Alternaria tenuissima

Alternaria tenuissima
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Subdivision: Pezizomycotina
Class: Dothideomycetes
Subclass: Pleosporomycetidae
Order: Pleosporales
Family: Pleosporaceae
Genus: Alternaria
Species: A. tenuissima
Binomial name
Alternaria tenuissima
Samuel Paul Wiltshire (1933)
Synonyms

Alternaria tenuissima is a saprophytic fungus and opportunistic plant pathogen. It is cosmopolitan in distribution, and can colonize a wide range of plant hosts.[1] Colonies of A. tenuissima produce chains on agar growth media.[1] The fungus often forms concentric ring patterns on infected plant leaves[2] or fruits, particularly citrus.[3] This species produces the allergen Alt a 1, one of the most important outdoor seasonal fungal allergens associated with allergy and asthma provocation.[4] In rare circumstances, this species is also known to infect immunosuppressed humans and animals.[5]

Growth and morphology

Unlike many other species of Alternaria, the conidiophores of A. tenuissima can develop in darkness after the colony has been exposed to light even very briefly; however its growth is more robust with longer periods of light exposure.[6] After 5–7 days in culture, colonies of A. tenuissima reach a diameter of 5 cm on PCA or V-8 agar (vegetable juice agar).[1] Colonies grown on PCA are brown in colour with a loose, cottony texture and bearing golden-brown conidia in chains.[1] Conidia are on the areas of the colony that receive the most light exposure, forming concentric sporulating rings of uncrowded conidial chains growing from branching hyphae on PCA.[1] Sporulation tends to be much more crowded in colonies grown on V-8 agar.[1] Simple unbranched and branched conidial chains of moderate length as well as solitary conidia are interspersed across the colony especially areas that receive little light.[1]

The light, golden-brown colour of the conidia, and their tendency to taper into long beaks, distinguish A. tenuissima from similar species notably A. alternata which produces dark brown conidia with short beaks.[5] Conidia of A. tenuissima also grow individually or in short chains[7] of 2-5 units,[1] while A. alternata tends to grow in longer chains.[8] Alternaria tenuissima conidia are smooth-walled[7] and have a median and subconstricting transverse septum.[1] Colonies of A. tenuissima on natural substrates (e.g., plant leaves) often develop a concentric, ringed pattern.[2] This species is also responsible for "black rot" of citrus fruits.[3]

Physiology

Alternaria tenuissima is a saprophyte, living on dead matter.[9] It produces the mycotoxins alternariol (AOH), alternariol methyl ester (AME), altenuene (ALT), altertoxin (ATX), and tenuazonic acid (TA), that are variously involved pathogenicity and interference competition.[9] Mycotoxins of this species are optimally produced at 25 °C.[10]

Habitat and ecology

Alternaria tenuissima is a cosmopolitan species, common on an array of various plant hosts in many countries spanning a range of environmental conditions.[11] It often colonizes blueberries,[12] tomatoes, grapevine, and strawberries.[8] It has also been found on several cereal grain species.[9] Optimal growth occurs between 25–30 °C (77–86 °F).[13] Although A. tenuissima is normally an opportunistic pathogen of plants, rare cases of skin infections in immunocompromised people have been reported.[14][15]

Medical significance

Cutaneous and subcutaneous alternariosis is a skin or tissue infection caused by members of the genus Alternaria, most commonly A. alternata and A. tenuissima.[5] Because of the inability of A. tenuissima to invade healthy host tissue, alternariosis tends to be restricted to people with abrogated cellular immunity and occasionally the elderly.[5] Complication following organ transplantion, Cushing's syndrome and immunosuppressive therapies are some of the typical settings in which alternariosis has been reported.[5] Alternariosis appears on the skin as red pustules that may produce ulcers over time.[5] Alternaria tenuissima is a prolific producer of the allergen Alt a 1.[16] Exposure to this protein can induce an allergic reaction in sensitized individuals by reacting with circulating IgE antibody.[4] Exposure to Alt a 1 has been associated with asthmatic exacerbation.[17] Alternaria tenuissima also produces the mycotoxin tenuazonic acid[18] which has received attention as a candidate antitumor medication.[19]

External links

References

  1. 1 2 3 4 5 6 7 8 9 Simmons, Emory G. (2007). Alternaria: An Identification Manual (fully illustrated and with catalogue raisonné 1796-2007). Utrecht, The Netherlands: CBS Fungal Biodiversity Centre. pp. 500–502. ISBN 978-90-70351-68-7.
  2. 1 2 Nasehi, A.; Kadir, J. B.; Abidin, M. A. Zainal; Wong, M. Y.; Mahmodi, F. (August 2012). "First Report of Alternaria tenuissima Causing Leaf Spot on Eggplant in Malaysia". Plant Disease 96 (8): 1226–1226. doi:10.1094/PDIS-03-12-0237-PDN.
  3. 1 2 Mojerlou, Shideh (2012). "Phylogenetic Analysis of Alternaria species Associated with Citrus Black Rot in Iran". Journal of Plant Pathology & Microbiology 03 (07). doi:10.4172/2157-7471.1000144.
  4. 1 2 Ibarrola, Ignacio; Suárez-Cervera, María; Arilla, M. Carmen; Martínez, Alberto; Monteseirín, Javier; Conde, José; Asturias, Juan A. (December 2004). "Production profile of the major allergen Alt a 1 in Alternaria alternata cultures". Annals of Allergy, Asthma & Immunology 93 (6): 589–593. doi:10.1016/S1081-1206(10)61268-9.
  5. 1 2 3 4 5 6 Pastor, F.J.; Guarro, J. (August 2008). "Alternaria infections: laboratory diagnosis and relevant clinical features". Clinical Microbiology and Infection 14 (8): 734–746. doi:10.1111/j.1469-0691.2008.02024.x.
  6. ↑ Rotem, Joseph (1998). The genus Alternaria : biology, epidemiology, and pathogenicity (2nd print ed.). St. Paul, Minn: APS-Press. ISBN 978-0890541524.
  7. 1 2 Ellis, Martin B.; Ellis, J. Pamela (1997). Microfungi on land plants : an identification handbook (New enl. ed.). Slough: RP Richmond Publ. p. 289. ISBN 085546-245-0.
  8. 1 2 Domsch, K.H.; Gams, Walter; Andersen, Traute-Heidi (1980). Compendium of soil fungi (2nd ed.). London, UK: Academic Press. ISBN 9780122204029.
  9. 1 2 3 Chełkowski, J; Visconti, A (1992). Alternaria: biology, plant diseases and metabolites. Amsterdam [u.a.]: Elsevier. pp. 364–365. ISBN 0-444-88998-1.
  10. ↑ Weidenbörner, Martin (2001). Encyclopedia of Food Mycotoxins. Berlin, Heidelberg: Springer Berlin Heidelberg. ISBN 978-3-662-04464-3.
  11. ↑ Farr, David F.; Bills, Gerald F.; Chamuris, George P.; Rossman, Amy Y. (1989). Fungi: on plants and plant products in the United States. Minnesota, USA: The American Phytopathological Society.
  12. ↑ Lee, Hyang Burm; Patriarca, Andrea; Magan, Naresh (2015). "Alternaria in Food: Ecophysiology, Mycotoxin Production and Toxicology". Mycobiology 43 (2): 93–106. doi:10.5941/MYCO.2015.43.2.93.
  13. ↑ Patriarca, A.; Medina, A.; Pinto, V. Fernández; Magan, N. (January 2014). "Temperature and water stress impacts on growth and production of altertoxin-II by strains of Alternaria tenuissima from Argentinean wheat". World Mycotoxin Journal 7 (3): 329–334. doi:10.3920/WMJ2013.1711.
  14. ↑ Robertshaw, H.; Higgins, E. (2005). "Cutaneous infection with Alternaria tenuissima in an immunocompromised patient". British Journal of Dermatology 153 (5): 1047–1049. doi:10.1111/j.1365-2133.2005.06833.x.
  15. ↑ Romano, C; Fimiani, M; Pellegrino, M; Valenti, L; Casini, L; Miracco, C; Faggi, E (1996). "Cutaneous phaeohyphomycosis due to Alternaria tenuissima". Mycoses (39): 211–215.
  16. ↑ Saenz-de-Santamaria, M.; Postigo, I.; Gutierrez-Rodriguez, A.; Cardona, G.; Guisantes, J. A.; Asturias, J.; Martinez, J. (March 2006). "The major allergen of Alternaria alternata (Alt a 1) is expressed in other members of the Pleosporaceae family". Mycoses 49 (2): 91–95. doi:10.1111/j.1439-0507.2006.01195.x.
  17. ↑ Denning, David W; Pashley, Catherine; Hartl, Domink; Wardlaw, Andrew; Godet, Cendrine; Del Giacco, Stefano; Delhaes, Laurence; Sergejeva, Svetlana (2014). "Fungal allergy in asthma–state of the art and research needs". Clinical and Translational Allergy 4 (1): 14. doi:10.1186/2045-7022-4-14.
  18. ↑ Davis, ND; Diener, UL; Morgan-Jones, G (August 1977). "Tenuazonic acid production by Alternaria alternata and Alternaria tenuissima isolated from cotton.". Applied and environmental microbiology 34 (2): 155–7. PMID 562128.
  19. ↑ Antony, M; Gupta, KP; Janardanan, KK; Mehrotra, NK (9 December 1991). "Inhibition of mouse skin tumor promotion by tenuazonic acid.". Cancer letters 61 (1): 21–5. PMID 1764695.
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