Production of high molecular-ordered stilbene oligomers for the study of their biological activity: total synthesis, bio-catalyzed synthesis and production by plant systems.

Though the iconic stilbene resveratrol and its related dimers constitute a top storyline in the field of natural product research, resveratrol oligomers (condensation >2) have been left aside despite their higher biological activity compared to that of the monomers. This situation largely results from the difficulty of getting them in sufficient quantities to enable evaluation of their biological properties in vivo. We present here a synthetic and critical analysis of the methods used for the production of high molecular-ordered stilbene oligomers of potential biomedical interest, gathering the most salient data regarding the approaches employed to prepare them by total synthesis, use of biomimetic approaches or through plant systems.

Protecting-group free synthesis of glycoconjugates displaying dual fungicidal and plant defense-eliciting activities.

A straightforward synthesis of carbohydrate templated isoxazolidines is described, by reaction of unprotected glycosylhydroxylamines (operating as 1,3-dipoles) with methyl acrylate using microwave activation. Rhamno- and erythro-isoxazolidines are recognized by plant cells, resulting in a strong ROS-production as a plant immune response, and exert a high antifungal activity against Botrytis cinerea.

Photocatalytic Degradation of Methylene Blue and Anticancer Response of In2O3/RGO Nanocomposites Prepared by a Microwave-Assisted Hydrothermal Synthesis Process.

The incorporation of graphene with metal oxide has been widely explored in various fields, including energy storage devices, optical applications, biomedical applications, and water remediation. This research aimed to assess the impact of reduced graphene oxide (RGO) doping on the photocatalytic and anticancer properties of In2O3 nanoparticles. Pure and In2O3/RGO nanocomposites were effectively synthesized using the single-step microwave hydrothermal process. XRD, TEM, SEM, EDX, XPS, Raman, UV-Vis, and PL spectroscopy were carefully utilized to characterize the prepared samples. XRD data showed that synthesized In2O3 nanoparticles had high crystallinity with a decreased crystal size after RGO doping. TEM and SEM images revealed that the In2O3 NPs were spherical and uniformly embedded onto the surface of RGO sheets. Elemental analysis of In2O3/RGO NC confirmed the presence of In, O, and C without impurities. Raman analysis indicated the successful fabrication of In2O3 onto the RGO surface. Uv-Vis analysis showed that the band gap energy was changed with RGO addition. Raman spectra confirmed that In2O3 nanoparticles were successfully anchored onto the RGO sheet. PL results indicated that the prepared In2O3/RGO NCs can be applied to enhance photocatalytic activity and biomedical applications. In the degradation experiment, In2O3/RGO NCs exhibited superior photocatalytic activity compared to that of pure In2O3. The degradation efficiency of In2O3/RGO NCs for MB dye was up to 90%. Biological data revealed that the cytotoxicity effect of In2O3/RGO NCs was higher than In2O3 NPs in human colorectal (HCT116) and liver (HepG2) cancer cells. Importantly, the In2O3/RGO NCs exhibited better biocompatibility against human normal peripheral blood mononuclear cells (PBMCs). All the results suggest that RGO addition improves the photocatalytic and anticancer activity of In2O3 NPs. This study highlights the potential of In2O3/RGO NCs as an efficient photocatalyst and therapeutic material for water remediation and biomedicine.

Camalexin accumulation as a component of plant immunity during interactions with pathogens and beneficial microbes.

MAIN CONCLUSION: This review provides an overview on the role of camalexin in plant immunity taking into account various plant-pathogen and beneficial microbe interactions, regulation mechanisms and the contribution in basal and induced plant resistance. In a hostile environment, plants evolve complex and sophisticated defense mechanisms to counteract invading pathogens and herbivores. Several lines of evidence support the assumption that secondary metabolites like phytoalexins which are synthesized de novo, play an important role in plant defenses and contribute to pathogens' resistance in a wide variety of plant species. Phytoalexins are synthesized and accumulated in plants upon pathogen challenge, root colonization by beneficial microbes, following treatment with chemical elicitors or in response to abiotic stresses. Their protective properties against pathogens have been reported in various plant species as well as their contribution to human health. Phytoalexins are synthesized through activation of particular sets of genes encoding specific pathways. Camalexin (3'-thiazol-2'-yl-indole) is the primary phytoalexin produced by Arabidopsis thaliana after microbial infection or abiotic elicitation and an iconic representative of the indole phytoalexin family. The synthesis of camalexin is an integral part of cruciferous plant defense mechanisms. Although the pathway leading to camalexin has been largely elucidated, the regulatory networks that control the induction of its biosynthetic steps by pathogens with different lifestyles or by beneficial microbes remain mostly unknown. This review thus presents current knowledge regarding camalexin biosynthesis induction during plant-pathogen and beneficial microbe interactions as well as in response to microbial compounds and provides an overview on its regulation and interplay with signaling pathways. The contribution of camalexin to basal and induced plant resistance and its detoxification by some pathogens to overcome host resistance are also discussed.

Priming of camalexin accumulation in induced systemic resistance by beneficial bacteria against Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000.

Plants harbor various beneficial microbes that modulate their innate immunity, resulting in induced systemic resistance (ISR) against a broad range of pathogens. Camalexin is an integral part of Arabidopsis innate immunity, but the contribution of its biosynthesis in ISR is poorly investigated. We focused on camalexin accumulation primed by two beneficial bacteria, Pseudomonas fluorescens and Bacillus subtilis, and its role in ISR against Botrytis cinerea and Pseudomonas syringae Pst DC3000. Our data show that colonization of Arabidopsis thaliana roots by beneficial bacteria triggers ISR against both pathogens and primes plants for enhanced accumulation of camalexin and CYP71A12 transcript in leaf tissues. Pseudomonas fluorescens induced the most efficient ISR response against B. cinerea, while B. subtilis was more efficient against Pst DC3000. Analysis of cyp71a12 and pad3 mutants revealed that loss of camalexin synthesis affected ISR mediated by both bacteria against B. cinerea. CYP71A12 and PAD3 contributed significantly to the pathogen-triggered accumulation of camalexin, but PAD3 does not seem to contribute to ISR against Pst DC3000. This indicated a significant contribution of camalexin in ISR against B. cinerea, but not always against Pst DC3000. Experiments with Arabidopsis mutants compromised in different hormonal signaling pathways highlighted that B. subtilis stimulates similar signaling pathways upon infection with both pathogens, since salicylic acid (SA), but not jasmonic acid (JA) or ethylene, is required for ISR camalexin accumulation. However, P. fluorescens-induced ISR differs depending on the pathogen; both SA and JA are required for camalexin accumulation upon B. cinerea infection, while camalexin is not necessary for priming against Pst DC3000.

Epidemiological and hematological investigation of dengue virus infection.

Dengue is a mosquito-borne viral illness that infects humans. For the past few decades, it has been declared a global public health problem. The current study, conducted at the district headquarter hospital (DHQ) Bannu between June to September 2018, was based on the seroprevalence of antibodies against dengue virus serotypes and their hematological parameters among the patients. A total of 1738 individuals suspected of having dengue were diagnosed through NS1, IgG, and IgM antibodies and RT-PCR techniques. Of all the samples, 716 (41.19%) were found to be positive for dengue. A higher infection rate was found in males (65.92%) compared with females (34.07%). The most affected age group was 16-40 years, whereas the most affected tehsil was Bannu, where the DENV-3 serotype was prevalent. The rare serotype (DENV-4) was found in 1% of cases. Symptoms including fever (100%), myalgia (100%), headache (61.31%), vomiting (34.63%), and rashes were common among the dengue patients. However, the mild cases showed fewer clinical signs compared with the severely infected cases. The study also revealed a significant association (P < 0.05) between hematological parameters and dengue infection, showing a significant decrease in TC, eosinophils, neutrophils, and platelets and a significant increase in monocytes and lymphocytes. Based on the current report, it is concluded that patients with the above symptoms and hematological changes may have an increased probability of dengue and should be kept under observation to separate dengue-positive patients and to enhance the treatment process.

Rare Sugars: Recent Advances and Their Potential Role in Sustainable Crop Protection.

Rare sugars are monosaccharides with a limited availability in the nature and almost unknown biological functions. The use of industrial enzymatic and microbial processes greatly reduced their production costs, making research on these molecules more accessible. Since then, the number of studies on their medical/clinical applications grew and rare sugars emerged as potential candidates to replace conventional sugars in human nutrition thanks to their beneficial health effects. More recently, the potential use of rare sugars in agriculture was also highlighted. However, overviews and critical evaluations on this topic are missing. This review aims to provide the current knowledge about the effects of rare sugars on the organisms of the farming ecosystem, with an emphasis on their mode of action and practical use as an innovative tool for sustainable agriculture. Some rare sugars can impact the plant growth and immune responses by affecting metabolic homeostasis and the hormonal signaling pathways. These properties could be used for the development of new herbicides, plant growth regulators and resistance inducers. Other rare sugars also showed antinutritional properties on some phytopathogens and biocidal activity against some plant pests, highlighting their promising potential for the development of new sustainable pesticides. Their low risk for human health also makes them safe and ecofriendly alternatives to agrochemicals.

Differential phosphorylation regulates the shear stress-induced polar activity of Rho-specific guanine nucleotide dissociation inhibitor α.

The activity of Rho-specific guanine nucleotide dissociation inhibitor α (RhoGDIα) is regulated by its own phosphorylation at different amino acid sites. These phosphorylation sites may have a crucial role in local Rho GTPases activation during cell migration. This paper is designed to explore the influence of phosphorylation on shear stress-induced spatial RhoGDIα activation. Based on the fluorescence resonance energy transfer biosensor sl-RhoGDIα, which was constructed to test the RhoGDIα activity in living cells, new RhoGDIα phosphomimetic mutation (sl-S101E/S174E, sl-Y156E, sl-S101E, sl-S174E) and phosphorylation-deficient mutation (sl-S101A/S174A, sl-Y156A, sl-S101A, sl-S174A) biosensors were designed to test their effects on RhoGDIα activation upon shear stress application in human umbilical vein endothelial cells (HUVECs). The results showed lower RhoGDIα activity at the downstream of HUVECs (the region from the edge of the nucleus to the edge of the cell along with the flow). The overall decrease in RhoGDIα activity was inhibited by Y156A-mutant, whereas the polarized RhoGDIα and Rac1 activity were blocked by S101A/S174A mutant. It is concluded that the Tyr156 phosphorylation mainly mediates shear stress-induced overall RhoGDIα activity, while Ser101/Ser174 phosphorylation mediates its polarization. This study demonstrates that differential phosphorylation of RhoGDIα regulates shear stress-induced spatial RhoGDIα activation, which could be a potential target to control cell migration.

Bladder cancer hunting: A microfluidic paper-based analytical device.

Bladder cancer is the fourth most common cancer in men, and it is becoming a prevalent malignancy. Most of the regular clinical examinations are prompt evaluations with cystoscopy, renal function testing, which require high-precision instrument, well-trained operators, and high cost. In this study, a microfluidic paper-based analytical device (µPAD) was fabricated to detect nuclear matrix protein 22 (NMP22) and bladder cancer antigen (BTA) from the urine samples. Urine samples were collected from 11 bladder cancer patients and 10 well-beings as experiment and control groups, respectively, to verify the working efficiency of µPAD. A remarkable checkout efficiency of up to 90.91% was found from the results. Meanwhile, this method is feasible for home-based self-detection from urine samples within 10 min for the total process, which provides a new way for quick, economical, and convenient tumor diagnosis, prognosis evaluation, and drug response.

Anti-Cancer Activity of Resveratrol and Derivatives Produced by Grapevine Cell Suspensions in a 14 L Stirred Bioreactor.

In the present study, resveratrol and various oligomeric derivatives were obtained from a 14 L bioreactor culture of elicited grapevine cell suspensions (Vitis labrusca L.). The crude ethyl acetate stilbene extract obtained from the culture medium was fractionated by centrifugal partition chromatography (CPC) using a gradient elution method and the major stilbenes contained in the fractions were subsequently identified by using a 13C-NMR-based dereplication procedure and further 2D NMR analyses including HSQC, HMBC, and COSY. Beside δ-viniferin (2), leachianol F (4) and G (4'), four stilbenes (resveratrol (1), ε-viniferin (5), pallidol (3) and a newly characterized dimer (6)) were recovered as pure compounds in sufficient amounts to allow assessment of their biological activity on the cell growth of three different cell lines, including two human skin malignant melanoma cancer cell lines (HT-144 and SKMEL-28) and a healthy human dermal fibroblast HDF line. Among the dimers obtained in this study, the newly characterized resveratrol dimer (6) has never been described in nature and its biological potential was evaluated here for the first time. ε-viniferin as well as dimer (6) showed IC50 values on the three tested cell lines lower than the ones exerted by resveratrol and pallidol. However, activities of the first two compounds were significantly decreased in the presence of fetal bovine serum although that of resveratrol and pallidol was not. The differential tumor activity exerted by resveratrol on healthy and cancer lines was also discussed.

13C NMR and LC-MS Profiling of Stilbenes from Elicited Grapevine Hairy Root Cultures.

Resveratrol and related oligostilbenes are defense molecules produced by grapevine in response to stresses including various elicitors or signal molecules. Together with their prominent role in planta, these compounds have been the center of much attention in recent decades due to their pharmacological properties. The cost-effective production of resveratrol derivatives such as viniferins or more structurally complex stilbene oligomers remains a challenging task. In this study, the chemical diversity of stilbenes produced by Vitis vinifera Pinot Noir hairy roots was investigated after elicitation for 4 days with a mixture of methyl jasmonate (100 µM) and cyclodextrins (50 mM). Two crude extracts obtained from the culture medium and from the hairy roots were fractionated by centrifugal partition chromatography. The fractions were chemically investigated by two complementary identification approaches involving a 13C NMR-based dereplication method and liquid chromatography coupled to mass spectrometry (LC-MS). In total, groups of 21 and 18 molecules, including flavonoids and stilbenes, were detected in the culture medium and root extracts, respectively. These included resveratrol monomers, dimers, trimers, and a tetramer, thus highlighting the ability of elicited hairy root culture systems to synthesize a wide diversity of secondary metabolites of pharmaceutical significance. The main compounds were unambiguously identified as trans-resveratrol, ε-viniferin, trans-piceatannol, pallidol, scirpusin A, eriodictyol, naringenin, vitisin B, and maackin.

Enhanced Stilbene Production and Excretion in Vitis vinifera cv Pinot Noir Hairy Root Cultures.

Stilbenes are defense molecules produced by grapevine in response to stresses including various elicitors and signal molecules. Together with their prominent role in planta, stilbenes have been the center of much attention in recent decades due to their pharmaceutical properties. With the aim of setting up a cost-effective and high purity production of resveratrol derivatives, hairy root lines were established from Vitis vinifera cv Pinot Noir 40024 to study the organ-specific production of various stilbenes. Biomass increase and stilbene production by roots were monitored during flask experiments. Although there was a constitutive production of stilbenes in roots, an induction of stilbene synthesis by methyl jasmonate (MeJA) after 18 days of growth led to further accumulation of ε-viniferin, δ-viniferin, resveratrol and piceid. The use of 100 µM MeJA after 18 days of culture in the presence of methyl-ß-cyclodextrins (MCDs) improved production levels, which reached 1034µg/g fresh weight (FW) in roots and 165 mg/L in the extracellular medium, corresponding to five-and 570-foldincrease in comparison to control. Whereas a low level of stilbene excretion was measured in controls, addition of MeJA induced excretion of up to 37% of total stilbenes. The use of MCDs increased the excretion phenomenon even more, reaching up to 98%. Our results demonstrate the ability of grapevine hairy roots to produce various stilbenes. This production was significantly improved in response to elicitation by methyl jasmonate and/or MCDs. This supports the interest of using hairy roots as a potentially valuable system for producing resveratrol derivatives.

Pseudomonas fluorescens PTA-CT2 Triggers Local and Systemic Immune Response Against Botrytis cinerea in Grapevine.

Although induced systemic resistance (ISR) is well-documented in the context of plant-beneficial bacteria interactions, knowledge about the local and systemic molecular and biochemical defense responses before or upon pathogen infection in grapevine is very scarce. In this study, we first investigated the capacity of grapevine plants to express immune responses at both above- and below-ground levels upon interaction with a beneficial bacterium, Pseudomonas fluorescens PTA-CT2. We then explored whether the extent of priming state could contribute to the PTA-CT2-induced ISR in Botrytis cinerea-infected leaves. Our data provide evidence that this bacterium colonized grapevine roots but not the above-ground plant parts and altered the plant phenotype that displayed multiple defense responses both locally and systemically. The grapevine roots and leaves exhibited distinct patterns of defense-related gene expression during root colonization by PTA-CT2. Roots responded faster than leaves and some responses were more strongly upregulated in roots than in leaves and vice versa for other genes. These responses appear to be associated with some induction of cell death in roots and a transient expression of HSR, a hypersensitive response-related gene in both local (roots) and systemic (leaves) tissues. However, stilbenic phytoalexin patterns followed opposite trends in roots compared with leaves but no phytoalexin was exuded during plant-bacterium interaction, suggesting that roots could play an important role in the transfer of metabolites contributing to immune response at the systemic level. Unexpectedly, in B. cinerea-infected leaves PTA-CT2-mediated ISR was accompanied in large part by a downregulation of different defense-related genes, including HSR. Only phytoalexins and glutathion-S-transferase 1 transcripts were upregulated, while the expression of anthocyanin biosynthetic genes was maintained at a higher level than the control. This suggests that decreased expression of HSR, as a marker of cell death, and activation of secondary metabolism pathways could be responsible for a reduced B. cinerea colonization capacity in bacterized plants.

Drought stress tolerance in grapevine involves activation of polyamine oxidation contributing to improved immune response and low susceptibility to Botrytis cinerea.

Environmental factors including drought stress may modulate plant immune responses and resistance to pathogens. However, the relationship between mechanisms of drought tolerance and resistance to pathogens remained unknown. In this study, the effects of drought stress on polyamine (PA) homeostasis and immune responses were investigated in two grapevine genotypes differing in their drought tolerance; Chardonnay (CHR), as sensitive and Meski (MSK), as tolerant. Under drought conditions, MSK plants showed the lowest leaf water loss and reduction of photosynthetic efficiency, and expressed a lower level of NCED2, a gene involved in abscisic acid biosynthesis, compared with CHR plants. The improved drought tolerance in MSK was also coincident with the highest change in free PAs and up-regulation of the genes encoding arginine decarboxylase (ADC), copper amine-oxidase (CuAO), and PA-oxidases (PAO) and their corresponding enzyme activities. MSK plants also accumulated the highest level of amino acids, including Arg, Glu, Gln, Pro, and GABA, emphasizing the participation of PA-related amino acid homeostasis in drought tolerance. Importantly, drought-tolerant plants also exhibited enhanced phytoalexin accumulation and up-regulation of PR genes, especially PR-2 and Chit4c, compared with the sensitive plants. This is consistent with a lower susceptibility of MSK than CHR to Botrytis cinerea. Data suggest a possible connection between water stress tolerance and immune response in grapevine. Pharmacological experiments revealed that under drought conditions CuAO and PAO pathways were involved in the regulation of photosynthetic efficiency, and also of immune response and resistance of grapevine to a subsequent pathogen attack. These results open new views to improve our understanding of crosstalk between drought tolerance mechanisms and immune response.

Osmotic stress-induced polyamine oxidation mediates defence responses and reduces stress-enhanced grapevine susceptibility to Botrytis cinerea.

Abiotic factors inducing osmotic stress can influence the plant immune response and resistance to pathogen infections. In this study, the effect of polyethylene glycol (PEG)- and sucrose-induced osmotic stress on polyamine (PA) homeostasis and the basal immune response in grapevine plantlets before and after Botrytis cinerea infection was determined. Pharmacological approaches were also addressed to assess the contribution of osmotic stress-induced PA oxidation to the regulation of defence responses and the susceptibility of grapevine to B. cinerea. Following osmotic stress or pathogen infection, PA homeostasis was linked to enhanced activity of diamine oxidases (CuAO) and PA oxidases (PAO) and the production of 1,3-diaminopropane. These responses paralleled the accumulation of the main stilbenic phytoalexins, resveratrol and ε-viniferin and upregulation of gene transcripts including STS (a stilbene synthase), PR-2 (a ß-1,3-glucanase), PR3-4c (acidic chitinase IV), and PR-5 (a thaumatin-like protein), as well as NCED2 involved in abscisic acid biosynthesis. It was also demonstrated that leaves pre-exposed to osmotic stress and later inoculated with B. cinerea showed enhanced PA accumulation and attenuation of CuAO and PAO activities. This was consistent with the impaired production of phytoalexins and transcript levels of defence- and stress-related genes following infection, and the enhanced susceptibility to B. cinerea. Pharmacological experiments revealed that, under osmotic stress conditions, CuAO and PAO were involved in PA homeostasis and in the regulation of defence responses. Specific inhibition of CuAO and PAO in osmotically stressed leaves strongly attenuated the induction of defence responses triggered by B. cinerea infection and enhanced susceptibility to the pathogen. Taken together, this study reveals a contribution of PA catabolism to the resistance state through modulation of immune response in grapevine following osmotic stress and/or after B. cinerea infection.

Deciphering the role of phytoalexins in plant-microorganism interactions and human health.

Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In this review we present the key features of this diverse group of molecules, namely their chemical structures, biosynthesis, regulatory mechanisms, biological activities, metabolism and molecular engineering.

Concurrent overactivation of the cytosolic glutamine synthetase and the GABA shunt in the ABA-deficient sitiens mutant of tomato leads to resistance against Botrytis cinerea.

Deficiency of abscisic acid (ABA) in the sitiens mutant of tomato (Solanum lycopersicum) culminates in increased resistance to Botrytis cinerea through a rapid epidermal hypersensitive response (HR) and associated phenylpropanoid pathway-derived cell wall fortifications. This study focused on understanding the role of primary carbon : nitrogen (C : N) metabolism in the resistance response of sitiens to B. cinerea. How alterations in C : N metabolism are linked with the HR-mediated epidermal arrest of the pathogen has been also investigated. Temporal alterations in the γ-aminobutyric acid (GABA) shunt, glutamine synthetase/glutamate synthase (GS/GOGAT) cycle and phenylpropanoid pathway were transcriptionally, enzymatically and metabolically monitored in both wild-type and sitiens plants. Virus-induced gene silencing, microscopic analyses and pharmacological assays were used to further confirm the data. Our results on the sitiens-B. cinerea interaction favor a model in which cell viability in the cells surrounding the invaded tissue is maintained by a constant replenishment of the tricarboxylic acid (TCA) cycle through overactivation of the GS/GOGAT cycle and the GABA shunt, resulting in resistance through both tightly controlling the defense-associated HR and slowing down the pathogen-induced senescence. Collectively, this study shows that maintaining cell viability via alterations in host C : N metabolism plays a vital role in the resistance response against necrotrophic pathogens.

Profiling and Localization of Stilbene Phytoalexins Revealed by MALDI-MSI during the Grapevine-Botrytis cinerea Interaction.

Stilbene phytoalexins are among the most accumulated compounds during grapevine-pathogen interactions. However, their steady-state accumulation level and spatial distribution within the tissues to counteract Botrytis cinerea infection remain to be explored. In this work, matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) was used to determine the spatial distribution of different phytoalexins in grapevine leaves upon infection with B. cinerea. Ultraperformance liquid chromatography-fluorescence (UPLC-FL) was also employed to monitor the accumulation pattern of these phytoalexins. This study showed that stilbene compounds accumulate in areas close to the pathogen infection sites. It was also revealed that the accumulation patterns of the stilbene phytoalexins can vary from one time point postinfection to another with specific accumulation patterns within each time point. To the best of our knowledge, this is the first time that the separate localization of grapevine stilbene phytoalexins has been revealed following B. cinerea infection.

Evaluation of Salt Stress-Induced Changes in Polyamine, Amino Acid, and Phytoalexin Profiles in Mature Fruits of Grapevine Cultivars Grown in Tunisian Oases.

Salinity stress has become an increasing threat to viticulture in the Tunisian oasis, and more generally, the characterization of salinity tolerance markers can be of great interest for sustainable grape production. This study investigated some metabolic adaptations in different tissues of the ripe berries of indigenous grapevine cultivars after exposure to salt stress to identify the key traits of salt stress tolerance under oasis conditions. We especially focused on the adaptive responses occurring at the level of amino acids, polyamines, and stilbene phytoalexins in the grape berry skin, pulp, and seeds of six grapevine cultivars differing in phenotypic and ampelographic characteristics. Our data showed that amino acids accumulated strongly in the pulp and skin, while resveratrol, trans-piceid and trans-ε-viniferin, as major phytoalexins, significantly accumulated in the seeds. High salinity was also found to increase both the berry skin and pulp contents of essential amino acids such as threonine, valine, leucine, isoleucine, lysine, methionine, and phenylalanine. The amounts of stilbenes also increased under high salinity in the berry skin of all the studied cultivars. Polyamine homeostasis within the different berry tissues suggested enhanced polyamine biosynthesis rather than polyamine oxidation in response to high salinity. Our principal component analysis revealed a clear discrimination between the cultivars based on their metabolic profiles within the ripe berry tissues under high salinity.

Metabolic engineering of yeast and plants for the production of the biologically active hydroxystilbene, resveratrol.

Resveratrol, a stilbenic compound deriving from the phenyalanine/polymalonate route, being stilbene synthase the last and key enzyme of this pathway, recently has become the focus of a number of studies in medicine and plant physiology. Increased demand for this molecule for nutraceutical, cosmetic and possibly pharmaceutic uses, makes its production a necessity. In this context, the use of biotechnology through recombinant microorganisms and plants is particularly promising. Interesting results can indeed arise from the potential of genetically modified microorganisms as an alternative mechanism for producing resveratrol. Strategies used to tailoring yeast as they do not possess the genes that encode for the resveratrol pathway, will be described. On the other hand, most interest has centered in recent years, on STS gene transfer experiments from various origins to the genome of numerous plants. This work also presents a comprehensive review on plant molecular engineering with the STS gene, resulting in disease resistance against microorganisms and the enhancement of the antioxidant activities of several fruits in transgenic lines.