Pseudomonas syringae
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Cultures of Pseudomonas syringae |
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| Pseudomonas syringae | ||||||||||||
| Van Hall , 1904 |
Pseudomonas syringae is a gram-negative , rod-shaped bacterium of the genus Pseudomonas . It wasisolatedas a plant pathogen of the common lilac ( Syringa vulgaris )in 1902. Since it catalyses the ice nucleation of supercooled water, which remains liquid at absolute purity down to −40 ° C, up to a temperature of −1.5 ° C, it is of interest in agriculture and biotechnology.
features
Pseudomonas syringae is a gram-negative , rod-shaped and motile bacterium. It is strictly aerobic and produces fluorescent pigments on media that are low in iron. It is distinguished from other species of the genus Pseudomonas by a negative reaction in oxidase and arginine dihydrolase tests.
Nucleation
A special feature of the bacterium is that intact cells can serve as organic germs for the formation of water ice. It catalyzes the process down to a temperature of −1.5 ° C. This is very effective in that most organic or inorganic particles used for nucleation are active below −10 ° C.
Occurrence
Exact distribution information is missing. However, studies of microorganisms that form ice nuclei have shown that they are ubiquitous on plants ( phyllosphere ). In surveys of 95 plant species, Pseudomonas syringae was found in almost all of them . The extent to which different phyla are dependent on certain plant species has yet to be researched.
These microorganisms belong to the ice-forming organisms that can also be responsible for the formation of snowflakes and raindrops in clouds. The microorganisms sometimes leave the phylosphere and are carried away by the air. In this way, they can also get into the cool, high air layers, where they become the nucleus of crystallization for supercooled water (tiny, −40 ° C to −1.5 ° C cold but still liquid water droplets) , as was only known from solid particles for a long time . First as a snowflake, often thawed into a raindrop in deeper layers of the air, P. syringae falls back to earth as precipitation, where the microorganism can colonize new plants.
Damage pattern
Pseudomonas syringae causes various plant diseases such as tree cancer , wilt or spots. Different strains, so-called pathovars , attack different plant species, including some important crops. Originally 48 pathovars were known. However, after genetic analyzes, many of them were assigned to other Pseudomonas species. The following pathovars of Pseudomonas syringae are known:
- Pseudomonas syringae pv. Aceris attacks maples ( Acer )
- Pseudomonas syringae pv. Actinidiae affects Chinese Actinidia ( Actinidia chinensis ) and is responsible for a significant drop in production of golden kiwifruit in New Zealand .
- Pseudomonas syringae pv. Aesculi attacks the common horse chestnut ( Aesculus hippocastanum )
- Pseudomonas syringae pv. Aptata affects beet ( Beta vulgaris )
- Pseudomonas syringae pv. Atrofaciens attacks common wheat ( Triticum aestivum )
- Pseudomonas syringae pv. Dysoxylis attacks Dysoxylum spectabile
- Pseudomonas syringae pv. Glycinea infects soybean ( Glycine max )
- Pseudomonas syringae pv. Japonica attacks barley ( Hordeum vulgare )
- Pseudomonas syringae pv. Lapsa attacks common wheat ( Triticum aestivum )
- Pseudomonas syringae pv. Maculicola attacks potatoes ( Solanum tuberosum )
- Pseudomonas syringae pv. Panici infects bluegrass ( Panicum )
- Pseudomonas syringae pv. Papulans attacks crab apple ( Malus sylvestris )
- Pseudomonas syringae pv. Phaseolicola attacks bean ( Phaseolus vulgaris )
- Pseudomonas syringae pv. Pisi attacks peas ( Pisum sativum )
- Pseudomonas syringae pv. Syringae attacks species of the genera lilac ( Syringa ), Prunus and Phaseolus
- Pseudomonas syringae pv. Tabaci attacks tobacco ( Nicotiana )
- Pseudomonas syringae pv. Tomato infects tomato ( Solanum lycopersicum ) is called Modellpathogen for studies of thale cress ( Arabidopsis thaliana ) and Nicotiana attenuata used
Importance in agriculture and biotechnology
Since this bacterium causes frost damage to plants, field trials were carried out in the USA in 1983 with strains that lack the ice-nucleating gene (ice-). The aim was to promote intraspecific competition between the wild-type strain and the mutated strain and thus to reduce frost damage in potato plants. This was one of the first deliberate releases of genetically modified microorganisms.
Due to its ice-forming properties, the bacterium is also used in the production of artificial snow.
Individual evidence
- ↑ Leroy R. Maki, Elizabeth L. Galyan, Mei-Mon Chang-Chien and Daniel R. Caldwell: Ice Nucleation Induced by Pseudomonas syringae . Applied Microbiology, Vol. 28, No. 3, 1974, pp. 456-459. PMC 186742 (free full text)
- ^ Rain phenomena. (Original title: Rain.) Episode in: TV series 'Mysterious Planet' (Original title: 'Secrets of the Earth'), Season 1, Episode 1 (Pilot), USA, 2013, German first broadcast: December 2, 2013, episode online view from March 23 to April 21, 2014 . Accessed March 23, 2014.
- ↑ L. Gardan, H. Shafik, S. Belouin, R. Broch, F. Grimont and PAD Grimont: DNA relatedness among the pathovars of Pseudomonas syringae and description of Pseudomonas tremae sp. nov. and Pseudornonas cannabina sp. nov. (ex Sutic and Dowson 1959) . International Journal of Systematic Bacteriology, Vol. 49, 1999, 469-478
- ↑ James C. Liao, Kam C. Ng: Effect of ice nucleators on snow making and spray freezing . Industrial & Engineering Chemistry Research, Vol. 29 (3), 1990, pp. 361-366. doi : 10.1021 / ie00099a010
literature
- Susan S. Hirano: Ecology and Physiology of Pseudomonas syringae . In: Nature Biotechnology . Volume 3, 1985, pp. 1073-1078. doi : 10.1038 / nbt1285-1073
