Plant and environmental sensory signals control the expression of hrp genes in Pseudomonas syringae pv. phaseolicola

• Published in: Journal of Bacteriology Vol. 174; no. 11; pp. 3499 - 3507
• Main Authors: Rahme, L.G. (Massachusetts General Hosital, Boston, MA), Mindrinos, M.N, Panopoulos, N.J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.06.1992
• Subjects: ACIDE AMINE; ACIDE SUCCINIQUE; ACIDO SUCCINICO; Agronomy. Soil science and plant productions; Amino Acids - pharmacology; AMINOACIDOS; Bacteria; Bacterial plant pathogens; Bacteriology; Biological and medical sciences; Carbohydrates - pharmacology; CITRATE; Citrates - pharmacology; CITRATOS; Citric Acid; Culture Media - pharmacology; Enzyme Induction; EXPERIMENTACION IN VITRO; EXPERIMENTATION IN VITRO; EXPRESION GENICA; EXPRESSION DES GENES; Fabaceae - metabolism; Fabaceae - microbiology; FRUCTOSA; FRUCTOSE; Fundamental and applied biological sciences. Psychology; GENE; Gene Expression Regulation, Bacterial; GENES; Genetics; Host-Parasite Interactions; Hydrogen-Ion Concentration; Nicotiana - metabolism; Nicotiana - microbiology; Phytopathology. Animal pests. Plant and forest protection; Plants - metabolism; Plants - microbiology; Plants, Medicinal; Plants, Toxic; PRESION OSMOTICA; PRESSION OSMOTIQUE; Pseudomonas - drug effects; Pseudomonas - genetics; Pseudomonas - pathogenicity; PSEUDOMONAS SYRINGAE; Pseudomonas syringae phaseolicola; Recombinant Fusion Proteins - biosynthesis; SACCHAROSE; Signal Transduction; Succinates - pharmacology; Succinic Acid; SUCROSA; Systematics. Structure, properties and multiplication. Genetics; Water-Electrolyte Balance - physiology; Pseudomonadales; Regulation(control); Plant pathogen; Transcription; Medium effect; Pseudomonas syringae; Vegetal microorganism relation; Bacteria; Pseudomonadaceae; Gene expression; Mechanism
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.174.11.3499-3507.1992

The hrp genes of Pseudomonas syringae pv. phaseolicola control the development of primary disease symptoms in bean plants and the elicitation of the hypersensitive response in resistant plants. We examined the expression of the seven operons located in the 22-kb hrp cluster (L. G. Rahme, M. N. Mindrinos, and N. J. Panopoulos, J. Bacteriol. 173:575-586, 1991) in planta and in vitro under different physiological and nutritional conditions by using chromosomally located hrp::inaZ reporter fusions. We show that (i) a plant signal(s) is specifically required for the induction of the seven hrp operons, during both compatible and incompatible interactions; (ii) hrpL and hrpRS are regulated by different mechanisms in planta and in vitro; and (iii) expression of individual hrp loci is differentially affected by pH, osmotic strength, and type of carbon source: hrpAB, hrpC, and hrpD were downregulated similarly by osmolarity, pH, and certain carbon sources; hrpE expression was affected strongly by pH and carbon substrate and slightly by osmolarity; and hrpF was not substantially affected by any of these factors. These findings suggest complex signaling mechanisms taking place during plant-pathogen interactions