Additive and Specific Effects of Elicitor Treatments on the Metabolic Profile of Arabidopsis thaliana.

Several elicitors of plant defense have been identified and numerous efforts to use them in the field have been made. Exogenous elicitor treatments mimic the in planta activation of pattern-triggered immunity (PTI), which relies on the perception of pathogen-associated molecular patterns (PAMPs) such as bacterial flg22 or fungal chitins. Early transcriptional responses to distinct PAMPs are mostly overlapping, regardless of the elicitor being used. However, it remains poorly known if the same patterns are observed for metabolites and proteins produced later during PTI. In addition, little is known about the impact of a combination of elicitors on PTI and the level of induced resistance to pathogens. Here, we monitored Arabidopsis thaliana resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pto DC3000) following application of flg22 and chitosan elicitors, used individually or in combination. A slight, but not statistically significant increase in induced resistance was observed when the elicitors were applied together when compared with individual treatments. We investigated the effect of these treatments on the metabolome by using an untargeted analysis. We found that the combination of flg22 and chitosan impacted a higher number of metabolites and deregulated specific metabolic pathways compared with the elicitors individually. These results contribute to a better understanding of plant responses to elicitors, which might help better rationalize their use in the field. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Fungal Cell Wall-Associated Effectors: Sensing, Integration, Suppression, and Protection.

The cell wall (CW) of plant-interacting fungi, as the direct interface with host plants, plays a crucial role in fungal development. A number of secreted proteins are directly associated with the fungal CW, either through covalent or non-covalent interactions, and serve a range of important functions. In the context of plant-fungal interactions many are important for fungal development in the host environment and may therefore be considered fungal CW-associated effectors (CWAEs). Key CWAE functions include integrating chemical/physical signals to direct hyphal growth, interfering with plant immunity, and providing protection against plant defenses. In recent years, a diverse range of mechanisms have been reported that underpin their roles, with some CWAEs harboring conserved motifs or functional domains, while others are reported to have novel features. As such, the current understanding regarding fungal CWAEs is systematically presented here from the perspective of their biological functions in plant-fungal interactions. An overview of the fungal CW architecture and the mechanisms by which proteins are secreted, modified, and incorporated into the CW is first presented to provide context for their biological roles. Some CWAE functions are reported across a broad range of pathosystems or symbiotic/mutualistic associations. Prominent are the chitin interacting-effectors that facilitate fungal CW modification, protection, or suppression of host immune responses. However, several alternative functions are now reported and are presented and discussed. CWAEs can play diverse roles, some possibly unique to fungal lineages and others conserved across a broad range of plant-interacting fungi. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Metabolic engineering of artificially modified transcription factor SmMYB36-VP16 for high-level production of tanshinones and phenolic acids.

Tanshinones and phenolic acids are the two main chemical constituents in Salvia miltiorrhiza, which are used clinically for the treatment of hypertension, coronary heart disease, atherosclerosis, and many other diseases, and have broad medicinal value. The efficient synthesis of the target products of these two metabolites in isolated plant tissues cannot be achieved without the regulation and optimization of metabolic pathways, and transcription factors play an important role as common regulatory elements in plant tissue metabolic engineering. However, most of the regulatory effects are specific to one class of metabolites, or an opposing regulation of two classes of metabolites exists. In this study, an artificially modified transcription factor, SmMYB36-VP16, was constructed to enhance tanshinones and phenolic acids in Salvia miltiorrhiza hair roots simultaneously. Further in combination with the elicitors dual-screening technique, by applying the optimal elicitors screened, the tanshinones content in the transgenic hairy roots of Salvia miltiorrhiza reached 6.44 mg/g DW, which was theoretically 6.08-fold that of the controls without any treatment, and the content of phenolic acids reached 141.03 mg/g DW, which was theoretically 5.05-fold that of the controls without any treatment. The combination of artificially modified transcriptional regulatory and elicitors dual-screening techniques has facilitated the ability of plant isolated tissue cell factories to produce targeted medicinal metabolites. This strategy could be applied to other species, laying the foundation for the production of potential natural products for the medicinal industry.

Endophyte-based fungal elicitors for enhanced production of valepotriates and sesquiterpenoids in leaf cell suspension cultures of Valeriana jatamansi Jones.

AIMS: The immense therapeutic value of Valeriana jatamansi is attributed to the presence of bioactive secondary metabolites (valepotriates and sesquiterpenoids). Its over-exploitation in wild habitats resulted in extensive depletion, necessitating alternative approaches to produce its therapeutic metabolites. This study sought to assess the ability of endophytes of V. jatamansi to boost the biosynthesis of secondary metabolites in the leaf-cell suspension (LCS) culture of V. jatamansi. METHODS AND RESULTS: A total of 11 fungal endophytes were isolated from the rhizomes of V. jatamansi. Isolated endophytes were found to belong to phylum Ascomycota, Basidiomycota, and Mucoromycota. Supplementation of extracts of endophyte Phaeosphaeriaceae sp. VRzFB, Mucor griseocyanus VRzFD, Penicillium raistrickii VRzFK, and Penicillium sajarovii VRzFL in the LCS culture of V. jatamansi increased the fresh cell biomass by 19.6%-39.1% and dry cell biomass by 23.4%-37.8%. Most of the endophytes' extract could increase the content of valepotriates (26.5%-76.5% valtrate and 40.5%-77.9% acevaltrate) and sesquiterpenoids (19.9%-61.1% hydroxyl valerenic acid) in LCS culture. However, only two endophytes, Irpex lacteus VRzFI and Fusarium oxysporum VRzFF, could increase the sesquiterpenoids acetoxy valerenic acid (36.9%-55.3%). In contrast, some endophytes' extracts caused negative or no significant effect on the cell biomass and targeted metabolites. Increased secondary metabolites were corroborated with increased expression of iridoid biosynthesis genes in LCS culture. Production of H2O2 and lipid peroxidation was also varied with different endophytes indicating the modulation of cellular oxidative stress due to endophyte elicitors. CONCLUSIONS: The results suggest the distinct effect of different fungal endophytes-extract on LCS culture, and endophytes can serve as biotic elicitors for increasing the secondary metabolite production in plant in vitro systems.

Hernandulcin Production in Elicited Hairy Roots of Phyla scaberrima: Toward Sustainable Production of a Non-Caloric Sweetener with Nutraceutical Properties.

Herein we report on the generation of hairy root lines of P. scaberrima able to produce hernandulcin (HE), a non-caloric sweetener with nutraceutical properties. From ten different lines analyzed, three synthesized up to 100 mg ⋅ L-1 HE under the batch culture conditions standardized in this investigation. Adding elicitors (salicylic acid, chitin, Glucanex, polyethylene glycol) and biosynthetic precursors (farnesol and (+)-epi-alpha-bisabolol) significantly altered HE accumulation. Chitin and Glucanex enhanced HE production from 130 to 160 mg ⋅ L-1 , whereas farnesol and (+)-epi-alpha-bisabolol from 165 to 200 mg ⋅ L-1 without dependence on biomass accumulation. Improved batch cultures containing liquid Murashige & Skoog medium (MS; pH 7), added with 4 % sucrose, 0.5 mg ⋅ L-1 naphthaleneacetic acid, 100 mg ⋅ L-1 Glucanex, 150 mg ⋅ L-1 chitin, 250 mg ⋅ L-1 farnesol, and 150 mg ⋅ L-1 (+)-epi-alpha-bisabolol at 25 °C (12 h light/12 h darkness), triggered HE accumulation to 250 mg ⋅ L-1 in 25 days. The efficiency of each recombinant line is discussed.

Effects of Exogenous Application of Methyl Jasmonate and Salicylic Acid on the Physiological and Molecular Response of 'Dusa' Avocado to Rosellinia necatrix.

Methyl jasmonate (MeJA) and salicylic acid (SA) are important in mediating plant responses to abiotic and biotic stresses. MeJA and SA can act as elicitors by triggering plant defense responses similar to those induced by pathogens and may even provide long-term protection against them. Thus, exogenous application of MeJA and SA could protect susceptible avocado plants against white root rot (WRR) disease caused by the necrotrophic fungus Rosellinia necatrix, one of the main diseases affecting avocado orchards. This work evaluates the effects of MeJA or SA on the physiological and molecular response of susceptible 'Dusa' avocado rootstock and their ability to provide some protection against WRR. The application of MeJA and SA in avocado increased photoprotective mechanisms (nonphotochemical chlorophyll fluorescence quenching) and upregulated the glutathione S-transferase, suggesting the triggering of mechanisms closely related to oxidative stress relief and reactive oxygen species scavenging. In contrast to SA, MeJA's effects were more pronounced at the morphoanatomical level, including functional traits such as high leaf mass area, high stomatal density, and high root/shoot ratio, closely related to strategies to cope with water scarcity and WRR disease. Moreover, MeJA upregulated a greater number of defense-related genes than SA, including a glu protease inhibitor, a key gene in avocado defense against R. necatrix. The overall effects of MeJA increased 'Dusa' avocado tolerance to R. necatrix by inducing a primed state that delayed WRR disease symptoms. These findings point toward the use of MeJA application as an environmentally friendly strategy to mitigate the impact of this disease on susceptible avocado orchards.

Eliciting Polyphenols in Strawberry Leaves: Preliminary Experiments in Fragaria × ananassa cv. Festival.

Polyphenols are plant secondary metabolites that function mostly as a general stress-induced protective mechanism. Polyphenols have also gained interest due to their beneficial properties for human health. Strawberry leaves represent an agro-industrial waste material with relevant bioactive polyphenol content, which could be incorporated into circular economy strategies. However, due to the low quantities of polyphenols in plants, their production needs to be improved for cost-effective applications. The objective of this research was to compare polyphenol production in strawberry (Fragaria × ananassa cv. Festival) leaves in plants grown in greenhouse conditions and plants grown in vitro, using three possible elicitor treatments (UV irradiation, cold exposure, and cysteine). General vegetative effects were morphologically evaluated, and specific polyphenolic compounds were quantified by UHPLC-DAD-MS/MS. Gallic acid was the most abundant polyphenol found in the leaves, both in vivo and in vitro. The results showed higher amounts and faster accumulation of polyphenols in the in vitro regenerated plants, highlighting the relevance of in vitro tissue culture strategies for producing compounds such as polyphenols in this species and cultivar.

Combining the Elicitor Up-Regulated Production of Unusual Linear Diterpene-Derived Variants for an In-Depth Assessment of the Application Value and Risk of the Medicinal and Edible Basidiomycete Schizophyllum commune.

To better assess the practical value and avoid potential risks of the traditionally medicinal and edible basidiomycete Schizophyllum commune, which may arise from undescribed metabolites, a combination of elicitors was introduced for the first time to discover products from cryptic and low-expressed gene clusters under laboratory cultivation. Treating S. commune NJFU21 with the combination of five elicitors led to the upregulated production of a class of unusual linear diterpene-derived variants, including eleven new ones (1-11), along with three known ones (12-14). The structures and stereochemistry were determined by 1D and 2D NMR, HRESIMS, ECD, OR and VCD calculations. Notably, the elongation terminus of all the diterpenes was decorated by an unusual butenedioic acid moiety. Compound 1 was a rare monocyclic diterpene, while 2-6 possessed a tetrahydrofuran moiety. The truncated metabolites 4, 5 and 13 belong to the trinorditerpenes. All the diterpenes displayed approximately 70% scavenging of hydroxyl radicals at 50 µM and null cytotoxic activity at 10 µM. In addition, compound 1 exhibited potent antifungal activity against the plant pathogenic fungi Colletotrichum camelliae, with MIC values of 8 µg/mL. Our findings indicated that this class of diterpenes could provide valuable protectants for cosmetic ingredients and the lead compounds for agricultural fungicide development.

The exogenous application of naringenin and rosmarinic acid modulates functional traits in Lepidium sativum.

BACKGROUND: Phenolic modulators have attracted attention for their potential in shaping functional traits in plants. This work investigated the impact of naringenin (Nar) and rosmarinic acid (RA) on the functional properties of Lepidium sativum leaves and roots. RESULTS: Untargeted metabolomics identified a diverse phenolic profile, including flavonoids, phenolic acids, low molecular weight phenolics, lignans, and stilbenes. Cluster, analysis of variance multiblock orthogonal partial least squares (AMOPLS), and orthogonal projection to latent structures discriminant analysis (OPLS-DA) multivariate analyses confirmed tissue-specific modulation of bioactive compounds. The tissue was the hierarchically most influential factor, explaining 27% of observed variability, while the treatment and their interaction were statistically insignificant. Thereafter, various in vitro assays were employed to assess antioxidant capacity, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, cupric ion reducing antioxidant capacity (CUPRAC), and ferric ion reducing antioxidant power (FRAP), metal chelating ability, and phosphomolybdenum (PMD) assays. Extracts were also tested for inhibitory effects on cholinesterase, amylase, glucosidase, and tyrosinase enzymes. RA application positively impacted antioxidant and enzyme inhibitory activities, holding valuable implications in shaping the health-promoting properties of L. sativum. CONCLUSION: The untargeted metabolomics analysis showed a significant tissue-dependent modulation of bioactive compounds, determining no synergistic effect between applying phenolic compounds in combination. Specifically, the sole application of RA increased anthocyanins and hydroxyphenyl propanoic acid content on leaves, which was strictly related to enhancing the biological activities. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Systemic biochemical changes in pepper (Capsicum annuum L.) against Rhizoctonia solani by kale (Brassica oleracea var. acephala L.) green manure application.

BACKGROUND: In the search for new alternatives to avoid the problems associated with the use of synthetic chemical fungicides in agriculture, the use of green manure (GrM) could help combat fungal diseases of crops, such as those produced by the necrotrophic pathogen Rhizoctonia solani. In the case of the use of Brassica tissues as GrM, it could have an elicitor capacity for systemic plant resistance. RESULTS: We used kale leaves as a GrM and applied it to pepper plants infected with R. solani. The application of freeze-dried kale tissues to the roots of pepper plants produced a systemic activation of foliar defences via the salicylic acid (SA) and ethylene (ET) pathways, significantly reducing pathogen damage. In addition, this systemic response led to the accumulation of secondary defence metabolites, such as pipecolic acid, hydroxycoumarin and gluconic acid, in leaves. Remarkably, pepper plants treated with lyophilised kale GrM accumulated glucosinolates when infected with R. solani. We also confirmed that autoclaving removed part of the glucobrassicin (85%) and sinigrin (19%) content of the kale tissues. CONCLUSIONS: GrM kale tissues can activate systemic defences in bell pepper against foliar pathogens through SA/ET hormonal pathways, accumulating secondary defence metabolites.

The role of signaling compounds in enhancing rice allelochemicals for sustainable agriculture: an overview.

MAIN CONCLUSION: Plant phytotoxin synthesis is influenced by intricate signaling networks like jasmonic acid (JA) and salicylic acid (SA). These compounds not only induce allelochemical production but also aid weed suppression and plant immunity. (-)-Loliolide, JA, SA, and their derivatives trigger rice allelochemical synthesis and gene expression. Enhancing allelochemical synthesis in crops offers an alternative, reducing reliance on traditional herbicides for effective weed management. Rice (Oryza sativa L.) serves as a crucial staple food crop, nourishing over half of the global population, particularly in South Asia. Within rice plants, various secondary metabolites are produced, contributing to its nutritional value and providing energy to consumers. Over the last 5 decades, researchers have investigated 276 distinct types of secondary metabolites found in rice plants. These metabolites predominantly include phenolic acids, flavonoids, steroids, alkaloids, terpenoids, and their derivatives. The role of these secondary metabolites is to regulate the growth and development of the rice plant. In this research paper, we have focused on the allelopathic potential of rice, which involves its active defense strategy to suppress other species in its vicinity. This defense mechanism is regulated by plant signaling compounds. These signaling compounds enable rice plants to recognize and detect competitors, pathogens, and herbivores in their environment. As a response, the rice plants elevate the production of defensive secondary metabolites. One crucial aspect of rice allelopathy is the phenomenon of neighbor detection. Rice plants can sense the presence of neighboring plants and respond accordingly to establish their competitive advantage and ensure their survival. This paper specifically highlights the impact of exogenously applied signaling compounds, namely Methyl salicylate (MeSA) and Methyl Jasmonate (MeJA), on paddy rice. The aim is to provide deeper insights into the signaling mechanisms involved in rice allelopathy and how the exogenous application of signaling compounds influence the induction and regulation of defensive secondary metabolites in rice plants. Comprehensive analysis of various researchers' studies clearly reveals that the application of these elicitor compounds noticeably augments the allelopathic potential of rice, resulting in heightened accumulation of phenolic acid compounds. Expansion in more enlistment of phenolics may be because of expansion in the activities of enzymes, such as cinnamate 4-hydroxylase (C4H) and phenylalanine ammonia-lyase (PAL), the two main enzymes of the phenylpropanoid pathway, which are associated with allelopathic crop plants, and along this, they recognize the presence of weeds and react by expanding allelochemical focuses. Consequently, substantial endeavors have been dedicated in recent times to discover and characterize plant-derived signaling molecules. In bioassays conducted by Patni et al. in 2019, both competitive and non-competitive rice genotypes exhibited elevated phytotoxicity against Echino colona following treatment with MeSA. MeSA-treated rice plants displayed accelerated growth, increased yield, and concurrently demonstrated weed-suppressing properties. Published studies from 1976 to 2021 are reviewed in this paper. The study indicates that signaling compounds induce allelochemical concentrations, enhancing allelopathic activity. This insight may lead to development of novel herbicides for effective sustainable weed management.

Formation, immunomodulatory activities, and enhancement of glucosinolates and sulforaphane in broccoli sprouts: a review for maximizing the health benefits to human.

Broccoli sprouts have been considered as functional foods which have received increasing attention because they have been highly prized for glucosinolates, phenolics, and vitamins in particular glucosinolates. One of hydrolysates-sulforaphane from glucoraphanin is positively associated with the attenuation of inflammatory, which could reduce diabetes, cardiovascular and cancer risk. In recent decades, the great interest in natural bioactive components especially for sulforaphane promotes numerous researchers to investigate the methods to enhance glucoraphanin levels in broccoli sprouts and evaluate the immunomodulatory activities of sulforaphane. Therefore, glucosinolates profiles are different in broccoli sprouts varied with genotypes and inducers. Physicochemical, biological elicitors, and storage conditions were widely studied to promote the accumulation of glucosinolates and sulforaphane in broccoli sprouts. These inducers would stimulate the biosynthesis pathway gene expression and enzyme activities of glucosinolates and sulforaphane to increase the concentration in broccoli sprouts. The immunomodulatory activity of sulforaphane was summarized to be a new therapy for diseases with immune dysregulation. The perspective of this review served as a potential reference for customers and industries by application of broccoli sprouts as a functional food and clinical medicine.

Cell wall polysaccharides of endophytic Pseudomonas putida elicit defense against rice blast disease.

AIMS: To characterize the functional role of extracellular polysaccharides and lipopolysaccharide (LPS) extracted from endophytic Pseudomonas putida BP25 (PpBP25) against rice blast. METHODS AND RESULTS: We profiled the transcriptome of endobacterized rice seedlings using RNA-seq. Fluorescence imaging of interaction between Magnaporthe:: gfp and P. putida:: mCherry was performed on rice phylloplane using confocal laser scanning microscopy (CLSM). Microbial polysaccharides, exopolysaccharide (EPS), and LPS extracted from PpBP25 were characterized using Fourier-transform infrared-spectroscopic analysis (FTIR). Biochemical assays and gene expression analysis were conducted on EPS- and LPS-treated rice seedlings. A detached-leaf assay was designed to test the blasticidal-effect of bacterial-endophyte, EPS, and LPS on rice phylloplane. PpBP25 elicited defense in rice with a consequently altered seedling phenotype. Rice cultivar, Pusa Basmati-1, colonized by PpBP25 showed an altered transcriptome profile displaying a total of 110-downregulated and 68-upregulated genes (P < 0.005) representing growth/development and defense pathways, respectively. CLSM of PpBP25 bacterized phylloplane showed reduced conidial-germination and mycelial-biomass of Magnaporthe oryzae. To decipher the elicitor role of polysaccharides, we purified and characterized EPS and LPS using FTIR. Rice treated with the EPS and LPS showed root-growth inhibition the phenotype of MAMP-triggered immunity. While the EPS showed blast suppressive activity at 1-20 mg mL-1 (79.80%-86.87% reduction over control), the LPS exhibited 78.0%-79.8% reduction at 20-200 µg mL-1on rice. Polysaccharides treated seedling showed elevated activities of peroxidase and polyphenol-oxidase activities, and total-phenols content. Treated plantlets showed up regulation of OsPR1.1,OsPR3, OsGLP3-3,OsZFP179, and Oshox24 as well as downregulation of OsACS6. CONCLUSIONS: We showed that P. putida Bp25 and its cell wall-associated polysaccharides could elicit defense against rice blast.

Small molecule inducers of actinobacteria natural product biosynthesis.

Actinobacteria are a large and diverse group of bacteria that are known to produce a wide range of secondary metabolites, many of which have important biological activities, including antibiotics, anti-cancer agents, and immunosuppressants. The biosynthesis of these compounds is often highly regulated with many natural products (NPs) being produced at very low levels in laboratory settings. Environmental factors, such as small molecule elicitors, can induce the production of secondary metabolites. Specifically, they can increase titers of known NPs as well as enabling discovery of novel NPs typically produced at undetectable levels. These elicitors can be NPs, including antibiotics or hormones, or synthetic compounds. In recent years, there has been a growing interest in the use of small molecule elicitors to induce the production of secondary metabolites from actinobacteria, especially for the discovery of NPs from "silent" biosynthetic gene clusters. This review aims to highlight classes of molecules that induce secondary metabolite production in actinobacteria and to describe the potential mechanisms of induction. ONE-SENTENCE SUMMARY: This review describes chemical elicitors of actinobacteria natural products described to date and the proposed mechanisms of induction.

An update on anaphylaxis and urticaria.

Notable scientific developments have taken place in the field of anaphylaxis and urticaria in recent years; they are highlighted in this review. Case-control studies, genome-wide association studies, and large omics analyses have promoted further insights into not only the underlying genetics but also the biomarkers of both anaphylaxis and urticaria. New evidence regarding IgE-dependent and non-IgE-dependent mechanisms of anaphylaxis and urticaria, including the Mas-related G protein-coupled receptor (MRGPR [formerly MRG]) signaling pathway, has been gained. Putative elicitors of anaphylactic reactions in the context of coronavirus disease 2019 (COVID-19) vaccination and impact of the COVID-19 pandemic on the management and course of chronic urticaria have been reported. Clinical progress has also been made regarding the severity grading and risk factors of anaphylaxis, as well as the distinction of phenotypes and elicitors of both diseases. Furthermore, novel treatment approaches for anaphylaxis and subtypes of urticaria have been assessed, with different outcome and potential for a better disease control or prevention.

Synergistic Influence of Yeast Extract and Calcium Oxide Nanoparticles on the Synthesis of Bioactive Antioxidants and Metabolites in Swertia chirata In Vitro Callus Cultures.

The challenges in the production of metabolites of medicinal potential from wild plants include low yields, slow growth rates, seasonal variations, genetic variability and regulatory as well as ethical constraints. Overcoming these challenges is of paramount significance and interdisciplinary approaches and innovative strategies are prevalently applied to optimize phytoconstituents' production, enhance yield, biomass, ensure sustainable consistency and scalability. In this study, we investigated the effects of elicitation with yeast extract and calcium oxide nanoparticles (CaONPs) on in vitro cultures of Swertia chirata (Roxb. ex Fleming) Karsten. Specifically, we examined the effects of different concentrations of CaONPs in combination with different concentrations of yeast extract on various parameters related to callus growth, antioxidant activity, biomass and phytochemical contents. Our results showed that elicitation with yeast extract and CaONPs had significant effects on the growth and characteristics of callus cultures of S. chirata. The treatments involving yeast extract and CaONPs were found to be the most effective in increasing the contents of total flavonoid contents (TFC), total phenolic contents (TPC), amarogentin and mangiferin. These treatments also led to an improvement in the contents of total anthocyanin and alpha tocopherols. Additionally, the DPPH scavenging activity was significantly increased in the treated samples. Furthermore, the treatments involving elicitation with yeast extract and CaONPs also led to significant improvements in callus growth and characteristics. These treatments promoted callus response from an average to an excellent level and improved the color and nature of the callus from yellow to yellow-brown and greenish and from fragile to compact, respectively. The best response was observed in treatments involving 0.20 g/L yeast extract and 90 ug/L CaONPs. Overall, our findings suggest that elicitation with yeast extract and CaONPs can be a useful strategy for promoting the growth, biomass, phytochemical contents and antioxidant activity of callus cultures of S. chirata in comparison to wild plant herbal drug samples.

Application of seaweed extracts to mitigate biotic and abiotic stresses in plants.

Agriculture sector is facing a lot of constraints such as climate change, increasing population and the use of chemicals, and fertilizers which have significant influence on sustainability. The excessive usage of chemical fertilizers and pesticides has created a significant risk to humans, animals, plants, and the environment. To reduce the dependency on chemical fertilizers and pesticides a biological-based alternative is required. Seaweeds are essential marine resources that contain bioactive compounds and they have several uses in agriculture. The use of seaweed extracts in agriculture can mitigate stress, enhance nutrient efficiency, and boost plant growth. The use of seaweed extracts and their components activate several signaling pathways and defense-related genes/enzymes. In this review, an attempt has been made to explain how seaweed extracts and their bioactive components induce tolerance and promote growth under stress conditions.

[Screening and molecular identification of endophytic fungi promoting accumulation of flavonoids in callus of Scutellaria baicalensis].

To screen and identify the endophytic fungal strains that could promote the accumulation of flavonoids in the callus of Scutellaria baicalensis. Seventeen endophytic fungal strains from S. baicalensis were used to prepare mycelium elicitors and fermentation broth elicitors. Their effects on flavonoid accumulation in S. baicalensis callus were then determined. The results showed that the fermentation broth elicitors of two strains(CL79, CL105) promoted the accumulation of flavonoids. The fermentation broth elicitor of CL79 significantly promoted accumulation of baicalin, wogonoside, baicalein, and wogonin, with the maximum levels increased by 37.8%, 40.4%, 44.7%, and 42.2%(vs. blank), respectively. Similarly, the fermentation broth elicitor of CL105 significantly promoted the accumulation of baicalin, wogonoside, baicalein, and wogonin, with the maximum levels increased by 78.1%, 140.9%, 275.6%, and 208.5%(vs. blank), respectively. CL79 was identified as Alternaria alternata, and CL105 as Fusarium solani. The fermentation broth elicitors of A. alternata CL79 and F. solani CL105 were able to promote the flavonoid accumulation in the callus of S. baicalensis, which enriched the resources of endophytic fungi and provided candidate strains for the development of microbial fertili-zers for improving the quality of S. baicalensis.

Influence of Flagellin Polymorphisms, Gene Regulation, and Responsive Memory on the Motility of Xanthomonas Species That Cause Bacterial Spot Disease of Solanaceous Plants.

Increasingly, new evidence has demonstrated variability in the epitope regions of bacterial flagellin, including in regions harboring the microbe-associated molecular patterns flg22 and flgII-28 that are recognized by the pattern recognition receptors FLS2 and FLS3, respectively. Additionally, because bacterial motility is known to contribute to pathogen virulence and chemotaxis, reductions in or loss of motility can significantly reduce bacterial fitness. In this study, we determined that variations in flg22 and flgII-28 epitopes allow some but not all Xanthomonas spp. to evade both FLS2- and FLS3-mediated oxidative burst responses. We observed variation in the motility for many isolates, regardless of their flagellin sequence. Instead, we determined that past growth conditions may have a significant impact on the motility status of isolates, because we could minimize this variability by inducing motility using chemoattractant assays. Additionally, motility could be significantly suppressed under nutrient-limited conditions, and bacteria could "remember" its prior motility status after storage at ultracold temperatures. Finally, we observed larger bacterial populations of strains with flagellin variants predicted not to be recognized by either FLS2 or FLS3, suggesting that these bacteria can evade flagellin recognition in tomato plants. Although some flagellin variants may impart altered motility and differential recognition by the host immune system, external growth parameters and gene expression regulation appear to have more significant impacts on the motility phenotypes for these Xanthomonas spp.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Recognition of Microbe- and Damage-Associated Molecular Patterns by Leucine-Rich Repeat Pattern Recognition Receptor Kinases Confers Salt Tolerance in Plants.

In plants, a first layer of inducible immunity is conferred by pattern recognition receptors (PRRs) that bind microbe- and damage-associated molecular patterns to activate pattern-triggered immunity (PTI). PTI is strengthened or followed by another potent form of immunity when intracellular receptors recognize pathogen effectors, termed effector-triggered immunity. Immunity signaling regulators have been reported to influence abiotic stress responses as well, yet the governing principles and mechanisms remain ambiguous. Here, we report that PRRs of a leucine-rich repeat ectodomain also confer salt tolerance in Arabidopsis thaliana, following recognition of cognate ligands such as bacterial flagellin (flg22 epitope) and elongation factor Tu (elf18 epitope), and the endogenous Pep peptides. Pattern-triggered salt tolerance (PTST) requires authentic PTI signaling components; namely, the PRR-associated kinases BAK1 and BIK1 and the NADPH oxidase RBOHD. Exposure to salt stress induces the release of Pep precursors, pointing to the involvement of the endogenous immunogenic peptides in developing plant tolerance to high salinity. Transcriptome profiling reveals an inventory of PTST target genes, which increase or acquire salt responsiveness following a preexposure to immunogenic patterns. In good accordance, plants challenged with nonpathogenic bacteria also acquired salt tolerance in a manner dependent on PRRs. Our findings provide insight into signaling plasticity underlying biotic or abiotic stress cross-tolerance in plants conferred by PRRs.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.