Pythium porphyrae

Pythium porphyrae, is a parasitic species of oomycete in the family Pythiaceae.[6] It is the cause of red rot disease or red wasting disease, also called akagusare (赤ぐされ) in Japanese.[2][7] 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.[8] However, many of its hosts have been moved from the genus Porphyra to Pyropia.

This article is about the organism that causes red rot disease in seaweeds. For the chemical process that degrades leather, see red rot.

Pythium porphyrae
Not evaluated (IUCN 3.1)[1]
Scientific classification
Kingdom: Chromista
Phylum: Oomycota
Order: Peronosporales
Family: Pythiaceae
Genus: Pythium
Species:
P. porphyrae
Binomial name
Pythium porphyrae
M. Takah. & M. Sasaki, 1977[2]
Synonyms[3][4][5]
  • Pythium chondricola De Cock, 1986

Economic impact

P. porphyrae can destroy an entire crop of nori within 3 weeks.[9][10][7] It prefers low salinity and warm water (24-28 °C).[11][12][13][7] It will only grow in the 15-35 °C range.[14] Mild winters correlate with higher infestations and lower crop yields,[15] possibly due to decreased temperatures inducing the development of sex organs in the oomycete.[2] Losses can be combated by destroying diseased fronds and exposing thalli to the air for 3–4 hours daily.[7] The oospores can be spread in contaminated organic matter and the sporangia can spread through the water.[16]

Description

P. porphyrae has a mycelial thallus that is eucarpic, meaning only part of the thallus turns into sporangia.[16] It is primarily a facultative parasite of algae, but can also be saprobic.[16]

Its hyphae can grow up to 4.5 µm wide,[14][16] and are not septate.[2] On algae, the hyphae will extend through the cell wall.[2] It does not have haustoria not chlamydospores.[16] The appressoria are club-shaped.[16] It has sporangia that are unbranched, filamentous,[2][4] and non-inflated,[4] typically forming 6-17 zoospores per vesicle.[2][14][16] Encysted zoospores are 8-12 µm in diameter.[16] Hyphal swellings are intercalary and globose, from 12-28 µm in diameter.[16] Oogonia average 17 µm in diameter and are also intercalary and globose, but rarely are terminal.[14][16] In each oogonium are 1-2 diclinous antheridia[4][16][2] coming out far away from the oogonial stalk.[14] The antheridia's cells are clavate (club shaped) or globose.[2][14][16] The antheridia will be apical to the oogonial wall.[16] Sometimes there will be two antheridial cells on one stalk.[14] The yellowish oospores average 15 µm in diameter, have thick (~2 µm) walls, and are plerotic (fill the whole oogonium).[14][16] Conidia are spherical at 8.8-30.8 μm diameter, but rarely produced.[2]

P. porphyrae shares many physical traits with P. marinum and P. monospermum,[14] and appears to be most closely related to P. adhaerens.[3][4] However it has up to four diclinous antheridia and sometimes two antheridial cells per stalk; P. monospermum has 1-4 either diclinous or monoclinous antheridia and P. marinum has only a single diclinous antheridium.[14] P. monospermum and P. marinum also have oogonia terminally on short branches, yet in P. porphyrae they tent to be intercalary.[14]

In a laboratory it will grow 5 mm per day[4] on seawater-cornmeal agar with low aerial mycelium[16] and colorless colonies,[2] but will not grow at all on potato-carrot agar.[14]

Ecology

P. porphyrae has been found in Japan,[2] Netherlands, New Zealand,[3] and Korea, but this range is likely underreported.[16] It has a parasitic relationship with the following hosts. Though some species of Pyropia and Porphyra are susceptible to infection in their gametophytic phase, they are resistant in their Conchocelis (sporophytic) phase.[3]

Taxonomy

A 2005 study concerning a case of Pythiosis from a related species (P. insidiosum) indicated that P. porphyrae is related to P. dissotocum, P. myriotylum, P. volutum, and P. vanterpoolii.[18]

In 2004, molecular analysis of Pythium determined that P. porphyrae is in "Clade A" along with P. adhaerens, P. deliense, P. aphanidermatum, and P. monospermum[4] Clade A has two clusters, and P. porphyrae shares one with the species also originating on algae, P. adhaerens.[4]

A 2017 study of Pythium species in Clade A showed the following phylogenetic tree.[3] It further demonstrated that P. porphyrae and P. chondricola are the same species.[3][4] P. adhaerens may also be conspecific based solely on genetic comparison, but showed a number of physical differences that show it may be a separate but very closely related species.[3]

 
 
 

P. deliense

 
 

P. aphanidermatum

 
 
 
 

P. monospermum

 
 
 

P. adhaerens

 
 

P. porphyrae/P. chondricola

 
 
 
 
 

P. insidiosum

 
gollark: Probably not practical to do it in the US *now*, though, or most other places.
gollark: Also, New Zealand managed it.
gollark: The timing matters, though.
gollark: There's not enough testing capacity to make all that work.
gollark: That's not very practical.

See also

References
  1. "Pythium porphyrae". IUCN Red List of Threatened Species. 2017. Retrieved 4 October 2017. This taxon has not yet been assessed for the IUCN Red List, but is in the Catalogue of Life: Pythium porphyrae M. Takah. & M. Sasaki, 1977
  2. Takahashi, Minoru; Ichitani, Takio; Sasaki, Minoru (1977). "ノリ赤腐病を起因するPythium porphyrae" [Pythium porphyrae sp. nov. causing red rot of marine algae Porphyra spp.]. Transactions of the Mycological Society of Japan. 18 (3): 279–285.
  3. Diehl, Nora; Kim, Gwang Hoon; Zuccarello, Giuseppe C. (March 2017). "A pathogen of New Zealand Pyropia plicata (Bangiales, Rhodophyta), Pythium porphyrae (Oomycota)" (PDF). Algae. 32 (1): 29–39. doi:10.4490/algae.2017.32.2.25. ISSN 1226-2617. OCLC 7067179428. Retrieved 5 October 2017.
  4. LéVesque, C.André; De Cock, Arthur W.A.M. (December 2004). "Molecular phylogeny and taxonomy of the genus Pythium". Mycological Research. 108 (12): 1363–1383. doi:10.1017/S0953756204001431. ISSN 0953-7562. OCLC 358362888.
  5. "Pythium porphyrae". MycoBank. Utrecht, Netherlands. 2016. Retrieved 4 October 2017.
  6. "Pythium porphyrae". NCBI Taxonomy. Bethesda, MD: National Center for Biotechnology Information. Retrieved 2 October 2017. Lineage( full ) cellular organisms; Eukaryota; Stramenopiles; Oomycetes; Pythiales; Pythiaceae; Pythium
  7. Andrews, John H. (May 1976). "The Pathology of Marine Algae. Diseases caused by phycomycetes: Chytridiomycetes; Hyphochytridiomycetes; Oomycetes". Biological Reviews. 51 (2): 211–252. doi:10.1111/j.1469-185X.1976.tb01125.x. ISSN 1464-7931.
  8. Griffith, Chuck (2005). "Dictionary of Botanical Epithets". Dictionary of Botanical Epithets. Retrieved 3 October 2017. purple-red porphyra porphyr noun/f πορφυρα the purple-fish or the dye that was made from it
  9. Arasaki, S. (1956). "The diseases of asakusanori and their control" [The diseases of asakusanori and their control]. 病蟲害雜誌 (Plant Protection) (in Japanese). 10: 243–6. OCLC 41036343.
  10. ARASAKI, S. (1962). Studies on the artificial culture of Porphyra tenera Kjellm. 111. On the red wasting disease of Porphyra, especially on the physiology of the causal fungus Pythium sp.nov. [In Japanese, English summary.] Journal of the Agricultural Laboratory, Abiko, Japan. Central Research Institute of Electric Power Industry 3, 87-93
  11. Arasaki, Satoshi (1947). "アサクサノリめ腐敗病に關する研究" [Studies on the Wasting Disease of the Cultured Lavers (Porphyra tenera)]. Nippon Suisan Gakkaishi (Bulletin of the Japanese Society of Scientific Fisheries) (in Japanese). 13 (3): 74–90. doi:10.2331/suisan.13.74. ISSN 0021-5392.
  12. SUTO, S., SAITO, Y., AKIYAMA, K. & UMEBAYASHI, 0. (1972). Text Book of Diseases and their Symptoms in Porphyra. [In Japanese.] Contribution E, Number I 8 of Tokai Regional Fisheries Research Laboratory, Japan. 37 pp.
  13. SAKURAI, Y., AKIYAMA, K. & SATO, S. (1974). On the formation and the discharge of zoospores of Pythium porphyrae in experimental conditions. [In Japanese, English summary.] Bulletin of the Tohoku Regional Fisheries Research Laboratory (33), I 19-27.
  14. van der Plaats-Niterink, J. (22 December 1981). "IX. Descriptions of the recognized species". Monograph of the genus Pythium. Studies in Mycology. 21. Baarn, Netherlands: Centraalbureau voor Schimmelcultures. OCLC 474297038. Retrieved 6 October 2017.
  15. Suto, S (1953). "Seaweed production and phycological research in Japan". Proceedings of the 1st International Seaweed Symposium, Edinburgh, 14–17 July 1952: 96–99. OCLC 22404162.
  16. Spencer, M. A. (2004). "Pythium porphyrae. (Descriptions of Fungi and Bacteria)". IMI Descriptions of Fungi and Bacteria. 162 (Sheet 1617). Retrieved 10 October 2017. A description is provided for Pythium porphyrae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASES: Red-rot disease, red-wasting disease. HOSTS: Bangia atropurpurea, Callophyllis adhaerens, Polyopes affinis (syn
  17. "Turkish Washcloth or Black Tar Spot". Slater Museum of Natural History. Slater Museum of Natural History. Marine Panel. Tacoma, WA: University of Puget Sound. 2017. Retrieved 6 October 2017.
  18. Rivierre, Christine; Laprie, Caroline; Guiard-Marigny, Olivier; Bergeaud, Patrick; Berthelemy, Madeleine; Guillot, Jacques (March 2005). "Pythiosis in Africa". Emerging Infectious Diseases. 11 (3): 479–481. doi:10.3201/eid1103.040697. ISSN 1080-6059. OCLC 815385893. PMC 3298269. PMID 15757572. Retrieved 5 October 2017.
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