Pathogenic and Nonhost Bacterial Strains in Arabidopsis

Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) [3 (link)] and P. syringae pv. maculicola ES4326 (Psm ES4326) [29 (link)] were used as pathogenic strains on Arabidopsis. The hrcC mutant defective in type III secretion [16 (link)] and a COR-defective mutant, DB29 [14 (link)], were used as virulence mutants of Pst DC3000. Pst DC3000 carrying AvrRpt2 [44 (link)] was used as an avirulent or incompatible pathogen to study ETI. Nonhost pathogens P. syringae pv. tabaci 6605 (Psta) [45 ], pv. glycinea race 4 (Psg) [46 (link)], pv. tomato T1 (Pst T1) [47 (link)] and Xanthomonas campestris pv. vesicatoria (Xcv) [40 (link)] were used to study NHR. Psta ΔfliC mutant defective in flagellin [35 (link)] and the ΔhrcC mutant defective in type III secretion [48 (link)] were used to study HR cell death. P. syringae were grown at 28°C on mannitol-glutamate (MG) medium [49 ] containing appropriate antibiotics as needed in the following concentrations (μg ml^-1): rifampicin, 50; kanamycin, 25; chloramphenicol, 25; and spectinomycin, 25, for 36-48 h. Xcv was grown at 28°C on Luria-Bertani (LB) media. Prior to inoculation, bacteria were suspended in sterile distilled H₂O and bacterial cell densities (OD₆₀₀) were measured using a Jenway 6320D spectrophotometer (Bibby Scientific Limited, Staffordshire, UK)