scholarly journals Isolation of New Arabidopsis Mutants With Enhanced Disease Susceptibility to Pseudomonas syringae by Direct Screening

Genetics ◽  
1998 ◽  
Vol 149 (2) ◽  
pp. 537-548
Author(s):  
Sigrid M Volko ◽  
Thomas Boller ◽  
Frederick M Ausubel
Keyword(s):  
Pseudomonas Syringae ◽  
Fungal Pathogen ◽  
Systemic Acquired Resistance ◽  
Disease Susceptibility ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
Avirulent Strain ◽  
Resistance Response ◽  
Arabidopsis Mutants ◽  
Pathogen Response

Abstract To identify plant defense components that are important in restricting the growth of virulent pathogens, we screened for Arabidopsis mutants in the accession Columbia (carrying the transgene BGL2-GUS) that display enhanced disease susceptibility to the virulent bacterial pathogen Pseudomonas syringae pv. maculicola (Psm) ES4326. Among six (out of a total of 11 isolated) enhanced disease susceptibility (eds) mutants that were studied in detail, we identified one allele of the previously described npr1/nim1/sai1 mutation, which is affected in mounting a systemic acquired resistance response, one allele of the previously identified EDS5 gene, and four EDS genes that have not been previously described. The six eds mutants studied in detail (npr1-4, eds5-2, eds10-1, eds11-1, eds12-1, and eds13-1) displayed different patterns of enhanced susceptibility to a variety of phytopathogenic bacteria and to the obligate biotrophic fungal pathogen Erysiphe orontii, suggesting that particular EDS genes have pathogen-specific roles in conferring resistance. All six eds mutants retained the ability to mount a hypersensitive response and to restrict the growth of the avirulent strain Psm ES4326/avrRpt2. With the exception of npr1-4, the mutants were able to initiate a systemic acquired resistance (SAR) response, although enhanced growth of Psm ES4326 was still detectable in leaves of SAR-induced plants. The data presented here indicate that eds genes define a variety of components involved in limiting pathogen growth, that many additional EDS genes remain to be discovered, and that direct screens for mutants with altered susceptibility to pathogens are helpful in the dissection of complex pathogen response pathways in plants.

Isolation and Characterization of Broad-Spectrum Disease-Resistant Arabidopsis Mutants

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1661-1671
Author(s):  
Klaus Maleck ◽  
Urs Neuenschwander ◽  
Rebecca M Cade ◽  
Robert A Dietrich ◽  
Jeffery L Dangl ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Constitutive Expression ◽  
Firefly Luciferase ◽  
Marker Genes ◽  
Arabidopsis Mutants ◽  
Isolation And Characterization ◽  
Firefly Luciferase Gene

Abstract To identify Arabidopsis mutants that constitutively express systemic acquired resistance (SAR), we constructed reporter lines expressing the firefly luciferase gene under the control of the SAR-inducible PR-1 promoter (PR-1/luc). After EMS mutagenesis of a well-characterized transgenic line, we screened 250,000 M2 plants for constitutive expression of the reporter gene in vivo. From a mutant collection containing several hundred putative mutants, we concentrated on 16 mutants lacking spontaneous hypersensitive response (HR) cell death. We mapped 4 of these constitutive immunity (cim) mutants to chromosome arms. Constitutive expression of disease resistance was established by analyzing responses to virulent Peronospora parasitica and Pseudomonas syringae strains, by RNA blot analysis for endogenous marker genes, and by determination of salicylic acid levels in the mutants. The variety of the cim phenotypes allowed us to define distinct steps in both the canonical SAR signaling pathway and a separate pathway for resistance to Erysiphe cichoracearum, active in only a subset of the mutants.

scholarly journals Systemic Acquired Resistance in Canola Is Linked with Pathogenesis-Related Gene Expression and Requires Salicylic Acid

2007 ◽  
Vol 97 (7) ◽  
pp. 794-802 ◽  
Author(s):  
Shobha D. Potlakayala ◽  
Darwin W. Reed ◽  
Patrick S. Covello ◽  
Pierre R. Fobert
Keyword(s):  
Salicylic Acid ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Induced Defense ◽  
Acquired Resistance ◽  
Microbial Pathogens ◽  
Broad Host Range ◽  
Avirulent Strain ◽  
Enhanced Resistance ◽  
Pathogenesis Related

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.

scholarly journals Arabidopsis UGT76B1 glycosylates N-hydroxy-pipecolic acid and inactivates systemic acquired resistance in tomato

2020 ◽  
Author(s):  
Eric C. Holmes ◽  
Yun-Chu Chen ◽  
Mary Beth Mudgett ◽  
Elizabeth S. Sattely
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
Defense Responses ◽  
Pipecolic Acid ◽  
Systemic Resistance ◽  
Biosynthetic Genes ◽  
Solanaceous Plants

AbstractSystemic acquired resistance (SAR) is a mechanism that plants utilize to connect a local pathogen infection to global defense responses. N-hydroxy-pipecolic acid (NHP) and a glycosylated derivative are produced during SAR, yet their individual roles in the response have not yet been elucidated. Here we report that Arabidopsis thaliana UGT76B1 can generate glycosylated NHP (NHP-Glc) in vitro and when transiently expressed alongside Arabidopsis NHP biosynthetic genes in two Solanaceous plants. During infection, Arabidopsis ugt76b1 mutants do not accumulate NHP-Glc and accumulate less glycosylated salicylic acid (SA-Glc) than wild type plants. The metabolic changes in ugt76b1 mutant plants are accompanied by enhanced defense to the bacterial pathogen Pseudomonas syringae, suggesting that glycosylation of SAR molecules NHP and SA by UGT76B1 plays an important role in defense modulation. Transient expression of Arabidopsis UGT76B1 with the Arabidopsis NHP biosynthesis genes ALD1 and FMO1 in tomato increases NHP-Glc production and reduces NHP accumulation in local tissue, and abolishes the systemic resistance seen when expressing NHP-biosynthetic genes alone. These findings reveal that the glycosylation of NHP by UGT76B1 alters defense priming in systemic tissue and provide further evidence for the role of the NHP aglycone as the active metabolite in SAR signaling.

scholarly journals Arabidopsis thaliana EDS4 Contributes to Salicylic Acid (SA)-Dependent Expression of Defense Responses: Evidence for Inhibition of Jasmonic Acid Signaling by SA

2000 ◽  
Vol 13 (5) ◽  
pp. 503-511 ◽  
Author(s):  
Vaijayanti Gupta ◽  
Michael G. Willits ◽  
Jane Glazebrook
Keyword(s):  
Gene Expression ◽  
Salicylic Acid ◽  
Jasmonic Acid ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Defense Responses ◽  
Avirulence Gene ◽  
Signal Molecule ◽  
Resistance Response

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.

scholarly journals Trichoderma asperelloides enhances local and systemic acquired resistance response under low nitrate nutrition in Arabidopsis

2018 ◽  
Author(s):  
Aakanksha Wany ◽  
Pradeep K. Pathak ◽  
Alisdair R Fernie ◽  
Kapuganti Jagadis Gupta
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
N Uptake ◽  
Acquired Resistance ◽  
Marker Genes ◽  
Defense Gene Expression ◽  
Resistance Response ◽  
Defense Gene ◽  
Protein Levels

AbstractNitrogen (N) is essential for growth, development and defense but, how low N affects defense and the role of Trichoderma in enhancing defense under low nitrate is not known. Low nitrate fed Arabidopsis plants displayed reduced growth and compromised local and systemic acquired resistance responses when infected with both avirulent and virulent Pseudomonas syringae DC3000. These responses were enhanced in the presence of Trichoderma. The mechanism of increased local and systemic acquired resistance mediated by Trichoderma involved increased N uptake and enhanced protein levels via modulation of nitrate transporter genes. The nrt2.1 mutant is compromised in local and systemic acquired resistance responses suggesting a link between enhanced N transport and defense. Enhanced N uptake was mediated by Trichoderma elicited nitric oxide (NO). Low NO producing nia1,2 mutant and nsHb+ over expressing lines were unable to induce nitrate transporters and thereby compromised defense in the presence of Trichoderma under low N suggesting a signaling role of Trichoderma elicited NO. Trichoderma also induced SA and defense gene expression under low N. The SA deficient NahG transgenic line and the npr1 mutant were also compromised in Trichoderma-mediated local and systemic acquired resistance responses. Collectively our results indicated that the mechanism of enhanced plant defense under low N mediated by Trichoderma involves NO, ROS, SA production as well as the induction of NRT and marker genes for systemic acquired resistance.One-sentence summaryTrichoderma enhances local and systemic acquired resistance under low nitrate nutrition

scholarly journals Pseudomonas syringae Elicits Emission of the Terpenoid (E,E)-4,8,12-Trimethyl-1,3,7,11-Tridecatetraene in Arabidopsis Leaves Via Jasmonate Signaling and Expression of the Terpene Synthase TPS4

2008 ◽  
Vol 21 (11) ◽  
pp. 1482-1497 ◽  
Author(s):  
Elham Attaran ◽  
Michael Rostás ◽  
Jürgen Zeier
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Induced Defense ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
Microbial Pathogens ◽  
Terpene Synthase ◽  
Knockout Mutant ◽  
Direct Role ◽  
Ja Signaling

Volatile, low–molecular weight terpenoids have been implicated in plant defenses, but their direct role in resistance against microbial pathogens is not clearly defined. We have examined a possible role of terpenoid metabolism in the induced defense of Arabidopsis thaliana plants against leaf infection with the bacterial pathogen Pseudomonas syringae. Inoculation of plants with virulent or avirulent P. syringae strains induces the emission of the terpenoids (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT), β-ionone and α-farnesene. While the most abundant volatile, the C16-homoterpene TMTT, is produced relatively early in compatible and incompatible interactions, emission of both β-ionone and α-farnesene only increases in later stages of the compatible interaction. Pathogen-induced synthesis of TMTT is controlled through jasmonic acid (JA)-dependent signaling but is independent of a functional salicylic acid (SA) pathway. We have identified Arabidopsis T-DNA insertion lines with defects in the terpene synthase gene TPS4, which is expressed in response to P. syringae inoculation. The tps4 knockout mutant completely lacks induced emission of TMTT but is capable of β-ionone and α-farnesene production, demonstrating that TPS4 is specifically involved in TMTT formation. The tps4 plants display at least wild type–like resistance against P. syringae, indicating that TMTT per se does not protect against the bacterial pathogen in Arabidopsis leaves. Similarly, the ability to mount SA-dependent defenses and systemic acquired resistance (SAR) is barely affected in tps4, which excludes a signaling function of TMTT during SAR. Besides P. syringae challenge, intoxication of Arabidopsis leaves with copper sulfate, a treatment that strongly activates JA biosynthesis, triggers production of TMTT, β-ionone, and α-farnesene. Taken together, our data suggest that induced TMTT production in Arabidopsis is a by-product of activated JA signaling, rather than an effective defense response that contributes to resistance against P. syringae.

Role of Salicylic Acid and NIM1/NPR1 in Race-Specific Resistance in Arabidopsis

Genetics ◽  
2002 ◽  
Vol 161 (2) ◽  
pp. 803-811
Author(s):  
Gregory J Rairdan ◽  
Terrence P Delaney
Keyword(s):  
Salicylic Acid ◽  
Pseudomonas Syringae ◽  
Leucine Zipper ◽  
Systemic Acquired Resistance ◽  
Specific Resistance ◽  
Strong Dependence ◽  
Acquired Resistance ◽  
R Genes ◽  
Resistance Response

Abstract Salicylic acid (SA) and the NIM1/NPR1 protein have both been demonstrated to be required for systemic acquired resistance (SAR) and implicated in expression of race-specific resistance. In this work, we analyzed the role that each of these molecules play in the resistance response triggered by members of two subclasses of resistance (R) genes, members of which recognize unrelated pathogens. We tested the ability of TIR and coiled-coil-class (also known as leucine-zipper-class) R genes to confer resistance to Pseudomonas syringae pv. tomato or Peronospora parasitica in SA-depleted (NahG) and nim1/npr1 plants. We found that all of the P. syringae pv. tomato-specific R genes tested were dependent upon SA accumulation, while none showed strong dependence upon NIM1/NPR1 activity. A similar SA dependence was observed for the P. parasitica TIR and CC-class R genes RPP5 and RPP8, respectively. However, the P. parasitica-specific R genes differed in their requirement for NIM1/NPR1, with just RPP5 depending upon NIM1/NPR1 activity for effectiveness. These data are consistent with the hypothesis that at least in Arabidopsis, SA accumulation is necessary for the majority of R-gene-triggered resistance, while the role of NIM1/NPR in race-specific resistance is limited to resistance to P. parasitica mediated by TIR-class R genes.

scholarly journals Pipecolic Acid Is Induced in Barley upon Infection and Triggers Immune Responses Associated with Elevated Nitric Oxide Accumulation

2019 ◽  
Vol 32 (10) ◽  
pp. 1303-1313 ◽  
Author(s):  
Miriam Lenk ◽  
Marion Wenig ◽  
Kornelia Bauer ◽  
Florian Hug ◽  
Claudia Knappe ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Immune Responses ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
Pipecolic Acid ◽  
Systemic Immunity ◽  
Exogenous Application ◽  
Barley Leaves

Pipecolic acid (Pip) is an essential component of systemic acquired resistance, priming resistance in Arabidopsis thaliana against (hemi)biotrophic pathogens. Here, we studied the potential role of Pip in bacteria-induced systemic immunity in barley. Exudates of barley leaves infected with the systemic immunity–inducing pathogen Pseudomonas syringae pv. japonica induced immune responses in A. thaliana. The same leaf exudates contained elevated Pip levels compared with those of mock-treated barley leaves. Exogenous application of Pip induced resistance in barley against the hemibiotrophic bacterial pathogen Xanthomonas translucens pv. cerealis. Furthermore, both a systemic immunity–inducing infection and exogenous application of Pip enhanced the resistance of barley against the biotrophic powdery mildew pathogen Blumeria graminis f. sp. hordei. In contrast to a systemic immunity-inducing infection, Pip application did not influence lesion formation by a systemically applied inoculum of the necrotrophic fungus Pyrenophora teres. Nitric oxide (NO) levels in barley leaves increased after Pip application. Furthermore, X. translucens pv. cerealis induced the accumulation of superoxide anion radicals and this response was stronger in Pip-pretreated compared with mock-pretreated plants. Thus, the data suggest that Pip induces barley innate immune responses by triggering NO and priming reactive oxygen species accumulation.

scholarly journals GmRAR1 and GmSGT1 Are Required for Basal, R Gene–Mediated and Systemic Acquired Resistance in Soybean

2009 ◽  
Vol 22 (1) ◽  
pp. 86-95 ◽  
Author(s):  
Da-Qi Fu ◽  
Said Ghabrial ◽  
Aardra Kachroo
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Soybean Mosaic Virus ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
R Gene ◽  
Extreme Resistance ◽  
Basal Resistance ◽  
Effector Triggered Immunity ◽  
Specific Proteins

RAR1, SGT1, and HSP90 are important components of effector-triggered immunity (ETI) in diverse plants, where RAR1 and SGT1 are thought to serve as HSP90 co-chaperones. We show that ETI in soybean requires RAR1 and SGT1 but not HSP90. Rsv1-mediated extreme resistance to Soybean mosaic virus (SMV) and Rpg-1b-mediated resistance to Pseudomonas syringae were compromised in plants silenced for GmRAR1 and GmSGT1-2 but not GmHSP90. This suggests that RAR1- or SGT1-dependant signaling is not always associated with a dependence on HSP90. Unlike in Arabidopsis, SGT1 in soybean also mediates ETI against the bacterial pathogen P. syringae. Similar to Arabidopsis, soybean RAR1 and SGT1 proteins interact with each other and two related HSP90 proteins. Plants silenced for GmHSP90 genes or GmRAR1 exhibited altered morphology, suggesting that these proteins also contribute to developmental processes. Silencing GmRAR1 and GmSGT1-2 impaired resistance to virulent bacteria and systemic acquired resistance (SAR) in soybean as well. Because the Arabidopsis rar1 mutant also showed a defect in SAR, we conclude that RAR1 and SGT1 serve as a point of convergence for basal resistance, ETI, and SAR. We demonstrate that, although soybean defense signaling pathways recruit structurally conserved components, they have distinct requirements for specific proteins.

scholarly journals Arabidopsismlo3mutant plants exhibit spontaneous callose deposition and signs of early leaf senescence

2019 ◽  
Author(s):  
Stefan Kusch ◽  
Susanne Thiery ◽  
Anja Reinstädler ◽  
Katrin Gruner ◽  
Krzysztof Zienkiewicz ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Powdery Mildew ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
Resistance Locus ◽  
Callose Deposition ◽  
Powdery Mildew Fungi ◽  
Hyaloperonospora Arabidopsidis

The family of Mildew resistance Locus O (MLO) proteins is best known for its profound effect on the outcome of powdery mildew infections: when the appropriate MLO protein is absent, the plant is fully resistant to otherwise virulent powdery mildew fungi. However, most members of the MLO protein family remain functionally unexplored. Here, we investigateArabidopsis thaliana MLO3, the closest relative ofAtMLO2, AtMLO6andAtMLO12, which are the ArabidopsisMLOgenes implicated in the powdery mildew interaction. The co-expression network ofAtMLO3suggests association of the gene with plant defense-related processes such as salicylic acid homeostasis. Our extensive analysis shows thatmlo3mutants are unaffected regarding their infection phenotype upon challenge with the powdery mildew fungiGolovinomyces orontiiandErysiphe pisi, the oomyceteHyaloperonospora arabidopsidis, and the bacterial pathogenPseudomonas syringae(the latter both in terms of basal and systemic acquired resistance), indicating that the protein does not play a major role in the response to any of these pathogens. However,mlo3genotypes display spontaneous callose deposition as well as signs of early senescence in six-or seven-week-old rosette leaves in the absence of any pathogen challenge, a phenotype that is reminiscent ofmlo2mutant plants. We hypothesize that de-regulated callose deposition inmlo3genotypes is the result of a subtle transient aberration of salicylic acid-jasmonic acid homeostasis during development.

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