scholarly journals A small cysteine-rich phytotoxic protein of Phytophthora capsici functions as both plant defense elicitor and virulence factor

2021 ◽  
Author(s):  
Zi-Hui Zhang ◽  
Jinghao Jin ◽  
Gui-Lin Sheng ◽  
Yu-Ping Xing ◽  
Wang Liu ◽  
...  
Keyword(s):  
Plant Defense ◽  
Virulence Factor ◽  
Phytophthora Capsici ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Phytophthora Species ◽  
Plant Interactions ◽  
Defense Gene Expression ◽  
Callose Deposition ◽  
Defense Gene

Small cysteine-rich (SCR) proteins including fungal avirulence proteins play important roles in the pathogen-plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens, but their functions during the pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein, namely SCR82 with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologues of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially scr82 was weakly expressed during the mycelium, sporangium and zoospore stages, but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses including the induction of defense gene expression, reactive oxygen species burst and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and reduced significantly its resistance againstoxidative stress. Inversely, its overexpression increased the pathogen’s virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora species.

scholarly journals Cyclic Lipopeptides of Bacillus amyloliquefaciens subsp. plantarum Colonizing the Lettuce Rhizosphere Enhance Plant Defense Responses Toward the Bottom Rot Pathogen Rhizoctonia solani

2015 ◽  
Vol 28 (9) ◽  
pp. 984-995 ◽  
Author(s):  
Soumitra Paul Chowdhury ◽  
Jenny Uhl ◽  
Rita Grosch ◽  
Sylvia Alquéres ◽  
Sabrina Pittroff ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Plant Defense ◽  
Bacillus Amyloliquefaciens ◽  
Defense Responses ◽  
Disease Suppression ◽  
Plant Defense Responses ◽  
Defense Gene Expression ◽  
Defense Gene ◽  
Pathogen Challenge ◽  
Bottom Rot

The commercially available inoculant Bacillus amyloliquefaciens FZB42 is able to considerably reduce lettuce bottom rot caused by Rhizoctonia solani. To understand the interaction between FZB42 and R. solani in the rhizosphere of lettuce, we used an axenic system with lettuce bacterized with FZB42 and inoculated with R. solani. Confocal laser scanning microscopy showed that FZB42 could delay the initial establishment of R. solani on the plants. To show which secondary metabolites of FZB42 are produced under these in-situ conditions, we developed an ultra-high performance liquid chromatography coupled to time of flight mass spectrometry–based method and identified surfactin, fengycin, and bacillomycin D in the lettuce rhizosphere. We hypothesized that lipopeptides and polyketides play a role in enhancing the plant defense responses in addition to the direct antagonistic effect toward R. solani and used a quantitative real-time polymerase chain reaction–based assay for marker genes involved in defense signaling pathways in lettuce. A significant higher expression of PDF 1.2 observed in the bacterized plants in response to subsequent pathogen challenge showed that FZB42 could enhance the lettuce defense response toward the fungal pathogen. To identify if surfactin or other nonribosomally synthesized secondary metabolites could elicit the observed enhanced defense gene expression, we examined two mutants of FZB42 deficient in production of surfactin and the lipopetides and polyketides, by expression analysis and pot experiments. In the absence of surfactin and other nonribosomally synthesized secondary metabolites, there was no enhanced PDF 1.2–mediated response to the pathogen challenge. Pot experiment results showed that the mutants failed to reduce disease incidence in lettuce as compared with the FZB42 wild type, indicating, that surfactin as well as other nonribosomally synthesized secondary metabolites play a role in the actual disease suppression and on lettuce health. In conclusion, our study showed that nonribosomally synthesized secondary metabolites of FZB42 are actually produced in the lettuce rhizosphere and contribute to the disease suppression by mediating plant defense gene expression toward the pathogen R. solani.

scholarly journals The Xanthomonas type-III effector protein XopS stabilizes CaWRKY40a to regulate defense hormone responses and preinvasion immunity in pepper (Capsicum annuum)

2021 ◽  
Author(s):  
Margot Raffeiner ◽  
Suayib Üstün ◽  
Tiziana Guerra ◽  
Daniela Spinti ◽  
Maria Fitzner ◽  
...  
Keyword(s):  
Gene Expression ◽  
Xanthomonas Campestris ◽  
Stomatal Closure ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Dependent Manner ◽  
Plant Tolerance ◽  
Defense Gene Expression ◽  
Type Iii Effector ◽  
Type Iii

A critical component of plant immunity against invading pathogens is the rapid transcriptional reprogramming of the attacked cell to minimize virulence. Many adapted plant bacterial pathogens use type III effector (T3E) proteins to interfere with plant defense responses, including the induction of immunity genes. The elucidation of effector function is essential to understanding bacterial pathogenesis. Here, we show that XopS, a T3E of Xanthomonas campestris pv. vesicatoria (Xcv), interacts with and inhibits the proteasomal degradation of the transcriptional regulator of defense gene expression WRKY40. Virus-induced gene silencing of WRKY40 in pepper enhanced plant tolerance towards Xcv infection, indicating it represses immunity. Stabilization of WRKY40 by XopS reduces the expression of its targets including salicylic acid (SA)-responsive genes and the jasmonic acid (JA) signaling repressor JAZ8. Xcv bacteria lacking XopS display significantly reduced virulence when surface inoculated onto susceptible pepper leaves. XopS delivery by Xcv, as well as ectopic expression of XopS in Arabidopsis or Nicotiana benthamiana prevented stomatal closure in response to bacteria and biotic elicitors in a WRKY40 dependent manner. This suggests that XopS interferes with preinvasion as well as with apoplastic defense by manipulating WRKY40 stability and gene expression eventually altering phytohormone crosstalk to promote pathogen proliferation.

scholarly journals A Phytophthora capsici RXLR effector manipulates plant immunity by targeting RAB proteins and disturbing vesicle-mediated protein trafficking pathway

2021 ◽  
Author(s):  
Tianli Li ◽  
Gan Ai ◽  
Xiaowei Fu ◽  
Jin Liu ◽  
Hai Zhu ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Plant Immunity ◽  
Phytophthora Capsici ◽  
Functional Characterization ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Infection Process ◽  
Small Gtpase ◽  
Rab Proteins ◽  
Rxlr Effector

The oomycete pathogen Phytophthora capsici encodes hundreds of RXLR effectors to enter plant cells and suppress host defense responses. Only few of them are conserved across different strains and species. Such ‘core effectors’ may target hub immunity pathways that are essential during Phytophthora pathogens interacting with their hosts. However, the underlying mechanisms of core RXLRs-mediated host immunity manipulation are largely unknown. Here, we report the functional characterization of a P. capsici RXLR effector, RXLR242. RXLR242 expression is highly induced during the infection process. Its ectopic expression in Nicotiana benthamiana promotes Phytophthora infection. RXLR242 physically interacts with a group of RAB proteins, which belong to the small GTPase family and function in specifying transport pathways in the intracellular membrane trafficking system. RXLR242 impedes the secretion of PATHOGENESIS-RELATED 1 (PR1) protein to the apoplast by interfering the formation of RABE1-7-labeled vesicles. Further analysis indicated that such phenomenon is resulted from competitive binding of RXLR242 to RABE1-7. RXLR242 also interferes trafficking of the membrane-located receptor FLAGELLIN-SENSING 2 (FLS2) through competitively interacting with RABA4-3. Taken together, our work demonstrates that RXLR242 manipulates plant immunity by targeting RAB proteins and disturbing vesicle-mediated protein transporting pathway in plant hosts.

Differential accumulation of plant defense gene transcripts in a compatible and an incompatible plant-pathogen interaction

1986 ◽  
Vol 6 (5) ◽  
pp. 1615-1623
Author(s):  
J N Bell ◽  
T B Ryder ◽  
V P Wingate ◽  
J A Bailey ◽  
C J Lamb
Keyword(s):  
Plant Defense ◽  
Phenylalanine Ammonia Lyase ◽  
Chalcone Synthase ◽  
Defense Responses ◽  
Infected Tissue ◽  
Colletotrichum Lindemuthianum ◽  
Specific Interactions ◽  
Defense Gene ◽  
Sequence Of Events ◽  
Gene Transcripts

Phenylalanine ammonia-lyase and chalcone synthase catalyze the first reaction of phenylpropanoid biosynthesis and the first reaction of a branch pathway specific for flavonoid-isoflavonoid biosynthesis, respectively. These enzymes are key control elements in the synthesis of kievitone, phaseollin, and related isoflavonoid-derived phytoalexins. RNA blot hybridization with 32P-labeled cDNA sequences was used to demonstrate marked accumulation of phenylalanine ammonia-lyase and chalcone synthase mRNAs in excision-wounded hypocotyls of Phaseolus vulgaris L. (dwarf French bean) and during race-cultivar-specific interactions between hypocotyls of P. vulgaris and the partially biotrophic fungus Colletotrichum lindemuthianum, the causal agent of anthracnose. In an incompatible interaction (host resistant), early concomitant accumulation of phenylalanine ammonia-lyase and chalcone synthase mRNAs, localized mainly but not entirely in tissue adjacent to the site of infection, was observed prior to the onset of phytoalexin accumulation and expression of localized, hypersensitive resistance. In contrast, in a compatible interaction (host susceptible) there was no early accumulation of these transcripts; instead, there was a delayed widespread response associated with phytoalexin accumulation during attempted lesion limitation. Two-dimensional gel electrophoresis of [35S]methionine-labeled polypeptides synthesized in vitro by translation of isolated polysomal RNA demonstrated stimulation of the synthesis of characteristic sets of phenylalanine ammonia-lyase and chalcone synthase isopolypeptides in directly infected tissue and distant, hitherto uninfected tissue in both compatible and incompatible interactions. Our data show that specific accumulation of plant defense gene transcripts is a key early component in the sequence of events leading to expression of defense responses in wounded tissue and in infected tissue during race-cultivar-specific interactions and that an elicitation signal is transmitted intercellularly in response to infection.

scholarly journals Tomato SOBIR1/EVR Homologs Are Involved in Elicitin Perception and Plant Defense Against the Oomycete Pathogen Phytophthora parasitica

2015 ◽  
Vol 28 (8) ◽  
pp. 913-926 ◽  
Author(s):  
Ke-Chun Peng ◽  
Chao-Wen Wang ◽  
Chih-Hang Wu ◽  
Chun-Tzu Huang ◽  
Ruey-Fen Liou
Keyword(s):  
Cell Death ◽  
Plant Defense ◽  
Marker Gene ◽  
Defense Responses ◽  
Kinase Domain ◽  
Phytophthora Parasitica ◽  
Callose Deposition ◽  
Molecular Pattern ◽  
Molecular Events ◽  
Species Production

During host-pathogen interactions, pattern recognition receptors form complexes with proteins, such as receptor-like kinases, to elicit pathogen-associated molecular pattern-triggered immunity (PTI), an evolutionarily conserved plant defense program. However, little is known about the components of the receptor complex, as are the molecular events leading to PTI induced by the oomycete Phytophthora pathogen. Here, we demonstrate that tomato (Solanum lycopersicum) SlSOBIR1 and SlSOBIR1-like genes are involved in defense responses to Phytophthora parasitica. Silencing of SlSOBIR1 and SlSOBIR1-like enhanced susceptibility to P. parasitica in tomato. Callose deposition, reactive oxygen species production, and PTI marker gene expression were compromised in SlSOBIR1- and SlSOBIR1-like–silenced plants. Interestingly, P. parasitica infection and elicitin (ParA1) treatment induced the relocalization of SlSOBIR1 from the plasma membrane to endosomal compartments and silencing of NbSOBIR1 compromised ParA1-mediated cell death on Nicotiana benthamiana. Moreover, the SlSOBIR1 kinase domain is indispensable for ParA1 to trigger SlSOBIR1 internalization and plant cell death. Taken together, these results support the idea of participation of solanaceous SOBIR1/EVR homologs in the perception of elicitins and indicate their important roles in plant basal defense against oomycete pathogens.

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 Induction of Plant Defense Gene Expression by Plant Activators and Pseudomonas syringae pv. tomato in Greenhouse-Grown Tomatoes

2008 ◽  
Vol 98 (11) ◽  
pp. 1226-1232 ◽  
Author(s):  
M. A. B. Herman ◽  
J. K. Davidson ◽  
C. D. Smart
Keyword(s):  
Gene Expression ◽  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Marker Gene ◽  
Gene Activation ◽  
Systemic Resistance ◽  
Defense Gene Expression ◽  
Defense Gene ◽  
Bacterial Speck

Plant activators provide an appealing management option for bacterial diseases of greenhouse-grown tomatoes. Two types of plant activators, one that induces systemic acquired resistance (SAR) and a second that activates induced systemic resistance (ISR), were evaluated for control of Pseudomonas syringae pv. tomato and effect on plant defense gene activation. Benzothiadiazole (BTH, SAR-inducing compound) effectively reduced bacterial speck incidence and severity, both alone and in combination with the ISR-inducing product. Application of BTH also led to elevated activation of salicylic acid and ethylene-mediated responses, based on real-time polymerase chain reaction analysis of marker gene expression levels. In contrast, the ISR-inducing product (made up of plant growth-promoting rhizobacteria) inconsistently modified defense gene expression and did not provide disease control to the same level as did BTH. No antagonism was observed by combining the two activators as control of bacterial speck was similar to or better than BTH alone.

StPIP1, a PAMP-induced peptide in potato, elicits plant defenses and is associated with disease symptom severity in a compatible interaction with Potato virus Y

2021 ◽  
Author(s):  
Max M Combest ◽  
Natalia Moroz ◽  
Kiwamu Tanaka ◽  
Conner J Rogan ◽  
Jeffrey C Anderson ◽  
...  
Keyword(s):  
Transgenic Plants ◽  
Plant Defense ◽  
Potato Virus ◽  
Potato Virus Y ◽  
Systemic Infection ◽  
Transgenic Potato ◽  
Defense Responses ◽  
Marker Genes ◽  
Plant Defense Responses ◽  
Callose Deposition

Abstract The role of small secreted peptides in plant defense responses to viruses has seldom been investigated. Here, we report a role for potato (Solanum tuberosum) PIP1, a gene predicted to encode a member of the pathogen-associated molecular pattern (PAMP)-induced peptide (PIP) family, in the response of potato to Potato virus Y (PVY) infection. We show that exogenous application of synthetic StPIP1 to potato leaves and nodes increased the production of reactive oxygen species and the expression of plant defense-related genes, revealing that StPIP1 triggers early defense responses. In support of this hypothesis, transgenic potato plants that constitutively overexpress StPIP1 had higher levels of leaf callose deposition and, based on measurements of viral RNA titers, were less susceptible to infection by a compatible PVY strain. Interestingly, systemic infection of StPIP1-overexpressing lines with PVY resulted in clear rugose mosaic symptoms that were absent or very mild in infected non-transgenic plants. A transcriptomics analysis revealed that marker genes associated with both pattern-triggered immunity and effector-triggered immunity were induced in infected StPIP1 overexpressors but not in non-transgenic plants. Together, our results reveal a role for StPIP1 in eliciting plant defense responses and in regulating plant antiviral immunity.

scholarly journals Heat Stress Pre-Exposure May Differentially Modulate Plant Defense to Powdery Mildew in a Resistant and Susceptible Barley Genotype

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 776
Author(s):  
Ildikó Schwarczinger ◽  
Judit Kolozsváriné Nagy ◽  
Lóránt Király ◽  
Klára Mészáros ◽  
Judit Bányai ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Powdery Mildew ◽  
Plant Defense ◽  
High Temperatures ◽  
Defense Gene Expression ◽  
Defense Gene ◽  
Barley Line ◽  
Prolonged Heat

Heat stress negatively affects barley production and under elevated temperatures defense responses to powdery mildew (Blumeria graminis f. sp. hordei, Bgh) are altered. Previous research has analyzed the effects of short-term (30 s to 2 h) heat stress, however, few data are available on the influence of long-term exposure to heat on powdery mildew infections. We simultaneously assessed the effects of short and long term heat pre-exposure on resistance/susceptibility of barley to Bgh, evaluating powdery mildew infection by analyzing symptoms and Bgh biomass with RT-qPCR in barley plants pre-exposed to high temperatures (28 and 35 °C from 30 s to 5 days). Plant defense gene expression after heat stress pre-exposure and inoculation was also monitored. Our results show that prolonged heat stress (24, 48 and 120 h) further enhanced Bgh susceptibility in a susceptible barley line (MvHV118-17), while a resistant line (MvHV07-17) retained its pathogen resistance. Furthermore, prolonged heat stress significantly repressed the expression of several defense-related genes (BAX inhibitor-1, Pathogenesis related-1b and Respiratory burst oxidase homologue F2) in both resistant and susceptible barley lines. Remarkably, heat-suppressed defense gene expression returned to normal levels only in MvHV07-17, a possible reason why this barley line retains Bgh resistance even at high temperatures.

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