Identification and Molecular Mechanisms of Key Nucleotides Causing Attenuation in Pathogenicity of Dahlia Isolate of Potato Spindle Tuber Viroid

While the potato spindle tuber viroid (PSTVd) variant, PSTVd-Dahlia (PSTVd-D or PSTVd-Dwt) induces very mild symptoms in tomato cultivar ‘Rutgers’, PSTVd-Intermediate (PSTVd-I or PSTVd-Iwt) induces severe symptoms. These two variants differ by nine nucleotides, of which six mutations are located in the terminal left (TL) to the pathogenicity (P) domains. To evaluate the importance of mutations located in the TL to the P domains, ten types of point mutants were created by swapping the nucleotides between the two viroid variants. Bioassay in tomato plants demonstrated that two mutants created on PSTVd-Iwt at positions 42 and 64 resulted in symptom attenuation. Phenotypic and RT-qPCR analysis revealed that mutation at position 42 of PSTVd-Iwt significantly reduced disease severity and accumulation of the viroid, whereas mutation at position 64 showed a significant reduction in stunting when compared to the PSTVd-Iwt infected plant. RT-qPCR analysis on pathogenesis-related protein 1b1 and chalcone synthase genes showed a direct correlation with symptom severity whereas the expansin genes were down-regulated irrespective of the symptom severity. These results indicate that the nucleotides at positions 42 and 64 are in concert with the ones at positions 43, 310, and 311/312, which determines the slower and stable accumulation of PSTVd-D without eliciting excessive host defense responses thus contributing in the attenuation of disease symptom.

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Metal ions and redox balance regulate distinct amyloid-like aggregation pathways of GAPR-1

Scientific Reports ◽

10.1038/s41598-019-51232-7 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Jie Sheng ◽

Nick K. Olrichs ◽

Willie J. Geerts ◽

Dora V. Kaloyanova ◽

J. Bernd Helms

Keyword(s):

Metal Ions ◽

Metal Binding ◽

Molecular Mechanisms ◽

Quaternary Structure ◽

Copper Ions ◽

Redox Homeostasis ◽

Secretory Proteins ◽

Pathogenesis Related Protein ◽

Pathogenesis Related ◽

Induced Aggregation

Abstract Members of the CAP superfamily (Cysteine-rich secretory proteins, Antigen 5, and Pathogenesis-Related 1 proteins) are characterized by the presence of a structurally conserved CAP domain. The common structure-function relationship of this domain is still poorly understood. In this study, we unravel specific molecular mechanisms modulating the quaternary structure of the mammalian CAP protein GAPR-1 (Golgi-Associated plant Pathogenesis-Related protein 1). Copper ions are shown to induce a distinct amyloid-like aggregation pathway of GAPR-1 in the presence of heparin. This involves an immediate shift from native multimers to monomers which are prone to form amyloid-like fibrils. The Cu2+-induced aggregation pathway is independent of a conserved metal-binding site and involves the formation of disulfide bonds during the nucleation process. The elongation process occurs independently of the presence of Cu2+ ions, and amyloid-like aggregation can proceed under oxidative conditions. In contrast, the Zn2+-dependent aggregation pathway was found to be independent of cysteines and was reversible upon removal of Zn2+ ions. Together, our results provide insight into the regulation of the quaternary structure of GAPR-1 by metal ions and redox homeostasis with potential implications for regulatory mechanisms of other CAP proteins.

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A sugarcane pathogenesis-related protein, ScPR10, plays a positive role in defense responses under Sporisorium scitamineum, SrMV, SA, and MeJA stresses

Plant Cell Reports ◽

10.1007/s00299-017-2166-4 ◽

2017 ◽

Vol 36 (9) ◽

pp. 1427-1440 ◽

Cited By ~ 6

Author(s):

Qiong Peng ◽

Yachun Su ◽

Hui Ling ◽

Waqar Ahmad ◽

Shiwu Gao ◽

...

Keyword(s):

Defense Responses ◽

Related Protein ◽

Positive Role ◽

Sporisorium Scitamineum ◽

Pathogenesis Related Protein ◽

Pathogenesis Related

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cDNA Cloning of a Sorghum Pathogenesis-Related Protein (PR-10) and Differential Expression of Defense-Related Genes Following Inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1999.12.6.479 ◽

1999 ◽

Vol 12 (6) ◽

pp. 479-489 ◽

Cited By ~ 71

Author(s):

Sze-Chung Clive Lo ◽

John D. Hipskind ◽

Ralph L. Nicholson

Keyword(s):

Fungal Pathogens ◽

Sequence Similarity ◽

Defense Responses ◽

Cochliobolus Heterostrophus ◽

Colletotrichum Sublineolum ◽

Pathogenesis Related Protein ◽

Pathogenesis Related ◽

Time Courses ◽

Related Proteins ◽

Phytoalexin Synthesis

A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from mesocotyls (cultivar DK18) inoculated with fungal pathogens. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts after appressoria had become mature. Accumulation of these transcripts was delayed in plants inoculated with C. sublineolum until penetration of host tissue had been completed and infection vesicles had formed. Results suggest that different recognition events are involved in the expression of resistance to the two fungi used or that C. sublineolum suppresses the nonspecific induction of defense responses.

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Pseudomonas fluorescens DN16 Enhances Cucumber Defense Responses Against the Necrotrophic Pathogen Botrytis cinerea by Regulating Thermospermine Catabolism

Frontiers in Plant Science ◽

10.3389/fpls.2021.645338 ◽

2021 ◽

Vol 12 ◽

Author(s):

Lin Zhu ◽

Nana Qian ◽

Yujun Sun ◽

Xiaoming Lu ◽

Haiming Duan ◽

...

Keyword(s):

Pseudomonas Fluorescens ◽

Botrytis Cinerea ◽

Defense Responses ◽

Pathogen Infection ◽

Necrotrophic Pathogen ◽

Catabolic Enzymes ◽

Catabolic Genes ◽

Pathogenesis Related Protein ◽

Pathogenesis Related

Plants can naturally interact with beneficial rhizobacteria to mediate defense responses against foliar pathogen infection. However, the mechanisms of rhizobacteria-mediated defense enhancement remain rarely clear. In this study, beneficial rhizobacterial strain Pseudomonas fluorescens DN16 greatly increased the resistance of cucumber plants against Botrytis cinerea infection. RNA-sequencing analyses showed that several polyamine-associated genes including a thermospermine (TSpm) synthase gene (CsACL5) and polyamine catabolic genes (CsPAO1, CsPAO5, and CsCuAO1) were notably induced by DN16. The associations of TSpm metabolic pathways with the DN16-mediated cucumber defense responses were further investigated. The inoculated plants exhibited the increased leaf TSpm levels compared with the controls. Accordantly, overexpression of CsACL5 in cucumber plants markedly increased leaf TSpm levels and enhanced defense against B. cinerea infection. The functions of TSpm catabolism in the DN16-mediated defense responses of cucumber plants to B. cinerea were further investigated by pharmacological approaches. Upon exposure to pathogen infection, the changes of leaf TSpm levels were positively related to the enhanced activities of polyamine catabolic enzymes including polyamine oxidases (PAOs) and copper amine oxidases (CuAOs), which paralleled the transcription of several defense-related genes such as pathogenesis-related protein 1 (CsPR1) and defensin-like protein 1 (CsDLP1). However, the inhibited activities of polyamine catabolic enzymes abolished the DN16-induced cucumber defense against B. cinerea infection. This was in line with the impaired expression of defense-related genes in the inoculated plants challenged by B. cinerea. Collectively, our findings unraveled a pivotal role of TSpm catabolism in the regulation of the rhizobacteria-primed defense states by mediating the immune responses in cucumber plants after B. cinerea infection.

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Transcriptome profiling in susceptible and tolerant rubber tree clones in response to cassiicolin Cas1, a necrotrophic effector from Corynespora cassiicola

PLoS ONE ◽

10.1371/journal.pone.0254541 ◽

2021 ◽

Vol 16 (7) ◽

pp. e0254541

Author(s):

Sébastien Ribeiro ◽

Philippe Label ◽

Dominique Garcia ◽

Pascal Montoro ◽

Valérie Pujade-Renaud

Keyword(s):

Hypersensitive Response ◽

Molecular Mechanisms ◽

De Novo ◽

Negative Impact ◽

Rubber Tree ◽

Defense Responses ◽

Differentially Expressed ◽

Corynespora Cassiicola ◽

Pathogenesis Related Protein ◽

Necrotrophic Effector

Corynespora cassiicola, a fungal plant pathogen with a large host range, causes important damages in rubber tree (Hevea brasiliensis), in Asia and Africa. A small secreted protein named cassiicolin was previously identified as a necrotrophic effector required for the virulence of C. cassiicola in specific rubber tree clones. The objective of this study was to decipher the cassiicolin-mediated molecular mechanisms involved in this compatible interaction. We comparatively analyzed the RNA-Seq transcriptomic profiles of leaves treated or not with the purified cassiicolin Cas1, in two rubber clones: PB260 (susceptible) and RRIM600 (tolerant). The reads were mapped against a synthetic transcriptome composed of all available transcriptomic references from the two clones. Genes differentially expressed in response to cassiicolin Cas1 were identified, in each clone, at two different time-points. After de novo annotation of the synthetic transcriptome, we analyzed GO enrichment of the differentially expressed genes in order to elucidate the main functional pathways impacted by cassiicolin. Cassiicolin induced qualitatively similar transcriptional modifications in both the susceptible and the tolerant clones, with a strong negative impact on photosynthesis, and the activation of defense responses via redox signaling, production of pathogenesis-related protein, or activation of the secondary metabolism. In the tolerant clone, transcriptional reprogramming occurred earlier but remained moderate. By contrast, the susceptible clone displayed a late but huge transcriptional burst, characterized by massive induction of phosphorylation events and all the features of a hypersensitive response. These results confirm that cassiicolin Cas1 is a necrotrophic effector triggering a hypersensitive response in susceptible rubber clones, in agreement with the necrotrophic-effector-triggered susceptibility model.

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Isolation and Characterization of a Cone Snail Protease with Homology to CRISP Proteins of the Pathogenesis-related Protein Superfamily

Journal of Biological Chemistry ◽

10.1074/jbc.m304843200 ◽

2003 ◽

Vol 278 (33) ◽

pp. 31105-31110 ◽

Cited By ~ 155

Author(s):

Trudy J. Milne ◽

Giovanni Abbenante ◽

Joel D. A. Tyndall ◽

Judy Halliday ◽

Richard J. Lewis

Keyword(s):

Cone Snail ◽

Related Protein ◽

Protein Superfamily ◽

Isolation And Characterization ◽

Pathogenesis Related Protein ◽

Pathogenesis Related

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A Genome-Wide Analysis of Pathogenesis-Related Protein-1 (PR-1) Genes from Piper nigrum Reveals Its Critical Role during Phytophthora capsici Infection

Genes ◽

10.3390/genes12071007 ◽

2021 ◽

Vol 12 (7) ◽

pp. 1007

Author(s):

Divya Kattupalli ◽

Asha Sreenivasan ◽

Eppurathu Vasudevan Soniya

Keyword(s):

Phytophthora Capsici ◽

Regulatory Elements ◽

Piper Nigrum ◽

Binding Motif ◽

Altered Expression ◽

Genome Wide ◽

A Genome ◽

Pathogenesis Related Protein ◽

Pathogenesis Related

Black pepper (Piper nigrum L.) is a prominent spice that is an indispensable ingredient in cuisine and traditional medicine. Phytophthora capsici, the causative agent of footrot disease, causes a drastic constraint in P. nigrum cultivation and productivity. To counterattack various biotic and abiotic stresses, plants employ a broad array of mechanisms that includes the accumulation of pathogenesis-related (PR) proteins. Through a genome-wide survey, eleven PR-1 genes that belong to a CAP superfamily protein with a caveolin-binding motif (CBM) and a CAP-derived peptide (CAPE) were identified from P. nigrum. Despite the critical functional domains, PnPR-1 homologs differ in their signal peptide motifs and core amino acid composition in the functional protein domains. The conserved motifs of PnPR-1 proteins were identified using MEME. Most of the PnPR-1 proteins were basic in nature. Secondary and 3D structure analyses of the PnPR-1 proteins were also predicted, which may be linked to a functional role in P. nigrum. The GO and KEGG functional annotations predicted their function in the defense responses of plant-pathogen interactions. Furthermore, a transcriptome-assisted FPKM analysis revealed PnPR-1 genes mapped to the P. nigrum-P. capsici interaction pathway. An altered expression pattern was detected for PnPR-1 transcripts among which a significant upregulation was noted for basic PnPR-1 genes such as CL10113.C1 and Unigene17664. The drastic variation in the transcript levels of CL10113.C1 was further validated through qRT-PCR and it showed a significant upregulation in infected leaf samples compared with the control. A subsequent analysis revealed the structural details, phylogenetic relationships, conserved sequence motifs and critical cis-regulatory elements of PnPR-1 genes. This is the first genome-wide study that identified the role of PR-1 genes during P. nigrum-P. capsici interactions. The detailed in silico experimental analysis revealed the vital role of PnPR-1 genes in regulating the first layer of defense towards a P. capsici infection in Panniyur-1 plants.

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An Insight into the Role of Apoptosis and Autophagy in Nitric Oxide–Induced Articular Chondrocyte Cell Death

Cartilage ◽

10.1177/1947603520976768 ◽

2020 ◽

pp. 194760352097676

Author(s):

Ekkapol Akaraphutiporn ◽

Takafumi Sunaga ◽

Eugene C. Bwalya ◽

Wang Yanlin ◽

Mwale Carol ◽

...

Keyword(s):

Nitric Oxide ◽

Cell Death ◽

Western Blot ◽

Cell Apoptosis ◽

Molecular Mechanisms ◽

Interleukin 1 ◽

Chondrocyte Apoptosis ◽

Protective Mechanism ◽

Autophagic Flux ◽

Qpcr Analysis

Objective To investigate the role and characterize the molecular mechanisms regulating apoptosis and autophagy in nitric oxide (NO)–induced chondrocyte cell death. Design Cell apoptosis and autophagy were evaluated in chondrocytes treated with sodium nitroprusside (SNP) combined with the presence or absence of interleukin-1 beta (IL-1β) and nutrient-deprived conditions. The concentration of nitrite was determined by Griess reaction. Activation of apoptosis and autophagy were determined by immunocytochemistry, Western blot, and quantitative real-time polymerase chain reaction (qPCR) analysis. Flow cytometry and MTT assay were used to assess cell viability. Results Cotreatment of chondrocytes with SNP and IL-1β under nutrient-deprived condition potentially enhanced the effect of NO-induced cell death. Immunocytochemistry, Western blot, and qPCR analysis indicated that treatment of chondrocytes with SNP significantly reduced autophagic activity, autophagic flux, and multiple autophagy-related (Atg) genes expression. These findings were associated with an increase in ERK, Akt, and mTOR phosphorylation, whereas autophagy induction through mTOR/p70S6K inhibition by rapamycin significantly suppressed NO-induced cell apoptosis. Furthermore, the cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-3 activation in response to apoptosis was weakly detected. These results corresponded with a significant increase in apoptosis-inducing factor (AIF) expression, suggesting the involvement of the caspase-independent pathway. Conclusions These results demonstrate that in chondrocyte cultures with cells induced into an osteoarthritis state, NO inhibits autophagy and induces chondrocyte apoptosis mainly, but not completely through the caspase-independent pathway. Our data suggest that autophagy is a protective mechanism in the pathogenesis of osteoarthritis and could be proposed as a therapeutic target for degenerative joint diseases.

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