Pseudomonas savastanoi is a gram-negative plant pathogenic bacterium that infects a variety of plants. It was once considered a pathovar of Pseudomonas syringae, but following DNA-relatedness studies, it was instated as a new species.[2]It is named after Savastano, a worker who proved between 1887 and 1898 that olive knot are caused by bacteria.[3][4]
| Pseudomonas savastanoi | |
|---|---|
 | |
| Twig of olive-tree with a tumour caused by Pseudomonas savastanoi | |
Scientific classification  | |
| Domain: | Bacteria |
| Phylum: | Pseudomonadota |
| Class: | Gammaproteobacteria |
| Order: | Pseudomonadales |
| Family: | Pseudomonadaceae |
| Genus: | Pseudomonas |
| Species: | P. savastanoi |
| Binomial name | |
| Pseudomonas savastanoi (Janse 1982) Gardan, et al. 1992 | |
| Type strain | |
| ATCC 13522 | |
| Pathovars | |
P. s. pv. fraxini | |
| Synonyms | |
Pseudomonas syringae pv. savastanoi (Smith 1908) Young et al. 1978 | |
The pathovar of greatest economical significance is Pseudomonas savastanoi pv. savastanoi, which causes the disease olive knot.[1] Symptoms include formation of galls on infected trees; tumour formation is induced by indoleacetic acid biosynthesis by the bacteria, in a similar manner to the well-studied crown gall pathogen, Agrobacterium tumefaciens.[5][6]
History
One of the first scientists to carry out scientific and modern research on the disease of olive trees caused by Pseudomonas savastanoi (Italian: la rogna dell'ulivo) was Giuseppe Maria Giovene (1753-1837), who explained his conclusions in his publication Sulla rogna degli ulivi (1789).[7]
Pathovars
Quorum sensing
P. s. pv. s. has an unusual quorum sensing dynamic: It shares quorum with an entirely different order, the Enterobacterales.[10] 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 toletana and Pantoea agglomerans.[10] Hosni find an avirulent mutant – defective for AHL production – is restored to virulence by the presence of E. toletana and P. agglomerans.[10] These results demonstrate disease enhancing cooperation but also reveal a possible way that undiscovered cheating may be occurring.[10]