''Pseudomonas savastanoi'' is a

gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

plant pathogen Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

that infects a variety of

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s. It was once considered a

pathovar A pathovar is a bacterial strain or set of strains with the same or similar characteristics, that is differentiated at infrasubspecific level from other strains of the same species or subspecies on the basis of distinctive pathogenicity to one o ...

of ''

Pseudomonas syringae ''Pseudomonas syringae'' is a rod-shaped, Gram-negative bacterium with polar flagella. As a plant pathogen, it can infect a wide range of species, and exists as over 50 different pathovars, all of which are available to researchers from internat ...

,'' but following DNA-relatedness studies, it was instated as a new species. It is named after Savastano, a worker who proved between 1887 and 1898 that olive knot are caused by bacteria.George M. Garrity: ''

Bergey's Manual of Systematic Bacteriology ''Bergey's Manual of Systematic Bacteriology'' is the main resource for determining the identity of prokaryotic organisms, emphasizing bacterial species, using every characterizing aspect. The manual was published subsequent to the ''Bergey's Manu ...

''. 2. Auflage. Springer, New York, 2005, Volume 2: ''The Proteobacteria, Part B: The Gammaproteobacteria'' The pathovar of greatest economical significance is ''Pseudomonas savastanoi'' pv. ''savastanoi'', which causes the disease

olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...

knot. Symptoms include formation of

galls Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

on infected trees; tumour formation is induced by

indoleacetic acid Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. IAA is a derivative of indole, con ...

biosynthesis by the bacteria, in a similar manner to the well-studied crown gall pathogen, ''

Agrobacterium tumefaciens ''Agrobacterium radiobacter'' (more commonly known as ''Agrobacterium tumefaciens'') is the causal agent of crown gall disease (the formation of tumours) in over 140 species of eudicots. It is a rod-shaped, Gram-negative soil bacterium. Sympto ...

''.Hosni T, et al. 2011. Sharing of quorum-sensing signals and role of interspecies communities in a bacterial plant disease. ISME J. .

History

One of the first scientists to carry out scientific and modern research on the disease of

olive trees The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' 'M ...

caused by ''Pseudomonas savastanoi'' ( it, la rogna dell'ulivo) was

Giuseppe Maria Giovene Giuseppe Maria Giovene (23 January 1753 – 2 January 1837) was an Italian archpriest, naturalist, agronomist, geologist, meteorologist, entomologist and ichthyologist. elogio-storico, pag. 9, note 8 He is best known for his studies on the "nit ...

(1753-1837), who explained his conclusions in his publication ''Sulla rogna degli ulivi'' (1789).

Pathovars

* ''Pseudomonas savastanoi'' causes

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

canker.Smith, Dunez, Lelliot, Phillips and Archer (1988) European Handbook of Plant Disease. Blackwell Scientific Publications. * ''Pseudomonas savastanoi'' attacks

oleander ''Nerium oleander'' ( ), most commonly known as oleander or nerium, is a shrub or small tree cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. It is the only species currently classified in the ge ...

. * ''Pseudomonas savastanoi'' causes

knot. * ''Pseudomonas savastanoi'' attacks ''

Phaseolus ''Phaseolus'' (bean, wild bean) is a genus of herbaceous to woody annual and perennial vines in the family Fabaceae containing about 70 plant species, all native to the Americas, primarily Mesoamerica. It is one of the most economically importan ...

'' (bean) plants B. P Borowicz, A Maćkowiak, H Pospieszny (2002) Improved identification of ''Pseudomonas savastanoi'' pv. ''phaseolicola'' at the molecular level. EPPO Bulletin 32 (3), 467–469.

Quorum sensing

''P. s.'' pv. ''s.'' has an unusual

quorum sensing In biology, quorum sensing or quorum signalling (QS) is the ability to detect and respond to cell population density by gene regulation. As one example, QS enables bacteria to restrict the expression of specific genes to the high cell densities at ...

dynamic: It shares quorum with an entirely different order, the Enterobacterales. Hosni et al., 2011 and Caballo-Ponce et al., 2018 find ''P. s.'' pv. ''s.'' produces very similar ''N''-Acyl homoserine lactones (AHLs) to the Erwiniaceae ''

Erwinia ''Erwinia'' is a genus of Enterobacterales bacteria containing mostly plant pathogenic species which was named for the famous plant pathologist, Erwin Frink Smith. It contains Gram-negative bacteria related to ''Escherichia coli'', ''Shigella'' ...

'' '' toletana'' and ''

Pantoea agglomerans ''Pantoea agglomerans'' is a Gram-negative bacterium that belongs to the family Erwiniaceae. It was formerly called ''Enterobacter agglomerans'', or ''Erwinia herbicola'' and is a ubiquitous bacterium commonly isolated from plant surfaces, seed ...

''. Hosni find an avirulent mutant – defective for AHL production – is restored to virulence by the presence of ''E. toletana'' and ''P. agglomerans''. These results demonstrate disease enhancing cooperation but also reveal a possible way that undiscovered cheating may be occurring.

References

External links

Type strain of ''Pseudomonas savastanoi'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
Pseudomonadales Bacterial plant pathogens and diseases Fruit tree diseases Pulse crop diseases Bacteria described in 1982 {{Pseudomonadales-stub