Identification and phylogenetic analysis of Pseudomonas savastanoi pv. savastanoi from two provinces in Iraq

Abstract

The causative agent of olive knot disease is Pseudomonas savastanoi pv. savastanoi (Psv), a member of the P. syringae complex that causes aerial tumors rather than the foliar necrosis and cankers typical of most members of this complex. Following its occurrence in Duhok and Ninevah provinces in Iraq in 2021–2022, this work sought to isolate and characterize Psv using conventionaland molecular methods, and phylogenetic analysis for the first time in Iraq. All 140 bacterial isolates tested negative for Levan production, Oxidase activity, Pectolytic activity on potatoes, and Arginine dihydrolase activity in the LOPAT (levanase test, pectolytic activity, and arginine hypersensitive reaction) assays. The bacteria were Gram-negative, hypersensitive to tobacco, and did not produce spores. Using PCR-based diagnostics and the sequence of iaaL, the phylogenetic placement of fourteen Psv strains were determined. Together with Psv strain LMG5385 (KM593985) in one clade, the phylogeny showed that all fourteen of the Iraqi isolates were grouped together. As a result, it appears that the Psv present in these two Iraqi provinces are monophyletic.