Physoderma

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Physoderma
Physoderma pulposum on Chenopodium
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Blastocladiomycota
Class: Physodermatomycetes
Order: Physodermatales
Family: Physodermataceae
Genus: Physoderma
Wallr.
(1833)
Type species
Wallr. (1833)[1]
Synonyms[2]

Physoderma is a

Urophlyctis).[5]

Taxonomic history

The genus was erected in 1833 on the basis of resting spore development.

Blastocladiales,[7] which later became the Blastocladiomycota.[8] Recent phylogenetic analyses indicate that Physoderma and Urophlycits might be separate genera.[7]

Morphology & life cycle

Physoderma species are characterized as having a both a monocentric thallus and an endobiotic polycentric thallus. Resting spores germinate in the spring to produce zoospores that will infect the host. The initial infection gives rise to monocentric, epibiotic zoosporangium anchored with endobiotic rhizoids confined to a single host cell. The zoosporangium has been characterized as

Urophlyctis appear to be inoperculate.) The liberated zoospores infect new host cells, and in this fashion, an infection can go through several generations. As well, the sporangia are internally proliferous; that is, they can produce a second round of zoospores after releasing the first one. In late spring and summer, the zoospores will begin to develop into an endobiotic polycentric thallus. This thallus is often extensive, infecting many host cells, with highly branched, fine rhizoids. These rhizoids can bear intercalary cells, which many be once or twice septate (and what Schroeter saw as evidence of sexual reproduction). The endobiotic thallus gives rise to large, thick-walled, dark-colored resting spores that take the shape of the host cell. It appears the resting spores are formed from the intercalary cells. These resting spores will over winter and germinate in the spring.[4][6]

Ecology

Many species of Physoderma infect marsh plants, and several are confined to the submerged portion of hosts.

zoospores, Physoderma species require free water. As an example, P. dulichii requires at least an inch of standing water to initiate the infection of a host plant. Once the plant is infected, however, high humidity, dew, or rain is sufficient to keep the infection going through the growing season.[9]

Species

References

  1. ^ Wallroth KFW. (1833). Flora Cryptogamica Germaniae (in German). Vol. 2. Nürnberg, Germany: J.L. Schrag. p. 192.
  2. ^ "Synonymy: Physoderma Wallr., Fl. crypt. Germ. (Norimbergae) 2: 192 (1833)". Species Fungorum. CAB International. Retrieved 27 March 2014.
  3. ISBN 978-0-12-383877-3
    .
  4. ^ a b c d e f g h Sparrow FK. 1960. Aquatic phycomycetes. 2nd ed. Ann Arbor, Michigan: University of Michigan Press.
  5. ^ a b c d e Karling, J.S. 1977. Chytridiomycetarum Iconographia. Monticello, New York: Lubrecht & Cramer.
  6. ^ a b c d e f Karling, J.S. 1950. The genus Physoderma (Chytridiales). Llyodia. 13(1): 29.
  7. ^ a b c Porter TM, W Martin, TY James, JE Longcore, FH Gleason, PH Adler, PM Letcher, & R Vilgalys. 2011. Molecular phylogeny of the Blastocladiomycota (Fungi) based on nuclear ribosomal DNA. Fungal Biology 115: 381–392.
  8. PMID 17486963
    .
  9. ^ a b Johns RM. 1966. Morphological and ecological study of Physoderma dulichii. American Journal of Botany 53(1):34–45.
  10. ^ Sparrow FK. 1979. Observations on chytridiaceous parasites of phanerograms XXVIII Physodermas on Sium suave. Mycologia 72(2):423–433

External links

Physoderma in Index Fungorum

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