scholarly journals Biochemical basis of systemic acquired resistance induced by different Systemic Acquired Resistance (SAR) elicitors in Brassica cultivars challenge inoculated with downy mildew pathogen

2021 ◽  
Vol 13 (1) ◽  
pp. 301-307
Author(s):  
Astha ◽  
P. S. Sekhon

In India, Brassica is attacked by many bacterial, fungal and viral pathogens causing various diseases among which, downy mildew caused by Hyaloperonospora brassicae, an oomycete is the most severe one.  The present investigation was conducted to reduce fungicide load on Brassica by testing an alternate method of disease control.  Different Systemic Acquired Resistance (SAR) compounds were tested as foliar sprays like Salicylic acid, Jasmonic acid and Bion (Benzothiadiazole-BTH) for inducing resistance in different genotypes of Raya (Brassica juncea) against downy mildew pathogen. Protein content in plants ranged between 43.5 to 57.7 mg/g fresh weight compared to 37.2 mg/g fresh weight in control. Induction of proteins and defense related enzymes was systemic in nature. The SAR compounds also surged the levels of defense related proteins, i.e. Polyphenol oxidase (PPO), Phenylalanine ammonia lyase (PAL) and pathogenesis related Pr- proteins i.e. ?-1,3 glucanase, Peroxidase (POD),  from 21 to 130 per cent indicating induction of resistance. Protein profiling of treated Brassica plants was also done electrophoreticaly, which further confirmed the induction of pathogenesis-related proteins ranging from 15- 75 kDa along with some other proteins. Salicylic acid @ 500µM showed best results with 71.27 per cent disease control followed by Jasmonic acid with 69.6 per cent; whereas both, Bion and ?eta amino butyric acid gave almost 63 per cent disease control as compared to control plants. Integration of disease tolerance in Brassica varieties/genotypes combined with prophylactic spray of salicylic acid proved to be very economical for managing downy mildew disease.

2014 ◽  
Vol 20 (1-2) ◽  
Author(s):  
A. Ezzat ◽  
Z. Szabó ◽  
J. Nyéki

Systemic acquired resistance (SAR) is a mechanism of induced defense that confers long-lasting protection against a broad spectrum of microorganisms. Salicylic acid (SA) is the signal molecule which is required for induce SAR and is associated with accumulation of pathogenesis-related proteins, which are thought to contribute to resistance. SA paly vital role in some related resistance gene expression in plant cell which have direct or indirect effect on pathogen growth as SA has direct toxicity for pathogen and in the same time has stimulation effect for some enzyme related to reduce the oxidative burst.


2007 ◽  
Vol 97 (7) ◽  
pp. 794-802 ◽  
Author(s):  
Shobha D. Potlakayala ◽  
Darwin W. Reed ◽  
Patrick S. Covello ◽  
Pierre R. Fobert

Systemic acquired resistance (SAR) is an induced defense response that confers long-lasting protection against a broad range of microbial pathogens. Here we show that treatment of Brassica napus plants with the SAR-inducing chemical benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) significantly enhanced resistance against virulent strains of the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Leptosphaeria maculans. Localized preinoculation of plants with an avirulent strain of P. syringae pv. maculicola also enhanced resistance to these pathogens but was not as effective as BTH treatment. Single applications of either SAR-inducing pretreatment were effective against P. syringae pv. maculicola, even when given more than 3 weeks prior to the secondary challenge. The pretreatments also led to the accumulation of pathogenesis-related (PR) genes, including BnPR-1 and BnPR-2, with higher levels of transcripts observed in the BTH-treatment material. B. napus plants expressing a bacterial salicylate hydroxylase transgene (NahG) that metabolizes salicylic acid to catechol were substantially compromised in SAR and accumulated reduced levels of PR gene transcripts when compared with untransformed controls. Thus, SAR in B. napus displays many of the hallmarks of classical SAR including long lasting and broad host range resistance, association with PR gene activation, and a requirement for salicylic acid.


2000 ◽  
Vol 13 (5) ◽  
pp. 503-511 ◽  
Author(s):  
Vaijayanti Gupta ◽  
Michael G. Willits ◽  
Jane Glazebrook

The Arabidopsis enhanced disease susceptibility 4 (eds4) mutation causes enhanced susceptibility to infection by the bacterial pathogen Pseudomonas syringae pv. Maculicola ES4326 (Psm ES4326). Gene-for-gene resistance to bacteria carrying the avirulence gene avrRpt2 is not significantly affected by eds4. Plants homozygous for eds4 exhibit reduced expression of the pathogenesis-related gene PR-1 after infection by Psm ES4326, weakened responses to treatment with the signal molecule salicylic acid (SA), impairment of the systemic acquired resistance response, and reduced accumulation of SA after infection with Psm ES4326. These phenotypes indicate that EDS4 plays a role in SA-dependent signaling. SA has been shown to have a negative effect on activation of gene expression by the signal molecule jasmonic acid (JA). Two mutations that cause reduced SA levels, eds4 and pad4, cause heightened responses to inducers of JA-dependent gene expression, providing genetic evidence to support the idea that SA interferes with JA-dependent signaling. Two possible working models of the role of EDS4 in governing activation of defense responses are presented.


2018 ◽  
Vol XI ◽  
pp. 21-30
Author(s):  
Emilia Wilmowicz ◽  
Agata Kućko ◽  
Jan Kopcewicz

This paper presents a comprehensive study on the mechanisms of tree responses to pathogens. We describe natural resistance concerning the presence of different types of barriers protecting plants from invasion and also give them strength after a pathogen attack. We put emphasis on induced resistance functioning both locally and systemically and involvement of phytohormones signaling networks. Systemic acquired resistance (SAR) involved the action of salicylic acid and H202 and accumulation of pathogenesis-related proteins. In turn, jasmonates and ethylene are signaling molecules in the induced resistance (SIR). All these substances play a crucial role in the forest management and can be applied in the tree protection strategies based on the natural and synthetic active compounds.


2020 ◽  
Vol 145 ◽  
pp. 01038
Author(s):  
Pan Wang ◽  
Meiqin Xiang

Salicylic acid (SA) is considered to be an endogenous signal molecule in plants, and it is related to many resistances in plants. In Arabidopsis, Non-expressor of pathogenesis-related gene1 (NPR1) mediates the expression of pathogenesis-related genes (PRs) and systemic acquired resistance (SAR) induced by SA. NPR1 is a key factor in SA signaling pathway, and the research shows that NPR1, NPR3 and NPR4 play a key role in SA mediated plant disease resistance. In this review, the interaction between NPR and transcription factors is discussed, and we also describe the progress of NPR in SA mediated SAR signal transduction pathway, likewise, we introduce the relationship between NPR1 and its paralogues NPR3/NPR4. This paper analyzes the research prospect of NPR as the intersection of multiple signal paths.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian F. Beyer ◽  
Paloma Sánchez Bel ◽  
Victor Flors ◽  
Holger Schultheiss ◽  
Uwe Conrath ◽  
...  

AbstractHormones orchestrate the physiology of organisms. Measuring the activity of defense hormone-responsive genes can help understanding immune signaling and facilitate breeding for plant health. However, different from model species like Arabidopsis, genes that respond to defense hormones salicylic acid (SA) and jasmonic acid (JA) have not been disclosed in the soybean crop. We performed global transcriptome analyses to fill this knowledge gap. Upon exogenous application, endogenous levels of SA and JA increased in leaves. SA predominantly activated genes linked to systemic acquired resistance and defense signaling whereas JA mainly activated wound response-associated genes. In general, SA-responsive genes were activated earlier than those responding to JA. Consistent with the paradigm of biotrophic pathogens predominantly activating SA responses, free SA and here identified most robust SA marker genes GmNIMIN1, GmNIMIN1.2 and GmWRK40 were induced upon inoculation with Phakopsora pachyrhizi, whereas JA marker genes did not respond to infection with the biotrophic fungus. Spodoptera exigua larvae caused a strong accumulation of JA-Ile and JA-specific mRNA transcripts of GmBPI1, GmKTI1 and GmAAT whereas neither free SA nor SA-marker gene transcripts accumulated upon insect feeding. Our study provides molecular tools for monitoring the dynamic accumulation of SA and JA, e.g. in a given stress condition.


2021 ◽  
Author(s):  
Sebastian F. Beyer ◽  
Paloma Sánchez Bel ◽  
Victor Flors ◽  
Holger Schutheiss ◽  
Uwe Conrath ◽  
...  

Abstract Hormones orchestrate the physiology of organisms. Measuring the activity of defense hormone-responsive genes can help understanding immune signaling and facilitate breeding for plant health. However, different from model species like Arabidopsis, genes that respond to defense hormones salicylic acid (SA) and jasmonic acid (JA) have not been disclosed in the soybean crop. We performed global transcriptome analyses to fill this knowledge gap. Upon exogenous application, endogenous levels of SA and JA increased in leaves. SA predominantly activated genes linked to systemic acquired resistance and defense signaling whereas JA mainly activated wound response-associated genes. In general, SA-responsive genes were activated earlier than those responding to JA. Consistent with the paradigm of biotrophic pathogens predominantly activating SA responses, free SA and here identified most robust SA marker genes GmNIMIN1, GmNIMIN1.2 and GmWRK40 were induced upon inoculation with Phakopsora pachyrhizi, whereas JA marker genes did not respond to infection with the biotrophic fungus. Spodoptera exigua larvae caused a strong accumulation of JA-Ile and JA-specific mRNA transcripts of GmBPI1, GmKTI1 and GmAAT whereas neither free SA nor SA-marker gene transcripts accumulated upon insect feeding. Our study provides molecular tools for monitoring the dynamic accumulation of SA and JA, e.g. in a given stress condition.


2011 ◽  
Vol 24 (8) ◽  
pp. 888-896 ◽  
Author(s):  
Franco Rubén Rossi ◽  
Andrés Gárriz ◽  
María Marina ◽  
Fernando Matías Romero ◽  
María Elisa Gonzalez ◽  
...  

Botrytis cinerea, as a necrotrophic fungus, kills host tissues and feeds on the remains. This fungus is able to induce the hypersensitive response (HR) on its hosts, thus taking advantage on the host's defense machinery for generating necrotic tissues. However, the identity of HR effectors produced by B. cinerea is not clear. The aim of this work was to determine whether botrydial, a phytotoxic sesquiterpene produced by B. cinerea, is able to induce the HR on plant hosts, using Arabidopsis thaliana as a model. Botrydial induced the expression of the HR marker HSR3, callose deposition, and the accumulation of reactive oxygen species and phenolic compounds. Botrydial also induced the expression of PR1 and PDF1.2, two pathogenesis-related proteins involved in defense responses regulated by salicylic acid (SA) and jasmonic acid (JA), respectively. A. thaliana and tobacco plants defective in SA signaling were more resistant to botrydial than wild-type plants, as opposed to A. thaliana plants defective in JA signaling, which were more sensitive. It can be concluded that botrydial induces the HR on its hosts and its effects are modulated by host signaling pathways mediated by SA and JA.


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