scholarly journals Xanthan Pyruvilation Is Essential for the Virulence of Xanthomonas campestris pv. campestris

2016 ◽  
Vol 29 (9) ◽  
pp. 688-699 ◽  
Author(s):  
María Isabel Bianco ◽  
Laila Toum ◽  
Pablo Marcelo Yaryura ◽  
Natalia Mielnichuk ◽  
Gustavo Eduardo Gudesblat ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
In Planta ◽  
Callose Deposition ◽  
Disease Symptoms ◽  
The Relationship ◽  
Plant Surfaces ◽  
Xanthomonas Campestris Pv Campestris ◽  
Successful Colonization

Xanthan, the main exopolysaccharide (EPS) synthesized by Xanthomonas spp., contributes to bacterial stress tolerance and enhances attachment to plant surfaces by helping in biofilm formation. Therefore, xanthan is essential for successful colonization and growth in planta and has also been proposed to be involved in the promotion of pathogenesis by calcium ion chelation and, hence, in the suppression of the plant defense responses in which this cation acts as a signal. The aim of this work was to study the relationship between xanthan structure and its role as a virulence factor. We analyzed four Xanthomonas campestris pv. campestris mutants that synthesize structural variants of xanthan. We found that the lack of acetyl groups that decorate the internal mannose residues, ketal-pyruvate groups, and external mannose residues affects bacterial adhesion and biofilm architecture. In addition, the mutants that synthesized EPS without pyruvilation or without the external mannose residues did not develop disease symptoms in Arabidopsis thaliana. We also observed that the presence of the external mannose residues and, hence, pyruvilation is required for xanthan to suppress callose deposition as well as to interfere with stomatal defense. In conclusion, pyruvilation of xanthan seems to be essential for Xanthomonas campestris pv. campestris virulence.

scholarly journals The AvrB_AvrC Domain of AvrXccC of Xanthomonas campestris pv. campestris Is Required to Elicit Plant Defense Responses and Manipulate ABA Homeostasis

2013 ◽  
Vol 26 (4) ◽  
pp. 419-430 ◽  
Author(s):  
Yi-Ping Ho ◽  
Choon Meng Tan ◽  
Meng-Ying Li ◽  
Hong Lin ◽  
Wen-Ling Deng ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Plant Disease ◽  
Morphological Changes ◽  
Defense Responses ◽  
Host Gene Expression ◽  
Plant Defense Responses ◽  
Type Iii Effectors ◽  
Key Enzyme ◽  
Aba Biosynthesis ◽  
Xanthomonas Campestris Pv Campestris

Plant disease induced by Xanthomonas campestris pv. campestris depends on type III effectors but the molecular basis is poorly understood. Here, AvrXccC8004 was characterized, and it was found that the AvrB_AvrC domain was essential and sufficient to elicit defense responses in an Arabidopsis-resistant ecotype (Col-0). An upregulation of genes in responding to the AvrB_AvrC domain of AvrXccC8004 was shown in a profile of host gene expression. The molecular changes were correlated with morphological changes observed in phenotypic and ultrastructural characterizations. Interestingly, the abscisic acid (ABA)-signaling pathway was also a prominent target for the AvrB_AvrC domain of AvrXccC8004. The highly elicited NCED5, encoding a key enzyme of ABA biosynthesis, was increased in parallel with ABA levels in AvrXccC8004 transgenic plants. Consistently, the X. campestris pv. campestris 8004 ΔavrXccC mutant was severely impaired in the ability to manipulate the accumulation of ABA and induction of ABA-related genes in challenged leaves. Moreover, exogenous application of ABA also enhanced the susceptibility of Arabidopsis to the X. campestris pv. campestris strains. These results indicate that the AvrB_AvrC domain of AvrXccC8004 alone has the activity to manipulate ABA homeostasis, which plays an important role in regulating the interactions of X. campestris pv. campestris and Arabidopsis.

scholarly journals The Effect of Fusarium verticillioides Fumonisins on Fatty Acids, Sphingolipids, and Oxylipins in Maize Germlings

2021 ◽  
Vol 22 (5) ◽  
pp. 2435
Author(s):  
Marzia Beccaccioli ◽  
Manuel Salustri ◽  
Valeria Scala ◽  
Matteo Ludovici ◽  
Andrea Cacciotti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fusarium Verticillioides ◽  
Fungal Growth ◽  
Defense Responses ◽  
Ceramide Synthase ◽  
Ear Rot ◽  
In Planta ◽  
Disease Symptoms ◽  
The Impact

Fusarium verticillioides causes multiple diseases of Zea mays (maize) including ear and seedling rots, contaminates seeds and seed products worldwide with toxic chemicals called fumonisins. The role of fumonisins in disease is unclear because, although they are not required for ear rot, they are required for seedling diseases. Disease symptoms may be due to the ability of fumonisins to inhibit ceramide synthase activity, the expected cause of lipids (fatty acids, oxylipins, and sphingolipids) alteration in infected plants. In this study, we explored the impact of fumonisins on fatty acid, oxylipin, and sphingolipid levels in planta and how these changes affect F. verticillioides growth in maize. The identity and levels of principal fatty acids, oxylipins, and over 50 sphingolipids were evaluated by chromatography followed by mass spectrometry in maize infected with an F. verticillioides fumonisin-producing wild-type strain and a fumonisin-deficient mutant, after different periods of growth. Plant hormones associated with defense responses, i.e., salicylic and jasmonic acid, were also evaluated. We suggest that fumonisins produced by F. verticillioides alter maize lipid metabolism, which help switch fungal growth from a relatively harmless endophyte to a destructive necrotroph.

scholarly journals Flagella Mediate Endophytic Competence Rather Than Act as MAMPS in Rice–Azoarcus sp. Strain BH72 Interactions

2012 ◽  
Vol 25 (2) ◽  
pp. 191-199 ◽  
Author(s):  
Anna Buschart ◽  
Sabrina Sachs ◽  
Xi Chen ◽  
Julia Herglotz ◽  
Andrea Krause ◽  
...  
Keyword(s):  
Deletion Mutant ◽  
Defense Responses ◽  
Root Surface ◽  
Bacterial Motility ◽  
Structural Protein ◽  
Plant Defense Responses ◽  
Disease Symptoms ◽  
Endophytic Colonization ◽  
Rice Roots ◽  
Molecular Patterns

Azoarcus sp. strain BH72 is an endophytic betaproteobacterium able to colonize rice roots without induction of visible disease symptoms. BH72 possesses one polar flagellum. The genome harbors three copies of putative fliC genes, generally encoding the major structural protein flagellin. It is not clear whether, in endophytic interactions, flagella mediate endophytic competence or act as MAMPs (microbe-asscociated molecular patterns) inducing plant defense responses. Therefore, possible functions of the three FliC proteins were investigated. Only fliC3 was found to be highly expressed in pure culture and in association with rice roots and to be required for bacterial motility, suggesting that it encodes the major flagellin. Endophytic colonization of rice roots was significantly reduced in the in-frame deletion mutant, while the establishment of microcolonies on the root surface was not affected. Moreover, an elicitation of defense responses related to FliC3 was not observed. In conclusion, our data support the hypothesis that FliC3 does not play a major role as a MAMP but is required for endophytic colonization in the Azoarcus-rice interaction, most likely for spreading inside the plant.

scholarly journals DsbB Is Required for the Pathogenesis Process of Xanthomonas campestris pv. campestris

2008 ◽  
Vol 21 (8) ◽  
pp. 1036-1045 ◽  
Author(s):  
Bo-Le Jiang ◽  
Jiao Liu ◽  
Li-Feng Chen ◽  
Ying-Ying Ge ◽  
Xiao-Hong Hang ◽  
...  
Keyword(s):  
Disulfide Bond ◽  
Xanthomonas Campestris ◽  
Bond Formation ◽  
Disulfide Bond Formation ◽  
In Planta ◽  
Secretion Systems ◽  
Reading Frame ◽  
Type Iii Secretion Systems ◽  
Rot Disease ◽  
Xanthomonas Campestris Pv Campestris

The DsbA/DsbB oxidation pathway is one of the two pathways that catalyze disulfide bond formation of proteins in the periplasm of gram-negative bacteria. It has been demonstrated that DsbA is essential for multiple virulence factors of several animal bacterial pathogens. In this article, we present genetic evidence to show that the open reading frame XC_3314 encodes a DsbB protein that is involved in disulfide bond formation in periplasm of Xanthomonas campestris pv. campestris, the causative agent of crucifer black rot disease. The dsbB mutant of X. campestris pv. campestris exhibited attenuation in virulence, hypersensitive response, cell motility, and bacterial growth in planta. Furthermore, mutation in the dsbB gene resulted in ineffective type II and type III secretion systems as well as flagellar assembly. These findings reveal that DsbB is required for the pathogenesis process of X. campestris pv. campestris.

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 Xanthomonas campestris pv. vesicatoria Effector AvrBsT Induces Cell Death in Pepper, but Suppresses Defense Responses in Tomato

2010 ◽  
Vol 23 (8) ◽  
pp. 1069-1082 ◽  
Author(s):  
Nak Hyun Kim ◽  
Hyong Woo Choi ◽  
Byung Kook Hwang
Keyword(s):  
Xanthomonas Campestris ◽  
Marker Gene ◽  
Defense Responses ◽  
Gene Expressions ◽  
Callose Deposition ◽  
Tomato Plants ◽  
Type Iii Effector ◽  
Type Iii ◽  
Pepper Leaves ◽  
Pepper Plants

A type III effector protein, AvrBsT, is secreted into plant cells from Xanthomonas campestris pv. vesicatoria Bv5-4a, which causes bacterial spot disease on pepper (Capsicum annuum) and tomato (Solanum lycopersicum). To define the function and recognition of AvrBsT in the two host plants, avrBsT was introduced into the virulent pepper strain X. campestris pv. vesicatoria Ds1. Expression of AvrBsT in Ds1 rendered the strain avirulent to pepper plants. Infection of pepper leaves with Ds1 (avrBsT) expressing AvrBsT but not with near-isogenic control strains triggered a hypersensitive response (HR) accompanied by strong H2O2 generation, callose deposition, and defense-marker gene expressions. Mutation of avrBsT, however, compromised HR induction by X. campestris pv. vesicatoria Bv5-4a, suggesting its avirulence function in pepper plants. In contrast, AvrBsT acted as a virulence factor in tomato plants. Growth of strains Ds1 (avrBsT) and Bv5-4a ΔavrBsT was significantly enhanced and reduced, respectively, in tomato leaves. X. campestris pv. vesicatoria-expressed AvrBsT also significantly compromised callose deposition and defense-marker gene expression in tomato plants. Together, these results suggest that the X. campestris pv. vesicatoria type III effector AvrBsT is differentially recognized by pepper and tomato plants.

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 Ethylene Analog and 1-Methylcyclopropene Enhance Black Spot Disease Development in Pyrus pyrifolia Nakai

HortScience ◽  
2012 ◽  
Vol 47 (2) ◽  
pp. 228-231 ◽  
Author(s):  
Akihiro Itai ◽  
Takaaki Igori ◽  
Naoko Fujita ◽  
Mayumi Egusa ◽  
Motoichiro Kodama ◽  
...  
Keyword(s):  
Black Spot ◽  
Acc Synthase ◽  
Defense Responses ◽  
Pyrus Pyrifolia ◽  
Disease Symptoms ◽  
Spot Disease ◽  
Ethylene Action ◽  
Altered Gene ◽  
The Relationship ◽  
Black Spot Disease

Black spot disease is one of the most serious diseases in Asian pear cultivation, with the commercial cultivar Nijisseiki being susceptible. Ethylene is known to play major roles in regulating plant defense responses against various pathogens. We investigated the relationship between ethylene synthesis and black spot disease in ‘Nijisseiki’ pear leaves by treatment with an analog of ethylene and 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action. Interestingly, both treatments enhanced black spot disease symptoms. Both treatments also increased ethylene production in accordance with disease symptoms through altered gene expression of ethylene biosynthetic enzymes, especially 1-aminocyclopropane-1-carboxylate (ACC) synthase genes (PpACS3 and 4). Chemical names used: 1-methylcyclopropene (1-MCP), 1-aminocyclopropane-1-carboxylate (ACC).

scholarly journals Basal Defenses Induced in Pepper by Lipopolysaccharides Are Suppressed by Xanthomonas campestris pv. vesicatoria

2004 ◽  
Vol 17 (7) ◽  
pp. 805-815 ◽  
Author(s):  
Mansureh Keshavarzi ◽  
Soner Soylu ◽  
Ian Brown ◽  
Ulla Bonas ◽  
Michel Nicole ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Structural Changes ◽  
Plant Cell Wall ◽  
Defense Responses ◽  
Effector Proteins ◽  
Wild Type ◽  
Callose Deposition ◽  
Pepper Leaves ◽  
Mixed Inocula ◽  
Basal Defense

The nonpathogenic hrcC mutant of Xanthomonas campestris pv. vesicatoria 85-10∷hrpA22 multiplied in pepper leaves if it was mixed with pathogenic strains of X. campestris pv. vesicatoria. Reactions to the mutant alone included localized deposition of phenolics and callose in papillae, and alterations to the plant cell wall leading to increased electron density. Electron microscopy showed that the localized responses were suppressed in the presence of wild-type bacteria but other wall changes occurred at some sites, involving cellulose-rich ingrowth of the wall. Multiplication of the hrp mutant in mixed inocula was confirmed by tagging 85-10∷hrpA22 using immunocytochemical location of AvrBs3 expressed from the plasmid pD36. Elicitors of callose deposition and other wall changes were isolated from the hrcC mutant. Activity in extracts of bacteria was attributed to the presence of high molecular weight lipopolysaccharides (LPS). Wild-type X. campestris pv. vesicatoria suppressed induction of structural changes caused by purified LPS. Results obtained suggest that effector proteins produced by phytopathogenic bacteria and delivered by the type III secretion system may have a key role in suppressing the basal defense responses activated by bacterial LPS, which lead to restricted multiplication of nonpathogens such as hrp mutants.

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