= Pseudomonas syringae
{c}
<Pseudomonas syringae> is a <species> of <bacteria> in <Pseudomonas>, important in the study of interactions between plants and their associated microorganisms. Its nomenclatural <type strain> is deposited under identifiers including ATCC19310 and NCPPB281. Such collection identifiers locate reference material; they are not interchangeable with every experimental <bacterial strain> assigned to the species.<Pseudomonas syringae in LPSN>[Species record, parent genus and type-strain deposits]{ref}
A 2011 experiment used the strain reported as <Pseudomonas syringae pv. tomato DC3000> to challenge <Arabidopsis thaliana>. Plants were grown with or without candidate bacterial colonists. Some <Sphingomonas> isolates reduced both pathogen growth and disease symptoms, whereas the tested <Methylobacterium> strains did not show that protective effect. The experiment asked whether prior colonization changed an observed disease outcome, rather than merely whether both organisms could be detected on a leaf.<Protection of Arabidopsis thaliana against leaf-pathogenic Pseudomonas syringae by Sphingomonas strains in a controlled model system by Gerd Innerebner and others>[Abstract; Figures1–2, paired population and symptom measurements]{ref}
Pathogen population and host damage are distinct readouts. In an invented normalized-count example, $10^6$ versus $10^5$ <colony-forming units> per gram of leaf differs tenfold, or by one base-ten logarithmic unit. That calculation alone supplies neither a disease-severity score nor proof of a particular protective mechanism. Host, strain identity and measurement conditions remain part of the interpretation.
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