Alternaria carthami: Difference between revisions
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{{Short description|Species of fungus}} |
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{{Taxobox |
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{{Speciesbox |
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| image = |
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| regnum = [[Fungi]] |
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| phylum = [[Ascomycota]] |
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| classis = [[Dothideomycetes]] |
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| subclassis = [[Pleosporomycetidae]] |
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| ordo = [[Pleosporales]] |
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| familia = [[Pleosporaceae]] |
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| genus = ''[[Alternaria]]'' |
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| binomial = ''Alternaria carthami'' |
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| synonyms = |
| synonyms = |
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''Macrosporium carthami'' <small>Savul., (1943)</small> |
''Macrosporium carthami'' <small>Savul., (1943)</small> |
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'''''Alternaria carthami''''' is a necrotrophic plant pathogen of safflower (''[[Safflower|Carthamus tinctorius L.]]''). The fungus is in the order [[Pleosporales]] and family [[Pleosporaceae]]. It was first isolated in India, has spread globally and can have devastating effects on safflower yield, and resultant oilseed production.<ref name=":0">{{Cite journal |last=Chowdhury |first=S. |date=1944 |title=An Alternaria disease of Safflower |journal=Journal of the Indian Botanical Society |volume=23 |issue=2 |pages=59–65}}</ref> ''A. carthami'' is known to be seed-borne and appears as irregular brown lesions on safflower leaves and stems.<ref name=":0" /><ref name=":1">{{Cite journal |last=Irwin |first=J. A. G. |date=1976 |title=''Alternaria carthami'', a seed-borne pathogen of safflower |url=http://dx.doi.org/10.1071/ea9760921 |journal=Australian Journal of Experimental Agriculture |volume=16 |issue=83 |pages=921 |doi=10.1071/ea9760921 |issn=0816-1089}}</ref> |
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== Description == |
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'''''Alternaria carthami''''' is a plant pathogen. |
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=== Morphology === |
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''A. carthami'' is known to have [[Hypha|septate hyphae]] and exhibits only an asexual phase.<ref name=":0" /> In this phase, the fungus will produce unbranched [[Conidium|conidiophores]] and conidia that develop singly or in chains.<ref name=":0" /> These conidia are large, brown, and both longitudinally and transversely septate with a long beak.<ref name=":0" /> Although ''A. carthami'' has only been shown to reproduce asexually, it still has a relatively high genetic variation between strains.<ref name=":3">{{Cite journal |last1=Anand |first1=Garima |last2=Kapoor |first2=Rupam |date=2018 |title=Population structure and virulence analysis of ''Alternaria carthami'' isolates of India using ISSR and SSR markers |url=http://dx.doi.org/10.1007/s11274-018-2524-6 |journal=World Journal of Microbiology and Biotechnology |volume=34 |issue=9 |page=140 |doi=10.1007/s11274-018-2524-6 |pmid=30171375 |s2cid=255131746 |issn=0959-3993}}</ref> This could hint at possible asexual [[Genetic recombination|recombination]] or a high rate of [[mutation]].<ref name=":3" /> |
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=== Virulence factors === |
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It has been found that ''A. carthami'' produces [[phytotoxin]]s to assist in its pathogenic lifecycle.<ref name=":4">{{Cite journal |last1=Tietjen |first1=K.G. |last2=Schaller |first2=E. |last3=Matern |first3=U. |date=1983 |title=Phytotoxins from ''Alternaria carthami'' chowdhury: structural identification and physiological significance |url=http://dx.doi.org/10.1016/0048-4059(83)90023-1 |journal=Physiological Plant Pathology |volume=23 |issue=3 |pages=387–400 |doi=10.1016/0048-4059(83)90023-1 |issn=0048-4059}}</ref> While it produces several phytotoxins, the most prevalent in the disease cycle is [[brefeldin A]].<ref name=":4" /><ref name=":5">{{Cite journal |last1=Tietjen |first1=Klaus Günther |last2=Matern |first2=Ulrich |date=1984 |title=Induction and suppression of phytoalexin biosynthesis in cultured cells of safflower, ''Carthamus tinctorius'' L., by metabolites of ''Alternaria carthami'' Chowdhury |url=http://dx.doi.org/10.1016/0003-9861(84)90138-3 |journal=Archives of Biochemistry and Biophysics |volume=229 |issue=1 |pages=136–144 |doi=10.1016/0003-9861(84)90138-3 |pmid=6538399 |issn=0003-9861}}</ref> Brefeldin A is capable of inhibiting [[phytoalexin]] synthesis used in the safflower's chemical defense against pathogens.<ref name=":5" /> ''A. carthami'' also produces varying degrees of cell wall degrading [[enzyme]]s.<ref name=":3" /> Different individual strains in a singular geographic region have shown highly variable numbers of these enzymes and, therefore, variation in [[virulence]].<ref name=":3" /> |
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== Ecology == |
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''A. carthami'' is a necrotrophic pathogen (feeding on the dead tissues of plants they have killed) of safflower that only produces an [[Teleomorph, anamorph and holomorph|anamorph]].<ref name=":0" /> Conidia production is optimized in rainy, humid conditions with moderate temperatures (25-30°C).<ref name=":0" /><ref name=":6">{{Cite journal |last=Mortensen |first=K. |date=1983 |title=Importance of ''Alternaria carthami'' and ''A. alternata'' in Causing Leaf Spot Diseases of Safflower |url=http://dx.doi.org/10.1094/pd-67-1187 |journal=Plant Disease |volume=67 |issue=11 |pages=1187 |doi=10.1094/pd-67-1187 |issn=0191-2917}}</ref> |
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=== Infection lifecycle === |
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Conidia first land on the surface of the safflower plant. The conidia then germinate and the [[mycelium]] enters the plant to grow both inter- and intracellularly.<ref name=":0" /> Phytotoxins are released to induce cell death and wilting in safflower leaves.<ref name=":4" /> As seeds develop in the plant, ''A. carthami'' invades and infects them, able to penetrate into the [[Seed|embryo]].<ref name=":1" /><ref name=":6" /> Conidiophores then burst through the [[stoma]]ta and [[Epidermis (botany)|epidermis]] of the plant.<ref name=":0" /> [[Spore]]s are disseminated through wind and rain and mycelium is carried within the newly developed seeds.<ref name=":6" /> Spores then land on neighboring plants and germinate, or the infected seeds are planted to colonize seedlings.<ref name=":0" /><ref name=":6" /> |
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== Habitat and distribution == |
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''A. carthami'' is necrotrophically parasitic on leaves, stems, and seeds of safflower.<ref name=":0" /> The fungus has the ability to infect other plants, but it is very limited in this and has only been shown to fully colonize safflower.<ref name=":4" /> The fungus also thrives in moist, humid environments.<ref name=":0" /><ref name=":6" /> |
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''A. carthami'' has been found in all safflower-producing countries in the world. These countries are located across all continents (except Antarctica) including India, Australia, USA, Israel, Russia, East Africa, Canada, Mexico, Brazil, Ethiopia, Germany, Italy, Kenya, New Zealand, Pakistan, Romania, Spain, Tanzania, Zambia, Zimbabwe.<ref name=":3" /><ref name=":4" /><ref name=":6" /> This [[Cosmopolitan distribution|cosmopolitan]] nature is likely due to infected seeds being shared globally among safflower farmers.<ref name=":3" /> |
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== Pathology == |
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''A. carthami'' is known commonly as the leaf blight of safflower.<ref name=":4" /> This pathogen can lead to severe crop loss with a decrease in yield of up to 90% depending on how optimal conditions are for conidiophore growth.<ref name=":4" /><ref name=":6" /> The preference of the fungus for humid, moist environments has limited safflower commercial cultivation to hot and arid parts of the world in order to slow fungal growth.<ref name=":5" /> |
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The fungus can infect safflower in all growth stages and is seen through brown lesions on the plant body, most prominently on the leaves.<ref name=":0" /><ref name=":6" /> Lesions are typically first seen on seedling [[cotyledon]]s and [[hypocotyl]]s.{{cn|date=May 2023}} These small spots will turn into larger irregular concentric rings on mature leaves and can begin to discolor the stem as well.{{cn|date=May 2023}} These lesions are usually bigger than the actual colonized area due to phytotoxin production killing surrounding plant cells.<ref name=":4" /> Infection of the safflower seeds also negatively impacts seedling emergence and growth.<ref name=":1" /><ref name=":6" /> This seed infection can go unnoticed as the surface of the seed can remain intact and healthy in appearance while the fungus has colonized the seed embryo.<ref name=":1" /> The pathogen can also spread very rapidly after seedling emergence in the field.<ref name=":1" /> |
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Due to the global sharing of safflower seeds as well as local dissemination of spores by wind and rain, ''A. carthami'' exhibits high genetic and virulence variation in one area, meaning it does not exhibit geographically isolated [[Strain (biology)|strains]].<ref name=":3" /> This wide variety of virulence can put many strains of safflower at risk and can be catastrophic to crop yield.<ref name=":3" /> |
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=== Management === |
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Many commercially available chemical fungicides are unable to fully eradicate ''A. carthami'' in safflower seeds due to the internal infection.<ref name=":1" /><ref name=":6" /> |
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[[Biological agent|Bioagents]] (including fungal and bacterial) have also been tested ''in vitro'' to determine how they affect mycelial growth.{{cn|date=May 2023}} |
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Antifungal plant extracts are also being tested as a management option against ''A. carthami'' as an alternative to environmentally harmful chemicals.<ref name=":8">{{Cite journal |last1=Ranaware |first1=A. |last2=Singh |first2=V. |last3=Nimbkar |first3=N. |date=2010 |title=In vitro antifungal study of the efficacy of some plant extracts for inhibition of ''Alternaria carthami'' fungus. |journal=Indian Journal of Natural Products and Resources |volume=1 |issue=3 |pages=384–386}}</ref> Different options tested include extracts from Garlic (''[[Garlic|Allium sativum]]''), Ginger (''[[Ginger|Zingiber officinale]]''), [[Eucalyptus]], Neem (''[[Azadirachta indica]]''), Datura (''[[Datura metel]]''), Turmeric ([[Turmeric|''Curcuma longa'']]) and several others.<ref name=":8" /> Solutions containing garlic extracts or Datura extracts were found to cause the most inhibition.<ref name=":8" /> |
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Resistant plant breeds have also been a source of interest against safflower leaf blight.<ref name=":9">{{Cite journal |last1=Vijaya Kumar |first1=J. |last2=Ranjitha Kumari |first2=B. D. |last3=Sujatha |first3=G. |last4=Castaño |first4=Enrique |date=2008 |title=Production of plants resistant to ''Alternaria carthami'' via organogenesis and somatic embryogenesis of safflower cv. NARI-6 treated with fungal culture filtrates |url=http://dx.doi.org/10.1007/s11240-008-9346-4 |journal=Plant Cell, Tissue and Organ Culture |volume=93 |issue=1 |pages=85–96 |doi=10.1007/s11240-008-9346-4 |s2cid=26638848 |issn=0167-6857}}</ref> [[Selective breeding|Artificial breeding]] selection for resistance has been largely unsuccessful, however, there are promising results through ''in vitro'' methods.<ref name=":9" /> Through culturing safflower on [[Callus (cell biology)|callus]] that had been exposed to ''A. carthami'' toxins, researchers were able to grow resistant plants.<ref name=":9" /> This method is still not perfect, however, and results mostly in partial resistance.<ref name=":9" /> |
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{{reflist}} |
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==External links== |
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* [http://www.speciesfungorum.org/Names/Names.asp Index Fungorum] |
* [http://www.speciesfungorum.org/Names/Names.asp Index Fungorum] |
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* [http://nt.ars-grin.gov/fungaldatabases USDA ARS Fungal Database] |
* [https://web.archive.org/web/20070130123212/http://nt.ars-grin.gov/fungaldatabases/ USDA ARS Fungal Database] |
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{{Taxonbar|from=Q4736349}} |
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<references /> |
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[[Category:Alternaria|carthami]] |
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[[Category: |
[[Category:Fungal plant pathogens and diseases]] |
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[[Category: |
[[Category:Fungi described in 1943]] |
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[[Category:Fungus species]] |
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{{Pleosporales stub}} |
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{{plant-disease-stub}} |
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Latest revision as of 10:40, 31 March 2024
| Alternaria carthami | |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Dothideomycetes |
| Order: | Pleosporales |
| Family: | Pleosporaceae |
| Genus: | Alternaria |
| Species: | A. carthami
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| Binomial name | |
| Alternaria carthami S. Chowdhury, (1944)
| |
| Synonyms | |
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Macrosporium carthami Savul., (1943) | |
Alternaria carthami is a necrotrophic plant pathogen of safflower (Carthamus tinctorius L.). The fungus is in the order Pleosporales and family Pleosporaceae. It was first isolated in India, has spread globally and can have devastating effects on safflower yield, and resultant oilseed production.[1] A. carthami is known to be seed-borne and appears as irregular brown lesions on safflower leaves and stems.[1][2]
Description
[edit]Morphology
[edit]A. carthami is known to have septate hyphae and exhibits only an asexual phase.[1] In this phase, the fungus will produce unbranched conidiophores and conidia that develop singly or in chains.[1] These conidia are large, brown, and both longitudinally and transversely septate with a long beak.[1] Although A. carthami has only been shown to reproduce asexually, it still has a relatively high genetic variation between strains.[3] This could hint at possible asexual recombination or a high rate of mutation.[3]
Virulence factors
[edit]It has been found that A. carthami produces phytotoxins to assist in its pathogenic lifecycle.[4] While it produces several phytotoxins, the most prevalent in the disease cycle is brefeldin A.[4][5] Brefeldin A is capable of inhibiting phytoalexin synthesis used in the safflower's chemical defense against pathogens.[5] A. carthami also produces varying degrees of cell wall degrading enzymes.[3] Different individual strains in a singular geographic region have shown highly variable numbers of these enzymes and, therefore, variation in virulence.[3]
Ecology
[edit]A. carthami is a necrotrophic pathogen (feeding on the dead tissues of plants they have killed) of safflower that only produces an anamorph.[1] Conidia production is optimized in rainy, humid conditions with moderate temperatures (25-30°C).[1][6]
Infection lifecycle
[edit]Conidia first land on the surface of the safflower plant. The conidia then germinate and the mycelium enters the plant to grow both inter- and intracellularly.[1] Phytotoxins are released to induce cell death and wilting in safflower leaves.[4] As seeds develop in the plant, A. carthami invades and infects them, able to penetrate into the embryo.[2][6] Conidiophores then burst through the stomata and epidermis of the plant.[1] Spores are disseminated through wind and rain and mycelium is carried within the newly developed seeds.[6] Spores then land on neighboring plants and germinate, or the infected seeds are planted to colonize seedlings.[1][6]
Habitat and distribution
[edit]A. carthami is necrotrophically parasitic on leaves, stems, and seeds of safflower.[1] The fungus has the ability to infect other plants, but it is very limited in this and has only been shown to fully colonize safflower.[4] The fungus also thrives in moist, humid environments.[1][6]
A. carthami has been found in all safflower-producing countries in the world. These countries are located across all continents (except Antarctica) including India, Australia, USA, Israel, Russia, East Africa, Canada, Mexico, Brazil, Ethiopia, Germany, Italy, Kenya, New Zealand, Pakistan, Romania, Spain, Tanzania, Zambia, Zimbabwe.[3][4][6] This cosmopolitan nature is likely due to infected seeds being shared globally among safflower farmers.[3]
Pathology
[edit]A. carthami is known commonly as the leaf blight of safflower.[4] This pathogen can lead to severe crop loss with a decrease in yield of up to 90% depending on how optimal conditions are for conidiophore growth.[4][6] The preference of the fungus for humid, moist environments has limited safflower commercial cultivation to hot and arid parts of the world in order to slow fungal growth.[5]
The fungus can infect safflower in all growth stages and is seen through brown lesions on the plant body, most prominently on the leaves.[1][6] Lesions are typically first seen on seedling cotyledons and hypocotyls.[citation needed] These small spots will turn into larger irregular concentric rings on mature leaves and can begin to discolor the stem as well.[citation needed] These lesions are usually bigger than the actual colonized area due to phytotoxin production killing surrounding plant cells.[4] Infection of the safflower seeds also negatively impacts seedling emergence and growth.[2][6] This seed infection can go unnoticed as the surface of the seed can remain intact and healthy in appearance while the fungus has colonized the seed embryo.[2] The pathogen can also spread very rapidly after seedling emergence in the field.[2]
Due to the global sharing of safflower seeds as well as local dissemination of spores by wind and rain, A. carthami exhibits high genetic and virulence variation in one area, meaning it does not exhibit geographically isolated strains.[3] This wide variety of virulence can put many strains of safflower at risk and can be catastrophic to crop yield.[3]
Management
[edit]Many commercially available chemical fungicides are unable to fully eradicate A. carthami in safflower seeds due to the internal infection.[2][6]
Bioagents (including fungal and bacterial) have also been tested in vitro to determine how they affect mycelial growth.[citation needed]
Antifungal plant extracts are also being tested as a management option against A. carthami as an alternative to environmentally harmful chemicals.[7] Different options tested include extracts from Garlic (Allium sativum), Ginger (Zingiber officinale), Eucalyptus, Neem (Azadirachta indica), Datura (Datura metel), Turmeric (Curcuma longa) and several others.[7] Solutions containing garlic extracts or Datura extracts were found to cause the most inhibition.[7]
Resistant plant breeds have also been a source of interest against safflower leaf blight.[8] Artificial breeding selection for resistance has been largely unsuccessful, however, there are promising results through in vitro methods.[8] Through culturing safflower on callus that had been exposed to A. carthami toxins, researchers were able to grow resistant plants.[8] This method is still not perfect, however, and results mostly in partial resistance.[8]
References
[edit]- ^ a b c d e f g h i j k l m Chowdhury, S. (1944). "An Alternaria disease of Safflower". Journal of the Indian Botanical Society. 23 (2): 59–65.
- ^ a b c d e f Irwin, J. A. G. (1976). "Alternaria carthami, a seed-borne pathogen of safflower". Australian Journal of Experimental Agriculture. 16 (83): 921. doi:10.1071/ea9760921. ISSN 0816-1089.
- ^ a b c d e f g h Anand, Garima; Kapoor, Rupam (2018). "Population structure and virulence analysis of Alternaria carthami isolates of India using ISSR and SSR markers". World Journal of Microbiology and Biotechnology. 34 (9): 140. doi:10.1007/s11274-018-2524-6. ISSN 0959-3993. PMID 30171375. S2CID 255131746.
- ^ a b c d e f g h Tietjen, K.G.; Schaller, E.; Matern, U. (1983). "Phytotoxins from Alternaria carthami chowdhury: structural identification and physiological significance". Physiological Plant Pathology. 23 (3): 387–400. doi:10.1016/0048-4059(83)90023-1. ISSN 0048-4059.
- ^ a b c Tietjen, Klaus Günther; Matern, Ulrich (1984). "Induction and suppression of phytoalexin biosynthesis in cultured cells of safflower, Carthamus tinctorius L., by metabolites of Alternaria carthami Chowdhury". Archives of Biochemistry and Biophysics. 229 (1): 136–144. doi:10.1016/0003-9861(84)90138-3. ISSN 0003-9861. PMID 6538399.
- ^ a b c d e f g h i j Mortensen, K. (1983). "Importance of Alternaria carthami and A. alternata in Causing Leaf Spot Diseases of Safflower". Plant Disease. 67 (11): 1187. doi:10.1094/pd-67-1187. ISSN 0191-2917.
- ^ a b c Ranaware, A.; Singh, V.; Nimbkar, N. (2010). "In vitro antifungal study of the efficacy of some plant extracts for inhibition of Alternaria carthami fungus". Indian Journal of Natural Products and Resources. 1 (3): 384–386.
- ^ a b c d Vijaya Kumar, J.; Ranjitha Kumari, B. D.; Sujatha, G.; Castaño, Enrique (2008). "Production of plants resistant to Alternaria carthami via organogenesis and somatic embryogenesis of safflower cv. NARI-6 treated with fungal culture filtrates". Plant Cell, Tissue and Organ Culture. 93 (1): 85–96. doi:10.1007/s11240-008-9346-4. ISSN 0167-6857. S2CID 26638848.
External links
[edit]
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