Phenotypic expression of Pseudomonas syringae avr genes in E. coli is linked to the activities of the hrp-encoded secretion system

• Published in: Molecular plant-microbe interactions Vol. 9; no. 4; pp. 252 - 260
• Main Authors: Pirhonen, M.U. (Swedish University of Agricultural Sciences, Uppsala, Sweden.), Lidell, M.C, Rowley, D.L, Lee, S.W, Jin, S, Liang, Y, Silverstone, S, Keen, N.T, Hutcheson, S.W
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01-05-1996
• Subjects: ARABIDOPSIS THALIANA; BACTERIA; Bacterial plant pathogens; Bacteriology; Base Sequence; Biological and medical sciences; Cloning, Molecular; DNA Primers; DNA, Recombinant; ESCHERICHIA COLI; Escherichia coli - genetics; EXPERIMENTACION IN VIVO; EXPERIMENTATION IN VIVO; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; GENE; GENES; Genes, Bacterial; Genetics; GLYCINE MAX; INFECCION EXPERIMENTAL; INFECTION EXPERIMENTALE; Microbiology; Molecular Sequence Data; PATOGENICIDAD; Phenotype; Phytopathology. Animal pests. Plant and forest protection; POUVOIR PATHOGENE; PROTEINAS; PROTEINE; Pseudomonas - genetics; Pseudomonas - pathogenicity; PSEUDOMONAS SYRINGAE; SECRECION; SECRETION; Systematics. Structure, properties and multiplication. Genetics; TRANSFERENCIA DE GENES; TRANSFERT DE GENE; TRANSFORMACION GENETICA; TRANSFORMATION GENETIQUE; Virulence - genetics; Pseudomonadales; Phenotype; Plant pathogen; Pseudomonas syringae; Hypersensitivity; Bacteria; Pseudomonadaceae; Host agent relation; Defensive response
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-9-0252

The specific recognition of elicitors produced by plant pathogenic bacteria carrying avirulence (avr) genes is postulated to initiate cellular defense responses in plants expressing corresponding resistance genes. The biochemical functions of most avr genes, however, are not known. A heterologous system was developed to phenotypically express Pseudomonas syringae avr genes in Escherichia coli cells that required the P. syringae hrp cluster. E. coli MC4100 transformants carrying the plasmid-borne P. syringae pv. syringae Pss61 hrp cluster and P. syringae pv. glycinea avrB expressed from a triple lacUV5 promoter gained the ability to elicit the hypersensitive response in soybean cultivars expressing Rpg1 and in an Arabidopsis thaliana accession expressing RPM1. Inactivation of energy transducing or outer membrane components of the hrp-encoded secretion system blocked phenotypic expression of avrB in E. coli, but deletions abolishing harpin(Pss), production had little effect on the production of the AvrB phenotype by the E. coli transformants. Phenotypic expression of avrA, avrPto, avrRpm1, avrRpt2, and avrPph3 in E. coli was also shown to require the hrp cluster. The results indicate that generation of the Avr phenotype in P. syringae strains is specifically dependent on the secretion activities of the hrp cluster