Synchytrium endobioticum
Encyclopedia
Synchytrium endobioticum is a chytrid fungus that causes the potato wart disease or black scab. It also infects some other plants of the Solanum
genus, though potato
is the only cultivated host
.
At least 18 pathotypes of the fungus exist, most of them with quite limited ranges in Central Europe. The most widely distributed is the pathotype 1.
. The fungus produces a thick walled structure known as a winter sporangium
. It is 25-75 µm in diameter and contains 200-300 spores. Sporangia are clustered into thin-walled sorus
es.
The motile life stage, zoospore
is about 0,5 µm in diameter and has one posterior flagellum
.
s which infect suitable host epidermal
cells. In infected cells, the summer sporangia develop, which quickly release new populations of zoospores. The infection cycle may be repeated as long as infection conditions are suitable. The infected plant cells swell, divide and surround the dividing zoospores resulting in the wart.
Under certain stress conditions some zoospore pairs fuse, resulting in a zygote
. The zygote bearing host cells divide, forming eventually the walls of a new winter sporangium. In autumn, the warts rot and disintegrate, releasing new thick-walled resting spores of the fungus into the soil. The diploid resting spores (pro-sorus
es) undergo a dormancy period and before germination (probably) a meiotic division and several mitotic divisions, becoming a sorus.
that infects several plants of the genus Solanum
. The most favourable conditions for its development are warm temperatures (but not over 20°C) with enough humidity. Winter sporangia can remain viable for up to 20-30 years. It can survive at depths of 50 cm in the soil. Three different fungi have been observed to parasitize the resting sporangia.
S. endobioticum originates from the Andean region of South-America, with now almost worldwide distribution in areas where potatoes are cultivated (absent in most of tropical Africa
, Middle East
, most of Canada
, Japan
and Australia
).
list for agricultural plant pathogens in 2002 in accordance with the Public Health Security and Bioterrorism Preparedness Response Act
.
Solanum
Solanum, the nightshades, horsenettles and relatives, is a large and diverse genus of annual and perennial plants. They grow as forbs, vines, subshrubs, shrubs, and small trees, and often have attractive fruit and flowers. Many formerly independent genera like Lycopersicon or Cyphomandra are...
genus, though potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
is the only cultivated host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
.
Systematics
Traditionally, Synchytrium endobioticum has been placed to the subgenus Mesochytrium, but it has been suggested that on the basis of the mode of germination it should be transferred to the subgenus Microsynchytrium.At least 18 pathotypes of the fungus exist, most of them with quite limited ranges in Central Europe. The most widely distributed is the pathotype 1.
Morphology
Like some other Chytridiales, Synchytrium endobioticum develops no myceliumMycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
. The fungus produces a thick walled structure known as a winter sporangium
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
. It is 25-75 µm in diameter and contains 200-300 spores. Sporangia are clustered into thin-walled sorus
Sorus
A sorus is a cluster of sporangia .In fungi and lichens, the sorus is surrounded by an external layer. In some red algae it may take the form of a depression into the thallus....
es.
The motile life stage, zoospore
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some algae, bacteria and fungi to propagate themselves.-Flagella:...
is about 0,5 µm in diameter and has one posterior flagellum
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
.
Life cycle
In spring, at higher temperature and moisture, overwintering sporangia germinate to release mobile zoosporeZoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some algae, bacteria and fungi to propagate themselves.-Flagella:...
s which infect suitable host epidermal
Epidermis (botany)
The epidermis is a single-layered group of cells that covers plants' leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds,...
cells. In infected cells, the summer sporangia develop, which quickly release new populations of zoospores. The infection cycle may be repeated as long as infection conditions are suitable. The infected plant cells swell, divide and surround the dividing zoospores resulting in the wart.
Under certain stress conditions some zoospore pairs fuse, resulting in a zygote
Zygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
. The zygote bearing host cells divide, forming eventually the walls of a new winter sporangium. In autumn, the warts rot and disintegrate, releasing new thick-walled resting spores of the fungus into the soil. The diploid resting spores (pro-sorus
Sorus
A sorus is a cluster of sporangia .In fungi and lichens, the sorus is surrounded by an external layer. In some red algae it may take the form of a depression into the thallus....
es) undergo a dormancy period and before germination (probably) a meiotic division and several mitotic divisions, becoming a sorus.
Ecology
Synchytrium endobioticum is an obligate parasiteObligate parasite
An obligate parasite is a parasitic organism that cannot complete its life cycle without dependence on its host.-See also:*Obligate intracellular parasite*Parasitism*Parasitic plant*Facultative parasite...
that infects several plants of the genus Solanum
Solanum
Solanum, the nightshades, horsenettles and relatives, is a large and diverse genus of annual and perennial plants. They grow as forbs, vines, subshrubs, shrubs, and small trees, and often have attractive fruit and flowers. Many formerly independent genera like Lycopersicon or Cyphomandra are...
. The most favourable conditions for its development are warm temperatures (but not over 20°C) with enough humidity. Winter sporangia can remain viable for up to 20-30 years. It can survive at depths of 50 cm in the soil. Three different fungi have been observed to parasitize the resting sporangia.
S. endobioticum originates from the Andean region of South-America, with now almost worldwide distribution in areas where potatoes are cultivated (absent in most of tropical Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
, most of Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
).
Legal
Added to the federal bioterrorismBioterrorism
Bioterrorism is terrorism involving the intentional release or dissemination of biological agents. These agents are bacteria, viruses, or toxins, and may be in a naturally occurring or a human-modified form. For the use of this method in warfare, see biological warfare.-Definition:According to the...
list for agricultural plant pathogens in 2002 in accordance with the Public Health Security and Bioterrorism Preparedness Response Act
Public Health Security and Bioterrorism Preparedness Response Act
Signed into effect on 12 June 2002, the Public Health Security and Bioterrorism Preparedness Response Act, was signed by the President, the Department of Health and Human Services DHHS and the U.S...
.