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 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 How to Unravel the Key Functions of Cryptic Oomycete Elicitin Proteins and Their Role in Plant Disease

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1201
Author(s):  
Aayushree Kharel ◽  
Md Tohidul Islam ◽  
James Rookes ◽  
David Cahill
Keyword(s):  
Gene Editing ◽  
Plant Disease ◽  
Plant Cells ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Host Pathogen Interactions ◽  
Binding Ability ◽  
Host Pathogen ◽  
Pathogen Colonization

Pathogens and plants are in a constant battle with one another, the result of which is either the restriction of pathogen growth via constitutive or induced plant defense responses or the pathogen colonization of plant cells and tissues that cause disease. Elicitins are a group of highly conserved proteins produced by certain oomycete species, and their sterol binding ability is recognized as an important feature in sterol–auxotrophic oomycetes. Elicitins also orchestrate other aspects of the interactions of oomycetes with their plant hosts. The function of elicitins as avirulence or virulence factors is controversial and is dependent on the host species, and despite several decades of research, the function of these proteins remains elusive. We summarize here our current understanding of elicitins as either defense-promoting or defense-suppressing agents and propose that more recent approaches such as the use of ‘omics’ and gene editing can be used to unravel the role of elicitins in host–pathogen interactions. A better understanding of the role of elicitins is required and deciphering their role in host–pathogen interactions will expand the strategies that can be adopted to improve disease resistance and reduce crop losses.

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.

Multiple Xanthomonas campestris pv. campestris 8004 type III effectors inhibit immunity induced by flg22

Planta ◽  
2020 ◽  
Vol 252 (5) ◽  
Author(s):  
Yan Huang ◽  
Tongqi Li ◽  
Ting Xu ◽  
Zizhong Tang ◽  
Jingya Guo ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Type Iii Effectors ◽  
Type Iii ◽  
Xanthomonas Campestris Pv Campestris

scholarly journals Heat-killed endophytic bacterium induces robust plant defense responses against important pathogens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Roxana Portieles ◽  
Hongli Xu ◽  
Qiulin Yue ◽  
Lin Zhao ◽  
Dening Zhang ◽  
...  
Keyword(s):  
Plant Defense ◽  
Plant Disease ◽  
Control Plant ◽  
Endophytic Bacterium ◽  
Defense Responses ◽  
Plant Diseases ◽  
Plant Defense Responses ◽  
Gentisic Acid ◽  
Important Challenge ◽  
First Time

AbstractStress caused by pathogens strongly damages plants. Developing products to control plant disease is an important challenge in sustainable agriculture. In this study, a heat-killed endophytic bacterium (HKEB), Bacillus aryabhattai, is used to induce plant defense against fungal and bacterial pathogens, and the main defense pathways used by the HKEB to activate plant defense are revealed. The HKEB induced high protection against different pathogens through the salicylic and jasmonic acid pathways. We report the presence of gentisic acid in the HKEB for the first time. These results show that HKEBs may be a useful tool for the management of plant diseases.

scholarly journals Early Defense Mechanisms of Brassica oleracea in Response to Attack by Xanthomonas campestris pv. campestris

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2705
Author(s):  
Lu Lu ◽  
Sokrat G. Monakhos ◽  
Yong Pyo Lim ◽  
So Young Yi
Keyword(s):  
Brassica Oleracea ◽  
Defense Mechanisms ◽  
Xanthomonas Campestris ◽  
Radical Scavenging ◽  
Defense Responses ◽  
Black Rot ◽  
Enzymatic Antioxidants ◽  
Induced Expression ◽  
Rot Disease ◽  
Xanthomonas Campestris Pv Campestris

Black rot disease, caused by Xanthomonas campestris pv. campestris (Xcc), results in significant yield losses in Brassica oleracea crops worldwide. To find black rot disease-resistant cabbage lines, we carried out pathogenicity assays using the scissor-clipping method in 94 different B. oleracea lines. By comparing the lesion areas, we selected a relatively resistant line, Black rot Resistance 155 (BR155), and a highly susceptible line, SC31. We compared the two cabbage lines for the Xcc-induced expression pattern of 13 defense-related genes. Among them, the Xcc-induced expression level of PR1 and antioxidant-related genes (SOD, POD, APX, Trx H, and CHI) were more than two times higher in BR155 than SC31. Nitroblue tetrazolium (NBT) and diaminobenzidine tetrahydrochloride (DAB) staining analysis showed that BR155 accumulated less Xcc-induced reactive oxygen species (ROS) than did SC31. In addition, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays showed that BR155 had higher antioxidant activity than SC31. This study, focused on the defense responses of cabbage during the early biotrophic stage of infection, indicated that Xcc-induced ROS might play a role in black rot disease development. We suggest that non-enzymatic antioxidants are important, particularly in the early defense mechanisms of cabbage against Xcc.

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