculation. A later deficit was observed in the rotarod and in the grid walk tasks. Using this model, we found reduced tumor growth and maintenance of behavioral functions following treatment with Cytotoxic Necrotizing Factor 1 (CNF1) at a symptomatic stage. Our data provide a detailed and precise examination of how tumor growth reverberates on the behavioral functions of glioma-bearing mice, providing normative data for the study of therapeutic strategies for glioma treatment. The reduced tumor volume and robust functional sparing observed in CNF1-treated, glioma-bearing mice strengthen the notion that CNF1 delivery is a promising strategy for glioma therapy.

NMR spectroscopy and chemometrics as a tool for anti-TNFα activity screening in crude extracts of grapes and other berries.

The identification of active ingredients in crude plant extracts offers great advantages. In this study, nuclear magnetic resonance and chemometrics were used for the screening of in vitro anti-TNFα activity in different berry types. Solid phase extraction was applied and the resulting water, methanol-water (1:1), and methanol fractions were tested for the activity. The methanol-water fraction contained most of the phenolics and showed significantly higher activity than the other two fractions. In the second phase of this study, grapes from 'Trincadeira', 'Touriga Nacional', and 'Aragonês', at four developmental stages were metabolically classified and tested for the TNFα inhibition. The initial stages of grape development, green and veraison, were found more active against TNFα production as compared to the later ripe and harvest stages. Among the cultivars, 'Touriga Nacional' was found to be the most potent inhibitor. Different multivariate data analyses algorithms based on projections to latent structures were applied to correlate the NMR and TNFα inhibition data. The variable importance in the projections plot showed that phenolics like quercetin, myricetin, (+)-catechin, (-)-epicatechin, caftarate, and coutarate, were positively correlated with high activity. This work demonstrates the great potential of NMR spectroscopy in combination with chemometrics for the screening of large set of crude extracts, to study the effects of different variables on the activity, and identifying active compounds in complex mixtures like plant extracts. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-012-0406-8) contains supplementary material, which is available to authorized users.

Alterations in grapevine leaf metabolism upon inoculation with Plasmopara viticola in different time-points.

Grapevines are easily infected by plant pathogens. It was found that resistant grapevines induce a wide range of phenolics upon the pathogen-infection. In this study in order to gain insight into these processes in different time-points the metabolic changes during the interaction of two grapevine cultivars, 'Regent' (resistant) and 'Trincadeira' (susceptible), with the downy mildew pathogen (Plasmopara viticola) were investigated. Nuclear magnetic resonance (NMR) spectroscopy on leaf extracts was used at several time points after experimental inoculation. A wide range of metabolites were identified using various two-dimensional (2D)-NMR techniques. Multivariate data analysis characterized both the resistant and the susceptible cultivars and their response against the pathogen. Metabolites responsible for their discrimination were identified as a fertaric acid, caftaric acid, quercetin-3-O-glucoside, linolenic acid, and alanine in the resistant cultivar 'Regent', while the susceptible 'Trincadeira' showed higher levels of glutamate, succinate, ascorbate and glucose. This study portrays the analytical capability of NMR spectroscopy and multivariate data analyses methods for the metabolic profiling of plant samples. The results obtained will underline the role of phenylpropanoids and flavonoids in resistance against biotic stresses which in turn provides a firm platform for the metabolic engineering of grapevine cultivars with higher resistance towards pathogens.

Transcript and metabolite analysis in Trincadeira cultivar reveals novel information regarding the dynamics of grape ripening.

BACKGROUND: Grapes (Vitis vinifera L.) are economically the most important fruit crop worldwide. However, the complexity of molecular and biochemical events that lead to the onset of ripening of nonclimacteric fruits is not fully understood which is further complicated in grapes due to seasonal and cultivar specific variation. The Portuguese wine variety Trincadeira gives rise to high quality wines but presents extremely irregular berry ripening among seasons probably due to high susceptibility to abiotic and biotic stresses. RESULTS: Ripening of Trincadeira grapes was studied taking into account the transcriptional and metabolic profilings complemented with biochemical data. The mRNA expression profiles of four time points spanning developmental stages from pea size green berries, through véraison and mature berries (EL 32, EL 34, EL 35 and EL 36) and in two seasons (2007 and 2008) were compared using the Affymetrix GrapeGen® genome array containing 23096 probesets corresponding to 18726 unique sequences. Over 50% of these probesets were significantly differentially expressed (1.5 fold) between at least two developmental stages. A common set of modulated transcripts corresponding to 5877 unigenes indicates the activation of common pathways between years despite the irregular development of Trincadeira grapes. These unigenes were assigned to the functional categories of "metabolism", "development", "cellular process", "diverse/miscellanenous functions", "regulation overview", "response to stimulus, stress", "signaling", "transport overview", "xenoprotein, transposable element" and "unknown". Quantitative RT-PCR validated microarrays results being carried out for eight selected genes and five developmental stages (EL 32, EL 34, EL 35, EL 36 and EL 38). Metabolic profiling using 1H NMR spectroscopy associated to two-dimensional techniques showed the importance of metabolites related to oxidative stress response, amino acid and sugar metabolism as well as secondary metabolism. These results were integrated with transcriptional profiling obtained using genome array to provide new information regarding the network of events leading to grape ripening. CONCLUSIONS: Altogether the data obtained provides the most extensive survey obtained so far for gene expression and metabolites accumulated during grape ripening. Moreover, it highlighted information obtained in a poorly known variety exhibiting particular characteristics that may be cultivar specific or dependent upon climatic conditions. Several genes were identified that had not been previously reported in the context of grape ripening namely genes involved in carbohydrate and amino acid metabolisms as well as in growth regulators; metabolism, epigenetic factors and signaling pathways. Some of these genes were annotated as receptors, transcription factors, and kinases and constitute good candidates for functional analysis in order to establish a model for ripening control of a non-climacteric fruit.

Pre-analytical method for NMR-based grape metabolic fingerprinting and chemometrics.

Although metabolomics aims at profiling all the metabolites in organisms, data quality is quite dependent on the pre-analytical methods employed. In order to evaluate current methods, different pre-analytical methods were compared and used for the metabolic profiling of grapevine as a model plant. Five grape cultivars from Portugal in combination with chemometrics were analyzed in this study. A common extraction method with deuterated water and methanol was found effective in the case of amino acids, organic acids, and sugars. For secondary metabolites like phenolics, solid phase extraction with C-18 cartridges showed good results. Principal component analysis, in combination with NMR spectroscopy, was applied and showed clear distinction among the cultivars. Primary metabolites such as choline, sucrose, and leucine were found discriminating for 'Alvarinho', while elevated levels of alanine, valine, and acetate were found in 'Arinto' (white varieties). Among the red cultivars, higher signals for citrate and GABA in 'Touriga Nacional', succinate and fumarate in 'Aragonês', and malate, ascorbate, fructose and glucose in 'Trincadeira', were observed. Based on the phenolic profile, 'Arinto' was found with higher levels of phenolics as compared to 'Alvarinho'. 'Trincadeira' showed lowest phenolics content while higher levels of flavonoids and phenylpropanoids were found in 'Aragonês' and 'Touriga Nacional', respectively. It is shown that the metabolite composition of the extract is highly affected by the extraction procedure and this consideration has to be taken in account for metabolomics studies.

Intralipid prevents and rescues fatal pulmonary arterial hypertension and right ventricular failure in rats.

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling leading to right ventricular (RV) hypertrophy and failure. Intralipid (ILP), a source of parenteral nutrition for patients, contains γ-linolenic acid and soy-derived phytoestrogens that are protective for lungs and heart. We, therefore, investigated the therapeutic potential of ILP in preventing and rescuing monocrotaline-induced PAH and RV dysfunction. PAH was induced in male rats with monocrotaline (60 mg/kg). Rats then received daily ILP (1 mL of 20% ILP per day IP) from day 1 to day 30 for prevention protocol or from day 21 to day 30 for rescue protocol. Other monocrotaline-injected rats were left untreated to develop severe PAH by day 21 or RV failure by approximately day 30. Saline or ILP-treated rats served as controls. Significant increase in RV pressure and decrease in RV ejection fraction in the RV failure group resulted in high mortality. Therapy with ILP resulted in 100% survival and prevented PAH-induced RV failure by preserving RV pressure and RV ejection fraction and preventing RV hypertrophy and lung remodeling. In preexisting severe PAH, ILP attenuated most lung and RV abnormalities. The beneficial effects of ILP in PAH seem to result from the interplay of various factors, among which preservation and/or stimulation of angiogenesis, suppression and/or reversal of inflammation, fibrosis and hypertrophy, in both lung and RV, appear to be major contributors. In conclusion, ILP not only prevents the development of PAH and RV failure but also rescues preexisting severe PAH.

Estrogen rescues preexisting severe pulmonary hypertension in rats.

RATIONALE: Pulmonary hypertension (PH) is characterized by progressive increase in pulmonary artery pressure leading to right ventricular (RV) hypertrophy, RV failure, and death. Current treatments only temporarily reduce severity of the disease, and an ideal therapy is still lacking. OBJECTIVES: Estrogen pretreatment has been shown to attenuate development of PH. Because PH is not often diagnosed early, we examined if estrogen can rescue preexisting advanced PH. METHODS: PH was induced in male rats with monocrotaline (60 mg/kg). At Day 21, rats were either treated with 17-ß estradiol or estrogen (E2, 42.5 µg/kg/d), estrogen receptor-ß agonist (diarylpropionitrile, 850 µg/kg/d), or estrogen receptor α-agonist (4,4',4"-[4-Propyl-(1H)-pyrazole-1,3,5-triyl] trisphenol, 850 µg/kg/d) for 10 days or left untreated to develop RV failure. Serial echocardiography, cardiac catheterization, immunohistochemistry, Western blot, and real-time polymerase chain reaction were performed. MEASUREMENTS AND MAIN RESULTS: Estrogen therapy prevented progression of PH to RV failure and restored lung and RV structure and function. This restoration was maintained even after removal of estrogen at Day 30, resulting in 100% survival at Day 42. Estradiol treatment restored the loss of blood vessels in the lungs and RV. In the presence of angiogenesis inhibitor TNP-470 (30 mg/kg) or estrogen receptor-ß antagonist (PHTPP, 850 µg/kg/d), estrogen failed to rescue PH. Estrogen receptor-ß selective agonist was as effective as estrogen in rescuing PH. CONCLUSIONS: Estrogen rescues preexisting severe PH in rats by restoring lung and RV structure and function that are maintained even after removal of estrogen. Estrogen-induced rescue of PH is associated with stimulation of cardiopulmonary neoangiogenesis, suppression of inflammation, fibrosis, and RV hypertrophy. Furthermore, estrogen rescue is likely mediated through estrogen receptor-ß.

Metabolic characterization of Palatinate German white wines according to sensory attributes, varieties, and vintages using NMR spectroscopy and multivariate data analyses.

(1)H NMR (nuclear magnetic resonance spectroscopy) has been used for metabolomic analysis of 'Riesling' and 'Mueller-Thurgau' white wines from the German Palatinate region. Diverse two-dimensional NMR techniques have been applied for the identification of metabolites, including phenolics. It is shown that sensory analysis correlates with NMR-based metabolic profiles of wine. (1)H NMR data in combination with multivariate data analysis methods, like principal component analysis (PCA), partial least squares projections to latent structures (PLS), and bidirectional orthogonal projections to latent structures (O2PLS) analysis, were employed in an attempt to identify the metabolites responsible for the taste of wine, using a non-targeted approach. The high quality wines were characterized by elevated levels of compounds like proline, 2,3-butanediol, malate, quercetin, and catechin. Characterization of wine based on type and vintage was also done using orthogonal projections to latent structures (OPLS) analysis. 'Riesling' wines were characterized by higher levels of catechin, caftarate, valine, proline, malate, and citrate whereas compounds like quercetin, resveratrol, gallate, leucine, threonine, succinate, and lactate, were found discriminating for 'Mueller-Thurgau'. The wines from 2006 vintage were dominated by leucine, phenylalanine, citrate, malate, and phenolics, while valine, proline, alanine, and succinate were predominantly present in the 2007 vintage. Based on these results, it can be postulated the NMR-based metabolomics offers an easy and comprehensive analysis of wine and in combination with multivariate data analyses can be used to investigate the source of the wines and to predict certain sensory aspects of wine.

Metabolic constituents of grapevine and grape-derived products.

The numerous uses of the grapevine fruit, especially for wine and beverages, have made it one of the most important plants worldwide. The phytochemistry of grapevine is rich in a wide range of compounds. Many of them are renowned for their numerous medicinal uses. The production of grapevine metabolites is highly conditioned by many factors like environment or pathogen attack. Some grapevine phytoalexins have gained a great deal of attention due to their antimicrobial activities, being also involved in the induction of resistance in grapevine against those pathogens. Meanwhile grapevine biotechnology is still evolving, thanks to the technological advance of modern science, and biotechnologists are making huge efforts to produce grapevine cultivars of desired characteristics. In this paper, important metabolites from grapevine and grape derived products like wine will be reviewed with their health promoting effects and their role against certain stress factors in grapevine physiology.

Metabolic response of tomato leaves upon different plant-pathogen interactions.

INTRODUCTION: Plants utilise various defence mechanisms against their potential biotic stressing agents such as viroids, viruses, bacteria or fungi and abiotic environmental challenges. Among them metabolic alteration is a common response in both compatible and incompatible plant-pathogen interactions. However, the identification of metabolic changes associated with defence response is not an easy task due to the complexity of the metabolome and the plant response. To address the problem of metabolic complexity, a metabolomics approach was employed in this study. OBJECTIVE: To identify a wide range of pathogen (citrus exocortis viroid, CEVd, or Pseudomonas syringae pv. tomato)-induced metabolites of tomato using metabolomics. METHODOLOGY: Nuclear magnetic resonance (NMR) spectroscopy in combination with multivariate data analysis were performed to analyse the metabolic changes implicated in plant-pathogen interaction. RESULTS: NMR-based metabolomics of crude extracts allowed the identification of different metabolites implicated in the systemic (viroid) and hypersensitive response (bacteria) in plant-pathogen interactions. While glycosylated gentisic acid was the most important induced metabolite in the viroid infection, phenylpropanoids and a flavonoid (rutin) were found to be associated with bacterial infection. CONCLUSIONS: NMR metabolomics is a potent platform to analyse the compounds involved in different plant infections. A broad response to different pathogenic infections was revealed at metabolomic levels in the plant. Also, metabolic specificity against each pathogen was observed.

NMR metabolic fingerprinting based identification of grapevine metabolites associated with downy mildew resistance.

Grapevine (Vitis vinifera ssp. vinifera L.) and grapes have been extensively studied due to their numerous nutritional benefits and health affecting activities. In this study, metabolite fingerprinting of crude leaf extracts, based on (1)H nuclear magnetic resonance (NMR) spectroscopy and multivariate data analyses, has been used for the metabolic characterization of six different grapevine cultivars including downy and powdery mildew resistant 'Regent' and susceptible 'Lemberger' among others. Several two-dimensional (2D)-NMR techniques were also employed leading to the identification of a number of different types of compounds. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and partial least-squares-discriminant analysis (PLS-DA) of the processed (1)H NMR data revealed clear differences among the cultivars. Metabolites responsible for the discrimination in different grapevine cultivars belong to major classes, that is, organic acids, amino acids, carbohydrates, phenylpropanoids and flavonoids. A differentiation of the cultivars based on their resistance to downy mildew infection was also achieved, and metabolites associated with this trait, namely, quercetin-3-O-glucoside and a trans-feruloyl derivative, were identified. On the basis of these results, the distribution of different plant metabolites among the different grapevine cultivars is presented.