Pythium irregulare: Difference between revisions
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'''''Pythium irregulare''''' is a soil borne oomycete plant pathogen<ref name=":0">{{Cite web|url=https://projects.ncsu.edu/cals/course/pp728/Pythium_irregulare/Pythium_irregulare.html|title=Pythium irregulare|last=Katawczik|first=Melanie|date=|website=projects.ncsu.edu|publisher=North Carolina State University, College of Agriculture and Life Sciences, Department of Plant Pathology|access-date=2016-12-06}}</ref>. 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 (asexual motile spores) and oospores (sexual resting spores)<ref>{{Cite journal|last=Judelson|first=Howard S.|last2=Blanco|first2=Flavio A.|date=2005-01-01|title=The spores of Phytophthora: weapons of the plant destroyer|url=http://www.nature.com/nrmicro/journal/v3/n1/full/nrmicro1064.html|journal=Nature Reviews Microbiology|language=en|volume=3|issue=1|pages=47–58|doi=10.1038/nrmicro1064|issn=1740-1526}}</ref>. |
'''''Pythium irregulare''''' is a soil borne oomycete plant pathogen<ref name=":0">{{Cite web|url=https://projects.ncsu.edu/cals/course/pp728/Pythium_irregulare/Pythium_irregulare.html|title=Pythium irregulare|last=Katawczik|first=Melanie|date=|website=projects.ncsu.edu|publisher=North Carolina State University, College of Agriculture and Life Sciences, Department of Plant Pathology|access-date=2016-12-06}}</ref>. 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 (asexual motile spores) and oospores (sexual resting spores)<ref>{{Cite journal|last=Judelson|first=Howard S.|last2=Blanco|first2=Flavio A.|date=2005-01-01|title=The spores of Phytophthora: weapons of the plant destroyer|url=http://www.nature.com/nrmicro/journal/v3/n1/full/nrmicro1064.html|journal=Nature Reviews Microbiology|language=en|volume=3|issue=1|pages=47–58|doi=10.1038/nrmicro1064|issn=1740-1526}}</ref>. |
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''Pythium irregulare'' is an oomycete that causes pre- and post-emergence damping off, as well as root rot<ref name=":0" />. Pre-emergence damping off occurs when ''P. irregulare'' infects seeds before they emerge, causing them to rot and turn brown, thus preventing successful growth<ref name=":0" /><ref name=":1">{{Cite web|url=http://plantpath.psu.edu/pythium/module-1/disease|title=Disease Caused by Pythium|last=Moorman|first=Gary|last2=May|first2=Sara|date=|website=http://plantpath.psu.edu/pythium/|publisher=Penn State, College of Agricultural Sciences, Department of Plant Pathology and Environmental Microbiology|access-date=2016-12-06}}</ref>. Alternatively, post-emergence damping off occurs when the oomycete infects just after the seed has germinated<ref name=":0" /><ref name=":1" />. This usually causes infection in the roots and stem which appears as water soaking and necrosis<ref name=":0" /><ref name=":1" />. Depending on the severity, plants may collapse or be severely stunted<ref name=":0" />. In plants that are older and more established, ''P. irregulare'' causes root rot<ref name=":1" />. This will initially cause necrotic lesions, which leads to chlorosis, reduced yield, poor growth, and stunting due to inadequate water and nutrient acquisition by the roots<ref name=":0" />. Additionally, ''P. irregulare'' is often found coinfecting with other ''Pythium'' species<ref name=":0" />. All three of these diseases caused by ''P. irregulare'' can be caused by other pathogens as well, so a disease diagnosis is not necessarily indicative of ''P. irregulare''<ref name=":2">{{Cite web|url=http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/pythium|title=Pythium|last=|first=|date=|website=http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/pythium|publisher=Penn State College of Agricultural Sciences Extension|access-date=2016-12-06}}</ref> |
''Pythium irregulare'' is an oomycete that causes pre- and post-emergence damping off, as well as root rot<ref name=":0" />. Pre-emergence damping off occurs when ''P. irregulare'' infects seeds before they emerge, causing them to rot and turn brown, thus preventing successful growth<ref name=":0" /><ref name=":1">{{Cite web|url=http://plantpath.psu.edu/pythium/module-1/disease|title=Disease Caused by Pythium|last=Moorman|first=Gary|last2=May|first2=Sara|date=|website=http://plantpath.psu.edu/pythium/|publisher=Penn State, College of Agricultural Sciences, Department of Plant Pathology and Environmental Microbiology|access-date=2016-12-06}}</ref>. Alternatively, post-emergence damping off occurs when the oomycete infects just after the seed has germinated<ref name=":0" /><ref name=":1" />. This usually causes infection in the roots and stem which appears as water soaking and necrosis<ref name=":0" /><ref name=":1" />. Depending on the severity, plants may collapse or be severely stunted<ref name=":0" />. In plants that are older and more established, ''P. irregulare'' causes root rot<ref name=":1" />. This will initially cause necrotic lesions, which leads to chlorosis, reduced yield, poor growth, and stunting due to inadequate water and nutrient acquisition by the roots<ref name=":0" />. Additionally, ''P. irregulare'' is often found coinfecting with other ''Pythium'' species<ref name=":0" />. All three of these diseases caused by ''P. irregulare'' can be caused by other pathogens as well, so a disease diagnosis is not necessarily indicative of ''P. irregulare''<ref name=":2">{{Cite web|url=http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/pythium|title=Pythium|last=|first=|date=|website=http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/pythium|publisher=Penn State College of Agricultural Sciences Extension|access-date=2016-12-06}}</ref> |
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''Pythium irregulare'' has a very broad host range, including many agronomically and horticulturally important crops and is found on every continent except for Antarctica<ref name=":0" />. ''P. irregulare'' infects over 200 species, including cereals, legumes, fruits, vegetables, and ornamentals<ref name=":0" />. It differs from many other ''Pythium'' species in that it prefers cooler environments<ref name=":0" /><ref name=":1" />. A moist environment is also necessary for disease, which aids motility of spores<ref name=":0" /><ref name=":1" />. It is commonly found in both greenhouses and fields<ref name=":0" /><ref name=":2" /><ref>{{Cite web|url=https://www.extension.purdue.edu/extmedia/bp/bp-181-w.pdf|title=Pythium Root Rot of Herbaceous Plants|last=Beckerman|first=Janna|date=|website=Disease Management Strategies for Horticultural Crops|publisher=Purdue Agricultural Communication|access-date=2016-12-05}}</ref>. |
''Pythium irregulare'' has a very broad host range, including many agronomically and horticulturally important crops and is found on every continent except for Antarctica<ref name=":0" />. ''P. irregulare'' infects over 200 species, including cereals, legumes, fruits, vegetables, and ornamentals<ref name=":0" />. It differs from many other ''Pythium'' species in that it prefers cooler environments<ref name=":0" /><ref name=":1" />. A moist environment is also necessary for disease, which aids motility of spores<ref name=":0" /><ref name=":1" />. It is commonly found in both greenhouses and fields<ref name=":0" /><ref name=":2" /><ref name=":3">{{Cite web|url=https://www.extension.purdue.edu/extmedia/bp/bp-181-w.pdf|title=Pythium Root Rot of Herbaceous Plants|last=Beckerman|first=Janna|date=|website=Disease Management Strategies for Horticultural Crops|publisher=Purdue Agricultural Communication|access-date=2016-12-05}}</ref>. |
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== Disease Cycle == |
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''Pythium irregulare'', like most oomycetes, has a polycyclic life cycle with sexual and asexual stages<ref name=":0" />. During the winter, oospores, which are sexual resting spores, survive in the soil<ref name=":0" /><ref name=":3" />. Oospore germination occurs when the oospore senses chemicals released by seeds or roots<ref name=":0" />. Once germinated, oospores can produce either a germ tube, which directly infects the plant, or a sporangium, which releases zoospores that infect the plant<ref name=":0" /><ref name=":3" />. Sporangium that produce zoospores make up the asexual phase of the life cycle. The zoospores can move through soil when water is present, which is why water is important for disease to occur<ref name=":0" />. Once zoospores reach the root or seed, they encyst, germinate, and infect via a germ tube<ref name=":0" /><ref name=":3" />. Once infection has been established, the pathogen grows hyphae both in and outside the plant and releases enzymes to breakdown plant tissue<ref name=":0" /><ref name=":3" />. The breakdown of tissue provides nutrients for the pathogen, also known as necrotrophy<ref name=":3" />. As the pathogen continues to grow, more sporangium can form throughout the season, releasing zoospores as a secondary inoculum, thus infecting more plants<ref name=":3" />. This represents the polycyclic portion of the disease cycle. The hyphae within the plant also continue to grow and develop “male” and “female” haploid mating structures, known as antheridium and oogonium, respectively<ref name=":0" />. The antheridium then transfers it’s genetic material to the oogonium (fertilization), resulting in the diploid oospore, which overwinters and starts the infection over again in the spring<ref name=":0" />. |
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== External links == |
== External links == |
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Revision as of 05:14, 6 December 2016
| Pythium irregulare | |
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| Species: | P. irregulare
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| Binomial name | |
| Pythium irregulare Buisman, (1927)
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Pythium irregulare is a soil borne oomycete plant pathogen[1]. 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 (asexual motile spores) and oospores (sexual resting spores)[2].
Hosts and Symptoms
Pythium irregulare is an oomycete that causes pre- and post-emergence damping off, as well as root rot[1]. Pre-emergence damping off occurs when P. irregulare infects seeds before they emerge, causing them to rot and turn brown, thus preventing successful growth[1][3]. Alternatively, post-emergence damping off occurs when the oomycete infects just after the seed has germinated[1][3]. This usually causes infection in the roots and stem which appears as water soaking and necrosis[1][3]. Depending on the severity, plants may collapse or be severely stunted[1]. In plants that are older and more established, P. irregulare causes root rot[3]. This will initially cause necrotic lesions, which leads to chlorosis, reduced yield, poor growth, and stunting due to inadequate water and nutrient acquisition by the roots[1]. Additionally, P. irregulare is often found coinfecting with other Pythium species[1]. All three of these diseases caused by P. irregulare can be caused by other pathogens as well, so a disease diagnosis is not necessarily indicative of P. irregulare[4]
Pythium irregulare has a very broad host range, including many agronomically and horticulturally important crops and is found on every continent except for Antarctica[1]. P. irregulare infects over 200 species, including cereals, legumes, fruits, vegetables, and ornamentals[1]. It differs from many other Pythium species in that it prefers cooler environments[1][3]. A moist environment is also necessary for disease, which aids motility of spores[1][3]. It is commonly found in both greenhouses and fields[1][4][5].
Disease Cycle
Pythium irregulare, like most oomycetes, has a polycyclic life cycle with sexual and asexual stages[1]. During the winter, oospores, which are sexual resting spores, survive in the soil[1][5]. Oospore germination occurs when the oospore senses chemicals released by seeds or roots[1]. Once germinated, oospores can produce either a germ tube, which directly infects the plant, or a sporangium, which releases zoospores that infect the plant[1][5]. Sporangium that produce zoospores make up the asexual phase of the life cycle. The zoospores can move through soil when water is present, which is why water is important for disease to occur[1]. Once zoospores reach the root or seed, they encyst, germinate, and infect via a germ tube[1][5]. Once infection has been established, the pathogen grows hyphae both in and outside the plant and releases enzymes to breakdown plant tissue[1][5]. The breakdown of tissue provides nutrients for the pathogen, also known as necrotrophy[5]. As the pathogen continues to grow, more sporangium can form throughout the season, releasing zoospores as a secondary inoculum, thus infecting more plants[5]. This represents the polycyclic portion of the disease cycle. The hyphae within the plant also continue to grow and develop “male” and “female” haploid mating structures, known as antheridium and oogonium, respectively[1]. The antheridium then transfers it’s genetic material to the oogonium (fertilization), resulting in the diploid oospore, which overwinters and starts the infection over again in the spring[1].
External links
See also
References
- ^ a b c d e f g h i j k l m n o p q r s t u v Katawczik, Melanie. "Pythium irregulare". projects.ncsu.edu. North Carolina State University, College of Agriculture and Life Sciences, Department of Plant Pathology. Retrieved 2016-12-06.
- ^ Judelson, Howard S.; Blanco, Flavio A. (2005-01-01). "The spores of Phytophthora: weapons of the plant destroyer". Nature Reviews Microbiology. 3 (1): 47–58. doi:10.1038/nrmicro1064. ISSN 1740-1526.
- ^ a b c d e f Moorman, Gary; May, Sara. "Disease Caused by Pythium". http://plantpath.psu.edu/pythium/. Penn State, College of Agricultural Sciences, Department of Plant Pathology and Environmental Microbiology. Retrieved 2016-12-06.
{{cite web}}: External link in|website= - ^ a b "Pythium". http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/pythium. Penn State College of Agricultural Sciences Extension. Retrieved 2016-12-06.
{{cite web}}: External link in|website= - ^ a b c d e f g Beckerman, Janna. "Pythium Root Rot of Herbaceous Plants" (PDF). Disease Management Strategies for Horticultural Crops. Purdue Agricultural Communication. Retrieved 2016-12-05.
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