Effects of galU Mutation on Pseudomonas syringae–Plant Interactions

• Published in: Molecular plant-microbe interactions Vol. 23; no. 9; pp. 1184 - 1196
• Main Authors: Deng, Wen-Ling, Lin, Yuan-Chun, Lin, Rong-Hwa, Wei, Chia-Fong, Huang, Yi-Chiao, Peng, Hwei-Ling, Huang, Hsiou-Chen
• Format: Journal Article
• Language: English
• Published: St. Paul, MN APS Press 01.09.2010; The American Phytopathological Society
• Subjects: Bacterial plant pathogens; biofilm; Biofilms; Biofilms - growth & development; Biological and medical sciences; cell motility; cell movement; Flagellin; Flagellin - genetics; Flagellin - metabolism; Fundamental and applied biological sciences. Psychology; genetics; growth & development; host plants; Host-Pathogen Interactions; host-pathogen relationships; Hydrogen Peroxide; hypersensitive response; induced resistance; Lipopolysaccharides; metabolism; microbiology; Molecular Sequence Data; mutants; Mutation; Nicotiana - microbiology; oligosaccharides; pathogen-associated molecular patterns; pathogenicity; physiology; Phytopathology. Animal pests. Plant and forest protection; plant pathogenic bacteria; polysaccharides; Pseudomonas syringae; Pseudomonas syringae - genetics; Pseudomonas syringae - metabolism; Pseudomonas syringae - physiology; Pseudomonas syringae pv. syringae; signs and symptoms (plants); Tobacco; transferases; translocation (plant physiology); Type III secretion system; uridine diphosphate; uridine diphosphate-glucose pyrophosphorylase; UTP-Glucose-1-Phosphate Uridylyltransferase; UTP-Glucose-1-Phosphate Uridylyltransferase - genetics; UTP-Glucose-1-Phosphate Uridylyltransferase - metabolism; Pseudomonadales; Plant; Plant pathogen; Pseudomonas syringae; Bacteria; Pseudomonadaceae; Mutation
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-23-9-1184

Bacterial galU coding for a uridine diphosphate-glucose pyrophosphorylase plays an important role in carbohydrates biosynthesis, including synthesis of lipopolysaccharides (LPS), membrane-derived oligosaccharides, and capsular polysaccharides. In this study, we characterized the galU mutant of Pseudomonas syringae pv. syringae 61 (Psy61), a necrotizing plant pathogen whose pathogenicity depends on a functional type III secretion system (T3SS), and showed that the Psy61 galU mutant had reduced biofilm formation ability, was nonmotile, and had an assembled T3SS structure but failed to elicit hypersensitive response in resistant plants and necrotic lesions in susceptible plants. Moreover, the defective LPS and other pathogen-associated molecular patterns (PAMPs) on the surface of the Psy61 galU mutant were capable of inducing PAMP-triggered immunity, which severely compromised the ability of the Psy61 galU mutant to survive in planta. Our results demonstrated that the complete LPS protected plant-pathogenic bacteria from host innate immunity, similar to what was found in animal pathogens, prior to the translocation of T3S effectors and bacterial multiplication.