The introduction of the stilbene synthase gene enhances the natural antiradical activity of Lycopersicon esculentum mill

Selenium Biofortification Impacts the Tomato Fruit Metabolome and Transcriptional Profile at Ripening

In the present work, the effects of enriching tomatoes with selenium were studied in terms of physiological, metabolic, and molecular processes in the last stages of fruit development, particularly during ripening. A selenium concentration of 10 mg L-1 with sodium selenate and selenium nanoparticles was used in the spray treatments on the whole plants. No significant effects of selenium enrichment were detected in terms of ethylene production or color changes in the ripening fruit. However, selenium enrichment had an influence on both the primary and secondary metabolic processes and thus the biochemical composition of ripe tomatoes. Selenium decreased the amount of β-carotene, increased the accumulation of naringenin and chlorogenic acid, and decreased the coumaric acid level. Selenium also affected the volatile organic compound profile, with changes in the level of specific apocarotenoid compounds, such as β-ionone. These metabolomic changes may, to some extent, be due to the impact of selenium treatment on the transcription of genes involved in the metabolism of these compounds. RNA-seq analysis showed that the selenium application mostly impacted the expression of the genes involved in hormonal signaling, secondary metabolism, flavonoid biosynthesis, and glycosaminoglycan degradation.

Identification and Expression Analysis of Stilbene Synthase Genes in Arachis hypogaea in Response to Methyl Jasmonate and Salicylic Acid Induction

Stilbene synthase is an important enzyme of the phenylpropanoid pathway, regulating the production of several biologically active stilbenoids. These compounds have antioxidant, anti-inflammatory, and anti-cancer properties. However, the detailed characterization of stilbene synthase genes in Arachis hypogaea has not yet been performed. In this study, the comprehensive characterization of stilbene synthase genes in A. hypogaea was conducted, commencing with identification, phylogenetic analysis, and study of their expression in response to exogenous hormonal treatment. We identified and isolated five AhSTSs genes and recorded their expression pattern in peanut (BARD-479) in response to methyl jasmonate (MeJA) and salicylic acid (SA) treatment. The presence of Chal_sti_synt, ACP_syn_III, and FAE1_CUT1_rppA domains in all AhSTSs indicated their role in the biosynthesis of stilbene and lipid metabolism. Cis-regulatory element analysis indicated their role in light responsiveness, defense responses, regulation of seed development, plant growth, and development. Despite close structural and functional similarities, expression and correlational analysis suggested that these genes may have a specific role in peanut, as individual AhSTS exhibited differential expression upon hormonal treatment in a genotype dependent manner. Further studies on functional characterization involving the transcriptional regulation of AhSTSs can clearly explain the differential expression of stilbene synthase genes to hormonal treatment.

Arachis hypogaea resveratrol synthase 3 alters the expression pattern of UDP-glycosyltransferase genes in developing rice seeds

The resveratrol-producing rice (Oryza sativa L.) inbred lines, Iksan 515 (I.515) and Iksan 526 (I.526), developed by the expression of the groundnut (Arachis hypogaea) resveratrol synthase 3 (AhRS3) gene in the japonica rice cultivar Dongjin, accumulated both resveratrol and its glucoside, piceid, in seeds. Here, we investigated the effect of the AhRS3 transgene on the expression of endogenous piceid biosynthesis genes (UGTs) in the developing seeds of the resveratrol-producing rice inbred lines. Ultra-performance liquid chromatography (UPLC) analysis revealed that I.526 accumulates significantly higher resveratrol and piceid in seeds than those in I.515 seeds and, in I.526 seeds, the biosynthesis of resveratrol and piceid reached peak levels at 41 days after heading (DAH) and 20 DAH, respectively. Furthermore, RNA-seq analysis showed that the expression patterns of UGT genes differed significantly between the 20 DAH seeds of I.526 and those of Dongjin. Quantitative real-time PCR (RT-qPCR) analyses confirmed the data from RNA-seq analysis in seeds of Dongjin, I.515 and I.526, respectively, at 9 DAH, and in seeds of Dongjin and I.526, respectively, at 20 DAH. A total of 245 UGTs, classified into 31 UGT families, showed differential expression between Dongjin and I.526 seeds at 20 DAH. Of these, 43 UGTs showed more than 2-fold higher expression in I.526 seeds than in Dongjin seeds. In addition, the expression of resveratrol biosynthesis genes (PAL, C4H and 4CL) was also differentially expressed between Dongjin and I.526 developing seeds. Collectively, these data suggest that AhRS3 altered the expression pattern of UGT genes, and PAL, C4H and 4CL in developing rice seeds.

Phytostilbenes as agrochemicals: biosynthesis, bioactivity, metabolic engineering and biotechnology

Covering: 1976 to 2020. Although constituting a limited chemical family, phytostilbenes represent an emblematic group of molecules among natural compounds. Ever since their discovery as antifungal compounds in plants and their ascribed role in human health and disease, phytostilbenes have never ceased to arouse interest for researchers, leading to a huge development of the literature in this field. Owing to this, the number of references to this class of compounds has reached the tens of thousands. The objective of this article is thus to offer an overview of the different aspects of these compounds through a large bibliography analysis of more than 500 articles. All the aspects regarding phytostilbenes will be covered including their chemistry and biochemistry, regulation of their biosynthesis, biological activities in plants, molecular engineering of stilbene pathways in plants and microbes as well as their biotechnological production by plant cell systems.

Evolvement of nutraceutical onion plants engineered for resveratrol biosynthetic pathway

Genetically engineered onion expressing codon-optimized VvSTS1 gene accumulated stilbenes and extended life span in yeast and can serve as potential nutraceutical. Resveratrol (RV) is a natural polyphenolic compound found in certain plant species including grapes. RV is well known for its nutraceutical properties and to assuage several disease conditions. Onion is the second most consumed vegetable worldwide and contains large quantities of precursor molecules, malonyl-CoA and para-coumaroyl-CoA that are needed for RV biosynthesis. The present study reports the development of nutraceutical onion by engineering RV biosynthetic pathway. A codon-optimized grapevine synthetic stilbene synthase gene (VvSTS1) was synthesized using native grapevine sequence. Six-week-old healthy yellowish compact nodular calli were co-cultivated with Agrobacterium tumefaciens harbouring pCAMBIA1300-hpt II-CaMV35S-VvSTS1-nos. PCR analysis revealed the presence of VvSTS1 and hpt II genes in putative transgenics. Southern blot analysis confirmed the integration of VvSTS1 gene and independent nature of transformants. LC-ESI-HRMS analysis revealed the accumulation of variable quantities of RV (24.98-50.18 µg/g FW) and its glycosylated form polydatin (33.6-67.15 µg/g FW) in both leaves and bulbs, respectively, indicating the successful engineering of RV biosynthetic pathway into onion. The transgenic onion bulb extracts extended the life span in haploid yeast. The transgenic onion accumulating RV and polydatin, developed for the first of its kind, may serve as a potential nutraceutical resource.

Expression of a Grape VqSTS36-Increased Resistance to Powdery Mildew and Osmotic Stress in Arabidopsis but Enhanced Susceptibility to Botrytis cinerea in Arabidopsis and Tomato

Stilbene synthase genes make a contribution to improving the tolerances of biotic and abiotic stress in plants. However, the mechanisms mediated by these STS genes remain unclear. To provide insight into the role of STS genes defense against biotic and abiotic stress, we overexpressed VqSTS36 in Arabidopsis thaliana and tomato (Micro-Tom) via Agrobacterium-mediated transformation. VqSTS36-transformed Arabidopsis lines displayed an increased resistance to powdery mildew, but both VqSTS36-transformed Arabidopsis and tomato lines showed the increased susceptibility to Botrytis cinerea. Besides, transgenic Arabidopsis lines were found to confer tolerance to salt and drought stress in seed and seedlings. When transgenic plants were treated with a different stress, qPCR assays of defense-related genes in transgenic Arabidopsis and tomato suggested that VqSTS36 played a specific role in different phytohormone-related pathways, including salicylic acid, jasmonic acid, and abscisic acid signaling pathways. All of these results provided a better understanding of the mechanism behind the role of VqSTS36 in biotic and abiotic stress.

Expression patterns and promoter characteristics of the Vitis quinquangularis VqSTS36 gene involved in abiotic and biotic stress response

Resveratrol is a stilbene compound that is synthesized by plants in response to biotic stress and has been linked to health benefits associated with the consumption of certain foods and food products, such as grapes and wine. The final step in the biosynthesis of resveratrol is catalyzed by the enzyme stilbene synthase (STS). Here, we assessed the expression of two STS genes (VqSTS36 and VpSTS36) from the wild grape species Vitis quinquangularis (accession 'Shang-24'; powdery mildew (PM) resistant) and Vitis pseudoreticulata (accession 'Hunan-1'; PM susceptible) following infection by Uncinula necator (Schw.) Burr, the causal agent of PM disease. Some correlation was observed between the relative levels of STS36 transcript and disease resistance. We also cloned the 5' upstream sequence of both VpSTS36 and VqSTS36 and generated a series of 5' VqSTS36 promoter deletions fused to the GUS reporter gene in order to analyze expression in response to wounding, the application of exogenous stress-associated hormones, and biotic stress in tobacco leaves. The promoter was shown to be induced by the hormone salicylic acid (SA), inoculation with the fungal pathogen Erysiphe cichoracearum, and by wounding. These results suggest that VqSTS36 is regulated by biotic stresses and that it plays an important role in mediating disease resistance in grape.

In vitro detection of diesel exhaust particles induced human lung carcinoma epithelial cells damage and the effect of resveratrol

People are taking up antioxidants in their daily diet and being exposed to a potential diesel exhaust particles (DEP)-containing environment. Thus it is important to study in vitro cellular responses when cells are exposed to DEP with or without antioxidant treatment. The investigation of DEP and resveratrol (RES) on cellular biophysical and biochemical changes is needed to better understand the mechanisms of DEP and RES in mammalian cells. A combination of two non-invasive techniques (atomic force microscopy, AFM, and Raman spectroscopy, RM) and multimodal tools were applied to evaluate the biophysical, biochemical alterations and cytokine, membrane potential and cell cycle of cells with or without RES pretreatment to different times of DEP exposure. AFM results indicated that RES protected cells from DEP-induced damage to cytoskeleton and cell architectures, and noted that RES treatments also attenuated DEP-induced alterations in cell elasticity and surface adhesion force over DEP incubation time. RM monitored the changes in characteristic Raman peak intensities of DNA and protein over the DEP exposure time for both RES and non-RES treated groups. The cytokine and chemokine changes quantified by Multiplex ELISA revealed that the inflammatory responses were enhanced with the increase in DEP exposure time and that RES enhanced the expression levels of cytokine and chemokine. This work demonstrated that significant biophysical and biochemical changes in cells might be relevant to early pathological changes induced by DEP damage. Copyright © 2016 John Wiley & Sons, Ltd.

Enhanced production of resveratrol derivatives in tobacco plants by improving the metabolic flux of intermediates in the phenylpropanoid pathway

The biosynthesis of flavonoids such as anthocyanin and stilbenes has attracted increasing attention because of their potential health benefits. Anthocyanins and stilbenes share common phenylpropanoid precursor pathways. We previously reported that the overexpression of sweetpotato IbMYB1a induced anthocyanin pigmentation in transgenic tobacco (Nicotiana tabacum) plants. In the present study, transgenic tobacco (Nicotiana tabacum SR1) plants (STS-OX and ROST-OX) expressing the RpSTS gene encoding stilbene synthase from rhubarb (Rheum palmatum L. cv. Jangyeop) and the RpSTS and VrROMT genes encoding resveratrol O-methyltransferase from frost grape (Vitis riparia) were generated under the control of 35S promoter. Phenotypic alterations in floral organs, such as a reduction in floral pigments and male sterility, were observed in STS-OX transgenic tobacco plants. However, we failed to obtain STS-OX and ROST-OX plants with high levels of resveratrol compounds. Therefore, to improve the production of resveratrol derivatives in plants, we cross-pollinated flowers of STS-OX or ROST-OX and IbMYB1a-OX transgenic lines (SM and RSM). Phenotypic changes in vegetative and reproductive development of SM and RSM plants were observed. Furthermore, by HPLC and LC-MS analyses, we found enhanced production of resveratrol derivatives such as piceid, piceid methyl ether, resveratrol methyl ether O-hexoside, and 5-methyl resveratrol-3,4'-O-β-D-diglucopyranoside in SM and RSM cross-pollinated lines. Here, total contents of trans- and cis-piceids ranged from approximately 104-240 µg/g fresh weight in SM (F2). Collectively, we suggest that coexpression of RpSTS and IbMYB1a via cross-pollination can induce enhanced production of resveratrol compounds in plants by increasing metabolic flux into stilbenoid biosynthesis.

Evaluating the Effect of Expressing a Peanut Resveratrol Synthase Gene in Rice

Resveratrol (Res) is a type of natural plant stilbenes and phytoalexins that only exists in a few plant species. Studies have shown that the Res could be biosynthesized and accumulated within plants, once the complete metabolic pathway and related enzymes, such as the key enzyme resveratrol synthase (RS), existed. In this study, a RS gene named PNRS1 was cloned from the peanut, and the activity was confirmed in E. coli. Using transgenic approach, the PNRS1 transgenic rice was obtained. In T3 generation, the Res production and accumulation were further detected by HPLC. Our data revealed that compared to the wild type rice which trans-resveratrol was undetectable, in transgenic rice, the trans-resveratrol could be synthesized and achieved up to 0.697 μg/g FW in seedlings and 3.053 μg/g DW in seeds. Furthermore, the concentration of trans-resveratrol in transgenic rice seedlings could be induced up to eight or four-fold higher by ultraviolet (UV-C) or dark, respectively. Simultaneously, the endogenous increased of Res also showed the advantages in protecting the host plant from UV-C caused damage or dark-induced senescence. Our data indicated that Res was involved in host-defense responses against environmental stresses in transgenic rice. Here the results describes the processes of a peanut resveratrol synthase gene transformed into rice, and the detection of trans-resveratrol in transgenic rice, and the role of trans-resveratrol as a phytoalexin in transgenic rice when treated by UV-C and dark. These findings present new outcomes of transgenic approaches for functional genes and their corresponding physiological functions, and shed some light on broadening available resources of Res, nutritional improvement of crops, and new variety cultivation by genetic engineering.

Creation of resveratrol-enriched rice for the treatment of metabolic syndrome and related diseases

Resveratrol has been clinically shown to possess a number of human health benefits. As a result, many attempts have been made to engineer resveratrol production in major cereal grains but have been largely unsuccessful. In this study, we report the creation of a transgenic rice plant that accumulates 1.9 µg resveratrol/g in its grain, surpassing the previously reported anti-metabolic syndrome activity of resveratrol through a synergistic interaction between the transgenic resveratrol and the endogenous properties of the rice. Consumption of our transgenic resveratrol-enriched rice significantly improved all aspects of metabolic syndrome and related diseases in animals fed a high-fat diet. Compared with the control animals, the resveratrol-enriched rice reduced body weight, blood glucose, triglycerides, total cholesterol, and LDL-cholesterol by 24.7%, 22%, 37.4%, 27%, and 59.6%, respectively. The resveratrol-enriched rice from our study may thus provide a safe and convenient means of preventing metabolic syndrome and related diseases without major lifestyle changes or the need for daily medications. These results also suggest that future transgenic plants could be improved if the synergistic interactions of the transgene with endogenous traits of the plant are considered in the experimental design.

Phytoalexin transgenics in crop protection--fairy tale with a happy end?

Phytoalexins are pathogen induced low molecular weight compounds with antimicrobial activities derived from secondary metabolism. Following their identification, phytoalexins were directly incorporated into the network of plant defense responses. Due to their heterogeneity, the metabolic pathways involved in phytoalexin formation and in particular the regulatory mechanisms remained elusive. Consequently, research focus shifted to the characterization of other components of plant immunity such as defense signaling and resistance mechanisms, including components of systemic acquired and induced systemic resistance, effector and pathogen-associated molecular pattern triggered immunity as well as R-gene resistance. Despite the obtained knowledge on these immunity mechanisms, genetic engineering employing these mechanisms and classical breeding reached too low improvements in crop protection, probably because classical breeding focused on yield performance and taste, rather than pathogen resistance. The increasing demand for disease resistant crop species and the aim to reduce pesticide application therefore requires alternative approaches. Recent advances in the understanding of phytoalexin function, biosynthesis and regulation, in combination with novel methods of molecular engineering and advances in instrumental analysis, returned attention to phytoalexins as a potent target for improving crop protection. Based on this, the advantages as well as potential bottlenecks for molecular approaches of modulating inducible phytoalexins to improve crop protection are discussed.

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.

Cloning a peanut resveratrol synthase gene and its expression in purple sweet potato

A resveratrol synthase gene was cloned from the peanut plant (Arachis hypogaea) by RT-PCR and was transformed into purple sweet potato (Ipomoea batatas) by Agrobacterium-mediated transformation. Stem sections were infected with bacterial solution of OD(600) = 0.4 for 20 min and then cocultured for 2 days. Infected explants were cultured on MS media containing 50 mg/l kanamycin, 0.02 mg/l NAA and 1 mg/l 6-BA for bud induction or containing 75 mg/l kanamycin, 1.0 mg/l NAA and 0.1 mg/l 6-BA for root formation. The bud and root induction rates were 37.5 and 25.0%, respectively. 105 regenerated plants were obtained, with 11 positive plants by PCR and Southern blotting analyses. A high level of resveratrol glucoside (340 μg/g dry weight), but no resveratrol, was detected in the transformed plants by HPLC. This study also provides a stable genetic transformation and plant regeneration method for metabolic modification of purple sweet potato.

Expression pattern, genomic structure, and promoter analysis of the gene encoding stilbene synthase from Chinese wild Vitis pseudoreticulata

The gene encoding stilbene synthase (STS) plays a central role in many biochemical and physiological actions, and its metabolite resveratrol possesses broad-spectrum resistance to pathogens, as well as diverse pharmacological properties, notably an anticancer effect. Here, we report the expression analysis of the gene encoding STS and its promoter function from a powdery mildew (PM)-resistant Chinese wild Vitis pseudoreticulata, and compare it with two PM-susceptible cultivated grapevines, Vitis vinifera cvs. Carignane and Thompson Seedless. We show an unusual expression pattern of STS in V. pseudoreticulata, which differs markedly from that of the cultivated species. Sequence comparisons reveal that the genomic DNA sequences encoding STS in the three grapevines are highly conserved, but a novel residue mutation within the key motif of STS is solely present in V. pseudoreticulata. Moreover, the STS promoter in V. pseudoreticulata displays a significantly different structure from that found in the two V. vinifera. The three promoter-driven GUS differential expression patterns in transformed tobacco plants induced with Alternaria alternata, methyl jasmonate, and wounding indicated that the structurally different STS promoter of V. pseudoreticulata is responsible for its specific regulatory function. We also demonstrate that the expression of STS genes from their native promoters are functional in transformed tobacco and retain pathogen inducibility. Importantly, the genomic DNA-2 of V. pseudoreticulata under its native promoter shows good induction and the maximum level of resveratrol content. These findings further our understanding of the regulation of STS expression in a resistant grapevine and provide a new pathogen-inducible promoter system for the genetic improvement of plant disease resistance.

Longevity nutrients resveratrol, wines and grapes

A mild-to-moderate wine drinking has been linked with reduced cardiovascular, cerebrovascular, and peripheral vascular risk as well as reduced risk due to cancer. The reduced risk of cardiovascular disease associated with wine drinking is popularly known as French Paradox. A large number of reports exist in the literature indicating that resveratrol present in wine is primarily responsible for the cardioprotection associated with wine. Recently, resveratrol was shown to extend life span in yeast through the activation of longevity gene SirT1, which is also responsible for the longevity mediated by calorie restriction. This review summarizes the reports available on the functional and molecular biological aspects of resveratrol, wine and grapes in potentiating the longevity genes.

Plant polyketide synthases: a fascinating group of enzymes

The polyketide synthases (PKSs) are condensing enzymes which form a myriad of polyketide compounds. Several PKSs have been identified and studied in plants. This mini-review summarizes what is known about plant PKSs and some of their aspects such as specificity, reaction mechanisms, structure, as well as their possible evolution are highlighted.

Molecular engineering of resveratrol in plants

The grapevine phytoalexin resveratrol, the synthesis of which is achieved by stilbene synthase (STS), displays a wide range of biological effects. Most interest has centred, in recent years, on STS gene transfer experiments from grapevine to the genome of numerous plants. This work presents a comprehensive review on plant molecular engineering with the STS gene. Gene and promoter options are discussed, namely the different promoters used to drive the transgene, as well as the enhancer elements and/or heterologous promoters used to improve transcriptional activity in the transformed lines. Factors modifying transgene expression and epigenetic modifications, for instance transgene copy number, are also presented. Resveratrol synthesis in plants, together with that of its glucoside as a result of STS expression, is described, as is the incidence of these compounds on plant metabolism and development. The ectopic production of resveratrol can lead to broad-spectrum resistance against fungi in transgenic lines, and to the enhancement of the antioxidant activities of several fruits, highlighting the potential role of this compound in health promotion and plant disease control.

Resveratrol induces glutathione synthesis by activation of Nrf2 and protects against cigarette smoke-mediated oxidative stress in human lung epithelial cells

Nuclear erythroid-related factor 2 (Nrf2), a redox-sensitive transcription factor, is involved in transcriptional regulation of many antioxidant genes, including glutamate-cysteine ligase (GCL). Cigarette smoke (CS) is known to cause oxidative stress and deplete glutathione (GSH) levels in alveolar epithelial cells. We hypothesized that resveratrol, a polyphenolic phytoalexin, has antioxidant signaling properties by inducing GSH biosynthesis via the activation of Nrf2 and protects lung epithelial cells against CS-mediated oxidative stress. Treatment of human primary small airway epithelial and human alveolar epithelial (A549) cells with CS extract (CSE) dose dependently decreased GSH levels and GCL activity, effects that were associated with enhanced production of reactive oxygen species. Resveratrol restored CSE-depleted GSH levels by upregulation of GCL via activation of Nrf2 and also quenched CSE-induced release of reactive oxygen species. Interestingly, CSE failed to induce nuclear translocation of Nrf2 in A549 and small airway epithelial cells. On the contrary, Nrf2 was localized in the cytosol of alveolar and airway epithelial cells due to CSE-mediated posttranslational modifications such as aldehyde/carbonyl adduct formation and nitration. On the other hand, resveratrol attenuated CSE-mediated Nrf2 modifications, thereby inducing its nuclear translocation associated with GCL gene transcription, as demonstrated by GCL-promoter reporter and Nrf2 small interfering RNA approaches. Thus resveratrol attenuates CSE-mediated GSH depletion by inducing GSH synthesis and protects epithelial cells by reversing CSE-induced posttranslational modifications of Nrf2. These data may have implications in dietary modulation of antioxidants in treatment of chronic obstructive pulmonary disease.

Detection and quantitation of resveratrol in tomato fruit (Lycopersicon esculentum Mill.)

Resveratrol is a stilbene phytoalexin well-known for its presence in grape, wine, and peanut. As a result of its antioxidant and chemopreventative properties, it has gained much attention as a functional food ingredient. A gas chromatography-mass spectrometry method for the detection of resveratrol, its 3-glucopyranoside piceid, and the cis isomers of both compounds has been developed and used to quantitate the levels of these compounds in the skin of commercially available tomato fruit (Lycopersicon esculentum Mill.). The resveratrol concentration remains relatively stable during fruit maturation, reaching a maximum concentration in the skin of 18.4 +/- 1.6 microg/g dry weight at 4 weeks postbreaker. No stilbenes were detected in the flesh of tomato fruit.