Resveratrol accumulation and its involvement in stilbene synthetic pathway of Chinese wild grapes during berry development using quantitative proteome analysis

Alfin-like transcription factor VqAL4 regulates a stilbene synthase to enhance powdery mildew resistance in grapevine

Resveratrol is a phytoalexin that is synthesized by stilbene synthase (STS). Resveratrol in the human diet is known to have beneficial effects on health. We previously identified six novel STS (VqNSTS) transcripts from the transcriptome data of Vitis quinquangularis accession Danfeng-2. However, the functions of and defensive mechanisms triggered by these VqNSTS transcripts remain unknown. In the present study, we demonstrate that the expression of five of these six novel members, VqNSTS2-VqNSTS6, can be induced by the powdery mildew-causing fungus Uncinula necator. Additionally, overexpression of VqNSTS4 in the V. vinifera susceptible cultivar Thompson Seedless promoted accumulation of stilbenes and enhanced resistance to U. necator by activating salicylic acid (SA) signalling. Furthermore, our results indicate that the Alfin-like (AL) transcription factor VqAL4 can directly bind to the G-rich element (CACCTC) in the VqNSTS4 promoter and activate gene expression. Moreover, overexpression of VqAL4 in Thompson Seedless enhanced resistance to U. necator by promoting stilbene accumulation and activating SA signalling. Conversely, RNA interference-mediated silencing of VqNSTS4 and VqAL4 resulted in increased susceptibility to U. necator. Collectively, our results reveal that VqNSTS4, regulated by VqAL4, enhances grapevine resistance to powdery mildew by activating SA signalling. Our findings may be useful to improve disease resistance in perennial fruit trees.

A Field Collection of Indigenous Grapevines as a Valuable Repository for Applied Research

The grapevine is an economically important plant, with a historical connection to the development of human culture. Currently, over 6000 accessions are known as individual grapevine varieties, some of which are important to national heritage, valuable for current viticultural practices, and as genetic resources to maintain plasticity under changing climatic conditions, environmental sustainability, and market demands. Recently, the diversity of cultivated grapevines has declined significantly, due to the increased focus of global wine industries on a few major cultivars. Moreover, due to biotic and abiotic stresses, the wild V. vinifera germplasm's genetic diversity has declined, with some varieties on the verge of extinction. Vitis germplasm conservation can be achieved via either in situ (e.g., protected areas) or Ex situ (e.g., field collections, seed banks, and tissue culture collections) methods. This study aims to highlight the importance of Vitis field bank collections. We demonstrate the research done in the Israeli indigenous Vitis vinifera collection. The multi-layer analysis of the varieties enabled the identification of drought stress-resistant varieties, and suggested a mechanism for this resistance through noting the dramatic phenological differences in foliage development between resistant and sensitive varieties. In addition, we show a general characterization of the varieties via major grape characteristics, including bunch and berry shape, as well as their possible utilization based on their aromatic and phenolic profiles.

Resveratrol production from several types of saccharide sources by a recombinant Scheffersomyces stipitis strain

Resveratrol is a plant-derived aromatic compound with a wide range of beneficial properties including antioxidant and anti-aging effects. The resveratrol currently available on the market is predominantly extracted from certain plants such as grape and the Japanese knotweed Polygonum cuspidatum. Due to the unstable harvest of these plants and the low resveratrol purity obtained, it is necessary to develop a stable production process of high-purity resveratrol from inexpensive feedstocks. Here, we attempted to produce resveratrol from a wide range of sugars as carbon sources by a using the genetically-engineered yeast Scheffersomyces stipitis (formerly known as Pichia stipitis), which possesses a broad sugar utilization capacity. First, we constructed the resveratrol producing strain by introducing genes coding the essential enzymes for resveratrol biosynthesis [tyrosine ammonia-lyase 1 derived from Herpetosiphon aurantiacus (HaTAL1), 4-coumarate: CoA ligase 2 derived from Arabidopsis thaliana (At4CL2), and stilbene synthase 1 derived from Vitis vinifera (VvVST1)]. Subsequently, a feedback-insensitive allele of chorismate mutase was overexpressed in the constructed strain to improve resveratrol production. The constructed strain successfully produced resveratrol from a broad range of biomass-derived sugars [glucose, fructose, xylose, N-acetyl glucosamine (GlcNAc), galactose, cellobiose, maltose, and sucrose] in shake flask cultivation. Significant resveratrol titers were detected in cellobiose and sucrose fermentation (529.8 and 668.6 mg/L after 120 h fermentation, respectively), twice above the amount obtained with glucose (237.6 mg/L). Metabolomic analysis revealed an altered profile of the metabolites involved in the glycolysis and shikimate pathways, and also of cofactors and metabolites of energy metabolisms, depending on the substrate used. The levels of resveratrol precursors such as L-tyrosine increased in cellobiose and sucrose-grown cells. The results indicate that S. stipitis is an attractive microbial platform for resveratrol production from broad types of biomass-derived sugars and the selection of suitable substrates is crucial for improving resveratrol productivity of this yeast.

Resveratrol and related stilbene derivatives induce stress granules with distinct clearance kinetics

Stress granules (SGs) are ribonucleoprotein functional condensates that form under stress conditions in all eukaryotic cells. Although their stress-survival function is far from clear, SGs have been implicated in the regulation of many vital cellular pathways. Consequently, SG dysfunction is thought to be a mechanistic point of origin for many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Additionally, SGs are thought to play a role in pathogenic pathways as diverse as viral infection and chemotherapy resistance. There is a growing consensus on the hypothesis that understanding the mechanistic regulation of SG physical properties is essential to understanding their function. Although the internal dynamics and condensation mechanisms of SGs have been broadly investigated, there have been fewer investigations into the timing of SG formation and clearance in live cells. Because the lifetime of SG persistence can be a key factor in their function and tendency toward pathological dysregulation, SG clearance mechanisms deserve particular attention. Here we show that resveratrol and its analogues piceatannol, pterostilbene, and 3,4,5,4'-tetramethoxystilbene induce G3BP-dependent SG formation with atypically rapid clearance kinetics. Resveratrol binds to G3BP, thereby reducing its protein-protein association valency. We suggest that altering G3BP valency is a pathway for the formation of uniquely transient SGs.

VqbZIP1 isolated from Chinese wild Vitis quinquangularis is involved in the ABA signaling pathway and regulates stilbene synthesis

Resveratrol is an important phytoalexin in grapevine. Not only does it confer increased disease resistance and but as a food component it offers significant benefits in human health. Abscisic acid (ABA) is an important phytohormone involved in many biological processes in plants and can also promote the accumulation of stilbenes. Stilbene synthase (STS) is an important enzyme which catalyzes the last step of resveratrol synthesis. Our study characterizes a basic leucine zipper (bZIP) transcription factor, VqbZIP1, isolated from Chinese wild Vitis quinquangularis accession Danfeng-2. The results show that VqbZIP1 encodes 299 amino acids and belongs to the Group A subfamily of the bZIP family. VqbZIP1 showed transcriptional activation activity in yeast and is predicted to be located in the nucleus. The yeast two-hybrid assay and bimolecular fluorescence complementation (BiFC) assay together show that VqbZIP1 interacts with VqSnRK2.4 and VqSnRK2.6. VqbZIP1, the STS genes, VqSnRK2.4 and VqSnRK2.6 can all be induced by ABA treatment. A GUS activity experiment indicates VqbZIP1 can activate the GUS reporter gene driven by STS promoters. Further studies show that co-expression of VqbZIP1 with VqSnRK2.4 or VqSnRK2.6 can confer higher efficiency than expression of VqbZIP1 alone in activating the STS promoters. Overexpression of VqbZIP1 in grape leaves promoted the transcript level of the STS genes and the accumulation of stilbenes. Overexpression of VqbZIP1 in Arabidopsis thaliana can confer ABA sensitivity. In summary, our results suggest VqbZIP1 participates in the ABA signaling pathway and regulates stilbene synthesis.

Characteristics, Biological Properties and Analytical Methods of Trans-Resveratrol: A Review

Trans-resveratrol (TR) is the biological active isomer of resveratrol and the one responsible for therapeutic effects; both molecules are non-flavonoid phenolics of the stilbenes class found mainly in berries and red grapes. TR biological properties lie in modulation of various enzymatic classes. It is a promising candidate to novel drugs due its applications in pharmaceutical and cosmetic industries, such as anticarcinogenic, antidiabetic, antiacne, antioxidant, anti-inflammatory, neuroprotective, and photoprotector agent. It has effects on bone metabolism, gastrointestinal tract, eyes, kidneys, and in obesity treatment as well. Nevertheless, its low solubility in water and other polar solvents may be a hindrance to its therapeutic effects. Various strategies been developed to overcome these issues, such as the drug delivery systems. The present study performed a research about methods to identify TR and RESV in several samples (raw materials, wines, food supplements, drug delivery systems, and blood plasma). Most of the studies tend to analyze TR and RESV by high performance liquid chromatography (HPLC) coupled with different detectors, even so, there are reports of the use of capillary electrophoresis, electron spin resonance, gas chromatography, near-infrared luminescence, UV-Vis spectrophotometer, and vibrational spectrophotometry, for this purpose. Thus, the review evaluates the biological activity of TR and demonstrates the currently used analytical methods for its quantification in different matrices.