Synchytrium endobioticum

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Synchytrium endobioticum
Synchytridium endobioticum.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Chytridiomycota
Class: Chytridiomycetes
Order: Chytridiales
Family: Synchytriaceae
Genus: Synchytrium
Species:
S. endobioticum
Binomial name
Synchytrium endobioticum
(Schilb.) Percival (1909)
Synonyms
  • Chrysophlyctis endobioticaSchilb. (1896)

Synchytrium endobioticum is a chytrid fungus that causes the potato wart disease, or black scab. [1] It also infects some other plants of the genus Solanum , though potato is the only cultivated host.

Contents

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. It was first identified and studied by Vera Charles. The New Zealand scientist Kathleen Maisey Curtis also studied Synchytrium endobioticum for her doctoral thesis that, in 1919, resulted in her being recognised as producing groundbreaking research on the organism's pathology. [2]

At least 18 pathotypes of the fungus exist, most of which have quite limited ranges in Central Europe. The most widely distributed is pathotype 1.

Morphology

Like some other Chytridiales, Synchytrium endobioticum develops no mycelium. 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 sori. The motile life stage, zoospore is about 0,5 µm in diameter and has one posterior flagellum.

Life cycle

In spring, at higher temperature and moisture, overwintering sporangia germinate to release motile zoospores 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-sori) undergo a dormancy period and before germination (probably) a meiotic division and several mitotic divisions, becoming a sorus.

Ecology

Synchytrium endobioticum is an obligate parasite 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 almost worldwide distribution in areas where potatoes are cultivated (absent in most of tropical Africa, Middle East, most of Canada, Japan and Australia).

Environment

Cool and wet soils are conducive to potato wart disease development. While there are discrepancies in the reported temperatures for maximal potato wart infection, summers with an average temperature of 18 °C or less, winters below 5 °C, and annual precipitation of 700 mm or more are considered to be favorable for the disease. [3] Soil pH does not appear to be associated with disease occurrence; S. endobioticum infections have been reported in soils with pH ranging from 3.9-8.5. [3]

Overwintering sporangia of S. endobioticum are extremely resilient. Dry sporangia can survive at 100 °C for 11–12 h, [4] composting for 12 days at 60– 65 °C, pasteurization for 90 min at 70 °C, [5] the digestive system of animals feeding on infected tubers, as well as treatment in 1% formaldehyde and 0.1% mercuric chloride for one hour and three hours, respectively. [6] A soil temperature of at least 8 °C and water is required for sporangia germination and the dispersal of zoospores. [7] The microelements B, Cu, Zn, and Mo, have been reported to induce the germination of sporangia following overwintering. [8]

Management

The resilient nature of the resting spores, the overwintering sporangia, is the principal challenge in managing the disease. Several means of control have been explored, including chemical [9] [10] and biological, [11] but have been largely ineffective, impractical, or neglected. Cultivation of resistant varieties is the best management approach. However, the development of resistant varieties is challenged by the discovery of novel pathotypes and the polygenic nature of resistance to potato wart. [12] Despite these challenges, legislative action has been taken that leverages the use of resistant varieties and has effectively curtailed the spread of potato wart. This action enforces the demarcation of contaminated plots and safety zones and the disposal of infected potato material. Safety zones are areas where only resistant varieties can be grown, and potatoes cannot be grown in sites until the absence of sporangia can be demonstrated. These legislative efforts also include measures that forbid the trade of infected potatoes and the presence of the disease in potato seed production.

Pathogenesis

Very little is known about the pathogenesis of S. endobioticum at a molecular level. Indeed, this is true of chytrids more generally, excepting a few well-studied species. [13] However, recent genome sequencing and annotation of S. endobioticum has shed light on the potential molecular mechanisms of pathogenesis. [14] For example, this analysis demonstrated the coding capacity of S. endobioticum to process complex sugars, which may include cellulose and starch. However, genes for cell wall degrading hemicellulases are reduced in S. endobioticum relative to the closely related, saprophytic chytrid, S. microbalum. The lack of hemicellulases may allow the pathogen to evade defense responses triggered by damage-associated molecular patterns from cell wall degradation. [15] Several regions within the genome have been identified as possible effector coding regions, but further work will need to be done to verify this. S. endobioticum did not contain genes coding for enzymes that are crucial to the biosynthesis of purine and pyrimidine. It is probable S. endobioticum exacts purine and pyrimidine from its host.

Added to the United States' federal bioterrorism list for agricultural plant pathogens in 2002, in accordance with the Public Health Security and Bioterrorism Preparedness Response Act.

Outbreaks

In late 2021, the discovery of the fungus in two potato fields on Prince Edward Island in Canada, led the country to ban potato exports from PEI to the United States. [16]

Related Research Articles

<span class="mw-page-title-main">Chytridiomycota</span> Division of fungi

Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek χυτρίδιον, meaning "little pot", describing the structure containing unreleased zoospores. Chytrids are one of the earliest diverging fungal lineages, and their membership in kingdom Fungi is demonstrated with chitin cell walls, a posterior whiplash flagellum, absorptive nutrition, use of glycogen as an energy storage compound, and synthesis of lysine by the α-amino adipic acid (AAA) pathway.

<span class="mw-page-title-main">Mucorales</span> Order of fungi

The Mucorales is the largest and best-studied order of zygomycete fungi. Members of this order are sometimes called pin molds. The term mucormycosis is now preferred for infections caused by molds belonging to the order Mucorales.

Phytophthora sojae is an oomycete and a soil-borne plant pathogen that causes stem and root rot of soybean. This is a prevalent disease in most soybean growing regions, and a major cause of crop loss. In wet conditions the pathogen produces zoospores that move in water and are attracted to soybean roots. Zoospores can attach to roots, germinate, and infect the plant tissues. Diseased roots develop lesions that may spread up the stem and eventually kill the entire plant. Phytophthora sojae also produces oospores that can remain dormant in the soil over the winter, or longer, and germinate when conditions are favourable. Oospores may also be spread by animals or machinery.

<i>Phytophthora palmivora</i> Species of single-celled organism

Phytophthora palmivora is an oomycete that causes bud-rot of palms, fruit-rot or kole-roga of coconut and areca nut. These are among the most serious diseases caused by fungi and moulds in South India. It occurs almost every year in Malnad, Mysore, North & South Kanara, Malabar and other areas. Similar diseases of palms are also known to occur in Sri Lanka, Mauritius, and Sumatra. The causative organism was first identified as P. palmivora by Edwin John Butler in 1917.

<span class="mw-page-title-main">Powdery scab</span> Disease of potatoes

Powdery scab is a disease of potato tubers. It is caused by the cercozoan Spongospora subterranea f. sp. subterranea and is widespread in potato growing countries. Symptoms of powdery scab include small lesions in the early stages of the disease, progressing to raised pustules containing a powdery mass. These can eventually rupture within the tuber periderm. The powdery pustules contain resting spores that release anisokont zoospores to infect the root hairs of potatoes or tomatoes. Powdery scab is a cosmetic defect on tubers, which can result in the rejection of these potatoes. Potatoes which have been infected can be peeled to remove the infected skin and the remaining inside of the potato can be cooked and eaten.

<i>Phytophthora cactorum</i> Species of single-celled organism

Phytophthora cactorum is a fungal-like plant pathogen belonging to the Oomycota phylum. It is the causal agent of root rot on rhododendron and many other species, as well as leather rot of strawberries.

Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosporales and family Peronosporaceae.

Pythium irregulare is a soil borne oomycete plant pathogen. Oomycetes, also known as "water molds", are fungal-like protists. They are fungal-like because of their similar life cycles, but differ in that the resting stage is diploid, they have coenocytic hyphae, a larger genome, cellulose in their cell walls instead of chitin, and contain zoospores and oospores.

<i>Phytophthora erythroseptica</i> Species of single-celled organism

Phytophthora erythroseptica—also known as pink rot along with several other species of Phytophthora—is a plant pathogen. It infects potatoes causing their tubers to turn pink and damages leaves. It also infects tulips (Tulipa) damaging their leaves and shoots.

Sclerophthora macrospora is a protist plant pathogen of the class Oomycota. It causes downy mildew on a vast number of cereal crops including oats, rice, maize, and wheat as well as varieties of turf grass. The common names of the diseases associated with Sclerophthora macrospora include “crazy top disease” on maize and yellow tuft disease on turf grass. The disease is present all over the world, but it is especially persistent in Europe.

<i>Albugo</i> Genus of plant-parasitic oomycetes

Albugo is a genus of plant-parasitic oomycetes. Those are not true fungi (Eumycota), although many discussions of this organism still treat it as a fungus. The taxonomy of this genus is incomplete, but several species are plant pathogens. Albugo is one of three genera currently described in the family Albuginaceae, the taxonomy of many species is still in flux.

<i>Bremia lactucae</i> Species of single-celled organism

Bremia lactucae is a plant pathogen. This microorganism causes a disease of lettuce denominated as downy mildew. Some other strains can be found on 36 genera of Asteraceae including Senecio and Sonchus. Experiments using sporangia from hosts do not infect lettuce and it is concluded that the fungus exists as a quantity of host-specific strains. Wild species, such as Lactuca serriola, or varieties of Lactuca can hold strains that infect lettuce, but these pathogens are not sufficiently common to seriously infect the plant.

<i>Plasmopara viticola</i> Species of single-celled organism

Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather the lesions sporulate and new secondary infections occur.

Phytophthora fragariae is a fungus-like (oomycete) plant pathogen that causes red stele, otherwise known as Lanarkshire disease, in strawberries. Symptoms of red stele can include a red core in the roots, wilting of leaves, reduced flowering, stunting, and bitter fruit. The pathogen is spread via zoospores swimming through water present in the soil, released from sporangia.

Phytophthora megakarya is an oomycete plant pathogen that causes black pod disease in cocoa trees in west and central Africa. This pathogen can cause detrimental loss of yield in the economically important cocoa industry, worth approximately $70 billion annually. It can damage any part of the tree, causing total yield losses which can easily reach 20-25%. A mixture of chemical and cultural controls, as well as choosing resistant plant varieties, are often necessary to control this pathogen.

<i>Conidiobolus coronatus</i> Species of fungus

Conidiobolus coronatus is a saprotrophic fungus, first described by Costantin in 1897 as Boudierella coronata. Though this fungus has also been known by the name Entomophthora coronata, the correct name is Conidiobolus coronatus. C. coronatus is able to infect humans and animals, and the first human infection with C. coronatus was reported in Jamaica in 1965.

<i>Synchytrium</i> Genus of fungi

Synchytrium is a large genus of plant pathogens within the phylum Chytridiomycota. Species are commonly known as false rust or wart disease. Approximately 200 species are described, and all are obligate parasites of angiosperms, ferns, or mosses. Early species were mistakenly classified among the higher fungi because of their superficial similarity to the rust fungi. Anton de Bary and Mikhail S. Woronin recognized the true nature of these fungi and established the genus to accommodate Synchytrium taraxaci, which grows on dandelions, and S. succisae, which grows on Succisa pratensis. Synchytrium taraxaci is the type of the genus. The genus has been divided into 6 subgenera based on differences in life cycles.

<span class="mw-page-title-main">Synchytriaceae</span> Family of fungi

Synchytriaceae is a chytrid fungus family in the division Chytridiomycota. The family was described by German mycologist Joseph Schröter in 1892. The type genus, Synchytrium, contains about 200 species of fungi that are parasitic on flowering plants, ferns, mosses, and algae. Synchytrium endobioticum causes potato wart disease, an economically important disease of cultivated potato.

<i>Physoderma</i> Genus of fungi

Physoderma is a genus of chytrid fungi. Described by German botanist Karl Friedrich Wilhelm Wallroth in 1833, the genus contains some species that are parasitic on vascular plants, including P. alfalfae and P. maydis, causative agents of crown wart of alfalfa and brown spot of corn, respectively. Of the chytrid genera, Physoderma is the oldest. However, species were confused with the rust fungi, the genus Synchytrium, and the genus Protomyces of Ascomycota. Members of Physoderma are obligate parasites of pteridophytes and angiosperms. There are approximately 80 species within this genus.

Black rot on orchids is caused by Pythium and Phytophthora species. Black rot targets a variety of orchids but Cattleya orchids are especially susceptible. Pythium ultimum and Phytophthora cactorum are known to cause black rot in orchids.

References

  1. ↑ Professor Alan Gemmell Gardening, The Mastermind Quiz Book (Editor: Richard Morgale)
  2. ↑ Thomson, A. D. "Lady Kathleen Rigg, pioneer plant scientist". New Zealand Science Monthly Online. Webcentre Ltd. Archived from the original on 14 January 2015. Retrieved 19 March 2015.
  3. 1 2 Weiss, Freeman (July 1925). "The Conditions of Infection in Potato Wart". American Journal of Botany. 12 (7): 413–443. doi:10.1002/j.1537-2197.1925.tb05846.x. ISSN   0002-9122.
  4. ↑ GLYNNE, MARY D. (February 1926). "The Viability of the Winter Sporangium of Synchytrium Endobioticum (Schilb.) Perc., the Organism Causing Wart Disease in Potato". Annals of Applied Biology. 13 (1): 19–36. doi:10.1111/j.1744-7348.1926.tb04250.x. ISSN   0003-4746.
  5. ↑ Steinmöller, Silke; Bandte, Martina; Büttner, Carmen; Müller, Petra (2012-02-09). "Effects of sanitation processes on survival of Synchytrium endobioticum and Globodera rostochiensis". European Journal of Plant Pathology. 133 (3): 753–763. doi:10.1007/s10658-012-9955-y. ISSN   0929-1873. S2CID   14648345.
  6. ↑ Weiss, Freeman (1928). "Factors of spread and repression in potato wart". Technical Bulletin. 56: 13.
  7. ↑ Chisnall Hampson, M. (December 1993). "History, biology, and control of potato wart disease in Canada". Canadian Journal of Plant Pathology. 15 (4): 223–244. doi:10.1080/07060669309501918. ISSN   0706-0661.
  8. ↑ Tarasova, VP (1969). "Role of environment in the decay of warts and germination of zoosporangia of Synchytrium endobioticum on potato". Byull VN 1 1 Zaschity Rastenii.
  9. ↑ Hampson, MC (1977). "Screening systemic fungicides for potato wart disease". Can Plant Dis Surv. 57: 75–78.
  10. ↑ Reigner, N (2006). "Potential chemical controls and crop protection industry contacts for recovery from establishment of select agent plant diseases in U.S. agriculture". Report from the Croplife Foundation Washington DC.
  11. ↑ ROACH, W. A.; GLYNNE, MARY D.; BRIERLEY, WM. B.; CROWTHER, E. M. (May 1925). "Experiments on the Control of Wart Disease of Potatoes by Soil Treatment with Particular Reference to the Use of Sulphur". Annals of Applied Biology. 12 (2): 152–190. doi:10.1111/j.1744-7348.1925.tb02261.x. ISSN   0003-4746.
  12. ↑ Maris, B. (November 1961). "Races of the potato wart causing fungus Synchytrium endobioticum (Schilb.) Perc. and some data on the inheritance of resistance to race 6". Euphytica. 10 (3): 269–276. doi:10.1007/bf00039096. ISSN   0014-2336. S2CID   19403203.
  13. ↑ van de Vossenberg, Bart T.L.H.; Prodhomme, Charlotte; van Arkel, Gert; van Gent-Pelzer, Marga P.E.; Bergervoet, Marjan; Brankovics, Balázs; Przetakiewicz, Jarosław; Visser, Richard G.F; van der Lee, Theo A.J. (2019-05-22). "The Synchytrium endobioticum AvrSen1 triggers a Hypersensitive Response in Sen1 potatoes while natural variants evade detection". doi: 10.1101/646984 . S2CID   182330467.{{cite journal}}: Cite journal requires |journal= (help)
  14. ↑ van de Vossenberg, Bart T. L. H.; Warris, Sven; Nguyen, Hai D. T.; van Gent-Pelzer, Marga P. E.; Joly, David L.; van de Geest, Henri C.; Bonants, Peter J. M.; Smith, Donna S.; Lévesque, C. André; van der Lee, Theo A. J. (2019-06-17). "Comparative genomics of chytrid fungi reveal insights into the obligate biotrophic and pathogenic lifestyle of Synchytrium endobioticum". Scientific Reports. 9 (1): 8672. Bibcode:2019NatSR...9.8672V. doi:10.1038/s41598-019-45128-9. ISSN   2045-2322. PMC   6572847 . PMID   31209237.
  15. ↑ Choi, Hyong Woo; Klessig, Daniel F. (2016-10-26). "DAMPs, MAMPs, and NAMPs in plant innate immunity". BMC Plant Biology. 16 (1): 232. doi: 10.1186/s12870-016-0921-2 . ISSN   1471-2229. PMC   5080799 . PMID   27782807.
  16. ↑ "Trudeau says he brought up P.E.I. potato trade to Biden during U.S. visit". Cbc.ca. Retrieved 1 December 2021.

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