Syringolide Elicitors Specified by Avirulence Gene D Alleles in Pseudomonas Syringae

Author(s):  
Noel Keen ◽  
Sharon L. Midland ◽  
Carol Boyd ◽  
Irem Yucel ◽  
Tetsu Tsurushima ◽  
...  
Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 401-412 ◽  
Author(s):  
Randall F Warren ◽  
Peter M Merritt ◽  
Eric Holub ◽  
Roger W Innes

Abstract The RPS5 disease resistance gene of Arabidopsis mediates recognition of Pseudomonas syringae strains that possess the avirulence gene avrPphB. By screening for loss of RPS5-specified resistance, we identified five pbs (avrPphB susceptible) mutants that represent three different genes. Mutations in PBS1 completely blocked RPS5-mediated resistance, but had little to no effect on resistance specified by other disease resistance genes, suggesting that PBS1 facilitates recognition of the avrPphB protein. The pbs2 mutation dramatically reduced resistance mediated by the RPS5 and RPM1 resistance genes, but had no detectable effect on resistance mediated by RPS4 and had an intermediate effect on RPS2-mediated resistance. The pbs2 mutation also had varying effects on resistance mediated by seven different RPP (recognition of Peronospora parasitica) genes. These data indicate that the PBS2 protein functions in a pathway that is important only to a subset of disease-resistance genes. The pbs3 mutation partially suppressed all four P. syringae-resistance genes (RPS5, RPM1, RPS2, and RPS4), and it had weak-to-intermediate effects on the RPP genes. In addition, the pbs3 mutant allowed higher bacterial growth in response to a virulent strain of P. syringae, indicating that the PBS3 gene product functions in a pathway involved in restricting the spread of both virulent and avirulent pathogens. The pbs mutations are recessive and have been mapped to chromosomes I (pbs2) and V (pbs1 and pbs3).


1993 ◽  
Vol 5 (8) ◽  
pp. 865 ◽  
Author(s):  
Barbara N. Kunkel ◽  
Andrew F. Bent ◽  
Douglas Dahlbeck ◽  
Roger W. Innes ◽  
Brian J. Staskawicz

Microbiology ◽  
1999 ◽  
Vol 145 (1) ◽  
pp. 135-141 ◽  
Author(s):  
D. L. Arnold ◽  
J. Brown ◽  
R. W. Jackson ◽  
A. Vivian

2000 ◽  
Vol 182 (12) ◽  
pp. 3498-3507 ◽  
Author(s):  
Erik L. Hendrickson ◽  
Pablo Guevera ◽  
Alejandro Peñaloza-Vàzquez ◽  
Jing Shao ◽  
Carol Bender ◽  
...  

ABSTRACT We cloned the rpoN (ntrA andglnF) gene encoding ς54 from the phytopathogen Pseudomonas syringae pv. maculicola strain ES4326. The P. syringae ES4326 rpoN gene complemented Pseudomonas aeruginosa, Escherichia coli, and Klebsiella aerogenes rpoN mutants for a variety of rpoN mutant phenotypes, including the inability to utilize nitrate as sole nitrogen source. DNA sequence analysis of the P. syringae ES4326 rpoN gene revealed that the deduced amino acid sequence was most similar (86% identity; 95% similarity) to the ς54 protein encoded by thePseudomonas putida rpoN gene. A marker exchange protocol was used to construct an ES4326 rpoN insertional mutation,rpoN::Kmr. In contrast to wild-type ES4326, ES4326 rpoN::Kmr was nonmotile and could not utilize nitrate, urea, C4-dicarboxylic acids, several amino acids, or concentrations of ammonia below 2 mM as nitrogen sources.rpoN was essential for production of the phytotoxin coronatine and for expression of the structural genes encoding coronamic acid. In addition, ES4326rpoN::Kmr did not multiply or elicit disease symptoms when infiltrated into Arabidopsis thalianaleaves, did not elicit the accumulation of severalArabidopsis defense-related mRNAs, and did not elicit a hypersensitive response (HR) when infiltrated into tobacco (Nicotiana tabacum) leaves. Furthermore, whereas P. syringae ES4326 carrying the avirulence gene avrRpt2elicited an HR when infiltrated into Arabidopsis ecotype Columbia leaves, ES4326 rpoN::Kmrcarrying avrRpt2 elicited no response. Constitutive expression of ES4326 hrpL in ES4326rpoN::Kmr partially restored defense-related mRNA accumulation, showing a direct role for thehrp cluster in host defense gene induction in a compatible host-pathogen interaction. However, constitutive expression ofhrpL in ES4326 rpoN::Kmrdid not restore coronatine production, showing that coronatine biosynthesis requires factors other than hrpL.


1997 ◽  
Vol 10 (2) ◽  
pp. 247-256 ◽  
Author(s):  
Nakul Puri ◽  
Carol Jenner ◽  
Mark Bennett ◽  
Ruth Stewart ◽  
John Mansfield ◽  
...  

Protein production encoded by the avirulence gene avrPphB from Pseudomonas syringae pv. phaseolicola was examined. Incorporation of [35S]-labeled methionine into the AvrPphB protein indicated processing of the full-length peptide in Escherichia coli to give a major 28-kDa product. The 28-kDa native peptide was isolated from E. coli following over-expression of avrPphB and found not to elicit the hypersensitive response (HR) after infiltration into bean leaves. Antiserum raised to the 28-kDa peptide allowed expression of avrPphB and processing of AvrPphB protein to be examined in P. syringae pv. phaseolicola; immunoreactive peptides of both 35 and 28-kDa were detected in races 3 and 4 (which contain avrPphB) only after induction in minimal medium + 10 mM sucrose. Antiserum raised to a synthetic peptide, derived from the sequence of the 62 amino acids found to be cleaved from the full-length AvrPphB protein, revealed the accumulation of peptides corresponding to the smaller cleavage products, in both E. coli and P. syringae pv. phaseolicola. Biochemical localization experiments showed that all AvrPphB peptides were cytoplasmic in P. syringae pv. phaseolicola. No AvrPphB peptides were produced in a hrpL mutant unless expression of the gene was directed by a strong vector promoter; induction kinetics similar to wild type were observed in a hrpY - strain, although it also failed to cause a confluent HR. Growth of P. syringae pv. phaseolicola under inducing conditions removed the requirement for rifampicin-sensitive mRNA synthesis by bacteria to allow HR development (the induction time) in bean and lettuce leaves. Constitutive expression of hrpL reduced but did not remove the induction time. Expression of the hrp gene cluster of P. syringae pv. phaseolicola from plasmid pPPY430 in E. coli enabled phenotypic expression of avrPphE (also carried by pPPY430) and avrPphB (if over-expressed from pPPY3031). Despite constitutive expression of the hrp and avr genes in E. coli, a protein synthesis dependent induction time was still required for development of the HR in bean genotypes with matching resistance genes. The significance of processing for the function of AvrPphB peptides and the delivery of elicitors of the HR are discussed.


2001 ◽  
Vol 14 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Michael J. Axtell ◽  
Timothy W. McNellis ◽  
Mary Beth Mudgett ◽  
Caroline S. Hsu ◽  
Brian J. Staskawicz

Plants have evolved a large number of disease resistance genes that encode proteins containing conserved structural motifs that function to recognize pathogen signals and to initiate defense responses. The Arabidopsis RPS2 gene encodes a protein representative of the nucleotide-binding site-leucine-rich repeat (NBS-LRR) class of plant resistance proteins. RPS2 specifically recognizes Pseudomonas syringae pv. tomato strains expressing the avrRpt2 gene and initiates defense responses to bacteria carrying avrRpt2, including a hypersensitive cell death response (HR). We present an in planta mutagenesis experiment that resulted in the isolation of a series of rps2 and avrRpt2 alleles that disrupt the RPS2-avrRpt2 gene-for-gene interaction. Seven novel avrRpt2 alleles incapable of eliciting an RPS2-dependent HR all encode proteins with lesions in the C-terminal portion of AvrRpt2 previously shown to be sufficient for RPS2 recognition. Ten novel rps2 alleles were characterized with mutations in the NBS and the LRR. Several of these alleles code for point mutations in motifs that are conserved among NBS-LRR resistance genes, including the third LRR, which suggests the importance of these motifs for resistance gene function.


2004 ◽  
Vol 17 (5) ◽  
pp. 447-455 ◽  
Author(s):  
Libo Shan ◽  
Hye-sook Oh ◽  
Jianfu Chen ◽  
Ming Guo ◽  
Jianmin Zhou ◽  
...  

Type III secretion systes are highly conserved among gram-negative plant and animal pathogenic bacteria. Through the type III secretion system, bacteria inject a number of virulence proteins into the host cells. Analysis of the whole genome sequence of Pseudomonas syringae pv. tomato DC3000 strain identified a locus, named HopPtoF, that is homologous to the avirulence gene locus avrPphF in P. syringae pv. phaseolicola. The HopPtoF locus harbors two genes, ShcFPto and HopFPto, that are preceded by a single hrp box promoter. We present evidence here to show that ShcFPto and HopFPto encode a type III chaperone and a cognate effector, respectively. ShcFPto interacts with and stabilizes the HopFPto protein in the bacterial cell. Translation of HopFPto starts at a rare initiation codon ATA that limits the synthesis of the HopFPto protein to a low level in bacterial cells.


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