Within-Species Flagellin Polymorphism inXanthomonas campestrispvcampestrisand Its Impact on Elicitation ofArabidopsis FLAGELLIN SENSING2–Dependent Defenses

Sun, Wenxian; Dunning, F. Mark; Pfund, Christine; Weingarten, Rebecca A.; Bent, Andrew F.

doi:10.1105/tpc.105.037648

Cited by 194 publications

(194 citation statements)

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“…Plant responses to pathogen attack can be differentiated into 'basal' and 'resistant (R)-gene-mediated' defences. These two defence responses can be distinguished experimentally by several assays, but they share some similar features and might even share some common molecular mechanisms 62 .…”

Section: Basal and R-gene-mediated Defences In Plantsmentioning

confidence: 99%

“…Flagellin proteins isolated from twelve strains of the black rot pathogen Xanthomonas campestris pv. campestris (Xcc) vary dramatically in their capability to elicit FLS2-mediated responses in Arabidopsis 62 . A single amino-acid polymorphism in the flg22 region of flagellin is primarily responsible for the observed variability.…”

Section: Bacterial Responses To Host Basal Defences Evasion Of Host Bmentioning

confidence: 99%

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Bacterial elicitation and evasion of plant innate immunity

Abramovitch

Anderson

Martin

2006

Nat Rev Mol Cell Biol

373

282

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Recent research on plant responses to bacterial attack has identified extracellular and intracellular host receptors that recognize conserved pathogen-associated molecular patterns and more specialized virulence proteins, respectively. These findings have shed light on our understanding of the molecular mechanisms by which bacteria elicit host defences and how pathogens have evolved to evade or suppress these defences.Plants are a rich source of nutrients and water for microbes, and they are infected by many bacterial pathogens from both the Proteobacteria and Actinobacteria phyla (Supplementary information 1 (table)). Because of their broad host range, serious economic consequences and experimental tractability, the most intensively studied bacteria are members of the Proteobacteria phylum (such as Agrobacterium, Erwinia, Pseudomonas, Ralstonia and Xanthomonas) [1][2][3][4] . These pathogens are spread by wind, rain, insects or cultivation practices. They enter plant tissues either by wounds or through natural openings such as lenticels, hydathodes or stomata 5 , and they occupy the inter cellular spaces (apoplast) of various plant tissues or the xylem.Plant-pathogenic members of the Proteobacteria cause diverse disease symptoms, including specks, spots, blights, wilts, galls and cankers, and they can cause host-cell death in roots, leaves, flowers, fruits, stems and tubers (FIG. 1). These symptoms affect both yield and quality of agricultural crops and bacterial diseases can have serious economic, social and even political consequences [6][7][8] . Control of bacterial diseases is only partially effective and consists of copper-based sprays, antibiotics, biocontrol strategies, large-scale removal of infected plants and, most importantly, host genetic resistance 5 . Therefore, research on bacterial diseases of plants helps to elucidate fundamental aspects of microbial pathogenesis and associated host responses and also to develop more effective and sustainable disease-control methods.Correspondence to G.B.M. gbm7@cornell.edu. Competing interests statementThe authors declare no competing financial interests. DATABASES NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptPlant-pathogenic bacteria use virulence strategies that are either specialized to plant tissues or are broadly conserved among pathogens of both plants and animals (FIG. 1). Bacterial virulence is manifested as increases in the rate of growth or final population size, as well as by enhanced disease symptoms, which promote the spread of the pathogen through the plant or the broader environment.Unlike mammals, plants have a complex cell wall that bacteria must surmount to gain access to water and nutrients. Bacteria attack this barrier with extracellular virulence factors, such as cell wall degrading enzymes, and bypass it by the secretion of cell wall-permeable toxins 5 . However, perhaps the most effective virulence strategy, and one shared with animal bacterial pathogens, is to breach the wall by use of the type III s...

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Section: Basal and R-gene-mediated Defences In Plantsmentioning

confidence: 99%

Section: Bacterial Responses To Host Basal Defences Evasion Of Host Bmentioning

confidence: 99%

Bacterial elicitation and evasion of plant innate immunity

Abramovitch

Anderson

Martin

2006

Nat Rev Mol Cell Biol

373

282

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“…These experiments, performed using a protoplast transient expression system, led to the development of a model in which a MAPK cascade composed of MEKK1-MKK4/MKK5-MPK3/MPK6 is responsible for transmitting the signal initiated when a plant recognizes flagellin. Flg22 is a 22-amino acid peptide sequence derived from the N-terminal portion of Pseudomonas aeruginosa flagellin that stimulates the FLS2 receptor and is sufficient to elicit innate immune responses in plants that include callose deposition, an oxidative burst, induction of pathogenesis-related (PR) gene expression, and seedling growth inhibition Chinchilla et al, 2006;Sun et al, 2006).…”

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confidence: 99%

MEKK1 Is Required for flg22-Induced MPK4 Activation in Arabidopsis Plants

et al. 2006

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The Arabidopsis (Arabidopsis thaliana) gene MEKK1 encodes a mitogen-activated protein kinase kinase kinase that has been implicated in the activation of the map kinases MPK3 and MPK6 in response to the flagellin elicitor peptide flg22. In this study, analysis of plants carrying T-DNA knockout alleles indicated that MEKK1 is required for flg22-induced activation of MPK4 but not MPK3 or MPK6. Experiments performed using a kinase-impaired version of MEKK1 (K361M) showed that the kinase activity of MEKK1 may not be required for flg22-induced MPK4 activation or for other macroscopic FLS2-mediated responses. MEKK1 may play a structural role in signaling, independent of its protein kinase activity. mekk1 knockout mutants display a severe dwarf phenotype, constitutive callose deposition, and constitutive expression of pathogen response genes. This dwarf phenotype was largely rescued by introduction into mekk1 knockout plants of either the MEKK1 (K361M) construct or a nahG transgene that degrades salicylic acid. When treated with pathogenic bacteria, the K361M plants were slightly more susceptible to an avirulent strain of Pseudomonas syringae and showed a delayed hypersensitive response, suggesting a role for MEKK1 kinase activity in this aspect of plant disease resistance. Our results indicate that MEKK1 acts upstream of MPK4 as a negative regulator of pathogen response pathways, a function that may not require MEKK1's full kinase activity.

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“…9 Another strategy is the avoidance of recognition by altering the recognized epitope, as shown for Agrobacteria and some species of Xanthomonas, which are modified in the flg22 epitope of flagellin. 4,10 However, it is noteworthy that pathogen recognition in plants is based on multiple, redundant perception systems detecting several MAMPs of a pathogen. Many MAMPs and PRRs are yet not identified and thus newly discovered MAMP-PRR pairs are essential for a better understanding of the plant innate immunity.…”

mentioning

confidence: 99%

“…Modification of MAMPs that reduce recognition by the corresponding pattern recognition receptors in different host plants has been shown for flagellin of Agrobacteria and Xanthomonas. 4,10 Whether such a strategy to avoid recognition also applies to Xcc will require the identification of eMax. Another possibility might be that these strains contain inhibitors that suppress MAMP recognition or downstream signaling.…”

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confidence: 99%