The Arabidopsis Thaliana-Pseudomonas Syringae Interaction

Pseudomonas syringae is a Gram-negative, rod-shaped bacterium with polar flagella (Figure Strains of P. syringae collectively infect a wide variety of plants. Different strains of P. syringae, however, are known for their diverse and host-specific interactions with plants A specific strain may be assigned to one of at least 40 pathovars based on its host range among different plant species Understanding the molecular basis of this high level of host specificity has been a driving force in using P. syringae as a model for the study of host-pathogen interactions. In crop fields, infected seeds are often an important source of primary inoculum in P. syringae diseases, and epiphytic bacterial growth on leaf surfaces often precedes disease development P. syringae enters the host tissues (usually leaves) through wounds or natural openings such as stomata, and in a susceptible plant it multiplies to high population levels in intercellular spaces. Infected leaves show water-soaked patches, which eventually become necrotic. Depending on P. syringae strains, necrotic lesions may be surrounded by diffuse chlorosis. Some strains of P. syringae also cause cankers and galls In resistant plants, on the other hand, P. syringae triggers the hypersensitive response (HR), a rapid, defense-associated death of plant cells in contact with the pathogen