Xanthomonas
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Leaf spot disease in ivy caused by X. campestris pv. Hederae. |
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| Xanthomonas | ||||||||||||
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Dowson 1939 (Approved Lists 1980) |
Xanthomonas (Greek xanthos "yellow", monas " monad ") is a genus of gram-negative bacteria belonging to the Lysobacteraceae family (formerly known as Xanthomonadaceae). The infestation of crops with different species and pathovars (pv.) Of Xanthomonas leads to differently pronounced bacteriosis and in some cases significant damage to the plant and thus to commercially grown crops . However, Xanthomonas is harmless tohumans.
description
Bacteria of the genus Xanthomonas are straight rod-shaped, 0.2–1 × 0.6–4 µm large unicellular cells . For locomotion they are polar flagellated (mostly monotrich). They grow aerobically , are oxidative and do not form spores . In the case of Gram staining, they belong to the Gram-negative group. Xanthomonas bacteria form water-insoluble yellow xanthomonadine color pigments, which may protect the bacterium from photobiological damage after a plant infection. The GC content for the Xanthomonas campestris group is 63.5–69.2 mol%.
Some strains of the species Xanthomonas campestris excrete xanthan . This is produced industrially and added to aqueous solutions to increase viscosity , for example in pudding, diet soups and printing ink.
Xanthomonas as a pathogen
Damage caused by Xanthomonas species and pathovars occurs worldwide and in almost all higher plants. There they cause plant diseases in agricultural crops such as rice , cabbage and wheat that are so important for the global economy . Typical symptoms of damage are: lesions in the form of necrosis on leaves , stems and fruits , wilting mainly on leaves and leaf and stem rot.
Xanthomonas campestris
Most plant diseases are caused by pathovars of the species X. campestris :
Xanthomonas campestris pv. Campestris is responsible for the so-called vein blackening in all cultivated forms of cabbage species such as white cabbage or cauliflower . The disease is a tracheobacteriosis with wilt and rot as a secondary symptom. The bacterium colonizes and clogs the pathways ( trachea ) of the plant and can occur in epidemic form in warm and humid weather .
Xanthomonas campestris pv. Begoniae causes leaf spot disease in cultivated begonias, especially begonias of the Elatior and Lorraine groups. Leaves initially have translucent, oil-spotted leaf spots that later develop into necrosis, often on the leaf margin. The leaf spot disease in the mentioned cultivated begonias is of great importance in correspondingly specialized ornamental plant growers.
Xanthomonas campestris pv. Pelargonii causes bacterial stem and leaf wilt in pelargoniums . The disease is of great importance in particular in the globally relevant culture of Pelargonium-Zonale hybrids and Pelargonium-Peltatum hybrids. Symptoms are the premature wilting of leaves in the lower stem area as well as the rot attack of the stem, which leads to the death of the shoot. Commercially used mother plants for the propagation of appropriate cutting material are therefore only propagated via plant tissue culture using a maximum 1 cm section of the upper shoot section using the bacteria-free apical meristem .
Xanthomonas campestris pv. Hyacinthii leads hyacinths for Gelbfäule . Symptoms of the disease are an overall inhibited budding of the onion and growth stoppages, glassy leaf strips, leaf waste and wilting as well as the escape of yellow juice from rotten areas ( yellow snot ).
Xanthomonas campestris pv. Phaseoli is the causative agent of bean blight . In addition to Phaseolus species, soybeans and lupins are also used as host plants . The bean burn leads to leaf spots and, in the later stage, necrosis of the pod . This leads to the escape of bacterial slime.
Xanthomonas campestris pv. Translucens caused in the grain of wheat that Schwarzspelzigkeit or stripe disease . Various Triticum species serve as host plants .
Xanthomonas campestris pv. Juglandis is the causative agent of walnut brandy in walnuts . Symptoms are necrotic spots in the area of the leaf veins, on young shoots and on fruits that fall off prematurely. It mainly affects older trees. The pathogen can persist in leaf buds.
Xanthomonas campestris pv. Citri causes so-called citrus cancer in citrus plants . The citrus farming in Australia , Brazil and the USA is currently suffering from this bacteriosis . To combat this, the USA issued a ban on the import of Szechuan pepper , which may contain the Xanthomonas bacteria , which are completely harmless to humans . Since 2005, Szechuan pepper previously heated to 70 ° C has been allowed to be reintroduced
Xanthomonas campestris pv. Malvacearum also damages an agriculturally important crop in that the bacterium causes leaf rot when cotton plants are attacked. There is also a seed-borne transmission of this disease.
Xanthomonas campestris pv. Oryzae causes white leaves in rice plants when infected .
Xanthomonas campestris pv. Graminis (and other genus-specific pathovars) primarily damage various forage grasses from the Poaceae family (formerly known as Graminae ) through leaf rot. The further division in genus-specific pathovars such as pv. Poae , arrhenateri or phlei has a further specialization of the bacterium through.
Xanthomonas stewartii
Pantoea stewartii is a pathogen that was previously placedin the genus Xanthomonas as Xanthomonas stewartii , the basonym is Erwinia stewartii . The disease caused by the pathogen is called Stewart's or corn wilt. The disease has been native to America for a long time, has been spread to other parts of the world by seed deliveries and can cause entire corn crops to die off and fail completely. Corn wilt is classified as a quarantine disease in the EU. It overwinters as a seed-borne bacterium in the soil or on remains of maize plants. It is transmitted over winter by the corn flea ( Chaetocnema pulicaria ), while the corn rootworm Diabrotica undecimpunctata and other corn pests are responsible for the vegetation. This disease is combated through the choice of resistant maize varieties, the use of infection-free seeds and early insecticide treatment to ward off disease vectors .
Xanthomonas translucens
Main article: Xanthomonas translucens
Xanthomonas translucens attacks grain and causes black furiness (also called bacterial streak disease).
Individual evidence
- ^ Jean Euzéby, Aidan C. Parte: Family Xanthomonadaceae. In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 16, 2019 .
- ^ Jean Euzéby, Aidan C. Parte: Classification of domains and phyla - Hierarchical classification of prokaryotes (bacteria). In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 16, 2019 .
- ^ AR Poplawsky, SC Urban, W. Chun: Biological Role of Xanthomonadin Pigments in Xanthomonas campestris pv. Campestris. - summary online at Applied and Environmental Microbiology
- ^ Jean Euzéby, Aidan C. Parte: Genus Pantoea. In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 16, 2019 .
- ↑ FAO Plant Protection Bulletin 31.96.
swell
- Günter M. Hoffmann, Franz Nienhaus, Hans-Michael Poehling, Fritz Schönbeck, Heinrich C. Weltzien, Hubert Wilbert: Textbook of Phytomedicine. 3. Edition. Blackwell Wissenschaftsverlag, Berlin 1994. ISBN 3-8263-3008-0
- Pschyrembel Clinical Dictionary , 256th edition. De Gruyter, Berlin 1990. ISBN 3-11-010881-X
- General microbiology ; Georg Thieme Verlag Stuttgart, Hans G. Schlegel. 1992, ISBN 3-13-444607-3
- FAO Plant Protection Bulletin 31.96.
Publications
- Gerhard Reuther, Martin Bahmann: Elimination of Xanthomonas campestris pv. Pelargonii by Means of Micropropagation of Pelargonium Stock Plants; In: 3rd International Geranium Conference, 1992. Proceedings, Ball Publishing Batavia, IL. UNITED STATES; (1992).