Reinforcing the bulwark: unravelling the efficient applications of plant phenolics and tannins against environmental stresses

Genetic mechanisms, biological function, and biotechnological advance in sorghum tannins research

Sorghum (Sorghum bicolor) holds a unique position in the human diet and serves as a stable food source in many developing countries especially in African and south Asian regions. Tannins, the primary secondary metabolites in sorghum, are pivotal in determining its characteristic bitter taste. Beyond their influence on flavor, tannins play a vital role in sorghum's resistance to biotic and abiotic stresses and serve as key indicators of grain quality. The concentration of tannins significantly affects the potential for diverse applications of sorghum. This review provides a comprehensive analysis of sorghum tannins, focusing on their genetic basis, biological activities, and biosynthesis mechanisms. It highlights the relationship between tannin levels and grain color and delves into the underlying biogenetic pathways. Furthermore, the potential of functional genomics and biotechnological approaches in precisely controlling tannin levels for sorghum breeding is discussed. This study aims to offer valuable insights and perspectives for advancing both the scientific understanding and practical applications of sorghum tannins.

Effects of Mulch and Fertilization on the Quantity and Quality of Perennial Wall-Rocket (Diplotaxis tenuifolia)

Diplotaxis tenuifolia, a species with high nutritional value, was recently introduced in Romania, making in-depth research necessary to develop an efficient cultivation technology to increase agronomic and economic potential. Therefore, the present study aimed to evaluate the influence of three mulch treatments-white polyethylene film (WLDPE), black polyethylene film (BLDPE), and nonmulched (NM)-along with three fertilization regimes-organic (OF), chemical (ChF), and nonfertilized (NF)-on the yield and quality of the Bologna cultivar of perennial wall-rocket under the climatic conditions of northeastern Romania. The results showed that mulching with white polyethylene films significantly increased the CO2 assimilation rate, although it did not lead to substantial differences in agro-morphological traits compared to the non-mulched variant. However, plants grown under WLDPE exhibited a significantly higher leaf area index and yield than those under BLDPE mulch. In contrast, BLDPE mulch had a positive effect on dry matter accumulation and β-carotene content. The variations in fertilization regime had no significant impact on most traits analyzed. Significant differences were noted in the CO2 assimilation rate and DPPH antioxidant activity, with organic fertilization increasing CO2 assimilation and decreasing DPPH activity compared to chemical and unfertilized regimes. Furthermore, the interaction between mulching practices and fertilization regimes revealed significant influences on the physiological performance and phytochemical composition of perennial wall-rocket. The highest CO2 assimilation rate and lowest antioxidant activity were recorded in the WLDPE × OF combination, suggesting improved photosynthetic efficiency and a reduced oxidative response resulting from the synergistic effects of reflective mulching and organic fertilization. In contrast, the Bologna cultivar experienced the greatest oxidative stress under the unfertilized regime, with the most pronounced effects observed under no mulching.

A Comparison of Methods for Assessing the Antioxidant Expression in Posidonia oceanica (L.) Delile

Non-enzymatic antioxidants, such as polyphenols, can counteract free radicals and other potentially toxic oxidants produced by marine plants exposed to stress. In this study, we assessed different methods for measuring antioxidant capacities and condensed tannins in the seagrass Posidonia oceanica (L.) Delile. Two polyphenol extraction methods, direct and sequential, were compared to determine their efficiencies. Condensed tannins were assayed directly on leaf flour using a modified HCl-butanol-acetone-iron reagent method. Total antioxidant capacities were assayed with the ABTS, CUPRAC, and ORAC methods, both on extracts and on powdered samples (QUENCHER). The direct assays showed higher sensitivity compared to their in-solution counterparts. Our results indicate that in-depth measurement of antioxidant compounds and capacities can be achieved by direct assays on P. oceanica powder samples, and these data can be used to assess changes in the plant biochemistry due to the exposure to varying biotic and abiotic conditions.

Enhancing Photostability of Prochloraz via Designing Natural Acid-Derived Prochloraz-Based Ionic Liquids

Converting pesticides into ionic liquids by designing counterions can modulate their physicochemical properties, thus improving their efficacy and environmental safety. In this study, eight prochloraz-based ionic liquids (PILs) were synthesized using natural organic acids, and their physicochemical properties, toxicity, antifungal activity, and efficacy in postharvest mango preservation were evaluated. The results showed that the physicochemical properties of propiconazole, including water solubility, logKow, surface activity, and light stability, could be adjusted by selecting counterions with varying structures. These properties were correlated with toxicity to zebrafish embryos and antifungal activity against Colletotrichum gloeosporioides. Notably, except for the benzoate PIL, the photostability of the other seven PILs was enhanced under UV irradiation, with the cinnamate PIL exhibiting a half-life 2.28 times longer than prochloraz. Spectral analysis indicated that the anions influenced photostability by shielding or interacting with the cations. Furthermore, the three selected PILs improved pesticide deposition on the mango surface during preservation, and the salicylate PIL enhanced pesticide penetration into the fruit, potentially contributing to its therapeutic activity. In conclusion, the ionic liquid strategy offers an effective method to modify pesticide properties, improve photostability, reduce losses, and optimize pesticide formulation.

Effects of Microalgae as Biostimulants on Plant Growth, Content of Antioxidant Molecules and Total Antioxidant Capacity in Chenopodium quinoa Exposed to Salt Stress

Chenopodium quinoa Willd. is a halophytic plant valued for its nutritional and nutraceutical properties, as well as its adaptability to diverse soil and climatic conditions. Biostimulant application enhances plant quality and resilience under adverse environmental conditions. The effects of microalgae extracts (Ettlia pseudoalveolaris and Chlorella vulgaris) and salt stress (NaCl 100, 200, 300 mM) were evaluated on 7-day-old seedlings of two quinoa varieties, 'Tunkahuan' and 'Regalona'. The analysis focused on the content of antioxidant molecules (total phenolics and flavonoids), total antioxidant capacity (measured by DPPH, 2,2-Diphenyl-1-picrylhydrazyl, and FRAP, Ferric Reducing Antioxidant Power, assays), reactive oxygen species (ROS), the levels of lutein, β-carotene, chlorophyll a and b. Microalgae extracts and salt stress treatments significantly increased antioxidant molecules in both quinoa varieties. The highest antioxidant activity, measured by the DPPH assay, was observed in 'Regalona', while a dose-dependent increase in antioxidant capacity, by the FRAP assay, was evident in 'Tunkahuan' treated with Ettlia. ROS level was reduced by Ettlia in 'Tunkahuan' but not in 'Regalona'. Pigment content increased with higher salt concentrations but decreased with the addition of biostimulants. These findings suggest that the application of microalgae extracts enhances bioactive compounds, improving salinity resistance and increasing the nutraceutical value of quinoa sprouts.

A Review of the Treatments to Reduce Anti-Nutritional Factors and Fluidized Bed Drying of Pulses

Pulses, rich in proteins, dietary fibers, and essential nutrients, play an important role in human nutrition, especially as alternatives to animal proteins. However, the presence of anti-nutritional factors (ANFs), such as trypsin inhibitors, chymotrypsin inhibitors, phytic acid, and tannins, can hinder nutrient absorption, reduce protein digestibility, and impair the overall nutritional value of these foods (pulses). This literature review critically examines fluidized bed drying (FBD) as a promising method for processing pulses, with a focus on the effectiveness of FBD in reducing ANFs while preserving protein quality. The review highlights the impact of FBD on the quality and nutritional properties of pulses, discussing the effect of FBD on different kind of ANFs. Although FBD shows significant potential in reducing certain enzyme inhibitors, it has limitations in removing thermally stable ANFs, such as phytic acid. Furthermore, the review explores energy and exergy efficiencies in FBD systems, emphasizing the need for advanced technologies such as air recycle systems to enhance sustainability. This review identifies significant gaps in existing research, particularly in optimizing FBD methods for the effective removal of ANFs and in developing energy-efficient processing strategies.

Phytochemical Analysis and Allelopathic Potential of an Aggressive Encroacher Shrub, Euryops floribundus (Asteraceae)

Euryops floribundus is an encroaching shrub species that poses a threat to grassland diversity and productivity in the Eastern Cape region of South Africa. This shrub inhibits understory herbaceous plant recruitment and establishment, thereby exposing soils to erosion, owing potentially to toxins it secretes. However, the allelochemicals of E. floribundus and their potential effects on the germination and establishment of plants remains poorly understood. We investigated the phytochemical classes of leaves and twigs of E. floribundus and evaluated the effects of extracts from these plant parts on seed germination and seedling growth of Lactuca sativa through a laboratory experiment. In the laboratory, we analysed phytochemicals in leaf and twig extracts and tested their allelopathic effects on Lactuca sativa seed germination and growth using the Petri dish method. In this proof-of-concept study, we identified 12 phytochemical classes of E. floribundus. Quantitative analysis showed that the leaves had significantly higher levels of flavonoids, phenolics, and tannins than twigs. As a result, leaf extracts caused 100% inhibition of seed germination, while twig extracts inhibited seed germination by 90% at 50 g L-1. Both leaf and twig extracts also significantly reduced radicle and plumule growth, with a stronger effect observed from the leaves than twigs. This study provides new insights into the phytochemical composition and strong allelopathic potential of E. floribundus, contributing to a better understanding of the mechanisms driving its encroachment in semi-arid grasslands.

Metabolome profiling dissects the oat (Avena sativa L.) innate immune response to Pseudomonas syringae pathovars

One of the most important characteristics of successful plant defence is the ability to rapidly identify potential threats in the surrounding environment. Plants rely on the perception of microbe-derived molecular pattern chemicals for this recognition, which initiates a number of induced defence reactions that ultimately increase plant resistance. The metabolome acts as a metabolic fingerprint of the biochemical activities of a biological system under particular conditions, and therefore provides a functional readout of the cellular mechanisms involved. Untargeted metabolomics was applied to decipher the biochemical processes related to defence responses of oat plants inoculated with pathovars of Pseudomonas syringae (pathogenic and non-pathogenic on oat) and thereby identify signatory markers that are involved in host or nonhost defence responses. The strains were P. syringae pv. coronafaciens (Ps-c), P. syringae pv. tabaci, P. syringae pv. tomato DC3000 and the hrcC mutant of DC3000. At the seedling growth stage, metabolic alterations in the Dunnart oat cultivar (tolerant to Ps-c) in response to inoculation with the respective P. syringae pathovars were examined following perception and response assays. Following inoculation, plants were monitored for symptom development and harvested at 2-, 4- and 6 d.p.i. Methanolic leaf extracts were analysed by ultra-high-performance liquid chromatography (UHPLC) connected to high-definition mass spectrometry. Chemometric modelling and multivariate statistical analysis indicated time-related metabolic reconfigurations that point to host and nonhost interactions in response to bacterial inoculation/infection. Metabolic profiles derived from further multivariate data analyses revealed a range of metabolite classes involved in the respective defence responses, including fatty acids, amino acids, phenolic acids and phenolic amides, flavonoids, saponins, and alkaloids. The findings in this study allowed the elucidation of metabolic changes involved in oat defence responses to a range of pathovars of P. syringae and ultimately contribute to a more comprehensive view of the oat plant metabolism under biotic stress during host vs nonhost interactions.

Salt Stress Enhanced Bioactivity of Quinoa Leaf Extracts: An In Vitro and In Silico Study of Acetylcholinesterase and Tyrosinase Inhibition for Sustainable Drug Development

Background: Quinoa is recognized for its nutritional and pharmacological properties. This study aims to investigate the impact of salt stress induced by varying concentrations of sodium chloride (NaCl) on the production of phenolic compounds and their biological activities in different quinoa accessions. Method: Leaves from three quinoa accessions (Q4, Q24, and Q45) cultivated under increasing NaCl treatments were subjected to chemical analysis using ethanol and water extract. The concentrations of various phenolic compounds, including polyphenols, tannins, anthocyanins, and flavonoids, were quantified. HPLC-DAD-ESI-MS/MS was employed to identify the major compounds in the water extract. Additionally, antioxidants (ABTS and FRAP), anti-tyrosinase, and anti-acetylcholinesterase effects were assessed using in vitro and in silico approaches. Results: NaCl treatment significantly increased the levels of phenolic compounds across all quinoa accessions. The Q45 accession exhibited the highest accumulation of these compounds, particularly in the aqueous extracts at the 200 mM NaCl concentration. Increases were observed in flavonoids (144%), anthocyanins (125%), tannins (89%), and total polyphenols (65%) relative to controls. HPLC-DAD-ESI-MS/MS analysis corroborated these findings, showing that the main compounds also increased with higher NaCl concentrations. Furthermore, the biological efficacy tests revealed that the IC50 values for both tyrosinase and acetylcholinesterase activities decreased with greater salt stress, indicating enhanced enzyme inhibition. The antioxidant activity of these extracts also showed a significant increase as the salt stress levels rose. Conclusions: Salt stress not only promotes the production of bioactive phenolic compounds in quinoa leaves but also enhances their inhibitory effects on key enzymes associated with neurodegenerative and pigmentary disorders. These findings suggest that quinoa may serve as a valuable resource for therapeutic applications, particularly under increased salinity conditions.

Ultraviolet C irradiation enhances the resistance of grape against postharvest black rot (Aspergillus carbonarius) by regulating the synthesis of phenolic compounds

UV-C irradiation can maintain fruit quality by inducing fruit disease resistance and reducing decay during storage. Grape (Vitis Vinifera L.) was exposed to 2.4 kJ m-2 UV-C irradiation then inoculated with Aspergillus carbonarius to investigate the changes in nutritional quality, defense related substances and enzyme activities. Postharvest UV-C irradiation can increased the levels of defense-related substances and enzyme activities, such as phenols, flavanols, lignin, proline, glutathione, phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and β-1,3-glucanase (GLU). In addition, Resveratrol plays an important role in grape resistance to A. carbonarius infection through further verification by gene expression levels, the transcription factors VvWRKY24 and VvMYB14 are highly correlated with the regulation of VvSTS gene expression. This study revealed the molecular mechanism of postharvest grape fruit response to UV-C irradiation and the defense mechanism against black rot, and provided a theoretical basis for postharvest grape storage and preservation technology.

Tailoring Core-Shell Metal Coordination for Smart Seed Coatings in Sustainable Agriculture

The international agriculture and food security sector is grappling with challenges like low crop yields, soil health deficiencies, and inefficient agrochemical use. The application of smart nanotechnology in agriculture, particularly surface functionalization, holds promise but has limited implementation. Engineered nanomaterials used as seed treatments, known as nanopriming, offer a simple technology to improve crop yield and stress tolerance. In this study, a multicomponent platform called Phelm (Phenolic network with a lipid core and metal coordinated shell) is proposed for encapsulating a commercial plant growth regulator, indole-3 acetic acid (IAA). Phelm comprises a hydrophobic solid lipid core, loaded with IAA, and an outer metal coordinated phenolic shell of tannic acid (TA) and Fe3+. The platform aims to treat seeds with encapsulated IAA, which can be controllably released, as well as protect the germination process at high salt concentrations. Phelm showed a remarkable increase in growth parameters of wheat seeds up to 58.6%, despite being irrigated with high concentrations of saltwater (100 mM). These findings suggest that nanopriming of seeds can effectively increase their efficacy even under abiotic stress conditions, which can drastically improve crop yields. Moreover, we envisage that the Phelm core/shell assembly can encapsulate a wide range of agrochemicals and biostimulants to promote sustainable and smart agricultural practices.

The interaction effect of water deficit stress and nanosilicon on phytochemical and physiological characteristics of hemp (Cannabis sativa L.)

Different practical approaches have been employed to attenuate the destructive impacts of water deficit stress on plants, such as utilization of humic acid, salicylic acid, algae extract, mulching, and microorganisms, as well as silicon application. Nanosilicon significantly moderates the ruinous effects of abiotic and biotic stress in plants through some physiological processes. In this study, the interaction effect of drought stress and nanosilicon on phytochemical and physiological characteristics of hemp (Cannabis sativa L.) was investigated, wherein the four-week-old seedlings were subjected to irrigation treatments at four levels, including 100% (control), 80% (mild stress), 60% (moderate stress), and 40% (severe stress) of field capacity and nanosilicon at three concentrations (0, 0.5, and 1.5 mM) was foliar applied every 10 days in a factorial completely randomized design experiment with three replications for 30 days. Phytochemical and physiological analyses such as photosynthetic pigments, total phenolic and flavonoid content, and antioxidant enzyme activities were conducted. The results indicated that the highest content of Cannabidiol and Tetrahydrocannabinol was achieved using 1.5 mM (1.89%) and 0.5 mM (0.63%) nanosilicon treatments, respectively, under moderate stress. The plants subjected to severe drought stress without nanosilicon application displayed the lowest values of chlorophyll a (0.50 mg/g FW) and b (0.20 mg/g FW). The use of nanosilicon excited the activation of antioxidant enzymes, wherein the plants treated with nanosilicon and drought stress exhibited significantly higher SOD, POD, and APX activities compared to the control. Under all drought stress levels, foliar application of nanosilicon at the highest concentration decreased proline content. The results proposed that the application of 1.5 mM nanosilicon, as a more efficient concentration, improved drought tolerance in hemp plants.

Study on the Mechanism of Flavonoid Enrichment in Black Soybean Sprouts by Abscisic Acid/Melatonin Under Slight Acid Treatment

Plant hormones play a critical role in the physiological and biochemical mechanisms of plants, with functions such as regulating the metabolic pathways of secondary metabolite production and alleviating external stresses. In this study, the synthesis of flavonoids in black soybean sprouts was induced by slight acid combined with the plant hormones abscisic acid (ABA) and melatonin (MT). The results indicated that the contents of daidzin, genistin, daidzein, and genistein in black soybean sprouts treated with slight acid were increased by 10 μM ABA and 75 μM MT, and the total flavonoid content was significantly enhanced. Compared with the slight acid treatment, the H2O2 and malondialdehyde (MDA) contents in black soybean sprouts were increased after ABA treatment, and the black soybean sprouts were further stressed. However, the H2O2 and MDA contents in black soybean sprouts were significantly decreased after MT treatment, indicating that the stress of black soybean sprouts can be alleviated by MT. Under slight acid stress, the genes related to flavonoid synthesis in black soybean sprouts were induced by exogenous ABA, promoting the accumulation of flavonoids; under exogenous MT treatment, the activity of phenylpropanoid metabolism enzymes was significantly increased, the genes related to flavonoid synthesis were upregulated, and flavonoid synthesis was induced. These results suggest that the combination of slight acid and plant hormone treatments promotes the accumulation of flavonoid substances during the germination of black soybeans. This research lays the foundation for improving the growth conditions of black soybeans and promoting the enrichment of flavonoid substances in black soybeans.

SmJAZs-SmbHLH37/SmERF73-SmSAP4 module mediates jasmonic acid signaling to balance biosynthesis of medicinal metabolites and salt tolerance in Salvia miltiorrhiza

Salvia miltiorrhiza holds significant importance in traditional Chinese medicine. Stress-associated proteins (SAP), identified by A20/AN1 zinc finger structural domains, play crucial roles in regulating plant growth, development, resistance to biotic and abiotic stress, and hormone responses. Herein, we conducted a genome-wide identification of the SAP gene family in S. miltiorrhiza. The expression analysis revealed a significant upregulation of SmSAP4 under methyl jasmonate (MeJA) and salt stress. Overexpressing SmSAP4 in S. miltiorrhiza hairy roots increased tanshinones content while decreasing salvianolic acids content, while RNAi-silencing SmSAP4 had the opposite effect. SmSAP4 overexpression in both Arabidopsis thaliana and S. miltiorrhiza hairy roots decreased their salt stress tolerance, accompanied by increased activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and a hindered ability to maintain the Na+ : K+ ratio. Further investigations demonstrated that MeJA alleviated the inhibitory effect of SmJAZ3 on SmSAP4 activation by SmbHLH37 and SmERF73. However, MeJA did not affect the inhibition of SmSAP4 activation by SmJAZ8 through SmbHLH37. In summary, our research reveals that SmSAP4 negatively regulates the accumulation of salvianic acid through the SmJAZs-SmbHLH37/SmERF73-SmSAP4 module and positively impacting the accumulation of tanshinones. Additionally, it functions as a negative regulator under salt stress.

Evaluating the Root Extract of Reynoutria ciliinervis (Nakai) Moldenke: An Analysis of Active Constituents, Antioxidant Potential, and Investigation of Hepatoprotective Effects in Rats

Reynoutria ciliinervis (Nakai) Moldenke (R. ciliinervis) root, a traditional Chinese medicine, was found to exhibit remarkable pharmacological properties through a series of comprehensive investigations. Our study commenced with a qualitative phytochemical analysis that identified 12 bioactive compounds within the plant. Subsequently, utilizing ultraviolet-visible spectrophotometry, the methanol extract emerged as the optimal solvent extract, which was abundant in diverse classes of compounds such as carbohydrates, phenolics, steroids, alkaloids, phenolic acids, and tannins. In vitro antioxidant assays underscored the exceptional free radical scavenging, metal ion chelation, hydrogen peroxide scavenging, singlet oxygen quenching, and β-carotene bleaching capabilities of the methanol extract, significantly outperforming other solvent extracts. Further ultra high-performance liquid chromatography-electrospray ionization-quadrupole time of flight-mass spectrometry analysis revealed the presence of 45 compounds, predominantly anthraquinones and phenolics, in the methanol extract. The extract demonstrated robust stability under various conditions, including high temperatures, varying pH levels, and simulated gastrointestinal digestion as well as efficacy in inhibiting the oxidation in edible oils. Acute toxicity tests in mice confirmed the safety of the methanol extract and provided a valuable dosage reference for future studies. Importantly, high-dose methanol extract exhibited a significant pre-protective effect against D-galactosamine-induced liver injury in rats, as evidenced by reduced alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, malondialdehyde levels, and elevated catalase and albumin levels. These findings suggest a potential role for the methanol extract of R. ciliinervis root in treating oxidative stress-related disorders, highlighting the plant's immense medicinal potential. Our research offers a thorough evaluation of the bioactive components, antioxidant properties, stability, and liver-protecting effects of the methanol extract, setting the stage for deeper investigation and potential clinical applications.

Phlorotannins contribute to the ameliorative bioactivities of Ecklonia maxima-derived bioproduct in salt-stressed Solanumlycopersicum

Seaweed-derived bioproducts are increasingly being deployed as an environmentally friendly and sustainable approach to crop management under stressful growth conditions including salinity. The bioactivities of seaweed-derived extracts are linked to the presence of diverse groups of bioactive compounds. In the present study, the phlorotannins present in the seaweed Ecklonia maxima and Kelpak®, an E. maxima-derived bioproduct, were quantified and identified. Three phlorotannins were identified in E. maxima, namely eckol, 2-phloroeckol, and dibenzodioxin-fucodiphloroethol. Eckol (589.11 - 822.54 μg l-1) and dibenzodioxin-fucodiphloroethol (85 - 895 μg l-1) were present in Kelpak®. Phlorotannin bioactivity was investigated in tomato seedlings grown under NaCl-induced salinity stress. The seedlings treated with either individual phlorotannins (i.e., eckol or a fraction containing 2-phloroeckol and dibenzodioxin-fucodiphloroethol) or Kelpak® resulted in a reprogramming of biomass allocation as indicated by an increased root-to-shoot ratio. Phlorotannin and Kelpak® treatments induced the accumulation of antioxidants with an attendant augmentation of the antioxidant capacities and inhibition of membrane damage in the NaCl-stressed seedlings. Kelpak® treatment induced an increase in abscisic acid (ABA) accumulation and phlorotannin treatments lowered the ABA content of the stressed seedlings. These results demonstrated that phlorotannins contributed to the ameliorative actions of Kelpak®. The more potent effects of Kelpak®, in comparison to phlorotannins, in improving dry matter accumulation, ABA content, antioxidative properties, and inhibiting tissue injury of the salt-stressed tomato seedlings may be attributed to the presence of other bioactive components in the Kelpak® product.

Involvement of glucosinolates and phenolics in the promotion of broccoli seedling growth through the modulation of primary and secondary metabolism

Secondary metabolites play an essential role in plant defense. However, the role of glucosinolates and phenols in brassica crop yield in the context of environmentally friendly agricultural practices has not been established. Our study investigated the effects of a Brassica extract, rich in these metabolites, on the physiology and metabolism of broccoli (Brassica oleracea L. var. italica) seedlings and the subsequent development of the plants in adult stages. The results showed an increase in growth in the extract-treated seedlings, which was associated with an alteration of primary and secondary metabolism. In particular, there was an increase in the levels of amino acids, phenolic compounds and hormones, while the levels of glucosinolates decreased. Lipid peroxidation diminished in treated plants, indicating improved membrane integrity. Treated plants subsequently grown in hydroponically showed increased water use efficiency, transpiration, and internal carbon, which contributed to the improved growth of these plants. Overall, our findings underscore the potential of the glucosinolates and phenols ratio as essential to improve crop growth and stress tolerance, as well as revealed the interest of studying the mechanisms involved in the possible uptake and integration of GSLs by broccoli seedlings after external application.

Recovery of green phenolic compounds from lignin-based source: Role of ferulic acid esterase towards waste valorization and bioeconomic perspectives

The production of chemicals/products so far relies on fossil-based resources with the creation of several environmental problems at the global level. In this situation, a sustainable and circular economy model is necessitated to mitigate global environmental issues. Production of biowaste from various processing industries also creates environmental issues which would be valorized for the production of industrially important reactive and bioactive compounds. Lignin acts as a vital part in biowaste composition which can be converted into a wide range of phenolic compounds. The phenolic compounds have attracted much attention, owing to their influence on diverse not only organoleptic parameters, such as taste or color, but also active agents for active packaging systems. Crop residues of varied groups, which are an affluent source of lignocellulosic biomass could serve as a renewable resource for the biosynthesis of ferulic acid (FA). FA is obtained by the FA esterase enzyme action, and it can be further converted into various tail end phenolic flavor green compounds like vanillin, vanillic acid and hydroxycinnamic acid. Lignin being renewable in nature, processing and management of biowastes towards sustainability is the need as far as the global industrial point is concerned. This review explores all the approaches for conversion of lignin into value-added phenolic compounds that could be included to packaging applications. These valorized products can exhibit the antioxidant, antimicrobial, cardioprotective, anti-inflammatory and anticancer properties, and due to these features can emerge to incorporate them into production of functional foods and be utilization of them at active food packaging application. These approaches would be an important step for utilization of the recovered bioactive compounds at the nutraceutical and food industrial sectors.

Nano-silicon and sodium mitigate damage by potassium deficiency in chicory

Chicory is a food with high nutritional. The use of beneficial elements in plants, such as sodium (Na) and silicon (Si), may be important to mitigate nutritional disorders, such as potassium (K) deficiency, but research is lacking on this topic. The objective was to evaluate the effects of sodium and nano-silicon on the nutritional, physiological, growth, and quality parameters of chicory under K deficiency and sufficiency. We used a concentration for sufficient K (3.0 mmol L-1), K-deficiency (1.5 mmol L-1), combined with the lack or presence of Na (2.0 mmol L-1) and Si (2.0 mmol L-1). The experiment was carried out in a greenhouse with six treatments corresponding to K sufficiency, K-sufficiency with Na, K-sufficiency with Si, K deficiency, K-deficiency with Na, and K-deficiency with Si, with six replications. The following growth variables were evaluated: (i) plant height, (ii) stem diameter, (iii) number of leaves, (iv) leaf area, and (v) plant biomass. Potassium and Si contents in the above ground part and K utilization efficiency were assessed, and the accumulation of K, Na, and Si was calculated. The efficiency of the quantum yield of photosystem II (Fv/Fm) and the photosynthetic pigments was determined. Electrolyte leakage index and relative water content, as well as phenolic compounds, ascorbic acid, and leaf firmness index were also determined. We found that supplying nano-Si and Na to a K-deficient nutrient solution increased K accumulation by 60% and 50% and K use efficiency by 79% and 62% compared to plants without supply of those elements. Nano-Si reduced electrolyte leakage, being 41% less than Na in K-deficient chicory. However, when Na was added to a nutrient solution with sufficient potassium, the K use efficiency decreased by 48% compared to sufficient potassium without Na. Under the same condition of sufficient supply of potassium and Na, K accumulation decreased by 20% in chicory compared to sufficient potassium without Na, and the photosynthetic pigments-total chlorophyll and carotenoids-were reduced by 5% and 10%, respectively. Our findings contribute to improve cultivation systems with low supply of K as the supply of Na and nano-Si mitigates the damage caused to the metabolism of chicory under K deficiency.

Basidiomycetes Polysaccharides Regulate Growth and Antioxidant Defense System in Wheat

Higher-fungi xylotrophic basidiomycetes are known to be the reservoirs of bioactive metabolites. Currently, a great deal of attention has been paid to the exploitation of mycelial fungi products as an innovative alternative in crop protection. No data exist on the mechanisms behind the interaction between xylotrophic mushrooms' glycopolymeric substances and plants. In this study, the effects of basidiomycete metabolites on the morphophysiological and biochemical variables of wheat plants have been explored. Wheat (Triticum aestivum L. cv. Saratovskaya 29) seedlings were treated with extracellular polysaccharides (EPSs) isolated from the submerged cultures of twenty basidiomycete strains assigned to 13 species and 8 genera. The EPS solutions at final concentrations of 15, 40, and 80 mg/L were applied to wheat seedlings followed by their growth for 10 days. In the plant samples, the biomass, length of coleoptile, shoot and root, root number, rate of lipid peroxidation by malondialdehyde concentration, content of hydrogen peroxide, and total phenols were measured. The peroxidase and superoxide dismutase activity were defined. Most of the EPS preparations improved biomass yields, as well as the morphological parameters examined. EPS application enhanced the activities of antioxidant enzymes and decreased oxidative damage to lipids. Judging by its overall effect on the growth indices and redox system of wheat plants, an EPS concentration of 40 mg/L has been shown to be the most beneficial compared to other concentrations. This study proves that novel bioformulations based on mushroom EPSs can be developed and are effective for wheat growth and antioxidative response. Phytostimulating properties found for EPSs give grounds to consider extracellular metabolites produced in the xylotrophic basidiomycete cultures as an active component capable of inducing plant responses to stress.

Identification of mungbean yellow mosaic India virus and susceptibility-related metabolites in the apoplast of mung bean leaves

KEY MESSAGE

The investigation of MYMIV-infected mung bean leaf apoplast revealed viral genome presence, increased EVs secretion, and altered stress-related metabolite composition, providing comprehensive insights into plant-virus interactions. The apoplast, an extracellular space around plant cells, plays a vital role in plant-microbe interactions, influencing signaling, defense, and nutrient transport. While the involvement of apoplast and extracellular vesicles (EVs) in RNA virus infection is documented, the role of the apoplast in plant DNA viruses remains unclear. This study explores the apoplast's role in mungbean yellow mosaic India virus (MYMIV) infection. Our findings demonstrate the presence of MYMIV genomic components in apoplastic fluid, suggesting potential begomovirus cell-to-cell movement via the apoplast. Moreover, MYMIV infection induces increased EVs secretion into the apoplast. NMR-based metabolomics reveals altered metabolic profiles in both apoplast and symplast in response to MYMIV infection, highlighting key metabolites associated with stress and defense mechanisms. The data show an elevation of α- and β-glucose in both apoplast and symplast, suggesting a shift in glucose utilization. Interestingly, this increase in glucose does not contribute to the synthesis of phenolic compounds, potentially influencing the susceptibility of mung bean to MYMIV. Fructose levels increase in the symplast, while apoplastic sucrose levels rise significantly. Symplastic aspartate levels increase, while proline exhibits elevated concentration in the apoplast and reduced concentration in the cytosol, suggesting a role in triggering a hypersensitive response. These findings underscore the critical role of the apoplast in begomovirus infection, providing insights for targeted viral disease management strategies.

A Comprehensive Analysis of Diversity, Structure, Biosynthesis and Extraction of Biologically Active Tannins from Various Plant-Based Materials Using Deep Eutectic Solvents

This paper explores the emerging subject of extracting tannins from various plant sources using deep eutectic solvents (DESs). Tannins are widely used in the food and feed industries as they have outstanding antioxidant qualities and greatly enhance the flavor and nutritional content of a wide range of food products. Organic solvents are frequently used in traditional extraction techniques, which raises questions about their safety for human health and the environment. DESs present a prospective substitute because of their low toxicity, adaptability, and environmental friendliness. The fundamental ideas supporting the application of DESs in the extraction of tannins from a range of plant-based materials frequently used in daily life are all well covered in this paper. Furthermore, this paper covers the impact of extraction parameters on the yield of extracted tannins, as well as possible obstacles and directions for future research in this emerging subject. This includes challenges such as high viscosity, intricated recovery of compounds, thermal degradation, and the occurrence of esterification. An extensive summary of the diversity, structure, biosynthesis, distribution, and roles of tannins in plants is given in this paper. Additionally, this paper thoroughly examines various bioactivities of tannins and their metabolites.

Improving productivity and soil fertility in Medicago sativa and Hordeum marinum through intercropping under saline conditions

BACKGROUND AND AIMS

Intercropping is an agriculture system used to enhance the efficiency of resource utilization and maximize crop yield grown under environmental stress such as salinity. Nevertheless, the impact of intercropping forage legumes with annual cereals on soil salinity remains unexplored. This research aimed to propose an intercropping system with alfalfa (Medicago sativa)/sea barley (Hordeum marinum) to explore its potential effects on plant productivity, nutrient uptake, and soil salinity.

METHODS

The experiment involved three harvests of alfalfa and Hordeum marinum conducted under three cropping systems (sole, mixed, parallel) and subjected to salinity treatments (0 and 150 mM NaCl). Agronomical traits, nutrient uptake, and soil properties were analyzed.

RESULTS

revealed that the variation in the measured traits in both species was influenced by the cultivation mode, treatment, and the interaction between cultivation mode and treatment. The cultivation had the most significant impact. Moreover, the mixed culture (MC) significantly enhanced the H. marinum and M. sativa productivity increasing biomass yield and development growth under salinity compared to other systems, especially at the second harvest. Furthermore, both intercropping systems alleviated the nutrient uptake under salt stress, as noted by the highest levels of K+/Na+ and Ca2+/Mg2+ ratios compared to monoculture. However, the intercropping mode reduced the pH and the electroconductivity (CEC) of the salt soil and increased the percentage of organic matter and the total carbon mostly with the MC system.

CONCLUSIONS

Intercropped alfalfa and sea barely could mitigate the soil salinity, improve their yield productivity, and enhance nutrient uptake. Based on these findings, we suggest implementing the mixed-culture system for both target crops in arid and semi-arid regions, which further promotes sustainable agricultural practices.

Chitosan nanoparticles encapsulating curcumin counteract salt-mediated ionic toxicity in wheat seedlings: an ecofriendly and sustainable approach

Over-accumulating salts in soil are hazardous materials that interfere with the biochemical pathways in growing plants drastically affecting their physiological attributes, growth, and productivity. Soil salinization poses severe threats to highly-demanded and important crops directly challenging food security and sustainable productivity. Recently, there has been a great demand to exploit natural sources for the development of nontoxic nanoformulations of growth enhancers and stress emulators. The chitosan (CS) has growth-stimulating properties and widespread use as nanocarriers, while curcumin (CUR) has a well-established high ROS scavenging potential. Herein, we use CS and CUR for the preparation of CSNPs encapsulating CUR as an ecofriendly nanopriming agent. The hydroprimed, nanoprimed (0.02 and 0.04%), and unprimed (control) wheat seeds were germinated under salt stress (150 mM NaCl) and normal conditions. The seedlings established from the aforementioned seeds were employed for germination studies and biochemical analyses. Priming imprints mitigated the ionic toxicity by upregulating the machinery of antioxidants (CAT, POD, APX, and SOD), photosynthetic pigments (Chl a, Chl b, total Chl, and lycopene), tannins, flavonoids, and protein contents in wheat seedlings under salt stress. It controlled ROS production and avoided structural injuries, thus reducing MDA contents and regulating osmoregulation. The nanopriming-induced readjustments in biochemical attributes counteracted the ionic toxicity and positively influenced the growth parameters including final germination, vigor, and germination index. It also reduced the mean germination time, significantly validating the growth-stimulating and stress-emulating role of the prepared nanosystem. Hence, the nanopriming conferred tolerance against salt stress during germination and seedling development, ensuring sustainable growth.

Unraveling lipid peroxidation-mediated regulation of redox homeostasis for sustaining plant health

Lipid peroxidation (LPO) is a complex process that, depending on the context, can either result in oxidative injury or promote redox homeostasis. LPO is a series of reactions in which polyunsaturated fatty acids are attacked by free radicals that result in the synthesis of lipid peroxides. LPO can alter membrane fluidity and operation and produce secondary products that amplify oxidative stress. LPO can activate cellular signaling pathways that promote antioxidant defense mechanisms that provide oxidative stress protection by elevating antioxidant enzyme action potentials. Enzymatic and nonenzymatic mechanisms tightly regulate LPO to prevent excessive LPO and its adverse consequences. This article emphasizes the dual nature of LPO as a mechanism that can both damage cells and regulate redox homeostasis. In addition, it also highlights the major enzymatic and nonenzymatic mechanisms that tightly regulate LPO to prevent excessive oxidative damage. More importantly, it emphasizes the importance of understanding the cellular and biochemical complexity of LPO for developing strategies targeting this process for efficient management of plant stress.

Investigation of Melatonin Incorporated CMC-Gelatin Based Edible Coating on the Alleviation of Chilling Injury Induced Pericarp Browning in Longkong

Longkong (Aglaia dookkoo Griff.) fruit is prone to rapid pericarp browning and shortened shelf life (<7 days) under prolonged low-temperature storage. This study investigates the effect of an edible coating, comprising carboxymethyl cellulose (CMC) and gelatin in a fixed 3:1 ratio, integrated with various concentrations of melatonin (MT) (0.4, 0.8, and 1.2 mM/L) to mitigate chilling injury in longkong fruit. Coated longkong fruits were stored at 13 °C with 90% relative humidity for 18 days and underwent physicochemical evaluations every three days. Samples coated with CMC-Gel without MT and uncoated fruits were served as controls. The findings indicated that the CMC-Gel-MT coating significantly mitigated pericarp browning, chilling injury, weight loss, and respiration rate increase under extended cold storage conditions. High concentrations of MT (≥0.8 mM/L) in the coating notably inhibited the activities of cellular degrading enzymes such as lipoxygenase and phospholipase D. This inhibition contributed to reduced membrane permeability, lower reactive oxygen species accumulation (H2O2, OH-, O2-), and decreased malondialdehyde levels in the longkong pericarp. Furthermore, the CMC-Gel-MT coating increased the activity of phenylalanine ammonia lyase, leading to an enhancement in phenolic content. Consequently, it improved the fruit's ability to scavenge DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,20-azino-di-3-ethylbenzthiazoline sulfonic acid) radicals. Control samples exhibited high levels of pericarp browning-related enzymes (polyphenol oxidase, peroxidase), whereas CMC-Gel-MT-coated fruits, particularly at higher MT concentrations, showed significant reductions in those enzyme activities. In conclusion, incorporating high concentrations of MT in a CMC-Gel-based edible coating is a promising alternative for mitigating chilling injury in longkong fruit.

Beneficial Interactive Effects Provided by an Arbuscular Mycorrhizal Fungi and Yeast on the Growth of Oenothera picensis Established on Cu Mine Tailings

Phytoremediation, an environmentally friendly and sustainable approach for addressing Cu-contaminated environments, remains underutilized in mine tailings. Arbuscular mycorrhizal fungi (AMF) play a vital role in reducing Cu levels in plants through various mechanisms, including glomalin stabilization, immobilization within fungal structures, and enhancing plant tolerance to oxidative stress. Yeasts also contribute to plant growth and metal tolerance by producing phytohormones, solubilizing phosphates, generating exopolysaccharides, and facilitating AMF colonization. This study aimed to assess the impact of AMF and yeast inoculation on the growth and antioxidant response of Oenothera picensis plants growing in Cu mine tailings amended with compost. Plants were either non-inoculated (NY) or inoculated with Meyerozyma guilliermondii (MG), Rhodotorula mucilaginosa (RM), or a combination of both (MIX). Plants were also inoculated with Claroideoglomus claroideum (CC), while others remained non-AMF inoculated (NM). The results indicated significantly higher shoot biomass in the MG-NM treatment, showing a 3.4-fold increase compared to the NY-NM treatment. The MG-CC treatment exhibited the most substantial increase in root biomass, reaching 5-fold that in the NY-NM treatment. Co-inoculation of AMF and yeast influenced antioxidant activity, particularly catalase and ascorbate peroxidase. Furthermore, AMF and yeast inoculation individually led to a 2-fold decrease in total phenols in the roots. Yeast inoculation notably reduced non-enzymatic antioxidant activity in the ABTS and CUPRAC assays. Both AMF and yeast inoculation promoted the production of photosynthetic pigments, further emphasizing their importance in phytoremediation programs for mine tailings.

Nutrient Solution Flowing Environment Affects Metabolite Synthesis Inducing Root Thigmomorphogenesis of Lettuce (Lactuca sativa L.) in Hydroponics

The principal difference between hydroponics and other substrate cultivation methods is the flowing liquid hydroponic cultivation substrate. Our previous studies have revealed that a suitable flowing environment of nutrient solution promoted root development and plant growth, while an excess flow environment was unfavorable for plants. To explain the thigmomorphogenetic response of excess flow-induced metabolic changes, six groups of lettuce (Lactuca sativa L.), including two flow conditions and three time periods, were grown. Compared with the plants without flow, the plants with flow showed decreased root fresh weight, total root length, root surface area, and root volume but increased average root diameter and root density. The roots with flow had more upregulated metabolites than those without flow, suggesting that the flow may trigger metabolic synthesis and activity. Seventy-nine common differential metabolites among six groups were screened, and enrichment analysis showed the most significant enrichment in the arginine biosynthesis pathway. Arginine was present in all the groups and exhibited greater concentrations in roots with flow than without flow. It can be speculated from the results that a high-flowing environment of nutrient solution promotes arginine synthesis, resulting in changes in root morphology. The findings provide insights on root thigmomorphogenesis affected by its growing conditions and help understand how plants respond to environmental mechanical forces.

Emerging Role of Plant-Based Bioactive Compounds as Therapeutics in Parkinson's Disease

Neurological ailments, including stroke, Alzheimer's disease (AD), epilepsy, Parkinson's disease (PD), and other related diseases, have affected around 1 billion people globally to date. PD stands second among the common neurodegenerative diseases caused as a result of dopaminergic neuron loss in the midbrain's substantia nigra regions. It affects cognitive and motor activities, resulting in tremors during rest, slow movement, and muscle stiffness. There are various traditional approaches for the management of PD, but they provide only symptomatic relief. Thus, a survey for finding new biomolecules or substances exhibiting the therapeutic potential to patients with PD is the main focus of present-day research. Medicinal plants, herbal formulations, and natural bioactive molecules have been gaining much more attention in recent years as synthetic molecules orchestrate a number of undesired effects. Several in vitro, in vivo, and in silico studies in the recent past have demonstrated the therapeutic potential of medicinal plants, herbal formulations, and plant-based bioactives. Among the plant-based bioactives, polyphenols, terpenes, and alkaloids are of particular interest due to their potent anti-inflammatory, antioxidant, and brain-health-promoting properties. Further, there are no concise, elaborated articles comprising updated mechanism-of-action-based reviews of the published literature on potent, recently investigated (2019-2023) medicinal plants, herbal formulations, and plant based-bioactive molecules, including polyphenols, terpenes, and alkaloids, as a method for the management of PD. Therefore, we designed the current review to provide an illustration of the efficacious role of various medicinal plants, herbal formulations, and bioactives (polyphenols, terpenes, and alkaloids) that can become potential therapeutics against PD with greater specificity, target approachability, bioavailability, and safety to the host. This information can be further utilized in the future to develop several value-added formulations and nutraceutical products to achieve the desired safety and efficacy for the management of PD.

The Adaptive Role of Carotenoids and Anthocyanins in Solanum lycopersicum Pigment Mutants under High Irradiance

The effects of high-intensity light on the pigment content, photosynthetic rate, and fluorescence parameters of photosystem II in high-pigment tomato mutants (hp 3005) and low-pigment mutants (lp 3617) were investigated. This study also evaluated the dry weight percentage of low molecular weight antioxidant capacity, expression patterns of some photoreceptor-regulated genes, and structural aspects of leaf mesophyll cells. The 3005 mutant displayed increased levels of photosynthetic pigments and anthocyanins, whereas the 3617 mutant demonstrated a heightened content of ultraviolet-absorbing pigments. The photosynthetic rate, photosystem II activity, antioxidant capacity, and carotenoid content were most pronounced in the high-pigment mutant after 72 h exposure to intense light. This mutant also exhibited an increase in leaf thickness and water content when exposed to high-intensity light, suggesting superior physiological adaptability and reduced photoinhibition. Our findings indicate that the enhanced adaptability of the high-pigment mutant might be attributed to increased flavonoid and carotenoid contents, leading to augmented expression of key genes associated with pigment synthesis and light regulation.

Microbial consortium mediated acceleration of the defense response in potato against Alternaria solani through prodigious inflation in phenylpropanoid derivatives and redox homeostasis

The present study was carried out in a pot experiment to examine the bioefficacy of three biocontrol agents, viz., Trichoderma viride, Bacillus subtilis, and Pseudomonas fluorescens, either alone or in consortium, on plant growth promotion and activation of defense responses in potato against the early blight pathogen Alternaria solani. The results demonstrate significant enhancement in growth parameters in plants bioprimed with the triple-microbe consortium compared to other treatments. In potato, the disease incidence percentage was significantly reduced in plants treated with the triple-microbe consortium compared to untreated control plants challenged with A. solani. Potato tubers treated with the consortium and challenged with pathogen showed significant activation of defense-related enzymes such as peroxidase (PO) at 96 h after pathogen inoculation (hapi) while, both polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) at 72 hapi, compared to the individual and dual microbial consortia-treated plants. The expression of antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT) and the accumulation of pathogenesis-related proteins such as chitinase and β-1,3-glucanase were observed to be highest at 72 hapi in the triple microbe consortium as compared to other treatments. HPLC analysis revealed significant induction in polyphenolic compounds in triple-consortium bioprimed plants compared to the control at 72 hapi. Histochemical analysis of hydrogen peroxide (H2O2) clearly showed maximum accumulation of H2O2 in pathogen-inoculated control plants, while the lowest was observed in triple-microbe consortium at 72 hapi. The findings of this study suggest that biopriming with a microbial consortium improved plant growth and triggered defense responses against A. solani through the induction of systemic resistance via modulation of the phenylpropanoid pathway and antioxidative network.

Metabolomic Reconfiguration in Primed Barley (Hordeum vulgare) Plants in Response to Pyrenophora teres f. teres Infection

Necrotrophic fungi affect a wide range of plants and cause significant crop losses. For the activation of multi-layered innate immune defences, plants can be primed or pre-conditioned to rapidly and more efficiently counteract this pathogen. Untargeted and targeted metabolomics analyses were applied to elucidate the biochemical processes involved in the response of 3,5-dichloroanthranilic acid (3,5-DCAA) primed barley plants to Pyrenophora teres f. teres (Ptt). A susceptible barley cultivar ('Hessekwa') at the third leaf growth stage was treated with 3,5-DCAA 24 h prior to infection using a Ptt conidia suspension. The infection was monitored over 2, 4, and 6 days post-inoculation. For untargeted studies, ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-MS) was used to analyse methanolic plant extracts. Acquired data were processed to generate the data matrices utilised in chemometric modelling and multi-dimensional data mining. For targeted studies, selected metabolites from the amino acids, phenolic acids, and alkaloids classes were quantified using multiple reaction monitoring (MRM) mass spectrometry. 3,5-DCAA was effective as a priming agent in delaying the onset and intensity of symptoms but could not prevent the progression of the disease. Unsupervised learning methods revealed clear differences between the sample extracts from the control plants and the infected plants. Both orthogonal projection to latent structure-discriminant analysis (OPLS-DA) and 'shared and unique structures' (SUS) plots allowed for the extraction of potential markers of the primed and naïve plant responses to Ptt. These include classes of organic acids, fatty acids, amino acids, phenolic acids, and derivatives and flavonoids. Among these, 5-oxo-proline and citric acid were notable as priming response-related metabolites. Metabolites from the tricarboxylic acid pathway were only discriminant in the primed plant infected with Ptt. Furthermore, the quantification of targeted metabolites revealed that hydroxycinnamic acids were significantly more prominent in the primed infected plants, especially at 2 d.p.i. Our research advances efforts to better understand regulated and reprogrammed metabolic responses that constitute defence priming in barley against Ptt.

Impact of High Light Intensity and Low Temperature on the Growth and Phenylpropanoid Profile of Azolla filiculoides

Exposure to high light intensity (HL) and cold treatment (CT) induces reddish pigmentation in Azolla filiculoides, an aquatic fern. Nevertheless, how these conditions, alone or in combination, influence Azolla growth and pigment synthesis remains to be fully elucidated. Likewise, the regulatory network underpinning the accumulation of flavonoids in ferns is still unclear. Here, we grew A. filiculoides under HL and/or CT conditions for 20 days and evaluated the biomass doubling time, relative growth rate, photosynthetic and non-photosynthetic pigment contents, and photosynthetic efficiency by chlorophyll fluorescence measurements. Furthermore, from the A. filiculoides genome, we mined the homologs of MYB, bHLH, and WDR genes, which form the MBW flavonoid regulatory complex in higher plants, to investigate their expression by qRT-PCR. We report that A. filiculoides optimizes photosynthesis at lower light intensities, regardless of the temperature. In addition, we show that CT does not severely hamper Azolla growth, although it causes the onset of photoinhibition. Coupling CT with HL stimulates the accumulation of flavonoids, which likely prevents irreversible photoinhibition-induced damage. Although our data do not support the formation of MBW complexes, we identified candidate MYB and bHLH regulators of flavonoids. Overall, the present findings are of fundamental and pragmatic relevance to Azolla's biology.

Lactic acid bacteria as a tool for biovanillin production: A review

Vanilla is the most commonly used natural flavoring agent in industries like food, flavoring, medicine, and fragrance. Vanillin can be obtained naturally, chemically, or through a biotechnological process. However, the yield from vanilla pods is low and does not meet market demand, and the use of vanillin produced by chemical synthesis is restricted in the food and pharmaceutical industries. As a result, the biotechnological process is the most efficient and cost-effective method for producing vanillin with consumer-demanding properties while also supporting industrial applications. Toxin-free biovanillin production, based on renewable sources such as industrial wastes or by-products, is a promising approach. In addition, only natural-labeled vanillin is approved for use in the food industry. Accordingly, this review focuses on biovanillin production from lactic acid bacteria (LAB), which is generally recognized as safe (GRAS), and the cost-cutting efforts that are utilized to improve the efficiency of biotransformation of inexpensive and readily available sources. LABs can utilize agro-wastes rich in ferulic acid to produce ferulic acid, which is then employed in vanillin production via fermentation, and various efforts have been applied to enhance the vanillin titer. However, different designs, such as response surface methods, using immobilized cells or pure enzymes for the spontaneous release of vanillin, are strongly advised.

Microalgae as next generation plant growth additives: Functions, applications, challenges and circular bioeconomy based solutions

Sustainable agriculture practices involve the application of environment-friendly plant growth promoters and additives that do not negatively impact the health of the ecosystem. Stringent regulatory frameworks restricting the use of synthetic agrochemicals and the increase in demand for organically grown crops have paved the way for the development of novel bio-based plant growth promoters. In this context, microalgae biomass and derived agrochemicals offer novel sources of plant growth promotors that enhance crop productivity and impart disease resistance. These beneficial effects could be attributed to the presence of wide range of biomolecules such as soluble amino acid (AA), micronutrients, polysaccharides, phytohormones and other signaling molecules in microalgae biomass. In addition, their phototrophic nature, high photosynthetic efficiency, and wide environmental adaptability make them an attractive source of biostimulants, biofertilizers and biopesticides. The present review aims to describe the various plant growth promoting metabolites produced by microalgae and their effects on plant growth and productivity. Further, the effects elicited by microalgae biostimulants with respect to different modes of applications such as seed treatments, foliar spray and soil/root drenching is reviewed in detail. In addition, the ability of microalgae metabolites to impart tolerance against various abiotic and biotic stressors along with the mechanism of action is discussed in this paper. Although the use of microalgae based biofertilizers and biostimulants is gaining popularity, the high nutrient and water requirements and energy intensive downstream processes makes microalgae based technology commercially unsustainable. Addressing this challenge, we propose a circular economy model of microalgae mediated bioremediation coupled with biorefinery approaches of generating high value metabolites along with biofertilizer applications. We discuss and review new trends in enhancing the sustainability of microalgae biomass production by co-cultivation of algae with hydroponics and utilization of agriculture effluents.

Widely targeted metabolome profiling of different plateau raspberries and berry parts provides innovative insight into their antioxidant activities

Raspberries are highly nutritious and have powerful antioxidant properties, making them functional berries with positive effects on physiological functioning. However, there is limited information available on the diversity and variability of metabolites in raspberry and its parts, especially in plateau raspberries. To address this, commercial raspberries and their pulp and seeds from two plateaus in China were subjected to LC-MS/MS-based metabolomics analysis and evaluated for antioxidant activity using four assays. A metabolite-metabolite correlation network was established based on antioxidant activity and correlation analysis. The results showed that 1661 metabolites were identified and classified into 12 categories, with significant variations in composition between the whole berry and its parts from different plateaus. Flavonoids, amino acids and their derivatives, and phenolic acids were found to be up-regulated in Qinghai's raspberry compared to Yunnan's raspberry. The main differently regulated pathways were related to flavonoid, amino acid, and anthocyanin biosynthesis. The antioxidant activity of Qinghai's raspberry was stronger than Yunnan's raspberry, and the order of antioxidant capacity was seed > pulp > berry. The highest FRAP (420.31 µM TE/g DW) values was found in the seed of Qinghai's raspberry. Overall, these findings suggest that the environment in which the berries grow can affect their chemical composition, and comprehensive exploitation and cultivation of whole raspberry and its parts from different plateaus can lead to new opportunities for phytochemical compositions and antioxidant activity.

Decrypting the multi-functional biological activators and inducers of defense responses against biotic stresses in plants

Plant diseases are still the main problem for the reduction in crop yield and a threat to global food security. Additionally, excessive usage of chemical inputs such as pesticides and fungicides to control plant diseases have created another serious problem for human and environmental health. In view of this, the application of plant growth-promoting rhizobacteria (PGPR) for controlling plant disease incidences has been identified as an eco-friendly approach for coping with the food security issue. In this review, we have identified different ways by which PGPRs are capable of reducing phytopathogenic infestations and enhancing crop yield. PGPR suppresses plant diseases, both directly and indirectly, mediated by microbial metabolites and signaling components. Microbial synthesized anti-pathogenic metabolites such as siderophores, antibiotics, lytic enzymes, hydrogen cyanide, and several others act directly on phytopathogens. The indirect mechanisms of reducing plant disease infestation are caused by the stimulation of plant immune responses known as initiation of systemic resistance (ISR) which is mediated by triggering plant immune responses elicited through pathogen-associated molecular patterns (PAMPs). The ISR triggered in the infected region of the plant leads to the development of systemic acquired resistance (SAR) throughout the plant making the plant resistant to a wide range of pathogens. A number of PGPRs including Pseudomonas and Bacillus genera have proven their ability to stimulate ISR. However, there are still some challenges in the large-scale application and acceptance of PGPR for pest and disease management. Further, we discuss the newly formulated PGPR inoculants possessing both plant growth-promoting activities and plant disease suppression ability for a holistic approach to sustaining plant health and enhancing crop productivity.

Confronting Secondary Metabolites with Water Uptake and Transport in Plants under Abiotic Stress

Phenolic compounds and glucosinolates are secondary plant metabolites that play fundamental roles in plant resistance to abiotic stress. These compounds have been found to increase in stress situations related to plant adaptive capacity. This review assesses the functions of phenolic compounds and glucosinolates in plant interactions involving abiotic stresses such as drought, salinity, high temperature, metals toxicity, and mineral deficiency or excess. Furthermore, their relation with water uptake and transport mediated through aquaporins is reviewed. In this way, the increases of phenolic compounds and glucosinolate synthesis have been related to primary responses to abiotic stress and induction of resistance. Thus, their metabolic pathways, root exudation, and external application are related to internal cell and tissue movement, with a lack of information in this latter aspect.

Genome-wide identification and expression analysis of AUX/LAX family genes in Chinese hickory (Carya cathayensis Sarg.) Under various abiotic stresses and grafting

Auxin is essential for regulating plant growth and development as well as the response of plants to abiotic stresses. AUX/LAX proteins are auxin influx transporters belonging to the amino acid permease family of proton-driven transporters, and are involved in the transport of indole-3-acetic acid (IAA). However, how AUX/LAX genes respond to abiotic stresses in Chinese hickory is less studied. For the first time identification, structural characteristics as well as gene expression analysis of the AUX/LAX gene family in Chinese hickory were conducted by using techniques of gene cloning and real-time fluorescent quantitative PCR. Eight CcAUX/LAXs were identified in Chinese hickory, all of which had the conserved structural characteristics of AUX/LAXs. CcAUX/LAXs were most closely related to their homologous proteins in Populus trichocarpa , which was in consistence with their common taxonomic character of woody trees. CcAUX/LAXs exhibited different expression profiles in different tissues, indicating their varying roles during growth and development. A number of light-, hormone-, and abiotic stress responsive cis-acting regulatory elements were detected on the promoters of CcAUX/LAX genes. CcAUX/LAX genes responded differently to drought and salt stress treatments to varying degrees. Furthermore, CcAUX/LAX genes exhibited complex expression changes during Chinese hickory grafting. These findings not only provide a valuable resource for further functional validation of CcAUX/LAXs, but also contribute to a better understanding of their potential regulatory functions during grafting and abiotic stress treatments in Chinese hickory.

Overexpression of SmMYC2 enhances salt resistance in Arabidopsis thaliana and Salvia miltiorrhiza hairy roots

Soil salinity significantly affects both Salvia miltiorrhiza growth and development as well as seed germination throughout field cultivation and production. The basic helix-loop-helix (bHLH) transcription factor (TF) MYC2 contributes significantly to plant stress resistance as a key regulator of the jasmonic acid signaling pathway. In transgenic S. miltiorrhiza hairy roots, SmMYC2 has been shown to promote the accumulation of tanshinone and salvianolic acid, but its role in S. miltiorrhiza of resistance to abiotic stress is unclear. Herein, we found methyl jasmonate (MeJA), NaCl, and PEG treatment all significantly increased SmMYC2 expression. In response to salt stress, SmMYC2 overexpression in yeast increased its rate of growth. Additionally, overexpression of SmMYC2 transgenic Arabidopsis thaliana and S. miltiorrhiza hairy root showed that it might improve salt resistance in transgenic plant. In particular, compared to WT, overexpression of SmMYC2 transgenic Arabidopsis had higher levels of three antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), proline (Pro) content, and ABA-dependent and ABA-independent genes expression. They also had lower levels of malondialdehyde (MDA) and reactive oxygen species (ROS) accumulation. What's more, overexpression of SmMYC2 increases the expression of flavonoid synthesis genes and the accumulation of related components in Arabidopsis. These findings imply that SmMYC2 functions as a positive regulator that regulates plant tolerance to salt through ABA-dependent and independent signaling pathways.

Defense Inducers Mediated Mitigation of Bacterial Canker in Tomato through Alteration in Oxidative Stress Markers

The bacterial canker disease of tomato caused by Clavibacter michiganensis subsp. michiganensis (Cmm) has been reported to adversely affect the tomato cultivation in the NE hilly regions of India. Defense inducers such as salicylic acid (SA), isonicotinic acid (INA), benzothiadiazole (BTH) and lysozyme were used as prophylactic and curative sprays at different concentrations to test their efficacy in inducing resistance in tomato plants against Cmm under protected conditions. The induced resistance was studied through the alteration in the activities of oxidative stress marker enzymes (PAL, PO, PPO, TPC and PR-2 protein), hydrogen peroxide formation in leaf tissues and lignin accumulation in stem tissues, as well as through the reduction in disease severity under glasshouse conditions. The results of the present study revealed that the enzymatic activity, hydrogen peroxide formation and lignin production were significantly higher in the BTH (500 ppm)-treated leaves than in those observed in the control. The lowest disease incidence was recorded when BTH was applied as a prophylactic spray (27.88%) in comparison to being applied as a curative spray (53.62%), thereby suggesting that a defense inducer, BTH, shows antibacterial activity against Cmm, reduces disease incidence severity and induces defense responses in the tomato plant.