Chitosan Application in Vineyards (Vitis vinifera L. cv. Tinto Cão) Induces Accumulation of Anthocyanins and Other Phenolics in Berries, Mediated by Modifications in the Transcription of Secondary Metabolism Genes

Exploring Seaweed and Glycine Betaine Biostimulants for Enhanced Phenolic Content, Antioxidant Properties, and Gene Expression of Vitis vinifera cv. "Touriga Franca" Berries

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum-ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run.

Terroir Dynamics: Impact of Vineyard and Canopy Treatment with Chitosan on Anthocyanins, Phenolics, and Volatile and Sensory Profiles of Pinot Noir Wines from South Tyrol

The effects of canopy treatment with chitosan and the effects of the vineyard location on the quality parameters, volatile and non-volatile profiles, and sensory profile of Pinot Noir wines from South Tyrol (Italy) were studied. Multivariate statistical analysis was applied to identify the most relevant compounds associated with the variability in phenolics and anthocyanins (analyzed by UHPLC-MS), volatile components (HS-SPME-GCxGC-ToF/MS), and basic enological parameters. A clear separation of low-altitude wines (350 m.a.s.l.), which had a high concentration of most of the identified volatile compounds, compared to high-altitude wines (800 and 1050-1150 m.a.s.l.) was pointed out. Low altitude minimized the concentration of the most significant anthocyanins in wines from a valley bottom, presumably due to reduced sun exposure. Wines obtained from chitosan-treated canopies, and, more particularly, those subjected to multiple treatments per year showed a higher amount of the main non-volatile phenolics and were sensorially described as having "unpleasant flavors" and "odors", which might suggest that grape metabolism is slightly altered compared to untreated grapevines. Thus, optimization of the treatment with chitosan should be further investigated.

Curd, seed yield and disease resistance of cauliflower are enhanced by oligosaccharides

Background

Oligosaccharides have been demonstrated as promoters for enhancing plant growth across several crops by elevating their secondary metabolites. However, the exploration of employing diverse oligosaccharides for qualitative trait improvements in cauliflower largely unknown. This study was intended to uncover the unexplored potential, evaluating the stimulatory effects of three oligosaccharides on cauliflower's curd and seed production.

Methods

Two experiments were initiated in the early (15 September) and mid-season (15 October). Four treatments were implemented, encompassing a control (water) alongside chitosan oligosaccharide (COS 50 mg.L-1) with a degree of polymerization (DP) 2-10, oligo galacturonic acid (OGA 50 mg.L-1) with DP 2-10 and alginate oligosaccharide (AOS 50 mg.L-1) with DP 2-7.

Results

Oligosaccharides accelerated plant height (4-17.6%), leaf number (17-43%), curd (5-14.55%), and seed yield (17.8-64.5%) in both early and mid-season compared to control. These enhancements were even more pronounced in the mid-season (7.6-17.6%, 21.37-43%, 7.27-14.55%, 25.89-64.5%) than in the early season. Additionally, three oligosaccharides demonstrated significant disease resistance against black rot in both seasons, outperforming the control. As a surprise, the early season experienced better growth parameters than the mid-season. However, performance patterns remained more or less consistent in both seasons under the same treatments. COS and OGA promoted plant biomass and curd yield by promoting Soil Plant Analysis Development (SPAD) value and phenol content. Meanwhile, AOS increased seed yield (56.8-64.5%) and elevated levels of chlorophyll, ascorbic acid, flavonoids, while decreasing levels of hydrogen per oxide (H2O2), malondialdehyde (MDA), half maximal inhibitory concentration (IC50), and disease index. The correlation matrix and principal component analysis (PCA) supported these relations and findings. Therefore, COS and OGA could be suggested for curd production and AOS for seed production in the early season, offering resistance to both biotic and abiotic stresses for cauliflower cultivation under field conditions.

Modifications in steroid and triterpenoid metabolism in Calendula officinalis plants and hairy root culture in response to chitosan treatment

BACKGROUND

Chitosan, a deacetylated derivative of chitin, is one of the most preferred biopolymers for use as biostimulants and biofertilizers in organic agriculture and as elicitors to enhance the productivity of plant in vitro cultures. Valued as a non-toxic, biodegradable, and environment-friendly agent, it is widely applied to improve plant growth and yield, the content of bioactive specialized metabolites, and resistance to stress conditions and pathogens. However, the influence of chitosan on the growth-defense trade-off, particularly the interplay between steroid and triterpenoid metabolism, has not been extensively investigated.

RESULTS

In this study, Calendula officinalis pot plants and hairy root cultures exposed to chitosan treatment displayed reduced biomass and altered steroid and triterpenoid metabolism. Biosynthesis and accumulation of free forms of sterols (particularly stigmasterol) were inhibited, while the content of sterol esters increased remarkably. The content of some triterpenoids (mainly free triterpenoid acids) was slightly enhanced; however, the biosynthesis of triterpenoid saponins was negatively affected.

CONCLUSIONS

These results indicate that in certain plants, chitosan treatment might not positively influence the growth and metabolite production. Therefore, to avoid unexpected effects, initial studies of the conditions of chitosan treatment are recommended, including the dose and the number of chitosan applications, the type of treatment (e.g., foliar or soil), and the vegetative stage of the treated plants.

Benzothiadiazole Affects Grape Polyphenol Metabolism and Wine Quality in Two Greek Cultivars: Effects during Ripening Period over Two Years

Grape berries are one of the most important sources of phenolic compounds, either consumed fresh or as wine. A pioneer practice aiming to enrich grape phenolic content has been developed based on the application of biostimulants such as agrochemicals initially designed to induce resistance against plant pathogens. A field experiment was conducted in two growing seasons (2019-2020) to investigate the effect of benzothiadiazole on polyphenol biosynthesis during grape ripening in Mouhtaro (red-colored) and Savvatiano (white-colored) varieties. Grapevines were treated at the stage of veraison with 0.3 mM and 0.6 mM benzothiadiazole. The phenolic content of grapes, as well as the expression level of genes involved in the phenylpropanoid pathway were evaluated and showed an induction of genes specifically engaged in anthocyanins and stilbenoids biosynthesis. Experimental wines deriving from benzothiadiazole-treated grapes exhibited increased amounts of phenolic compounds in both varietal wines, as well as an enhancement in anthocyanin content of Mouhtaro wines. Taken together, benzothiadiazole can be utilized to induce the biosynthesis of secondary metabolites with oenological interest and to improve the quality characteristics of grapes produced under organic conditions.

Chitosan application towards the improvement of grapevine performance and wine quality

Intensification of agrochemicals application in vineyards has raised several concerns in Viticulture and Oenology value chain. Efforts have been developed to optimize grapevine health and productivity, assuring that viticulture is sustainable and competitive in today’s wine market. Viticulture practices have constantly been improved for a more sustainable and environment-friendly production, reducing the application of agrochemicals, replacing them by natural compounds that can have a double effect: protect grapevine against pathogens and improve compounds related to grape organoleptic quality. In this context, the development and optimization of alternative strategies to improve and enhance plant defences and grape/wine quality is becoming a necessity. Since the 1980s, chitosan has become a compound of special interest due to its double effect as elicitor and grapevine biostimulant, representing a complement to soil fertilisation, and reducing the negative effects nutrients leaching into the groundwater. The present review aims to present the wide possibilities of chitosan applications on grapevines to prevent and combat the main diseases and to improve wine quality. In this way, relevant studies about chitosan application will be presented as well as some concerns and limitations in order to cover the knowledge gaps inherent to its application in vineyard and wine as well.

Abscisic Acid and Chitosan Modulate Polyphenol Metabolism and Berry Qualities in the Domestic White-Colored Cultivar Savvatiano

During the last decade, several studies demonstrated the effect of biostimulants on the transcriptional and metabolic profile of grape berries, suggesting their application as a useful viticultural practice to improve grape and wine quality. Herein, we investigated the impact of two biostimulants—abscisic acid (0.04% w/v and 0.08% w/v) and chitosan (0.3% w/v and 0.6% w/v)—on the polyphenol metabolism of the Greek grapevine cultivar, Savvatiano, in order to determine the impact of biostimulants’ application in the concentration of phenolic compounds. The applications were performed at the veraison stage and the impact on yield, berry quality traits, metabolome and gene expression was examined at three phenological stages (veraison, middle veraison and harvest) during the 2019 and 2020 vintages. Results showed that anthocyanins increased during veraison after treatment with chitosan and abscisic acid. Additionally, stilbenoids were recorded in higher amount following the chitosan and abscisic acid treatments at harvest. Both of the abscisic acid and chitosan applications induced the expression of genes involved in stilbenoids and anthocyanin biosynthesis and resulted in increased accumulation, regardless of the vintage. Alterations in other phenylpropanoid gene expression profiles and phenolic compound concentrations were observed as well. Nevertheless, they were mostly restricted to the first vintage. Therefore, the application of abscisic acid and chitosan on the Greek cultivar Savvatiano showed promising results to induce stilbenoid metabolism and potentially increase grape defense and quality traits.

The Role of Biostimulants as Alleviators of Biotic and Abiotic Stresses in Grapevine: A Review

The viticulture and wine industry contribute to the economy and reputation of many countries all over the world. With the predicted climate change, a negative impact on grapevine physiology, growth, production, and quality of berries is expected. On the other hand, the impact of these changes in phytopathogenic fungi development, survival rates, and host susceptibility is unpredictable. Grapevine fungal diseases control has been a great challenge to winegrowers worldwide. The use of chemicals in viticulture is high, which can result in the development of pathogen resistance, increasingly raising concerns regarding residues in wine and effects on human and environmental health. Promoting sustainable patterns of production is one of the overarching objectives and essential requirements for sustainable development. Alternative holistic approaches, such as those making use of biostimulants, are emerging in order to reduce the consequences of biotic and abiotic stresses in the grapevine, namely preventing grape fungal diseases, improving grapevine resistance to water stress, and increasing yield and berry quality.

Biostimulants in Viticulture: A Sustainable Approach against Biotic and Abiotic Stresses

Climate change and disproportionate anthropogenic interventions, such as the excess of phytopharmaceutical products and continuous soil tillage, are jeopardizing viticulture by subjecting plants to continuous abiotic stress. One of the main physiological repercussions of abiotic stress is represented by the unbalanced redox homeostasis due to the overproduction of reactive oxygen species (ROS), ultimately leading to a state of oxidative stress (detrimental to grape quality). To these are added the direct and indirect damages caused by pathogens (biotic stresses). In light of this scenario, it is inevitable that sustainable techniques and sensitivity approaches for environmental and human health have to be applied in viticulture. Sustainable viticulture can only be made with the aid of sustainable products. Biostimulant (PB) applications (including resistance inducers or elicitors) in the vineyard have become interesting maneuvers for counteracting vine diseases and improving grape quality. These also represent a partial alternative to soil fertilization by improving nutrient absorption and avoiding its leaching into the groundwater. Their role as elicitors has important repercussions in the stimulation of the phenylpropanoid pathway by triggering the activation of several enzymes, such as polyphenol oxidase, lipoxygenase, phenylalanine ammonia-lyase, and peroxidase (with the accumulation of phenolic compounds). The present review paper summarizes the PBs' implications in viticulture, gathering historical, functional, and applicative information. This work aims to highlight the innumerable beneficial effects on vines brought by these products. It also serves to spur the scientific community to a greater contribution in investigating the response mechanisms of the plant to positive inductions.

In vitro bioproduction and enhancement of moscatilin from a threatened tropical epiphytic orchid, Dendrobium ovatum (Willd.) Kraenzl

Moscatilin, a bibenzyl derivative (stilbenoid), mostly found in one of the largest genera of Orchidaceae; Dendrobium has many therapeutic benefits. Its function as an anticancer agent has been widely demonstrated through many research investigations. However, the compound has not been produced in vitro to date. The present study highlights the development of cultures viz., seedling generation, callus induction and callus regeneration (transformation of callus into plantlets). These cultures were devised to conserve the threatened tropical epiphytic orchid species, Dendrobium ovatum and identify their potential towards moscatilin bioproduction in vitro. Among the three culture platforms, callus-derived plantlets could yield high moscatilin when treated with l-Phenylalanine as a precursor. Tissue differentiation was found to be indispensable for the high production of this polyphenol. These cultures also offer potential commercial benefits as they can serve as appropriate platforms to decode moscatilin biosynthesis and other significant bibenzyl derivatives. Elicitors, such as chitosan, salicylic acid, and methyl jasmonate, were found, causing an enhancement in moscatilin content in the cultures. The seedlings obtained can serve towards ecorestoration and preservation of the studied species. Callogenesis was useful in plantlet regeneration, as callus-derived plantlets could be utilized for the enrichment and commercial scale-up of moscatilin-like chemicals.

Impact of Application of Abscisic Acid, Benzothiadiazole and Chitosan on Berry Quality Characteristics and Plant Associated Microbial Communities of Vitis vinifera L var. Mouhtaro Plants

The phenolic profile of the grape berries is a key quality factor for the red grapevine varieties and several techniques have been applied to improve it. An innovative technique is the application of resistance elicitors and phytohormones. In the present study, leaves and berries of a Greek red indigenous variety (Mouhtaro) sprayed with two elicitors, benzothiadiazole and chitosan and a plant hormone abscisic acid, during veraison. Physicochemical and phenolic characteristics of the berries and microbial communities of rhizosphere, phyllosphere and carposphere were analyzed at harvest. Differences in the microbial communities on different plant compartments were observed after the application of the plant activators. Chitosan treatment increased the abundance of the beneficial lactic acid bacteria, while the abscisic acid treatment decreased the presence of spoilage fungi on the carposphere. Treatments differentiate total phenolics, anthocyanins and in the chemical characteristics of grape must with chitosan treated grapes had increased anthocyanins and skin-derived phenolics that correlated positively with the microbial taxa that was discriminant by LefSe analysis. This research provides an overview of the effect of plant activators on the microbial ecology and grape quality of the Greek variety Mouhtaro and presents the potential of new and innovative approaches in the field of sustainable viticulture.

Chitosan-, alginate- carrageenan-derived oligosaccharides stimulate defense against biotic and abiotic stresses, and growth in plants: A historical perspective

During the last 20 years, the mechanisms involved in the stimulation of defense against pathogens, and growth triggered by chitosan-, alginate- and carrageenan-derived oligosaccharides have been studied in plants. Oligo-chitosan stimulate protection against pathogens by activation of salicylic acid (SA) or jasmonic acid/ethylene (JA/ET)-dependent pathways, protection against abiotic stress through abscisic acid (ABA)-dependent pathway, and growth by increasing photosynthesis, auxin and gibberellin content, C and N assimilation, and synthesis of secondary metabolites with antipathogenic and medicinal properties. Oligo-alginates stimulate protection against pathogens through SA-dependent pathway, abiotic stress via ABA-dependent pathway, and growth by increasing photosynthesis, auxin and gibberellins contents, C and N assimilation, and synthesis of secondary metabolites with antipathogenic and medicinal properties. Oligo-carrageenan increased protection against pathogens through JA/ET, SA- and Target of Rapamycin (TOR)-dependent pathways, and growth by activation of TOR-dependent pathway leading to an increase in expression of genes involved in photosynthesis, C, N, S assimilation, and enzymes that synthesize phenolic compounds and terpenes having antipathogenic activities. Thus, the latter oligosaccharides induce similar biological effects, but through different signaling pathways in plants.

Chitosan increases Pinus pinaster tolerance to the pinewood nematode (Bursaphelenchus xylophilus) by promoting plant antioxidative metabolism

The pine wilt disease (PWD), for which no effective treatment is available at the moment, is a constant threat to Pinus spp. plantations worldwide, being responsible for significant economic and environmental losses every year. It has been demonstrated that elicitation with chitosan increases plant tolerance to the pinewood nematode (PWN) Bursaphelenchus xylophilus, the causal agent of the PWD, but the biochemical and genetic aspects underlying this response have not been explored. To understand the influence of chitosan in Pinus pinaster tolerance against PWN, a low-molecular-weight (327 kDa) chitosan was applied to mock- and PWN-inoculated plants. Nematode population, malondialdehyde (MDA), catalase, carotenoids, anthocyanins, phenolic compounds, lignin and gene expression related to oxidative stress (thioredoxin 1, TRX) and plant defence (defensin, DEF, and a-farnesene synthase, AFS), were analysed at 1, 7, 14, 21 and 28 days post-inoculation (dpi). At 28 dpi, PWN-infected plants elicited with chitosan showed a sixfold lower nematode population when compared to non-elicited plants. Higher levels of MDA, catalase, carotenoids, anthocyanins, phenolic compounds, and lignin were detected in chitosan-elicited plants following infection. The expression levels of DEF gene were higher in elicited plants, while TRX and AFS expression was lower, possibly due to the disease containment-effect of chitosan. Combined, we conclude that chitosan induces pine defences against PWD via modulation of metabolic and transcriptomic mechanisms related with plant antioxidant system.

Rutin prevents inflammation induced by lipopolysaccharide in RAW 264.7 cells via conquering the TLR4-MyD88-TRAF6-NF-κB signalling pathway

OBJECTIVES

Inflammation widely exists in many diseases and poses a great threat to human and animal health. Rutin, quercetin-3-rhamnosyl glucoside, has a variety of pharmacological effects, including anti-oxidant, anti-inflammatory, antibacterial, anticancer and radioresistance effects. The current study focused on evaluation of its anti-inflammatory activity and described the mechanism of rutin in lipopolysaccharide-induced RAW 264.7 cells.

METHODS

The related gene and protein expression levels were investigated by quantification real-time PCR and western blotting, respectively.

KEY FINDINGS

This study revealed that rutin can decrease inducible nitric oxide synthase (iNOS) gene and protein expression levels, effectively increase IκB gene expression, reduce toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), tumour necrosis factor receptor-associated factor 6 (TRAF6) and p65 gene expression and inhibit the phosphorylation of IκB and p65 and the proteins expression of TLR4, MyD88 and TRAF6.

CONCLUSIONS

These results suggest that rutin might exert anti-inflammatory effect on LPS-stimulated RAW 264.7 cells and will be potentially useful as an adjuvant treatment for inflammatory diseases.

Phenolic compounds: current industrial applications, limitations and future challenges

Phenolic compounds are natural bioactive molecules found mainly in plant tissues that have shown interesting bioactivities, such as antioxidant, antimicrobial, anti-inflammatory, and antiproliferative activities, among others, which has led to great interest in their use by several industries. However, despite the large number of scientific studies on this topic, some issues still need to be studied and solved, such as the understanding of the main actions of these compounds in organisms. Besides their large potential applicability in industry, phenolic compounds still face some issues making it necessary to develop strategies to improve bioavailability, sustainable technologies of extraction and refinement, and stability procedures to increase the range of applicability. This review focuses on the most recent advances in the applications of phenolic compounds in different technological and medicinal areas. In addition, techniques to improve their sustainable resourcing, stability and bioavailability will be presented and discussed.

Eliciting effect of foliar application of chitosan lactate on the phytochemical properties of Ocimum basilicum L. and Melissa officinalis L

An increase in the content of secondary metabolites in herbal plants is desirable due to their therapeutic and nutraceutical properties. Therefore, the effects of foliar spray of 100 mg/L or 500 mg/L of chitosan lactate (ChL) on the accumulation of selected phenolics and physiological parameters of basil and lemon balm were investigated. In basil, the concentration of rosmarinic acid (RA) increased after application of 100 mg/L of ChL. In turn, in lemon balm both ChL concentrations increased the accumulation of RA and anthocyanins, while the level of total phenolic compounds (TPC) was elevated only at the dose of 100 mg/L of ChL. Elicitation of basil with 500 mg/L of ChL increased the shoot biomass. Therefore, such an elicitor as ChL can enhance the accumulation of valuable phytochemicals in Lamiaceae species. This simple and non-laborious method can be used for elicitation of herbal plants in production of functional food.

Ectopic Expression of Production of Anthocyanin Pigment 1 (PAP1) Improves the Antioxidant and Anti-Melanogenic Properties of Ginseng (Panax ginseng C.A. Meyer) Hairy Roots

The development of genetically engineered cell cultures has been suggested as a potential approach for the production of target compounds from medicinal plants. In this study, we generated PAP1 (production of anthocyanin pigment 1)-overexpressing ginseng (Panax ginseng C.A. Meyer) hairy roots to improve the production of anthocyanins, as well as the bioactivity (e.g., antioxidant and whitening activities) of ginseng. Based on differentially expressed gene analysis, we found that ectopic expression of PAP1 induced the expression of genes involved in the ‘phenylpropanoid biosynthesis’ (24 genes), and ‘flavonoid biosynthesis’ (17 genes) pathways, resulting in 191- to 341-fold increases in anthocyanin production compared to transgenic control (TC) hairy roots. Additionally, PAP1-overexpressing ginseng hairy roots exhibited an approximately seven-fold higher DPPH-free radical scavenging activity and 10-fold higher ORAC value compared to the TC. In α-melanocyte-stimulating hormone-stimulated B16F10 cells, PAP1-overexpressing ginseng hairy roots strongly inhibited the accumulation of melanin by 50 to 59% compared to mock-control. Furthermore, results obtained by quantitative real-time PCR, western blot, and tyrosinase inhibition assay suggested that the anti-melanogenic activity of PAP1-overexpressing ginseng hairy roots is mediated by tyrosinase activity inhibition. Taken together, our results suggested that the ectopic expression of PAP1 is an effective strategy for the enhancement of anthocyanin production, which improves the biological activities of ginseng root cultures.

Comparative Insight upon Chitosan Solution and Chitosan Nanoparticles Application on the Phenolic Content, Antioxidant and Antimicrobial Activities of Individual Grape Components of Sousão Variety

Chitosan, a natural polysaccharide, has been previously proposed as an elicitor in plants to prevent pathogen infections. The present study aimed to analyze the effect of chitosan solution and chitosan nanoparticles treatment applied on the grapevine variety Sousão with respect to the phenolic composition, antioxidant potential and antibacterial activity of its individual grape components. Grapevine plants of selected lines were sprayed with chitosan solution and chitosan nanoparticles, and ethanolic extracts of stems, seeds and skins were prepared from grapevines treated and not treated with chitosan. Total phenolic, anthocyanin and tannin contents were studied, and the identification of the individual phenolic compounds was performed by HPLC-DAD. The antimicrobial susceptibility method was performed using the Kirby-Bauer disc diffusion method against multidrug-resistant bacteria. Overall, there was small increase in the concentration of phenolic compounds, antioxidant and antimicrobial activities in grape components treated with chitosan solution. Seed extracts showed the highest antioxidant and antimicrobial activities. The studied individual components obtained from chitosan-treated grapevines could represent an added value due to the increased antioxidant and antibacterial potentials. The phenolic compounds found in components may be used in food and pharmaceutical industries as natural food preservers and antibiotic adjuvants.