scholarly journals Ocimum sanctum, OscWRKY1, regulates phenylpropanoid pathway genes and promotes resistance to pathogen infection in Arabidopsis

2022 ◽  
Author(s):  
Ashutosh Joshi ◽  
Gajendra Singh Jeena ◽  
Shikha ◽  
Ravi Kumar ◽  
Alok Pandey ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Bacterial Pathogen ◽  
Defense Responses ◽  
Phenylpropanoid Pathway ◽  
Wrky Transcription Factor ◽  
Ocimum Sanctum ◽  
Plant Defense Responses ◽  
Cis Element ◽  
Pal Activity ◽  
Direct Regulation

WRKY transcription factor (TF) family regulates various developmental and physiological functions in plants. PAL genes encode enzymes which are involved in plant defense responses, but the direct regulation of PAL genes and phenylpropanoid pathway through WRKY TF is not well characterized. In the present study, we have characterized an OscWRKY1 gene from O. sanctum which shows induced expression after methyl jasmonate (MeJA), salicylic acid (SA), and wounding. Recombinant OscWRKY1 protein binds to the W-box cis-element TTGAC[C/T] and activates the reporter gene in yeast. Overexpression of OscWRKY1 enhances Arabidopsis resistance towards Pseudomonas syringae pv. tomato Pst DC3000. Upstream activator sequences of PAL and C4H have identified the conserved W-box cis-element (TTGACC) in both O. sanctum and Arabidopsis. OscWRKY1 was found to interact with W-box cis-element present in the PAL and C4H promoters. Silencing of OscWRKY1 using VIGS resulted in reduced expression of PAL, C4H, COMT, F5H and 4CL transcripts. OscWRKY1 silenced plants exhibit reduced PAL activity, whereas, the overexpression lines of OscWRKY1 in Arabidopsis exhibit increased PAL activity. These results revealed that OscWRKY1 positively regulates the phenylpropanoid pathway genes and enhances the resistance against bacterial pathogen in Arabidopsis.

scholarly journals Isolation of Arabidopsis Mutants With Enhanced Disease Susceptibility by Direct Screening

Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 973-982 ◽  
Author(s):  
Jane Glazebrook ◽  
Elizabeth E Rogers ◽  
Frederick M Ausubel
Keyword(s):  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Disease Susceptibility ◽  
Bacterial Pathogen ◽  
Defense Responses ◽  
Screening Strategy ◽  
Genetic Dissection ◽  
Plant Defense Responses ◽  
Defense Genes ◽  
Increased Susceptibility

Abstract To discover which components of plant defense responses make significant contributions to limiting pathogen attack, we screened a mutagenized population of Arabidopsis thalzana for individuals that exhibit increased susceptibility to the moderately virulent bacterial pathogen Pseudomonas syringae pv. maculicola ES4326 (Psm ES4326). The 12 enhanced disease susceptibility (eds) mutants isolated included alleles of two genes involved in phytoalexin biosynthesis (pad2, which had been identified previously, and pad4, which had not been identified previously), two alleles of the previously identified npr1 gene, which affects expression of other defense genes, and alleles of seven previously unidentified genes of unknown function. The npr-1 mutations caused greatly reduced expression of the PRI gene in response to PsmES4326 infection, but had little effect on expression of two other defense genes, BGL2 and PR5, suggesting that PR1 expression may be important for limiting growth of PsmES4326. While direct screens for mutants with quantitative pathogen-susceptibility phenotypes have not been reported previously, our finding that mutants isolated in this way include those affected in known defense responses supports the notion that this type of screening strategy allows genetic dissection of the roles of various plant defense responses in disease resistance.

scholarly journals An efficient direct screening system for microorganisms that activate plant immune responses based on plant–microbe interactions using cultured plant cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mari Kurokawa ◽  
Masataka Nakano ◽  
Nobutaka Kitahata ◽  
Kazuyuki Kuchitsu ◽  
Toshiki Furuya
Keyword(s):  
Immune Responses ◽  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Large Scale ◽  
Plant Cells ◽  
Defense Responses ◽  
Root Tip ◽  
General Strategy ◽  
Plant Defense Responses ◽  
Microbe Interactions

AbstractMicroorganisms that activate plant immune responses have attracted considerable attention as potential biocontrol agents in agriculture because they could reduce agrochemical use. However, conventional methods to screen for such microorganisms using whole plants and pathogens are generally laborious and time consuming. Here, we describe a general strategy using cultured plant cells to identify microorganisms that activate plant defense responses based on plant–microbe interactions. Microbial cells were incubated with tobacco BY-2 cells, followed by treatment with cryptogein, a proteinaceous elicitor of tobacco immune responses secreted by an oomycete. Cryptogein-induced production of reactive oxygen species (ROS) in BY-2 cells served as a marker to evaluate the potential of microorganisms to activate plant defense responses. Twenty-nine bacterial strains isolated from the interior of Brassica rapa var. perviridis plants were screened, and 8 strains that enhanced cryptogein-induced ROS production in BY-2 cells were selected. Following application of these strains to the root tip of Arabidopsis seedlings, two strains, Delftia sp. BR1R-2 and Arthrobacter sp. BR2S-6, were found to induce whole-plant resistance to bacterial pathogens (Pseudomonas syringae pv. tomato DC3000 and Pectobacterium carotovora subsp. carotovora NBRC 14082). Pathogen-induced expression of plant defense-related genes (PR-1, PR-5, and PDF1.2) was enhanced by the pretreatment with strain BR1R-2. This cell–cell interaction-based platform is readily applicable to large-scale screening for microorganisms that enhance plant defense responses under various environmental conditions.

scholarly journals Two Arabidopsis Homologs of Human Lysine-Specific Demethylase Function in Epigenetic Regulation of Plant Defense Responses

2021 ◽  
Vol 12 ◽  
Author(s):  
Seong Woo Noh ◽  
Ri-Ra Seo ◽  
Hee Jin Park ◽  
Ho Won Jung
Keyword(s):  
Pseudomonas Syringae ◽  
Epigenetic Regulation ◽  
Plant Immunity ◽  
Systemic Disease ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Promoter Regions ◽  
Lysine Specific Demethylase ◽  
Genome Wide ◽  
Histone H3k4

Epigenetic marks such as covalent histone modification and DNA methylation are crucial for mitotically and meiotically inherited cellular memory-based plant immunity. However, the roles of individual players in the epigenetic regulation of plant immunity are not fully understood. Here we reveal the functions of two Arabidopsis thaliana homologs of human lysine-specific demethylase1-like1, LDL1 and LDL2, in the maintenance of methyl groups at lysine 4 of histone H3 and in plant immunity to Pseudomonas syringae infection. The growth of virulent P. syringae strains was reduced in ldl1 and ldl2 single mutants compared to wild-type plants. Local and systemic disease resistance responses, which coincided with the rapid, robust transcription of defense-related genes, were more stably expressed in ldl1 ldl2 double mutants than in the single mutants. At the nucleosome level, mono-methylated histone H3K4 accumulated in ldl1 ldl2 plants genome-wide and in the mainly promoter regions of the defense-related genes examined in this study. Furthermore, in silico comparative analysis of RNA-sequencing and chromatin immunoprecipitation data suggested that several WRKY transcription factors, e.g., WRKY22/40/70, might be partly responsible for the enhanced immunity of ldl1 ldl2. These findings suggest that LDL1 and LDL2 control the transcriptional sensitivity of a group of defense-related genes to establish a primed defense response in Arabidopsis.

scholarly journals Molecular characterization of differences between the tomato immune receptors Fls3 and Fls2

2020 ◽  
Author(s):  
Robyn Roberts ◽  
Alexander E. Liu ◽  
Lingwei Wan ◽  
Annie M. Geiger ◽  
Sarah R. Hind ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Molecular Mechanisms ◽  
Bacterial Pathogen ◽  
Transcript Abundance ◽  
Defense Responses ◽  
Structural Features ◽  
Host Responses ◽  
Pathogen Invasion

AbstractPlants mount defense responses by recognizing indications of pathogen invasion, including microbe-associated molecular patterns (MAMPs). Flagellin from the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) contains two MAMPs, flg22 and flgII-28, that are recognized by tomato receptors Flagellin sensing 2 (Fls2) and Flagellin sensing 3 (Fls3), respectively. It is unknown to what degree each receptor contributes to immunity and if they promote immune responses using the same molecular mechanisms. Characterization of CRISPR/Cas9-generated Fls2 and Fls3 tomato mutants revealed that the two receptors contribute equally to disease resistance both on the leaf surface and in the apoplast. However, striking differences were observed in certain host responses mediated by the two receptors. Compared to Fls2, Fls3 mediated a more sustained production of reactive oxygen species (ROS) and an increase in transcript abundance of 44 tomato genes, with two genes serving as reporters for Fls3. Fls3 had greater in vitro kinase activity and interacted differently with the Pst effector AvrPtoB as compared to Fls2. Using chimeric Fls2/Fls3 proteins, we found that no receptor domain was solely responsible for the Fls3 sustained ROS, suggesting involvement of multiple structural features. This work reveals differences in the immunity outputs between Fls2 and Fls3, suggesting they use distinct molecular mechanisms to activate pattern-triggered immunity in response to flagellin-derived MAMPs.

scholarly journals Jasmonic Acid at the Crossroads of Plant Immunity and Pseudomonas syringae Virulence

2020 ◽  
Vol 21 (20) ◽  
pp. 7482
Author(s):  
Aarti Gupta ◽  
Mamta Bhardwaj ◽  
Lam-Son Phan Tran
Keyword(s):  
Jasmonic Acid ◽  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Regulatory Networks ◽  
Genetic Manipulation ◽  
Plant Immunity ◽  
Stomatal Closure ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Callose Deposition

Sensing of pathogen infection by plants elicits early signals that are transduced to affect defense mechanisms, such as effective blockage of pathogen entry by regulation of stomatal closure, cuticle, or callose deposition, change in water potential, and resource acquisition among many others. Pathogens, on the other hand, interfere with plant physiology and protein functioning to counteract plant defense responses. In plants, hormonal homeostasis and signaling are tightly regulated; thus, the phytohormones are qualified as a major group of signaling molecules controlling the most widely tinkered regulatory networks of defense and counter-defense strategies. Notably, the phytohormone jasmonic acid mediates plant defense responses to a wide array of pathogens. In this review, we present the synopsis on the jasmonic acid metabolism and signaling, and the regulatory roles of this hormone in plant defense against the hemibiotrophic bacterial pathogen Pseudomonas syringae. We also elaborate on how this pathogen releases virulence factors and effectors to gain control over plant jasmonic acid signaling to effectively cause disease. The findings discussed in this review may lead to ideas for the development of crop cultivars with enhanced disease resistance by genetic manipulation.

scholarly journals Allelic Variants of the Pseudomonas syringae Type III Effector HopZ1 Are Differentially Recognized by Plant Resistance Systems

2009 ◽  
Vol 22 (2) ◽  
pp. 176-189 ◽  
Author(s):  
Huanbin Zhou ◽  
Robyn L. Morgan ◽  
David S. Guttman ◽  
Wenbo Ma
Keyword(s):  
Cell Death ◽  
Pseudomonas Syringae ◽  
Plant Resistance ◽  
Type Iii Secretion ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Type Iii Effectors ◽  
Type Iii ◽  
New Evidence ◽  
Bacterial Plant Pathogen

The bacterial plant pathogen Pseudomonas syringae depends on the type III secretion system and type III-secreted effectors to cause disease in plants. HopZ is a diverse family of type III effectors widely distributed in P. syringae isolates. Among the HopZ homologs, HopZ1 is ancient to P. syringae and has been shown to be under strong positive selection driven by plant resistance-imposed selective pressure. Here, we characterized the virulence and avirulence functions of the three HopZ1 alleles in soybean and Nicotiana benthamiana. In soybean, HopZ1 alleles have distinct functions: HopZ1a triggers defense response, HopZ1b promotes bacterial growth, and HopZ1c has no observable effect. In N. benthamiana, HopZ1a and HopZ1b both induce plant defense responses. However, they appear to trigger different resistance pathways, evidenced by two major differences between HopZ1a- and HopZ1b-triggered hypersensitive response (HR): i) the putative N-acylation sites had no effect on HopZ1a-triggered cell death, whereas it greatly enhanced HopZ1b-triggered cell death; and ii) the HopZ1b-triggered HR, but not the HopZ1a-triggered HR, was suppressed by another HopZ homolog, HopZ3. We previously demonstrated that HopZ1a most resembled the ancestral allelic form of HopZ1; therefore, this new evidence suggested that differentiated resistance systems have evolved in plant hosts to adapt to HopZ1 diversification in P. syringae.

scholarly journals Suppression of plant defense responses by extracellular metabolites from Pseudomonas syringae pv. tabaci in Nicotiana benthamiana

2013 ◽  
Vol 13 (1) ◽  
pp. 65 ◽  
Author(s):  
Seonghee Lee ◽  
Dong Sik Yang ◽  
Srinivasa Rao Uppalapati ◽  
Lloyd W Sumner ◽  
Kirankumar S Mysore
Keyword(s):  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Nicotiana Benthamiana ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Extracellular Metabolites

scholarly journals Analysis of Resistance Gene-Mediated Defense Responses in Arabidopsis thaliana Plants Carrying a Mutation in CPR5

1998 ◽  
Vol 11 (12) ◽  
pp. 1196-1206 ◽  
Author(s):  
Jens Boch ◽  
Michelle L. Verbsky ◽  
Tara L. Robertson ◽  
John C. Larkin ◽  
Barbara N. Kunkel
Keyword(s):  
Gene Expression ◽  
Arabidopsis Thaliana ◽  
Resistance Gene ◽  
Pseudomonas Syringae ◽  
Bacterial Pathogen ◽  
Defense Responses ◽  
Negative Regulator ◽  
Suppressor Mutations ◽  
Defense Related Gene ◽  
Rapid Activation

In resistant plants, pathogen attack often leads to rapid activation of defense responses that limit multiplication and spread of the pathogen. To investigate the signaling mechanisms underlying this process, we carried out a screen for mutants in the signaling pathway governing resistance in Arabidopsis thaliana to the bacterial pathogen Pseudomonas syringae. This involved screening for suppressor mutations that restored resistance to a susceptible line carrying a mutation in the RPS2 resistance gene. A mutant that conferred resistance by activating defense responses in the absence of pathogens was isolated. This mutant, which carries a mutation at the CPR5 locus and was thus designated cpr5-2, exhibited resistance to P. syringae, spontaneous development of necrotic lesions, elevated PR gene expression in the absence of pathogens, and abnormal trichomes. Resistance gene-mediated defenses, including the hypersensitive response, restriction of pathogen growth, and induction of defense-related gene expression, were functional in cpr5-2 mutant plants. Additionally, in cpr5-2 plants RPS2-mediated induction of PR-1 expression was enhanced, whereas RPM1-mediated induction of ELI3 was not. These findings suggest that CPR5 encodes a negative regulator of the RPS2 signal transduc-tion pathway.

scholarly journals Contrasting functions of Arabidopsis SUMO1/2 isoforms with SUMO3 intersect to modulate innate immunity and global SUMOylome responses

2020 ◽  
Author(s):  
Kishor Dnyaneshwar Ingole ◽  
Mritunjay Kasera ◽  
Harrold A. van den Burg ◽  
Saikat Bhattacharjee
Keyword(s):  
Arabidopsis Thaliana ◽  
Steady State ◽  
Heat Shock ◽  
Pseudomonas Syringae ◽  
Bacterial Pathogen ◽  
Defense Responses ◽  
Vital Role ◽  
Covalent Attachment ◽  
Developmental Defects ◽  
Small Proteins

AbstractReversible covalent attachment of SMALL UBIQUITIN-LIKE MODIFIERS (SUMOs) on target proteins regulate diverse cellular process across all eukaryotes. In Arabidopsis thaliana, most mutants with perturbed global SUMOylome display severe impairments in growth and adaptations to physiological stresses. Since SUMOs self-regulate activities of SUMOylation-associated proteins, existence of multiple isoforms introduces possibilities of their functional intersections which remain unexplored especially in plant systems. Using well-established defense responses elicited against virulent and avirulent Pseudomonas syringae pv. tomato strains, we investigated crosstalks in individual and combinatorial Arabidopsis sum mutants. Here we report that while SUM1 and SUM2 additively, but not equivalently suppress basal and TNL-specific immunity via down-regulation of salicylic acid (SA)-dependent responses, SUM3 promotes these defenses genetically downstream of SA. Remarkably, the expression of SUM3 is transcriptionally suppressed by SUMO1 or SUMO2. The loss of SUM3 not only lowers basal or post-bacterial challenge responsive enhancements of SUMO1/2-congugates but also reduces upregulation dynamics of defensive proteins and SUMOylation-associated transcripts. Combining a sum3 mutation partially attenuates heightened immunity of sum1 or sum2 mutants suggesting intricate functional impingements among these isoforms in optimizing immune amplitudes. Similar SUM1-SUM3 intersections also affect global SUMOylome responses to heat-shock affecting most notably the induction of selective heat-shock transcription factors. Overall, our investigations reveal novel insights into auto-regulatory mechanisms among SUMO isoforms in host SUMOylome maintenance and adjustments to environmental challenges.Author SummaryIn plants, similar to animals, protein functions are regulated at multiple levels. One prevalent mode is to allow covalent linkage of small proteins to specific amino acids on targets thereby affecting its fate and function. One such kind of modification named as SUMOylation involves attachment of SUMO proteins. A plant maintains strict control over its pool of SUMOylated proteins (termed SUMOylome) which upon biotic or abiotic stresses are altered to facilitate appropriate responses, returning back to steady-state when the threat subsides. In mutants of the model plant Arabidopsis thaliana having disturbed steady-state SUMOylome, growth and developmental defects ensue. These mutants are auto-immune showing more resistance to infection by the bacterial pathogen Pseudomonas syringae. However, Arabidopsis SUMO-family are comprised of multiple members raising the question about their specificity or functional crosstalks. We discovered that two SUMO members function in coordination to suppress immunity including the repression of a third member which supports defenses. The expression of this third member during pathogen attack or heat-shock influences the responsive changes in the host SUMOylome likely suggesting SUMOs themselves play vital role in these adaptations. Overall, our work highlights novel intersections of SUMO members in mounting stress-specific responses.

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.

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