scholarly journals Activation of an EDS1-Mediated R-Gene Pathway in the snc1 Mutant Leads to Constitutive, NPR1-Independent Pathogen Resistance

2001 ◽  
Vol 14 (10) ◽  
pp. 1131-1139 ◽  
Author(s):  
Xin Li ◽  
Joseph D. Clarke ◽  
Yuelin Zhang ◽  
Xinnian Dong
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Pathogen Resistance ◽  
R Gene ◽  
Signal Molecule ◽  
Gene Pathway ◽  
Constitutive Resistance ◽  
Resistance Pathway ◽  
Arabidopsis Mutant

The Arabidopsis NPR1 protein is an essential regulatory component of systemic acquired resistance (SAR). Mutations in the NPR1 gene completely block the induction of SAR by signals such as salicylic acid (SA). An Arabidopsis mutant, snc1 (suppressor of npr1-1, constitutive 1), was isolated in a screen for suppressors of npr1-1. In the npr1-1 background, the snc1 mutation resulted in constitutive resistance to Pseudomonas syringae maculicola ES4326 and Peronospora parasitica Noco2. High levels of SA were detected in the mutant and shown to be required for manifestation of the snc1 phenotype. The snc1 mutation was mapped to the RPP5 resistance (R) gene cluster and the eds1 mutation that blocks RPP5-mediated resistance suppressed snc1. These data suggest that a RPP5-related resistance pathway is activated constitutively in snc1. This pathway does not employ NPR1 but requires the signal molecule SA and the function of EDS1. Moreover, in snc1, constitutive resistance is conferred in the absence of cell death, which is often associated with R-gene mediated resistance.

scholarly journals Arabidopsis Clade I TGA Transcription Factors Regulate Plant Defenses in an NPR1-Independent Fashion

2012 ◽  
Vol 25 (11) ◽  
pp. 1459-1468 ◽  
Author(s):  
Heather L. Shearer ◽  
Yu Ti Cheng ◽  
Lipu Wang ◽  
Jinman Liu ◽  
Patrick Boyle ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Defense Responses ◽  
R Gene ◽  
Triple Mutant ◽  
Transcriptional Reprogramming ◽  
Tga Factors ◽  
Hyaloperonospora Arabidopsidis

Transcriptional reprogramming during induction of salicylic acid (SA)-mediated defenses is regulated primarily by NPR1 (NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1), likely through interactions with TGA bZIP transcription factors. To ascertain the contributions of clade I TGA factors (TGA1 and TGA4) to defense responses, a tga1-1 tga4-1 double mutant was constructed and challenged with Pseudomonas syringae and Hyaloperonospora arabidopsidis. Although the mutant displayed enhanced susceptibility to virulent P. syringae, it was not compromised in systemic acquired resistance against this pathogen or resistance against avirulent H. arabidopsidis. Microarray analysis of nonelicited and SA-treated plants indicated that clade I TGA factors regulate fewer genes than NPR1. Approximately half of TGA-dependent genes were regulated by NPR1 but, in all cases, the direction of change was opposite in the two mutants. In support of the microarray data, the NPR1-independent disease resistance observed in the autoimmune resistance (R) gene mutant snc1 is partly compromised by tga1-1 tga4-1 mutations, and a triple mutant of clade I TGA factors with npr1-1 is more susceptible than either parent. These results suggest that clade I TGA factors are required for resistance against virulent pathogens and avirulent pathogens mediated by at least some R gene specificities, acting substantially through NPR1-independent pathways.

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 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 Inducible biosynthesis and immune function of the systemic acquired resistance inducer N-hydroxypipecolic acid in monocotyledonous and dicotyledonous plants

2020 ◽  
Vol 71 (20) ◽  
pp. 6444-6459 ◽  
Author(s):  
Anika Schnake ◽  
Michael Hartmann ◽  
Stefan Schreiber ◽  
Jana Malik ◽  
Lisa Brahmann ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Brachypodium Distachyon ◽  
Acquired Resistance ◽  
Potent Inducer ◽  
Resistance Pathway ◽  
Xanthomonas Translucens ◽  
Dicotyledonous Plants ◽  
Soybean Leaves ◽  
And Function

Abstract Recent work has provided evidence for the occurrence of N-hydroxypipecolic acid (NHP) in Arabidopsis thaliana, characterized its pathogen-inducible biosynthesis by a three-step metabolic sequence from l-lysine, and established a central role for NHP in the regulation of systemic acquired resistance. Here, we show that NHP is biosynthesized in several other plant species in response to microbial attack, generally together with its direct metabolic precursor pipecolic acid and the phenolic immune signal salicylic acid. For example, NHP accumulates locally in inoculated leaves and systemically in distant leaves of cucumber in response to Pseudomonas syringae attack, in Pseudomonas-challenged tobacco and soybean leaves, in tomato inoculated with the oomycete Phytophthora infestans, in leaves of the monocot Brachypodium distachyon infected with bacterial (Xanthomonas translucens) and fungal (Magnaporthe oryzae) pathogens, and in M. oryzae-inoculated barley. Notably, resistance assays indicate that NHP acts as a potent inducer of acquired resistance to bacterial and fungal infection in distinct monocotyledonous and dicotyledonous species. Pronounced systemic accumulation of NHP in leaf phloem sap of locally inoculated cucumber supports a function for NHP as a phloem-mobile immune signal. Our study thus generalizes the existence and function of an NHP resistance pathway in plant systemic acquired resistance.

scholarly journals The Role of Nitric Oxide-Induced ATILL6 in Growth and Disease Resistance in Arabidopsis thaliana

2021 ◽  
Vol 12 ◽  
Author(s):  
Murtaza Khan ◽  
Tiba Nazar Ibrahim Al Azawi ◽  
Anjali Pande ◽  
Bong-Gyu Mun ◽  
Da-Sol Lee ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Plant Growth ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
R Gene ◽  
Transcript Accumulation ◽  
Positive Role ◽  
Basal Defense

Nitric oxide (NO) is a signaling molecule that regulates various processes, including plant growth and development, immunity, and environmental interactions. Using high throughput RNA-seq data, we explored the role of the NO-induced ATILL6 gene in plant growth and defense using functional genomics. The atill6 mutant and wild-types were challenged with either oxidative (H2O2, MV) or nitro-oxidative (CySNO, GSNO) stress conditions, and the phenotypic results showed that ATILL6 gene differentially regulates cotyledon development frequency (CDF) as well as the root and shoot lengths of the plants. To investigate whether ATILL6 plays a role in plant basal or resistance (R)-gene-mediated defense, the plants were challenged with either virulent or avirulent strains of Pseudomonas syringae pathovar tomato (Pst) DC3000. The atill6 line showed a susceptible phenotype, higher pathogen growth, and highly reduced transcript accumulation of PR1 and PR2 genes. These results suggested that ATILL6 positively regulates plant basal defense. Furthermore, after the inoculation of atill6 with avirulent Pst (DC3000), the expressions of the PR1 and PR2 genes decreased, suggesting a positive role in R-gene-mediated resistance in protecting the plant from further spread of disease. We also investigated the role of ATILL6 in systemic acquired resistance (SAR), and the results showed that ATILL6 positively regulates SAR, as the mutant line atill6 has significantly (p ≤ 0.05) lower transcript accumulation of PR, G3DPH, and AZI genes. Overall, these results indicate that the NO-induced ATILL6 gene differentially regulates plant growth and positively regulates plant basal defense, R-gene-mediated resistance, and SAR.

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 Ribonuclease activity as a new prospective disease resistance marker in potato

2019 ◽  
Vol 22 (8) ◽  
pp. 987-991 ◽  
Author(s):  
E. A. Trifonova ◽  
S. M. Ibragimova ◽  
O. A. Volkova ◽  
V. K. Shumny ◽  
A. V. Kochetov
Keyword(s):  
Disease Resistance ◽  
Late Blight ◽  
Systemic Acquired Resistance ◽  
Higher Plants ◽  
Wide Spectrum ◽  
Acquired Resistance ◽  
Pathogen Resistance ◽  
Rnase Activity ◽  
Measured Parameter ◽  
Resistance To Viruses

Disease resistance is an important characteristic for each variety of potato, and the search for pathogen resistance markers is one of the primary tasks of plant breeding. Higher plants possess a wide spectrum of enzymes catalyzing the hydrolysis of nucleic acids; it is believed that protection against pathogens is the most probable function of the enzymes. RNases are actively involved in several immune systems of higher plants, for example, systemic acquired resistance (SAR) and genetic silencing, hence RNase activity in plant leaves, as a relatively easily measured parameter, can serve as a good marker for the selection of pathogen resistant varieties. We have analyzed sixteen varieties of potatoes permitted for use on the territory of the Russian Federation and tested the correlation of the level of variety­specifc ribonuclease (RNase) activity with such economically valuable traits as maturity and resistance to viruses, late blight and common scab. In general, the level of RNase activity was variety­specifc, which was confrmed by very small values of average squared error for the majority of tested varieties. We have detected a statistically signifcant positive correlation of RNase activity in potato leaves with increased resistance of varieties to phytopathogenic viruses, a negative correlation with resistance to scab and an absence of a signifcant connection with maturity and resistance to late blight, regardless of the organ affected by the oomycete. Thus, the level of RNase activity in potato leaves can be used as a selective marker for resistance to viruses, while varieties with increased RNase activity should be avoided when selecting resistance to scab.

scholarly journals Novel bacterial control agent tolprocarb enhances systemic acquired resistance in Arabidopsis and rice as a second mode of action

2019 ◽  
Vol 86 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Hiroyuki Hagiwara ◽  
Rieko Ogura ◽  
Takeshi Fukumoto ◽  
Toshiaki Ohara ◽  
Mikio Tsuda ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Pseudomonas Syringae ◽  
Mode Of Action ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Control Agent ◽  
Melanin Biosynthesis ◽  
Biosynthesis Inhibitor ◽  
Pathogenesis Related Gene ◽  
Bacterial Control

Abstract The fungicide tolprocarb (TPC) is a melanin biosynthesis inhibitor, but it may also have another mode of action. Here in tests of TPC for inducing plant systemic acquired resistance (SAR), TPC induced promoter activity of the tobacco pathogenesis-related gene PR-1a in Arabidopsis thaliana and genes for PBZ1, β-1,3-glucanase, and chitinase 1 in the defense-related salicylic acid (SA) signaling pathway in rice, but not genes for the jasmonate signaling pathway. Probenazole (PBZ), a commercially used plant defense activator, induced genes in both signaling pathways. The antibacterial activity of TPC was equivalent to that of PBZ. Irrigation with 200 μM TPC prevented growth by Pseudomonas syringae pv. maculicola in A. thaliana, and 30 μM TPC inhibited Xanthomonas oryzae pv. oryzae growth in rice. The results of this study suggest that TPC functions not only as a melanin biosynthesis inhibitor but also as an SAR inducer and is applicable as a novel bacterial control agent that induces SAR activity in both A. thaliana and rice.

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