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

Influence of ZnSO4 and Methyl Jasmonate on the Metabolites and Bioactivity Present in Lemon-Fruit Membrane Vesicles

Membrane vesicles isolated from vegetable tissues have shown promise in encapsulation technologies used in industries like food and cosmetics, offering innovative approaches to product development. However, their associated linked metabolites have not been studied. Lemon vesicle research not only adds value to the lemon crop (Citrus × limon L.), one of the most widely cultivated fruit trees in the world, is a source of bioactive compounds such as phenolics and organic acids. In this study, the influence of elicitation with ZnSO4 and methyl jasmonate, which modulate the bioactive metabolites, on fruit membrane vesicle bond metabolites was studied. The study showed that foliar application of ZnSO4 increased phenolic compounds as caffeic, sinapic, and chlorogenic acids and the flavonoid hesperidin by about 20% in lemons. Furthermore, a clear interaction between vesicles and citrate and ascorbate that were increased by methyl jasmonate were associated with their higher bioactivity. This was related to the double intrinsic in vitro antioxidant activities of these vesicles.

Emerging Nanochitosan for Sustainable Agriculture

Chemical-intensive agriculture challenges environmental sustainability and biodiversity and must be changed. Minimizing the use of agrochemicals based on renewable resources can reduce or eliminate ecosystems and biodiversity threats. Nanochitosan as a sustainable alternative offers promising solutions for sustainable agricultural practices that work at multiple spatial and temporal scales throughout the plant growth cycle. This review focuses on the potential of nanochitosan in sustainable agricultural production and provides insights into the mechanisms of action and application options of nanochitosan throughout the plant growth cycle. We emphasize the role of nanochitosan in increasing crop yields, mitigating plant diseases, and reducing agrochemical accumulation. The paper discusses the sources of nanochitosan and its plant growth promotion, antimicrobial properties, and delivery capacity. Furthermore, we outline the challenges and prospects of research trends of nanochitosan in sustainable agricultural production practices and highlight the potential of nanochitosan as a sustainable alternative to traditional agrochemicals.

Enhanced accumulation of biologically active compounds in lichens with potential functional food applications

Lichens have great potential as food, functional food additives or flavourings. The presence of specific substances with multiple biological activities is one of the characteristics of lichens. However, research on lichens as a food source or functional food additive is limited. The present study simulated, for the first time, the potential bioaccessibility of active compounds from 6 lichen species in simulated gastric and intestinal conditions. An in vitro digestion showed that the lichen substances had different bioaccessibility and stability during digestion. It was found that the application of some metabolic modulators significantly altered the accumulation of metabolites in most species. In addition, the study demonstrated the antimicrobial activity of the tested extracts as well as of 14 isolated lichen metabolites. These multi-directional studies demonstrate the potential of lichens in terms of their use as antimicrobial functional food additives.

Differentiated response of Hypericum perforatum to foliar application of selected metabolic modulators: Elicitation potential of chitosan, selenium, and salicylic acid mediated by redox imbalance

Plants plastically alter their metabolism in response to environmental stimuli, which induces changes in the accumulation of specialized metabolites. This ability can be utilized to manipulate plant phytochemistry in a desired direction. However, the abundance of secondary metabolites in the different plant species, especially medicinal, is enormous; therefore, it is difficult to establish a clear direction for the effects of metabolic modulators on phytochemical composition, especially given the possibility of using different types thereof. In order to gain insight into these changes, we investigated the effects of foliar-applied chitosan (ChL, 100 mg/L), selenium (Se, 10 mg/L), salicylic acid (SA, 150 mg/L), or an equal volume mixture thereof on Hypericum perforatum L. metabolism. Selenium and SA proved to be the more effective than ChL in enhancing the accumulation of phenolic compounds. The greatest increase was found in the concentration of neochlorogenic acid after Se-spraying. The treatment with the elicitors generally increased the concentration of identified flavonoids, but not the level of naphthodianthrone or phloroglucinol metabolites. The most pronounced response was observed on day 10 following the application of the compounds, and is likely the consequence of elevated levels of O2-˙, free proline, and modulated activity of enzymatic antioxidants.

Investigating the simultaneous effect of chitosan and arbuscular mycorrhizal fungi on growth, phenolic compounds, PAL enzyme activity and lipid peroxidation in Salvia nemorosa L

Considering the importance of Salvia nemorosa L. in the pharmaceutical and food industries, and also beneficial approaches of arbuscular mycorrhizal fungi (AMF) symbiosis and the use of bioelicitors such as chitosan to improve secondary metabolites, the aim of this study was to evaluate the performance of chitosan on the symbiosis of AMF and the effect of both on the biochemical and phytochemical performance of this plant and finally introduced the best treatment. Two factors were considered for the factorial experiment: AMF with four levels (non-inoculated plants, Funneliformis mosseae, Rhizophagus intraradices and the combination of both), and chitosan with six levels (0, 50, 100, 200, 400 mg L-1 and 1% acetic acid). Four months after treatments, the aerial part and root length, the levels of lipid peroxidation, H2O2, phenylalanine ammonia lyase (PAL) activity, total phenol and flavonoid contents and the main secondary metabolites (rosmarinic acid and quercetin) in the leaves and roots were determined. The flowering stage was observed in R. intraradices treatments and the highest percentage of colonization (78.87%) was observed in the treatment of F. mosseae × 400 mg L-1 chitosan. Furthermore, simultaneous application of chitosan and AMF were more effective than their separate application to induce phenolic compounds accumulation, PAL activity and reduce oxidative compounds. The cluster and principal component analysis based on the measured variables indicated that the treatments could be classified into three clusters. It seems that different treatments in different tissues have different effects. However, in an overview, it can be concluded that 400 mg L-1 chitosan and F. mosseae × R. intraradices showed better results in single and simultaneous applications. The results of this research can be considered in the optimization of this medicinal plant under normal conditions and experiments related to abiotic stresses in the future.

A review on versatile applications of biomaterial/polycationic chitosan: An insight into the structure-property relationship

Chitosan is a versatile and generous biopolymer obtained by alkaline deacetylation of naturally occurring chitin, the second most abundant biopolymer after cellulose. The excellent physicochemical properties of polycationic chitosan are attributed to the presence of varied functional groups such as amino, hydroxyl, and acetamido groups enabling researchers to tailor the structure and properties of chitosan by different methods such as crosslinking, grafting, copolymerization, composites, and molecular imprinting techniques. The prepared derivatives have diverse applications in the food industry, water treatment, cosmetics, pharmaceuticals, agriculture, textiles, and biomedical applications. In this review, numerous applications of chitosan and its derivatives in various fields have been discussed in detail with an insight into their structure-property relationship. This review article concludes and explains the chitosan's biocompatibility and efficiency that has been done so far with future usage and applications as well. Moreover, the possible mechanism of chitosan's activity towards several emerging fields such as energy storage, biodegradable packaging, photocatalysis, biorefinery, and environmental bioremediation are also discussed. Overall, this comprehensive review discusses the science and complete information behind chitosan's wonder function to improve our understanding which is much needful as well as will pave the way towards a sustainable future.

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.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

Chitosan has received much attention for its role in designing and developing novel derivatives as well as its applications across a broad spectrum of biological and physiological activities, owing to its desirable characteristics such as being biodegradable, being a biopolymer, and its overall eco-friendliness. The main objective of this review is to explore the recent chemical modifications of chitosan that have been achieved through various synthetic methods. These chitosan derivatives are categorized based on their synthetic pathways or the presence of common functional groups, which include alkylated, acylated, Schiff base, quaternary ammonia, guanidine, and heterocyclic rings. We have also described the recent applications of chitosan and its derivatives, along with nanomaterials, their mechanisms, and prospective challenges, especially in areas such as antimicrobial activities, targeted drug delivery for various diseases, and plant agricultural domains. The accumulation of these recent findings has the potential to offer insight not only into innovative approaches for the preparation of chitosan derivatives but also into their diverse applications. These insights may spark novel ideas for drug development or drug carriers, particularly in the antimicrobial, medicinal, and plant agricultural fields.

Impact of Chitosan-Based Foliar Application on the Phytochemical Content and the Antioxidant Activity in Hemp (Cannabis sativa L.) Inflorescences

In the present study, the phytochemical content and the antioxidant activity in the inflorescences of the monoecious hemp cultivar Codimono grown in southern Italy were assessed, and their elicitation was induced by foliar spray application of 50 mg/L and 250 mg/L of chitosan (CHT) at three different molecular weights (low, CHT L; medium, CHT M; high CHT H). The analysis of the phytochemical profile confirmed that cannabinoids were the most abundant class (54.2%), followed by flavonoids (40.3%), tocopherols (2.2%), phenolic acids (1.9%), and carotenoids (1.4%). Cannabinoids were represented almost exclusively by cannabidiol, whereas cannabigerol and Δ9-tetrahydrocannabinol were detected at very low levels (the latter was below the legal limit of 0.3%). The most abundant flavonoids were orientin and vitexin, whereas tocopherols were mainly represented by α-tocopherol. The antioxidant activity was found to be positively correlated with flavonoids and tocopherols. Statistical analysis revealed that the CHT treatments significantly affected the phytochemical content and the antioxidant activity of hemp inflorescences. Notably, a significant increase in the total phenolic content (from +36% to +69%), the α-tocopherol (from +45% to +75%) and β+γ-tocopherol (from +35% to +82%) contents, and the ABTS radical scavenging activity (from +12% to +28%) was induced by all the CHT treatments. In addition, treatments with CHT 50 solutions induced an increase in the total flavonoid content (from +12% to +27%), as well as in the vitexin (from +17% to +20%) and orientin (from +20% to +30%) contents. Treatment with CHT 50 L almost always resulted in the greatest increases. Overall, our findings indicated that CHT could be used as a low-cost and environmentally safe elicitor to improve the health benefits and the economic value of hemp inflorescences, thus promoting their employment in the food, pharmaceutical, nutraceutical, and cosmetic supply chains.

Developing Sustainable Agriculture Systems in Medicinal and Aromatic Plant Production by Using Chitosan and Chitin-Based Biostimulants

Chitosan is illustrated in research as a stimulant of plant tolerance and resistance that promotes natural defense mechanisms against biotic and abiotic stressors, and its use may lessen the amount of agrochemicals utilized in agriculture. Recent literature reports indicate the high efficacy of soil or foliar usage of chitin and chitosan in the promotion of plant growth and the induction of secondary metabolites biosynthesis in various species, such as Artemisia annua, Curcuma longa, Dracocephalum kotschyi, Catharanthus roseus, Fragaria × ananassa, Ginkgo biloba, Iberis amara, Isatis tinctoria, Melissa officinalis, Mentha piperita, Ocimum basilicum, Origanum vulgare ssp. Hirtum, Psammosilene tunicoides, Salvia officinalis, Satureja isophylla, Stevia rebaudiana, and Sylibum marianum, among others. This work focuses on the outstanding scientific contributions to the field of the production and quality of aromatic and medicinal plants, based on the different functions of chitosan and chitin in sustainable crop production. The application of chitosan can lead to increased medicinal plant production and protects plants against harmful microorganisms. The effectiveness of chitin and chitosan is also due to the low concentration required, low cost, and environmental safety. On the basis of showing such considerable characteristics, there is increasing attention on the application of chitin and chitosan biopolymers in horticulture and agriculture productions.

The use of chitosan oligosaccharide to improve artemisinin yield in well-watered and drought-stressed plants

Introduction

Artemisinin is a secondary metabolite well-known for its use in the treatment of malaria. It also displays other antimicrobial activities which further increase its interest. At present, Artemisia annua is the sole commercial source of the substance, and its production is limited, leading to a global deficit in supply. Furthermore, the cultivation of A. annua is being threatened by climate change. Specifically, drought stress is a major concern for plant development and productivity, but, on the other hand, moderate stress levels can elicit the production of secondary metabolites, with a putative synergistic interaction with elicitors such as chitosan oligosaccharides (COS). Therefore, the development of strategies to increase yield has prompted much interest. With this aim, the effects on artemisinin production under drought stress and treatment with COS, as well as physiological changes in A. annua plants are presented in this study.

Methods

Plants were separated into two groups, well-watered (WW) and drought-stressed (DS) plants, and in each group, four concentrations of COS were applied (0, 50,100 and 200 mg•L-1). Afterwards, water stress was imposed by withholding irrigation for 9 days.

Results

Therefore, when A. annua was well watered, COS did not improve plant growth, and the upregulation of antioxidant enzymes hindered the production of artemisinin. On the other hand, during drought stress, COS treatment did not alleviate the decline in growth at any concentration tested. However, higher doses improved the water status since leaf water potential (YL) improved by 50.64% and relative water content (RWC) by 33.84% compared to DS plants without COS treatment. Moreover, the combination of COS and drought stress caused damage to the plant's antioxidant enzyme defence, particularly APX and GR, and reduced the amount of phenols and flavonoids. This resulted in increased ROS production and enhanced artemisinin content by 34.40% in DS plants treated with 200 mg•L-1 COS, compared to control plants.

Conclusion

These findings underscore the critical role of ROS in artemisinin biosynthesis and suggest that COS treatment may boost artemisinin yield in crop production, even under drought conditions.

Application of depolymerized chitosan in crop production: A review

Currently, chitosan (CHT) is well known for its uses, particularly in veterinary and agricultural fields. However, chitosan's uses suffer greatly due to its extremely solid crystalline structure, it is insoluble at pH levels above or equal to 7. This has sped up the process of derivatizing and depolymerizing it into low molecular weight chitosan (LMWCHT). As a result of its diverse physicochemical as well as biological features which include antibacterial activity, non-toxicity, and biodegradability, LMWCHT has evolved into new biomaterials with extremely complex functions. The most important physicochemical and biological property is antibacterial, which has some degree of industrialization today. CHT and LMWCHT have potential due to the antibacterial and plant resistance-inducing properties when applied in crop production. This study has highlighted the many advantages of chitosan derivatives as well as the most recent studies on low molecular weight chitosan applications in crop development.

Phytochemical characterization, antioxidant activity and antihypertensive evaluation of Ocimum basilicum L. in l-NAME induced hypertensive rats and its correlation analysis

Ocimum basilicum Linn. (basil) is an aromatic culinary herb that has shown a great potential in therapeutic world. It has many promising pharmacological activities that make it centre for investigations for many researchers. Current study has been planned to determine chemical constituents of basil leaves extracts and their in-vitro and ex-vivo antioxidant and in-vivo antihypertensive potential. GC-MS studies of non-polar extracts showed presence of 75 compounds including monoterpenes, hydrocarbons, sesquiterpenes, triterpenes, phyto-sterols and phthalates. Higher percentages of fatty acids were also identified. The major compounds include linalool (7.65%), terpineol (1.42%), tau-cadinol (13.55%), methyl palmitate (14.24%), palmitic acid (14.31%), linolenic acid (1.30%) and methyl linolenate (17.72%). Electron spray ionization mass spectrometry ESI-HRMS/MS of the polar extracts revealed the presence of alkaloids, phenolic acid, amino acid, coumarin, lignin, flavanoid and terpene derivative. Total phenolic content and total flavonoid content were determined using spectrophotometric technique and calculated as gallic acid equivalents GAE/g dry weight and rutin equivalent RE/g of dry weight respectively. The highest phenolic content and flavonoid content were found in ethyl acetate extract 9.40 mg GAE/g and 15.9 mg RE/g of dry weight. All the extracts showed significant antioxidant activity in DPPH and ABTS cation decolorization assays. Dichloromethane extract possess the highest DPPH scavenging activity, i.e., 64.12% ± 0.23 at concentration of 4 mg/ml. Moreover in ex-vivo studies all the extracts showed prominent effect by inhibiting AAPS induce oxidation in Human erythrocytes being 69.24% ± 0.18 in dichloromethane extract, 64.44% ± 0.04 in ethyl acetate and 53.33% ± 0.09 in acetone extract. The methanol extract of O. basilicum exhibited significant decrease in systolic blood pressure in l-Name induced hypertensive rats at the dose of 50 mg/kg for 28 days. Total phenolic content had a higher linear correlation (r = 0.678) with antihypertensive activity, with a level of significance 95% showing that phenolic compounds in the leaves of the plant has important role in inhibiting l -NAME induced hypertension while flavonoid compounds may play a key role in the antioxidant activities of the plant, through synergism. Conclusively, O. basilicum leaves with bioactive metabolites are a potential source for the development of antihypertensive drugs.

Comparative Effects of Two Forms of Chitosan on Selected Phytochemical Properties of Plectranthus amboinicus (Lour.)

In response to stress factors, plants produce a wide range of biologically active substances, from a group of secondary metabolites, which are applied in medicine and health prophylaxis. Chitosan is a well-known elicitor affecting secondary metabolism in plants, but its effect on the phytochemical profile of Plectranthus amboinicus has not been assessed yet. In the present experiment, the effectiveness of the foliar application of two forms of chitosan (chitosan suspension or chitosan lactate) was compared in order to evaluate their potential to induce the accumulation of selected polyphenolic compounds in the aboveground parts of P. amboinicus. It was shown that chitosan lactate had substantially higher elicitation efficiency, as the use of this form exerted a beneficial effect on the analysed quality parameters of the raw material, especially the content of selected polyphenolic compounds (total content of polyphenols, flavonols, anthocyanins, and caffeic acid derivatives) and the free radical-scavenging activity of extracts from elicited plants. Concurrently, it had no phytotoxic effects. Hence, chitosan lactate-based elicitation can be an effective method for optimisation of the production of high-quality P. amboinicus raw material characterised by an increased concentration of health-promoting and antioxidant compounds.

Impact of elicitors on essential oil compositions and phytochemical constituents in Lavandula stoechas L

Lavandula stoechas L. (LS) is an aromatic evergreen herb used broadly in the food, pharmaceutical, and perfume industries. However, the inducer effect of elicitors on secondary metabolites (SMs) biosynthesis in LS is nebulous. In addition, the precise mechanism of elicitors in cells remains unexplored. Hence, the primary objective of this study was to analyze the changes in phytochemical compositions of LSs treated with a biotic elicitor (chitin) and an abiotic one (copper nanoparticle) under in vitro and greenhouse conditions, with the aim of choosing an appropriate elicitor type, concentration, and exposure time for this species. In this study, the biochemical function of four chitin concentrations (i.e. 0, 50, 100 & 200 mg L^-1) and four copper oxide nanoparticle concentrations (i.e. 0, 25, 50, & 100 mg L^-1) at two exposure times (i.e. 5 & 10 days) was investigated in LS so as to compare with the un-elicited explants and the original plant materials. The analysis showed that the highest contents of the total phenolic (4.68 mg g^-1 FW), flavonoids (0.68 mg g^-1 FW), anthocyanins (36.51 mg g^-1 FW), and flavonols (0.29 mg g^-1 FW) compounds were observed in the elicited LSs. Besides, the role of elicitors in augmenting the percentage of SMs was intelligible, especially 'lavandulol', '1,8-cineole', 'germacrene D', and '(E)-nerolidol', which increased by 21.68%, 17.21%, 9.33%, and 8.11%, respectively. In conclusion, these findings indicate that utilizing elicitors at optimal concentrations and with timely durations of exposure can largely assist in improving the biotechnological production of SMs in LS, so that their potential for industrial use can be actualized.

Nanopriming-mediated memory imprints reduce salt toxicity in wheat seedlings by modulating physiobiochemical attributes

BACKGROUND

Around the globe, salinity is one of the serious environmental stresses which negatively affect rapid seed germination, uniform seedling establishment and plant developments restricting sustainable agricultural productivity. In recent years, the concepts of sustainable agriculture and cleaner production strategy have emphasized the introduction of greener agrochemicals using biocompatible and natural sources to maximize crop yield with minimum ecotoxicological effects. Over the last decade, the emergence of nanotechnology as a forefront of interdisciplinary science has introduced nanomaterials as fast-acting plant growth-promoting agents.

RESULTS

Herein, we report the preparation of nanocomposite using chitosan and green tea (CS-GTE NC) as an ecofriendly nanopriming agent to elicit salt stress tolerance through priming imprints. The CS-GTE NC-primed (0.02, 0.04 and 0.06%), hydroprimed and non-primed (control) wheat seeds were germinated under normal and salt stress (150 mM NaCl) conditions. The seedlings developed from aforesaid seeds were used for physiological, biochemical and germination studies. The priming treatments increased protein contents (10-12%), photosynthetic pigments (Chl a (4-6%), Chl b (34-36%), Total Chl (7-14%) and upregulated the machinery of antioxidants (CAT (26-42%), POD (22-43%)) in wheat seedlings under stress conditions. It also reduced MDA contents (65-75%) and regulated ROS production resulting in improved membrane stability. The priming-mediated alterations in biochemical attributes resulted in improved final germination (20-22%), vigor (4-11%) and germination index (6-13%) under both conditions. It reduced mean germination time significantly, establishing the stress-insulating role of the nanocomposite. The improvement of germination parameters validated the stimulation of priming memory in composite-treated seeds.

CONCLUSION

Pre-treatment of seeds with nanocomposite enables them to counter salinity at the seedling development stage by means of priming memory warranting sustainable plant growth and high crop productivity.

Protective, Biostimulating, and Eliciting Effects of Chitosan and Its Derivatives on Crop Plants

Chitosan is a biodegradable and biocompatible polysaccharide obtained by partial deacetylation of chitin. This polymer has been gaining increasing popularity due to its natural origin, favorable physicochemical properties, and multidirectional bioactivity. In agriculture, the greatest hopes are raised by the possibility of using chitosan as a biostimulant, a plant protection product, an elicitor, or an agent to increase the storage stability of plant raw materials. The most important properties of chitosan include induction of plant defense mechanisms and regulation of metabolic processes. Additionally, it has antifungal, antibacterial, antiviral, and antioxidant activity. The effectiveness of chitosan interactions is determined by its origin, deacetylation degree and acetylation pattern, molecular weight, type of chemical modifications, pH, concentration, and solubility. There is a need to conduct research on alternative sources of chitosan, extraction methods, optimization of physicochemical properties, and commercial implementation of scientific progress outcomes in this field. Moreover, studies are necessary to assess the bioactivity and toxicity of chitosan nanoparticles and chitosan conjugates with other substances and to evaluate the consequences of the large-scale use thereof. This review presents the unique properties of chitosan and its derivatives that have the greatest importance for plant production and yield quality as well as the benefits and limitations of their application.

The Effect of Ocimum basilicum L. and Its Main Ingredients on Respiratory Disorders: An Experimental, Preclinical, and Clinical Review

Ocimum basilicum L. (O. basilicum) and its constituents show anti-inflammatory, immunomodulatory, and antioxidant effects. The plant has been mainly utilized in traditional medicine for the treatment of respiratory disorders. In the present article, effects of O. basilicum and its main constituents on respiratory disorders, assessed by experimental and clinical studies, were reviewed. Relevant studies were searched in PubMed, Science Direct, Medline, and Embase databases using relevant keywords including “Ocimum basilicum,” “basilicums,” “linalool,” “respiratory disease,” “asthma,” “obstructive pulmonary disease,” “bronchodilatory,” “bronchitis,” “lung cancer,” and “pulmonary fibrosis,” and other related keywords.The reviewed articles showed both relieving and preventing effects of the plant and its ingredients on obstructive pulmonary diseases such as chronic obstructive pulmonary disease (COPD), asthma, and other respiratory disorders such as bronchitis, aspergillosis tuberculosis, and lung cancer. The results of the reviewed articles suggest the therapeutic potential of O. basilicum and its constituent, linalool, on respiratory disorders.

Sustainable Approaches to Boost Yield and Chemical Constituents of Aromatic and Medicinal Plants by Application of Biostimulants

INTRODUCTION

Biostimulants consist of natural ingredients, metabolites of fermentation, micro-organisms, algae or plant extracts, bacteria, mushrooms, humus substances, amino acids, biomolecules, etc. Methods: In this study, all relevant English-language articles were collected. The literature was reviewed using the keywords of biostimulant, medicinal plant, aromatic plant, natural products, and pharmaceutical benefits from Google Scholar, Scopus, and PubMed databases.

RESULTS

The significant and promoting impact of biostimulants has been reported for different medicinal and aromatic plants, such as salicylic acid for ajuga, artichoke, ajwain, basil, common rue, common sage, common thyme, coneflower, coriander, dendrobium, desert Indian wheat, dragonhead, fennel, fenugreek, feverfew, ginger, groundnut, guava, henna, Iranian soda, lavender, lemon balm, lemongrass, Malabar spinach; seaweed extract on almond, bird,s eye chili; amino acids on artemisia, broccoli, chamomile, beneficial bacteria on ashwagandha; humic acid on black cumin, cannabis, chicory, garlic, gerbera, Hungarian vetch, Moldavian dragonhead, niger plant; chitosan on dragon fruit, marigold, milk thistle, etc. The suggested mechanisms include the stimulatory impacts on the activity of enzymes involved in different biosynthetic processes, the hormone-like activity of biostimulant compounds and the improvement of nutrient uptake of plants.

CONCLUSION

The current manuscript gives many examples of the potential of biostimulants for medicinal and aromatic plant production. However, further studies are needed to better understand the effectiveness of different biostimulants and foliar applications in sustainable agriculture.

Traditional in vitro strategies for sustainable production of bioactive compounds and manipulation of metabolomic profile in medicinal, aromatic and ornamental plants

Precursor feeding, elicitation and culture medium parameters are traditional in vitro strategies to enhance bioactive compounds of medicinal, aromatic, and ornamental plants (MAOPs). Machine learning can help researchers find the best combination of these strategies to increase the secondary metabolites content of MAOPs. Many requirements for human life, from food, pharmaceuticals and cosmetics to clothes, fuel and building materials depend on plant-derived natural products. Essential oils, methanolic and ethanolic extracts of in vitro undifferentiated callus and organogenic cultures of medicinal, aromatic, and ornamental plants (MAOPs) contain bioactive compounds that have several applications for various industries, including food and pharmaceutical. In vitro culture systems provide opportunities to manipulate the metabolomic profile of MAOPs. Precursors feeding, elicitation and culture media optimization are the traditional strategies to enhance in vitro accumulation of favorable bioactive compounds. The stimulation of plant defense mechanisms through biotic and abiotic elicitors is a simple way to increase the production of secondary metabolites in different in vitro culture systems. Different elicitors have been applied to stimulate defense machinery and change the metabolomic profile of MAOPs in in vitro cultures. Plant growth regulators (PGRs), stress hormones, chitosan, microbial extracts and physical stresses are the most applied elicitors in this regard. Many other chemical tolerance-enhancer additives, such as melatonin and proline, have been applied along with stress response-inducing elicitors. The use of stress-inducing materials such as PEG and NaCl activates stress tolerance elicitors with the potential of increasing secondary metabolites content of MAOPs. The present study reviewed the state-of-the-art traditional in vitro strategies to manipulate bioactive compounds of MAOPs. The objective is to provide insights to researchers involved in in vitro production of plant-derived natural compounds. The present review provided a wide range of traditional strategies to increase the accumulation of valuable bioactive compounds of MAOPs in different in vitro systems. Traditional strategies are faster, simpler, and cost-effective than other biotechnology-based breeding methods such as genetic transformation, genome editing, metabolic pathways engineering, and synthetic biology. The integrate application of precursors and elicitors along with culture media optimization and the interpretation of their interactions through machine learning algorithms could provide an excellent opportunity for large-scale in vitro production of pharmaceutical bioactive compounds.

NaCl-Induced Elicitation Alters Physiology and Increases Accumulation of Phenolic Compounds in Melissa officinalis L

In nature, plants usually produce secondary metabolites as a defense mechanism against environmental stresses. Different stresses determine the chemical diversity of plant-specialized metabolism products. In this study, we applied an abiotic elicitor, i.e., NaCl, to enhance the biosynthesis and accumulation of phenolic secondary metabolites in Melissa officinalis L. Plants were subjected to salt stress treatment by application of NaCl solutions (0, 50, or 100 mM) to the pots. Generally, the NaCl treatments were found to inhibit the growth of plants, simultaneously enhancing the accumulation of phenolic compounds (total phenolics, soluble flavonols, anthocyanins, phenolic acids), especially at 100 mM NaCl. However, the salt stress did not disturb the accumulation of photosynthetic pigments and proper functioning of the PS II photosystem. Therefore, the proposed method of elicitation represents a convenient alternative to cell suspension or hydroponic techniques as it is easier and cheaper with simple application in lemon balm pot cultivation. The improvement of lemon balm quality by NaCl elicitation can potentially increase the level of health-promoting phytochemicals and the bioactivity of low-processed herbal products.

Impact of copper treatment on phenylpropanoid biosynthesis in adventitious root culture of Althaea officinalis L

Althaea officinalis has been widely used in various pharmaceutical applications. The biological effects and significance of phenylpropanoids in numerous industries are well studied. However, fulfilling consumer demand for these commercially important compounds is difficult. The effect of heavy-metal toxic influence on plants is primarily due to a strong and rapid suppression of growth processes, as well as the decline in activity of the photosynthetic apparatus, also associated with progressing senescence processes. Some of the secondary metabolite production was triggered by the application of heavy metals, but there was not a stress response. In the adventitious root culture of A. officinalis, copper-mediated phenylpropanoid biosynthesis has been investigated in both concentration-and duration-dependent manners. High-performance liquid chromatography (HPLC) analysis revealed a total of nine different phenolic compounds in response to different concentrations of copper chloride. In this study, high productivity of phenolic compounds was observed in the copper chloride treated-adventitious root culture of A. officianalis. In particular, a low concentration of copper chloride led to a significant accumulation of phenolic compounds under optimal conditions. Moreover, all genes responsible for phenylpropanoid biosynthesis may be sensitive to phenolic compound production following copper treatment. Especially, the highest change in transcript level was observed from AoANS at 6 h. According to our findings, treatment with copper chloride (0.5 mM) for 48 or 96 h can be an appropriate method to maximize phenylpropanoid levels in A. officinalis adventitious root culture.

Sustainable Agriculture Systems in Vegetable Production Using Chitin and Chitosan as Plant Biostimulants

Chitin and chitosan are natural compounds that are biodegradable and nontoxic and have gained noticeable attention due to their effective contribution to increased yield and agro-environmental sustainability. Several effects have been reported for chitosan application in plants. Particularly, it can be used in plant defense systems against biological and environmental stress conditions and as a plant growth promoter—it can increase stomatal conductance and reduce transpiration or be applied as a coating material in seeds. Moreover, it can be effective in promoting chitinolytic microorganisms and prolonging storage life through post-harvest treatments, or benefit nutrient delivery to plants since it may prevent leaching and improve slow release of nutrients in fertilizers. Finally, it can remediate polluted soils through the removal of cationic and anionic heavy metals and the improvement of soil properties. On the other hand, chitin also has many beneficial effects such as plant growth promotion, improved plant nutrition and ability to modulate and improve plants’ resistance to abiotic and biotic stressors. The present review presents a literature overview regarding the effects of chitin, chitosan and derivatives on horticultural crops, highlighting their important role in modern sustainable crop production; the main limitations as well as the future prospects of applications of this particular biostimulant category are also presented.

Impact of Foliar Application of Chitosan Dissolved in Different Organic Acids on Isozymes, Protein Patterns and Physio-Biochemical Characteristics of Tomato Grown under Salinity Stress

In this study, the anti-stress capabilities of the foliar application of chitosan, dissolved in four different organic acids (acetic acid, ascorbic acid, citric acid and malic acid) have been investigated on tomato (Solanum lycopersicum L.) plants under salinity stress (100 mM NaCl). Morphological traits, photosynthetic pigments, osmolytes, secondary metabolites, oxidative stress, minerals, antioxidant enzymes activity, isozymes and protein patterns were tested for potential tolerance of tomato plants growing under salinity stress. Salinity stress was caused a reduction in growth parameters, photosynthetic pigments, soluble sugars, soluble proteins and potassium (K⁺) content. However, the contents of proline, ascorbic acid, total phenol, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), sodium (Na⁺) and antioxidant enzyme activity were increased in tomato plants grown under saline conditions. Chitosan treatments in any of the non-stressed plants showed improvements in morphological traits, photosynthetic pigments, osmolytes, total phenol and antioxidant enzymes activity. Besides, the harmful impacts of salinity on tomato plants have also been reduced by lowering MDA, H₂O₂ and Na⁺ levels. Chitosan treatments in either non-stressed or stressed plants showed different responses in number and density of peroxidase (POD), polyphenol oxidase (PPO) and superoxide dismutase (SOD) isozymes. NaCl stress led to the diminishing of protein bands with different molecular weights, while they were produced again in response to chitosan foliar application. These responses were varied according to the type of solvent acid. It could be suggested that foliar application of chitosan, especially that dissolved in ascorbic or citric acid, could be commercially used for the stimulation of tomato plants grown under salinity stress.

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.