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![Schematic presentation of tyrosine metabolism leading to the production of hydroxycinnamic acid amides (HCAAs). A Tyramine and the two catecholamines have been shown to have high antioxidant properties [34]. B Each compound shown in the pathway may be conjugated to hydroxycinnamic acid (HCA) derivatives (e.g., ferulic acid as shown). The most common conjugates include coumaric- and ferulic acid. Several sources have described the incorporation of the HCAAs into the cell wall [36, 37]. Compounds that were not detected as discriminant ions due to the flagellin elicitor treatments are lightly shaded i.e., tyrosine and L-DOPA. Dashed arrows indicate multiple enzymatic reactions leading to the production of a specific compound. Abbreviations: TH, tyrosine hydroxylase; TDC, tyrosine decarboxylase; DDC, dopa decarboxylase; MPH, monophenol hydroxylase; DH, dopamine hydroxylase; THT, tyramine N-(hydroxycinnamoyl) transferase](publication/354744469/figure/fig8/AS:11431281118372768@1675741599410/Schematic-presentation-of-tyrosine-metabolism-leading-to-the-production-of.png)
Schematic presentation of tyrosine metabolism leading to the production of hydroxycinnamic acid amides (HCAAs). A Tyramine and the two catecholamines have been shown to have high antioxidant properties [34]. B Each compound shown in the pathway may be conjugated to hydroxycinnamic acid (HCA) derivatives (e.g., ferulic acid as shown). The most common conjugates include coumaric- and ferulic acid. Several sources have described the incorporation of the HCAAs into the cell wall [36, 37]. Compounds that were not detected as discriminant ions due to the flagellin elicitor treatments are lightly shaded i.e., tyrosine and L-DOPA. Dashed arrows indicate multiple enzymatic reactions leading to the production of a specific compound. Abbreviations: TH, tyrosine hydroxylase; TDC, tyrosine decarboxylase; DDC, dopa decarboxylase; MPH, monophenol hydroxylase; DH, dopamine hydroxylase; THT, tyramine N-(hydroxycinnamoyl) transferase
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Background
Surveillance of potential pathogens is a key feature of plant innate immunity. For non-self-recognition plants rely on the perception of pathogen-derived molecules. Early post-perception events activate signaling cascades, leading to the synthesis of defense-related proteins and specialized metabolites, thereby providing a broad-spectrum...
Citations
... This strain was used in previous studies regarding the metabo-phenotyping and metabolomics of the host response (disease tolerance) of the selected tomato cvs. (Zeiss et al., 2018; and the inducible changes of the metabolome to peptide elicitors derived from R. solanacearum flagellin (Zeiss et al., 2021a) and cold shock protein (Zeiss et al., 2022). LPS was purified from saturated cell cultures grown in the nutrient broth medium on an orbital shaker at 28°C, using the hot phenol protocol as previously described (Gerber et al., 2004) and incorporating DNase and protease digestion steps (Madala et al., 2011). ...
... The overall luminescence results (Figures 1B, C) confirmed the host plant's ability to respond to the LPS R. sol. elicitor through the production of ROS, albeit at a lower metabolic level compared to flagellin-derived peptides flg22 and flg28 (Zeiss et al., 2021a). ...
... treatment. Again, this observation is consistent with a single elicitor treatment rather than a cocktail of MAMPs (Zeiss et al., 2019;Zeiss et al., 2021a). When superimposed with the Hotellings T 2 95% confidence interval ellipse, no outliers were observed on the PCA scores plot. ...
Ralstonia solanacearum, one of the most destructive crop pathogens worldwide, causes bacterial wilt disease in a wide range of host plants. The major component of the outer membrane of Gram-negative bacteria, lipopolysaccharides (LPS), has been shown to function as elicitors of plant defense leading to the activation of signaling and defense pathways in several plant species. LPS from a R. solanacearum strain virulent on tomato (LPS R. sol . ), were purified, chemically characterized, and structurally elucidated. The lipid A moiety consisted of tetra- to hexa-acylated bis -phosphorylated disaccharide backbone, also decorated by aminoarabinose residues in minor species, while the O-polysaccharide chain consisted of either linear tetrasaccharide or branched pentasaccharide repeating units containing α-L-rhamnose, N -acetyl-β-D-glucosamine, and β-L-xylose. These properties might be associated with the evasion of host surveillance, aiding the establishment of the infection. Using untargeted metabolomics, the effect of LPS R. sol. elicitation on the metabolome of Solanum lycopersicum leaves was investigated across three incubation time intervals with the application of UHPLC-MS for metabolic profiling. The results revealed the production of oxylipins, e.g., trihydroxy octadecenoic acid and trihydroxy octadecadienoic acid, as well as several hydroxycinnamic acid amide derivatives, e.g., coumaroyl tyramine and feruloyl tyramine, as phytochemicals that exhibit a positive correlation to LPS R. sol. treatment. Although the chemical properties of these metabolite classes have been studied, the functional roles of these compounds have not been fully elucidated. Overall, the results suggest that the features of the LPS R. sol. chemotype aid in limiting or attenuating the full deployment of small molecular host defenses and contribute to the understanding of the perturbation and reprogramming of host metabolism during biotic immune responses.
... It has been shown that elicitors such as flg22 and oligogalacturonides (OGs) positively regulate key genes of secondary metabolism involved in the biosynthesis of glucosinolates, camalexin and phenylpropanoids such as cytochrome P450 (CYP) and PAL genes [45]. Recent metabolomics analysis also showed positive impact of flg22 treatment on secondary metabolites production in tomato [50]. ...
The rapeseed crop is susceptible to many pathogens such as parasitic plants or fungi attacking aerial or root parts. Conventional plant protection products, used intensively in agriculture, have a negative impact on the environment as well as on human health. There is therefore a growing demand for the development of more planet-friendly alternative protection methods such as bio-control compounds. Natural rhamnolipids (RLs) can be used as elicitors of plant defense mechanisms. These glycolipids, from bacteria secretome, are biodegradable, non-toxic and are known for their stimulating and protective effects, in particular on rapeseed against filamentous fungi. Characterizing the organ responsiveness to defense-stimulating compounds such as RLs is missing. This analysis is crucial in the frame of optimizing the effectiveness of RLs against various diseases. A Tandem Mass Tags (TMT) labeling of the proteins extracted from the shoots and roots of rapeseed has been performed and showed a differential pattern of protein abundance between them. Quantitative proteomic analysis highlighted the differential accumulation of parietal and cytoplasmic defense or stress proteins in response to RL treatments with a clear effect of the type of application (foliar spraying or root absorption). These results must be considered for further use of RLs to fight specific rapeseed pathogens.
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 .
This chapter overviews the latest developments in plant metabolomics, explicitly focusing on novel gene identifications, plant species identification, plant root metabolome, plant biomarkers, and plant single-cell metabolomics. This chapter explores the importance of identifying novel genes in plants and their role in enhancing crop yield and tolerance to environmental stresses. It also discusses the challenges of identifying plant species and the various techniques used to overcome them, including metabolite quantitative trait loci and genome-wide association studies. Furthermore, this chapter examines the plant root metabolome and its significance in plant growth and development. It highlights the role of metabolomics in plant biology research, particularly in identifying potential biomarkers for monitoring plant health and productivity. This chapter also covers the emerging field of plant single-cell metabolomics and its potential for advancing our understanding of plant metabolism at the cellular level. In addition, this chapter discusses the application of mass spectrometry imaging (MSI) techniques in plant biology research, particularly in visualizing and mapping the distribution of metabolites in plant tissues. It provides an overview of the different MSI techniques and their advantages and limitations in plant biology research. The information presented in this chapter is valuable to researchers and practitioners in plant biology. It can aid in developing new strategies for improving plant health and productivity.
To successfully infect plants, pathogens secrete effector proteins to the plant apoplast or inside plant cells, where they suppress plant immunity or interfere with other cellular processes to facilitate infection. Plant metabolism is crucial for most cellular processes and plays a key role in defense against pathogens, making it a major target for pathogen effectors. Effector proteins manipulate host metabolism to provide the pathogen with nutrients or to indirectly suppress plant chemical defense responses. Recent studies have shown that pathogens also utilize effectors to shape the microbiota composition by altering the concentration of certain plant metabolites. Here, we summarize current knowledge on the manipulation of plant metabolism by pathogen effectors. We also discuss what remains unknown regarding the manipulation of host metabolism by pathogen effectors.
Plants produce a high diversity of secondary metabolites that are involved in a wide range of different functions, including stress tolerance, signaling molecule for interactions with other species (allelopathy) and protecting plants against herbivores and pathogens. With the rise of more accessible, high-throughput mass spectrometry and new analytical tools it becomes feasible to identify and validate new secondary metabolites involved in pathogen resistance or assign new roles to previously detected compounds. In this review, we provide a brief overview of the major pathogen defence-associated classes of secondary metabolites, with a focus on those with direct anti-pathogen function. For each class we highlight one or more typical examples representing the class to give a comprehensive summary of some of the work done to date. In the second part of this review, we highlight how new technological advances and high throughput experiments in combination with other sources of -omics data, like genomics and transcriptomics can accelerate the studies on secondary metabolites and help to link these compounds to genotypes. Employing such approaches will improve our understanding of chemical defences against plant pathogens and allow rapid development of markers for resistance breeding.
Arachidonic acid (AA) is an oomycete-derived MAMP capable of eliciting robust defense responses and inducing resistance in plants. Similarly, extract (ANE) from the brown seaweed Ascophylum nodosum, a plant biostimulant that contains AA, can also prime plants for defense against pathogen challenge. A previous parallel study comparing the transcriptomes of AA and ANE root-treated tomato demonstrated significant overlap in transcriptional profiles, a shared induced resistance phenotype, and changes in accumulation of various defense-related phytohormones. In this work, untargeted metabolomic analysis via liquid chromatography-mass spectrometry was conducted to investigate the local and systemic metabolome-wide remodeling events elicited by AA- and ANE-root treatment in tomato. Our study demonstrated AA and ANE’s capacity to locally and systemically alter the metabolome of tomato with enrichment of chemical classes and accumulation of metabolites associated with defense-related secondary metabolism. AA and ANE root-treated plants showed enrichment of fatty acyl-glycosides and strong modulation of hydroxycinnamic acids and derivatives. Identification of specific metabolites whose accumulation was affected by AA and ANE treatment revealed shared metabolic changes related to ligno-suberin biosynthesis and the synthesis of phenolic compounds. This study highlights the extensive local and systemic metabolic changes in tomato induced by treatment with a fatty acid MAMP and a seaweed-derived plant biostimulant with implications for induced resistance and crop improvement.
The antagonistic effect of plant immunity on growth likely drove evolution of molecular mechanisms that prevent accidental initiation and prolonged activation of plant immune responses. Signaling networks of pattern-triggered and effector-triggered immunity, the two main layers of plant immunity, are tightly regulated by the activity of protein phosphatases that dephosphorylate their protein substrates and reverse the action of protein kinases. Members of the PP2C class of protein phosphatases have emerged as key negative regulators of plant immunity, primarily from research in the model plant Arabidopsis thaliana, revealing the potential to employ PP2C proteins to enhance plant disease resistance. As a first step towards focusing on the PP2C family for both basic and translational research, we analyzed the tomato genome sequence to ascertain the complement of the tomato PP2C family, identify conserved protein domains and signals in PP2C amino acid sequences, and examine domain combinations in individual proteins. We then identified tomato PP2Cs that are candidate regulators of single or multiple layers of the immune signaling network by in-depth analysis of publicly available RNA-seq datasets. These included expression profiles of plants treated with fungal or bacterial pathogen-associated molecular patterns, with pathogenic, nonpathogenic, and disarmed bacteria, as well as pathogenic fungi and oomycetes. Finally, we discuss the possible use of immunity-associated PP2Cs to better understand the signaling networks of plant immunity and to engineer durable and broad disease resistance in crop plants.
[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 .
