Globisporangium sylvaticum

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Globisporangium sylvaticum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Oomycota
Order: Peronosporales
Family: Pythiaceae
Genus: Globisporangium
Species:
G. sylvaticum
Binomial name
Globisporangium sylvaticum
(W.A. Campb. & F.F. Hendrix) Uzuhashi, Tojo & Kakish., 2010
Synonyms

Pythium sylvaticum

Globisporangium sylvaticum is a plant pathogen, an oomycete known to cause root rot and damping off in a multitude of species. These species include apples, carrot, cherry laurel, cress, cucumber, garlic, lettuce, pea, rhododendron, and spinach. [1] Symptoms of infection include stunting, wilt, chlorosis, and browning and eventual necrosis of roots. [2] The pathogen can by identified by the presence of thick, microscopic, round spores within the cells of the root.

Contents

The species was formerly placed in the genus Pythium , but that genus has been divided into five distinct clades, each characterized by the morphology of the sporangium. [3]

Disease cycle

Globisporangium sylvaticum is known to be heterothallic, whereas other species in the basionym Pythium were consistently known to be homothallic. [4] Additionally, oospores have been shown to occur only in specific pairings of certain sporangial isolates, a finding which reinforces its heterothallic nature. [4] Since the pathogen is an oomycete, it is known to produce several types of spores including sporangia, zoospores, and oospores. [5]

The pathogen begins its life cycle in the growth stage by constructing a well developed mycelium made of hyaline hyphae. This mycelium is the actively growing body of the pathogen and is responsible for the infection of the host, the subsequent colonization of the host plant, and the uptake of nutrients from its host.

This hyphal growth can occur in two different ways within Globisporangium sylvaticum, asexually or sexually.

During its asexual life cycle the pathogen produces sporangium that occur terminally and intercalary, and are globose and thin walled in shape as well as sub-globose and lemon shaped, respectively. [6] After a period of time biflagellate zoospores begin to develop within the protoplasm of the sporangium and are subsequently released during the proper conditions. [3] The motile zoospores proliferate through the vector medium until they reach the infection court of its host, in this case the seed or the roots. Once at the infection court, the zoospores encyst themselves on the root tips or seed of the host thereby infecting it and resulting in the occurrence of more mycelial growth and the eventual damping off/ root rot of the host plant.

However, during the sexual lifecycle the pathogen, as previously mentioned, needs two different compatible isolates to form a diploid structure called an oospore. The oospore is a survival structure for the pathogen which only germinates during non-adverse conditions. [1] In the case of Globisporangium sylvaticum, the oospore is globose, aplerotic(space between oospore wall and oogonium wall) and thick walled. [3] [6] The formation of the oospore is caused by the fusion of an antheridia and an oogonium, the male and female reproductive parts, respectively. The antheridia in Globisporangium sylvaticum is characterized as being diclinous and branched while the oogonia are intercalary and sub-globose. [3] [6] After an oospore is formed as a result of the fusion between the aforementioned reproductive structures the pathogen continues to undergo cell division giving rise to the mycelium where both cycles repeat under the proper conditions.

Environment

A moist environment is required for the propagation and dispersal of Globisporangium sylvaticum. The pathogen produces highly motile zoospores, which use flagella for locomotion. In the presence of water, the zoospore will use its flagella to propel itself through the surrounding water, in the direction of a prospective infection court. [7] In adverse environmental conditions, the pathogen exists in a structure called an oospore. This structure protects the pathogen for extended periods until conditions for its propagation are satisfied. [8] Additionally, during ideal temperature conditions, it has been observed that optimal radial growth for Globisporangium sylvaticum occurs between 28 °C and 30 °C. During this temperature range the pathogen has been observed to grow 2.7 cm over a 24-hour period. [6]

Related Research Articles

<span class="mw-page-title-main">Oomycete</span> Fungus-like eukaryotic microorganism

The Oomycetes, or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result of contact between hyphae of male antheridia and female oogonia; these spores can overwinter and are known as resting spores. Asexual reproduction involves the formation of chlamydospores and sporangia, producing motile zoospores. Oomycetes occupy both saprophytic and pathogenic lifestyles, and include some of the most notorious pathogens of plants, causing devastating diseases such as late blight of potato and sudden oak death. One oomycete, the mycoparasite Pythium oligandrum, is used for biocontrol, attacking plant pathogenic fungi. The oomycetes are also often referred to as water molds, although the water-preferring nature which led to that name is not true of most species, which are terrestrial pathogens.

<i>Saprolegnia</i> Genus of single-celled organisms

Saprolegnia is a genus of water moulds often called cotton moulds because of the characteristic white or grey fibrous patches they form. Current taxonomy puts Saprolegnia as a genus of the heterokonts in the order Saprolegniales.

<i>Pythium</i> Genus of single-celled organisms

Pythium is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but Pythium insidiosum is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequently a vector for their transmission.

Aphanomyces euteiches is a water mould, or oomycete, plant pathogen responsible for the disease Aphanomyces root rot. The species Aphanomyces euteiches can infect a variety of legumes. Symptoms of the disease can differ among hosts but generally include reduced root volume and function, leading to stunting and chlorotic foliage. Aphanomyces root rot is an important agricultural disease in the United States, Europe, Australia, New Zealand, and Japan. Management includes using resistant crop varieties and having good soil drainage, as well as testing soil for the pathogen to avoid infected fields.

<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.

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

Phytophthora medicaginis is an oomycete plant pathogen that causes root rot in alfalfa and chickpea. It is a major disease of these plants and is found wherever they are grown. P. medicaginis causes failure of stand establishment because of seedling death. Phytophthora medicaginis is part of a species complex with Phytophthora megasperma.

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.

Pythium ultimum is a plant pathogen. It causes damping off and root rot diseases of hundreds of diverse plant hosts including corn, soybean, potato, wheat, fir, and many ornamental species. P. ultimum belongs to the peronosporalean lineage of oomycetes, along with other important plant pathogens such as Phytophthora spp. and many genera of downy mildews. P. ultimum is a frequent inhabitant of fields, freshwater ponds, and decomposing vegetation in most areas of the world. Contributing to the widespread distribution and persistence of P. ultimum is its ability to grow saprotrophically in soil and plant residue. This trait is also exhibited by most Pythium spp. but not by the related Phytophthora spp., which can only colonize living plant hosts.

Pythium aphanidermatum is a soil borne plant pathogen. Pythium is a genus in the class Oomycetes, which are also known as water molds. Oomycetes are not true fungi, as their cell walls are made of cellulose instead of chitin, they are diploid in their vegetative state, and they form coenocytic hyphae. Also, they reproduce asexually with motile biflagelette zoospores that require water to move towards and infect a host. Sexually, they reproduce with structures called antheridia, oogonia, and oospores.

Pythium aristosporum is a species of pythium under the class oomycota that causes root dysfunction in creeping bentgrass.

Pythium graminicola is a plant pathogen infecting cereals.

Pythium myriotylum is a soil-borne oomycete necrotroph that has a broad host range, this means that it can infect a wide range of plants.

Pythium volutum is a plant pathogen infecting wheat, barley, and turfgrass. It is known to be sensitive to some of the compounds typically present in selective media commonly used for isolating Pythium spp., so isolation may require alternative methods.

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.

Aphanomyces cochlioides is a plant pathogen that can affect commodity crops like spinach, Swiss chard, beets and related species. In spinach the pathogen is responsible for the black root "rot" that can damage plants.

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

Phytophthora capsici is an oomycete plant pathogen that causes blight and fruit rot of peppers and other important commercial crops. It was first described by L. Leonian at the New Mexico State University Agricultural Experiment Station in Las Cruces in 1922 on a crop of chili peppers. In 1967, a study by M. M. Satour and E. E. Butler found 45 species of cultivated plants and weeds susceptible to P. capsici In Greek, Phytophthora capsici means "plant destroyer of capsicums". P. capsici has a wide range of hosts including members of the families Solanaceae and Cucurbitaceae as well as Fabaceae.

Pythium dissotocum is a plant pathogen infecting strawberry and rice.

Pythium porphyrae, is a parasitic species of oomycete in the family Pythiaceae. It is the cause of red rot disease or red wasting disease, also called akagusare (赤ぐされ) in Japanese. The specific epithet porphyrae (πορφυρα) stems from the genus of one of its common hosts, Porphyra, and the purple-red color of the lesions on the thallus of the host. However, many of its hosts have been moved from the genus Porphyra to Pyropia.

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.

Cranberry Root Rot (CRR) is a disease in cranberries that can cause a decline in yield.

References

  1. 1 2 Pettitt, Tim (April 2015). A desk-study to review global knowledge on best practice for Oomycete root-rot detection and control (Report).
  2. ↑ Moorman, Gary W. (12 June 2004). "Pythium". Penn State Extension.
  3. 1 2 3 4 Uzuhashi, Shihomi; Kakishima, Makoto; Tojo, Motoaki (September 2010). "Phylogeny of the genus Pythium and description of new genera". Mycoscience. 51 (5): 337–365. doi:10.1007/s10267-010-0046-7. S2CID   83622477.
  4. 1 2 Papa, K. E.; Campbell, W. A.; Hendrix, F. F. (1967). "Sexuality in Pythium sylvaticum: Heterothallism". Mycologia. 59 (4): 589–595. doi:10.2307/3757088. JSTOR   3757088. PMID   6042863.
  5. ↑ Heffer, V.; Powelson, M. L.; Johnson, K. B. (2002). "Oomycetes". The Plant Health Instructor. doi:10.1094/PHI-I-2002-0225-01.
  6. 1 2 3 4 Campbell, W. A.; Hendrix, F. F. (1967). "A New Heterothallic Pythium from Southern United States". Mycologia. 59 (2): 274–278. doi:10.2307/3756800. JSTOR   3756800.
  7. ↑ Raftoyannis, Yannis; Dick, Michael W. (1 January 2006). "Zoospore encystment and pathogenicity of Phytophthora and Pythium species on plant roots". Microbiological Research. 161 (1): 1–8. doi:10.1016/j.micres.2005.04.003. PMID   16338584.
  8. ↑ "Pythium". Integrated Pest Management. 7 July 2015.
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