The synthetic cationic lipid diC14 activates a sector of the Arabidopsis defense network requiring endogenous signaling components (original) (raw)
Related papers
Journal of Biological Chemistry, 2006
We describe an experimental setup using submerged cultures of Arabidopsis seedlings in 96-well microtiter plates that permits chemical intervention of rapid elicitor-mediated immune responses. Screening of a chemical library comprising 120 small molecules with known biological activities revealed four compounds reducing cellulysin-or flg22-activated gene expression of the early pathogen-associated molecular patterns (PAMP)responsive ATL2 gene. One chemical, oxytriazine, was found to induce ATL2 gene expression in the absence of PAMP. By monitoring additional flg22-triggered immediate early plant responses, we present evidence that two compounds, triclosan and fluazinam, interfere with the accumulation of reactive oxygen species and internalization of the activated plasma membrane resident FLS2 immune receptor. Using triclosan structure types and enzyme activity inhibition assays, Arabidopsis MOD1 enoyl-acyl carrier protein reductase, a subunit of the fatty-acid synthase type II (FAS II) complex, was identified as a likely cellular target of triclosan. Inhibition of all tested elicitor-triggered early immune responses by triclosan indicates a potential role for signaling lipids in flg22-triggered immunity. Chemical profiling of eca mutants, each showing deregulated ATL2 gene expression, with the identified compounds revealed mutantspecific response patterns and allowed us to deduce tentative action sites of ECA genes relative to the compound targets.
Microbes and Infection, 2008
Lipopolysaccharides, the ubiquitous part of the outer membrane of Gram-negative bacteria, and their derivatives are recognised by plants to trigger or potentiate particular defence responses such as induction of genes encoding pathogenesis-related proteins. The molecular mechanisms of LPS perception that underpin these effects in plants are, however, unknown. Here, lipid A from Halomonas magadiensis, which is an antagonist of lipid A action in human cells, was used to investigate lipid A action in plants. Our findings offer an insight into the different structural requirements for direct induction and potentiation of plant defences by lipid A.
Scientific Reports, 2016
Synthetic elicitors are drug-like compounds that are structurally distinct from natural defense elicitors. They can protect plants from diseases by activating host immune responses and can serve as tools for the dissection of the plant immune system as well as leads for the development of environmentally-safe pesticide alternatives. By high-throughput screening, we previously identified 114 synthetic elicitors that activate expression of the pathogen-responsive CaBP22 −333 ::GUS reporter gene in Arabidopsis thaliana (Arabidopsis), 33 of which are [(phenylimino)methyl]phenol (PMP) derivatives or PMP-related compounds. Here we report on the characterization of one of these compounds, 2,4-dichloro-6-{(E)-[(3-methoxyphenyl)imino]methyl}phenol (DPMP). DPMP strongly triggers disease resistance of Arabidopsis against bacterial and oomycete pathogens. By mRNA-seq analysis we found transcriptional profiles triggered by DPMP to resemble typical defense-related responses. Plant innate immunity is based on a complex set of integrated defense mechanisms protecting against microbial diseases 1-3. Plants can recognize microbe-associated molecular patterns (MAMPs), which are highly conserved molecular structures of microbes, via pattern recognition receptors (PRRs) on the surfaces of plant cells. These interactions activate pattern-triggered immunity (PTI) 4-11. To attenuate or block PTI, pathogens often secrete into plant cells effector molecules that enable them to use a given plant species as a host, resulting in compatible interactions, a condition also termed effector-triggered susceptibility (ETS). During this type of interaction plants can still exhibit a weakened immune response, called basal defense, which limits the spread of virulent pathogens, but is insufficient for preventing disease 11,12. As a countermeasure to ETS, plants often can recognize the presence or activity of effector proteins by highly specific plant resistance (R) proteins and induce effector-triggered immunity (ETI). This leads to incompatible interactions leaving the pathogen avirulent and the plant resistant 5,13. PTI, basal defense and ETI are controlled by a common set of defense signals including reactive oxygen intermediates (ROIs), Ca 2+ , salicylic acid (SA), ethylene (ET) and jasmonic acid (JA) 14. The massive release of ROIs at pathogen infection sites is one of the earliest observable features of a plant's defense program. Induced changes of ion fluxes typically precede this oxidative burst 15. The oxidative burst conditions a programmed form of localized cell death at infection sites, termed hypersensitive response (HR). HR can limit invasion of biotrophic pathogens, as these require host tissues to remain intact 16. These early responses are coordinated by various components of SA-dependent signaling mechanisms 14. In addition, crosstalk between the SA, JA and ET hormone pathways are important for the fine-tuning of plant defense responses 17 .
PLANT PHYSIOLOGY, 2012
Plant resistance to phytopathogenic microorganisms mainly relies on the activation of an innate immune response usually launched after recognition by the plant cells of microbe-associated molecular patterns. The plant hormones, salicylic acid (SA), jasmonic acid, and ethylene have emerged as key players in the signaling networks involved in plant immunity. Rhamnolipids (RLs) are glycolipids produced by bacteria and are involved in surface motility and biofilm development. Here we report that RLs trigger an immune response in Arabidopsis (Arabidopsis thaliana) characterized by signaling molecules accumulation and defense gene activation. This immune response participates to resistance against the hemibiotrophic bacterium Pseudomonas syringae pv tomato, the biotrophic oomycete Hyaloperonospora arabidopsidis, and the necrotrophic fungus Botrytis cinerea. We show that RL-mediated resistance involves different signaling pathways that depend on the type of pathogen. Ethylene is involved in RL-induced resistance to H. arabidopsidis and to P. syringae pv tomato whereas jasmonic acid is essential for the resistance to B. cinerea. SA participates to the restriction of all pathogens. We also show evidence that SA-dependent plant defenses are potentiated by RLs following challenge by B. cinerea or P. syringae pv tomato. These results highlight a central role for SA in RL-mediated resistance. In addition to the activation of plant defense responses, antimicrobial properties of RLs are thought to participate in the protection against the fungus and the oomycete. Our data highlight the intricate mechanisms involved in plant protection triggered by a new type of molecule that can be perceived by plant cells and that can also act directly onto pathogens.
The Plant Cell, 2012
Plant activators are compounds, such as analogs of the defense hormone salicylic acid (SA), that protect plants from pathogens by activating the plant immune system. Although some plant activators have been widely used in agriculture, the molecular mechanisms of immune induction are largely unknown. Using a newly established high-throughput screening procedure that screens for compounds that specifically potentiate pathogen-activated cell death in Arabidopsis thaliana cultured suspension cells, we identified five compounds that prime the immune response. These compounds enhanced disease resistance against pathogenic Pseudomonas bacteria in Arabidopsis plants. Pretreatments increased the accumulation of endogenous SA, but reduced its metabolite, SA-O-b-D-glucoside. Inducing compounds inhibited two SA glucosyltransferases (SAGTs) in vitro. Double knockout plants that lack both SAGTs consistently exhibited enhanced disease resistance. Our results demonstrate that manipulation of the active free SA pool via SA-inactivating enzymes can be a useful strategy for fortifying plant disease resistance and may identify useful crop protectants.
Synthetic Rhamnolipid Bolaforms trigger an innate immune response in Arabidopsis thaliana
Scientific reports, 2018
Stimulation of plant innate immunity by natural and synthetic elicitors is a promising alternative to conventional pesticides for a more sustainable agriculture. Sugar-based bolaamphiphiles are known for their biocompatibility, biodegradability and low toxicity. In this work, we show that Synthetic Rhamnolipid Bolaforms (SRBs) that have been synthesized by green chemistry trigger Arabidopsis innate immunity. Using structure-function analysis, we demonstrate that SRBs, depending on the acyl chain length, differentially activate early and late immunity-related plant defense responses and provide local increase in resistance to plant pathogenic bacteria. Our biophysical data suggest that SRBs can interact with plant biomimetic plasma membrane and open the possibility of a lipid driven process for plant-triggered immunity by SRBs.
Plant physiology, 2018
Salicylic acid (SA) plays a crucial role in plant innate immunity. The deployment of SA-associated immune responses is primarily affected by SA concentration, which is determined by a balance between SA biosynthesis and catabolism. However, the mechanisms regulating SA homeostasis are poorly understood. In this study, we characterized a unique UDP-glycosyltransferase, UGT76D1, which plays an important role in SA homeostasis and associated immune responses in Arabidopsis thaliana. Expression of UGT76D1 was induced by treatment with both the pathogen Pseudomonas syringae pv. tomato (Pst) DC3000 and SA. Overexpression of UGT76D1 resulted in high SA accumulation, significant up-regulation of pathogen-related genes, and a hypersensitive response (HR)-like lesion mimic phenotype. This HR-like phenotype was not observed following UGT76D1 overexpression in SA-deficient NahG transgenic or sid2 plants, suggesting that the phenotype is SA dependent. Biochemical assays showed that UGT76D1 glyco...
Molecular Plant-Microbe Interactions, 2013
Salicylic acid (SA) is one of the key hormones that orchestrate the pathogen-23 induced immune response in plants. This response is often characterized by the activation 24 of a local hypersensitive reaction (HR) involving programmed cell death, which constrains 25 proliferation of biotrophic pathogens. Here, we report the identification and functional 26 characterization of a SA-induced legume lectin-like protein 1 (SAI-LLP1), which is coded 27 by a gene that belongs to the group of early SA-activated Arabidopsis genes. SAI-LLP1 28 expression is induced upon inoculation with avirulent strains of Pseudomonas syringae pv 29 tomato (Pst), via a SA-dependent mechanism. Constitutive expression of SAI-LLP1 30 restrains proliferation of Pst Avr-Rpm1 and triggers more cell death in inoculated leaves. 31 Cellular and biochemical evidence indicates that SAI-LLP1 is a glycoprotein located 32 primarily at the apoplastic side of the plasma membrane. This work indicates that SAI-33 LLP1 is involved in resistance to Pst Avr-Rpm1 in Arabidopsis, as a component of the SA-34 mediated defense processes associated to the ETI response. 35 36
Plants, 2020
The use of beneficial rhizobacteria (bioeffectors) and their derived metabolic elicitors are efficient biotechnological alternatives in plant immune system elicitation. This work aimed to check the ability of 25 bacterial strains isolated from the rhizosphere of Nicotiana glauca, and selected for their biochemical traits from a group of 175, to trigger the innate immune system of Arabidopsis thaliana seedlings against the pathogen Pseudomonas syringae pv. tomato DC3000. The five strains more effective in preventing pathogen infection were used to elucidate signal transduction pathways involved in the plant immune response by studying the differential expression of Salicylic acid and Jasmonic acid/Ethylene pathway marker genes. Some strains stimulated both pathways, while others stimulated either one or the other. The metabolic elicitors of two strains, chosen for the differential expression results of the genes studied, were extracted using n-hexane, ethyl acetate, and n-butanol, an...