Alternaria alternata

Last updated

Alternaria alternata
Alternariaalternata.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Dothideomycetes
Order: Pleosporales
Family: Pleosporaceae
Genus: Alternaria
Species:
A. alternata
Binomial name
Alternaria alternata
(Fr.) Keissl. (1912)
Synonyms

Alternaria fasciculata(Cooke & Ellis) L.R. Jones & Grout (1897)
Alternaria rugosaMcAlpine (1896)
Alternaria tenuisNees (1817)
Macrosporium fasciculatumCooke & Ellis (1817)
Torula alternataFr. (1832)

Contents

Alternaria alternata is a fungus causing leaf spots, rots, and blights on many plant parts, and other diseases. It is an opportunistic[ citation needed ] pathogen on over 380 host species of plant.

It can also cause upper respiratory tract infections [1] and asthma in humans with compromised immunity. [2]

Hosts and symptoms

Alternaria alternata has many different hosts depending on its forma specialis.

A. a. f. sp. lycopersici (AAL) infects only certain cultivars of tomato plants and is often referred to as Alternaria stem canker of tomato. [3] AAL's main symptom is cankers in the stem. It resides in seeds and seedlings, and is often spread by spores as they become airborne and land on plants. It can also spread throughout other plants. [4] Under severe infection, lesions enlarge and become coalesced causing blighting of the leaves. This symptom progression occurred in research done in Pakistan: the symptoms on affected tomatoes started with yellowing and browning of the lower leaves, then began developing on the leaf tips and along the margins of the leaf petiole. This progression continued until the entire leaves were covered in diseased tissue and then fell off. [5] In addition to necrotic leaves and petioles, plants are found to have severe defoliation, with considerable yield losses when it occurs before flowering. [4] The tomato fruit can also be infected as well, with brown cankers dotting them and making them inedible. Once the disease has spread to a certain point, little can be done to save the tomato plant.[ citation needed ]

There are several host factors that affect disease development. For example, various signaling pathways in tomato plants affect their susceptibility to AAL. [6] Salicylic acid promotes resistance to AAL and antagonizes the ethylene response. Ethylene controls the synthesis of jasmonic acid, which is a necessary pathway for immunity. Independently of each other, salicylic acid, ethylene, and jasmonic acid can influence the susceptibility of tomato to AAL. Diagnosis of AAL is often from observing signs and symptoms from this fungal pathogen. In addition, a tomato cultivar's resistance to a toxin produced by AAL also affects disease development.[ citation needed ]

Environment

In order to survive, Alternaria alternata needs a moist warm environment. It is often found in areas with humid climates, or where there has been significant rainfall. [4] The fungus lives in seeds and seedlings, and is also spread by spores. This disease flourishes in dead plants that have been left in gardens over winter. Additionally, when dead infected debris is added to compost pile it can spread to other vegetables throughout the garden.[ citation needed ]

There are no insect vectors for this disease.[ citation needed ] This means that using insecticides has no effect on the spread of this pathogen. However, there are several cultural practices that can be followed to suppress this fungal pathogen's impact. The disease first occurs in the host's exposed leaves. Plants planted with rows in an east–west direction have more severe disease than do plants planted north–south. This implies that if one plants tomato plants in a north–south manner they will be less susceptible. It is also suggested to highly monitor plants in April through June[ clarification needed ]. This is when the pathogen is most prevalent. If monitoring indicates the presence of AAL, it is suggested to begin late-spring treatments of fungicide about mid-April[ clarification needed ]. However, if a garden has a history of disease, it is advised to take extra measures. This can be done by treating tomatoes in mid to late April[ clarification needed ] and 2 to 3 weeks later by applying a fungicide. [7] Because this is a fungal pathogen that thrives off of wet environments, overhead irrigation is never advised when irrigating. This causes the moisture to remain on the leaf tissue and increase susceptibility to the disease and provides an optimal environment for the fungus to survive and grow. Furrow irrigation or drip irrigation systems allow the plant to remain dry.[ citation needed ]

Overall, AAL thrives in moist warm environments. Cultural practices for preventing this disease include planting tomatoes in a row north to south, monitoring plants heavily April through June[ clarification needed ], and using a drip irrigation system to keep as much plant tissue dry and free of favorable environments for this pathogen.

While γ-aminobutyric acid (GABA) has no direct fungicidal activity on A. alternata, [8] it does induce resistance in tomato ( Solanum lycopersicum ). [8] Some or all of that resistance is by activation of the tomato's own enzymes exerting an antioxidant effect. [8]

Disease cycle

Teleomorph of Alternaria alternata is thought to be Clathrospora diplospora : this has yet to be confirmed. [9] If this is correct, as a result this pathogen would be propagating itself via asexual spores called conidia. [10] These conidia are produced in lesions on mature or dying leaves. [10] Their production can begin in as few as ten days after the first symptoms appear, and can continue for to up to fifty days. [11] A. alternata's conidia disperse via air currents, and their release from the lesions can be triggered by rainfall, or even just a sudden drop in humidity. [11] When the conidium lands on a leaf, it will wait until the nighttime dew, and then germinate. [10] It can either enter through the stomata, or penetrate directly through the top of the leaf, using its appressorium, infecting the leaf within 12 hours. [10]

Pathogenesis

At the cellular level, AAL produces toxins that are essential for pathogenicity on tomato. [12] This host specific mycotoxin is called fumonisin B1. It was identified and confirmed by research conducted on fast atom bombardment and ion spray mass spectrometry. [13] [ failed verification ] Thus, tomatoes that are resistant to this pathogen may be resistance to this specific toxin. Resistance to the pathogen in tomato is inherited as a single gene expressing complete dominance.[ dubious – discuss ] However, sensitivity to the fumonisin B1 gene is controlled by a single locus with two alleles expressing incomplete dominance when heterozygous. [14] In addition to resistance to the specific gene, resistance can be found from signaling pathways.[ clarification needed ]

At the organismal level[ clarification needed ], AAL grows very slowly. This makes it so its presence is often not known until seedlings become larger and are transplanted into the garden.[ citation needed ] A fungicide may be used to save the plants once they are infected; however, the disease cannot be completely eradicated. [7]

Ultimately, pathogenicity of this organism depends on a specific tomato cultivar's resistance to an AAL strain's specific fumonisin B1 variant. Additionally, the best way to prevent this pathogen from producing disease on tomato plants is to ensure the tomatoes are resistant cultivars.[ citation needed ]

Identification

Teleomorph

Thought to be Clathrospora diplospora (to be confirmed). [9]

Anamorph

Spores in a chain Alternaria spore chain 160X.png
Spores in a chain
Spores Alternaria spores 160X.png
Spores

Conidiophore

  • Pale brown to olive brown
  • 25–60 x 3–3.5 μm
  • Straight or flexuous
  • Individual conidiophores arise directly from substrate forming bushy heads consisting of 4–8 large catenate conidia chains
  • Secondary conidiophores are generally short and 1-celled

Conidia

  • Pale brown to light brown
  • Obclavate to obpyriform orellipsoid, short conical beak at the tip, or beakless
  • Surface smooth to verruculose
  • Size
    • 20–63 x 9–18 μm in size
    • (on PCA) mature conidia typically 10–30 x 5–12 μm
  • Septa
    • Several vertical and −8 transverse septa
    • (on PCA) 3–7 transepta, 1–5 longisepta
  • Chains
    • Produced in an often branched, long chain more than 5 conidia.
    • (on PCA) individual chains of 5–15 conidia, complex of branching chains may contain up to 50–60 conidia

Related Research Articles

<span class="mw-page-title-main">Fusarium wilt</span> Fungal plant disease

Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.

<span class="mw-page-title-main">Leaf spot</span> Damaged areas of leaves

A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis. Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves.

Leptosphaeria maculans is a fungal pathogen of the phylum Ascomycota that is the causal agent of blackleg disease on Brassica crops. Its genome has been sequenced, and L. maculans is a well-studied model phytopathogenic fungus. Symptoms of blackleg generally include basal stem cankers, small grey lesions on leaves, and root rot. The major yield loss is due to stem canker. The fungus is dispersed by the wind as ascospores or rain splash in the case of the conidia. L. maculans grows best in wet conditions and a temperature range of 5–20 degrees Celsius. Rotation of crops, removal of stubble, application of fungicide, and crop resistance are all used to manage blackleg. The fungus is an important pathogen of Brassica napus (canola) crops.

Alternaria triticina is a fungal plant pathogen that causes leaf blight on wheat. A. triticina is responsible for the largest leaf blight issue in wheat and also causes disease in other major cereal grain crops. It was first identified in India in 1962 and still causes significant yield loss to wheat crops on the Indian subcontinent. The disease is caused by a fungal pathogen and causes necrotic leaf lesions and in severe cases shriveling of the leaves.

<i>Leveillula taurica</i> Species of fungus

Leveillula taurica is an obligate fungal pathogen, from the phylum Ascomycota, which causes powdery mildew on onion. This disease prefers warm, dry environments. It is rare in the United States, and is currently restricted to western states. Globally, it is also a minor problem with limited occurrences in the Middle East, Europe, and South America. L. taurica causes powdery mildew of onions, but is also known to infect other allium, solanaceous, and cucurbit species. The disease has appeared in parts of the Middle East, the Mediterranean, and South and North America. Currently, it is not a cause for major concern in the U.S. and throughout the world, as its geographic extent is sparse. In addition, it is relatively easy to control through basic sanitation and reducing water stress.

<i>Stemphylium solani</i> Species of fungus

Stemphylium solani is a plant pathogen fungus in the phylum Ascomycota. It is the causal pathogen for grey leaf spot in tomatoes and leaf blight in alliums and cotton, though a wide range of additional species can serve as hosts. Symptoms include white spots on leaves and stems that progress to sunken red or purple lesions and finally leaf necrosis. S. solani reproduces and spreads through the formation of conidia on conidiophores. The teleomorph name of Stemphyllium is Pleospora though there are no naturally known occurrences of sexual reproduction. Resistant varieties of tomato and cotton are common, though the pathogen remains an important disease in Chinese garlic cultivation.

<i>Diplocarpon earlianum</i> Species of fungus

Diplocarpon earlianum is a species of fungus that causes disease in strawberry plants called strawberry leaf scorch. The disease overwinters in plant debris and infects strawberry plants during the spring season when it is wet. The five main methods to reduce strawberry leaf scorch include: irrigation techniques, crop rotation, planting resistant and disease-free seeds, fungicide use, and sanitation measures. Control of strawberry leaf scorch is important because it is responsible for the majority of disease in strawberries. Diplocarpon earliana affects the fruit quality and yield of the strawberry crop. Losses range from negligible to severe depending on numerous epidemiological factors including cultivar susceptibility, type of cropping system, and weather conditions

<i>Diaporthe helianthi</i> Species of fungus

Diaporthe helianthi is a fungal pathogen that causes Phomopsis stem canker of sunflowers. In sunflowers, Phomopsis helianthi is the causative agent behind stem canker. Its primary symptom is the production of large canker lesions on the stems of sunflower plants. These lesions can eventually lead to lodging and plant death. This disease has been shown to be particularly devastating in southern and eastern regions of Europe, although it can also be found in the United States and Australia. While cultural control practices are the primary method of controlling for Stem Canker, there have been a few resistant cultivars developed in regions of Europe where the disease is most severe.

Alternaria carthami is a necrotrophic plant pathogen of safflower. 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. A. carthami is known to be seed-borne and appears as irregular brown lesions on safflower leaves and stems.

Alternaria citri is a fungal plant pathogen that causes black rot in citrus plants.

Alternaria dauci is a plant pathogen. The English name of the disease it incites is "carrot leaf blight".

<i>Alternaria solani</i> Species of fungus

Alternaria solani is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Despite the name "early," foliar symptoms usually occur on older leaves. If uncontrolled, early blight can cause significant yield reductions. Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides. Early blight can also be caused by Alternaria tomatophila, which is more virulent on stems and leaves of tomato plants than Alternaria solani.

Septoria lycopersici is a fungal pathogen that is most commonly found infecting tomatoes. It causes one of the most destructive diseases of tomatoes and attacks tomatoes during any stage of development.

Alternaria helianthi is a fungal plant pathogen causing a disease in sunflowers known as Alternaria blight of sunflower.

Diaporthe phaseolorum var. caulivora is a fungal plant pathogen which infects soybean, causing soybean stem canker.

<i>Cercospora melongenae</i> Fungal disease of eggplant leaves

Cercospora melongenae is a fungal plant pathogen that causes leaf spot on eggplant. It is a deuteromycete fungus that is primarily confined to eggplant species. Some other host species are Solanum aethiopicum and Solanum incanum. This plant pathogen only attacks leaves of eggplants and not the fruit. It is fairly common among the fungi that infect community gardens and home gardens of eggplant. Generally speaking, Cercospora melongenae attacks all local varieties of eggplants, but is most severe on the Philippine eggplant and less parasitic on a Siamese variety.

<span class="mw-page-title-main">Corn grey leaf spot</span> Fungal disease of maize

Grey leaf spot (GLS) is a foliar fungal disease that affects maize, also known as corn. GLS is considered one of the most significant yield-limiting diseases of corn worldwide. There are two fungal pathogens that cause GLS: Cercospora zeae-maydis and Cercospora zeina. Symptoms seen on corn include leaf lesions, discoloration (chlorosis), and foliar blight. Distinct symptoms of GLS are rectangular, brown to gray necrotic lesions that run parallel to the leaf, spanning the spaces between the secondary leaf veins. The fungus survives in the debris of topsoil and infects healthy crops via asexual spores called conidia. Environmental conditions that best suit infection and growth include moist, humid, and warm climates. Poor airflow, low sunlight, overcrowding, improper soil nutrient and irrigation management, and poor soil drainage can all contribute to the propagation of the disease. Management techniques include crop resistance, crop rotation, residue management, use of fungicides, and weed control. The purpose of disease management is to prevent the amount of secondary disease cycles as well as to protect leaf area from damage prior to grain formation. Corn grey leaf spot is an important disease of corn production in the United States, economically significant throughout the Midwest and Mid-Atlantic regions. However, it is also prevalent in Africa, Central America, China, Europe, India, Mexico, the Philippines, northern South America, and Southeast Asia. The teleomorph of Cercospora zeae-maydis is assumed to be Mycosphaerella sp.

<span class="mw-page-title-main">Leucostoma canker</span> Plant fungal disease

Leucostoma canker is a fungal disease that can kill stone fruit. The disease is caused by the plant pathogens Leucostoma persoonii and Leucostoma cinctum (teleomorph) and Cytospora leucostoma and Cytospora cincta (anamorphs). The disease can have a variety of signs and symptoms depending on the part of the tree infected. One of the most lethal symptoms of the disease are the Leucostoma cankers. The severity of the Leucostoma cankers is dependent on the part of the plant infected. The fungus infects through injured, dying or dead tissues of the trees. Disease management can consist of cultural management practices such as pruning, late season fertilizers or chemical management through measures such as insect control. Leucostoma canker of stone fruit can cause significant economic losses due to reduced fruit production or disease management practices. It is one of the most important diseases of stone fruit trees all over the world.

<i>Alternaria brassicicola</i> Species of fungus

Alternaria brassicicola is a fungal necrotrophic plant pathogen that causes black spot disease on a wide range of hosts, particularly in the genus of Brassica, including a number of economically important crops such as cabbage, Chinese cabbage, cauliflower, oilseeds, broccoli and canola. Although mainly known as a significant plant pathogen, it also contributes to various respiratory allergic conditions such as asthma and rhinoconjunctivitis. Despite the presence of mating genes, no sexual reproductive stage has been reported for this fungus. In terms of geography, it is most likely to be found in tropical and sub-tropical regions, but also in places with high rain and humidity such as Poland. It has also been found in Taiwan and Israel. Its main mode of propagation is vegetative. The resulting conidia reside in the soil, air and water. These spores are extremely resilient and can overwinter on crop debris and overwintering herbaceous plants.

<span class="mw-page-title-main">Alternaria leaf spot</span> Fungal plant disease

Alternaria leaf spot or Alternaria leaf blight are a group of fungal diseases in plants, that have a variety of hosts. The diseases infects common garden plants, such as cabbage, and are caused by several closely related species of fungi. Some of these fungal species target specific plants, while others have been known to target plant families. One commercially relevant plant genus that can be affected by Alternaria Leaf Spot is Brassica, as the cosmetic issues caused by symptomatic lesions can lead to rejection of crops by distributors and buyers. When certain crops such as cauliflower and broccoli are infected, the heads deteriorate and there is a complete loss of marketability. Secondary soft-rotting organisms can infect stored cabbage that has been affected by Alternaria Leaf Spot by entering through symptomatic lesions. Alternaria Leaf Spot diseases that affect Brassica species are caused by the pathogens Alternaria brassicae and Alternaria brassicicola.

References

  1. ↑ Wiest, Peter; Wiese, Kurt; Jacobs, Michael R.; Morrissey, Anne B.; Abelson, Tom I.; Witt, William; Lederman, Michael M. (August 1987). "Alternaria Infection in a Patient with Acquired Immunodeficiency Syndrome: Case Report and Review of Invasive Alternaria Infections". Reviews of Infectious Diseases . 9 (4): 799–803. doi:10.1093/clinids/9.4.799. JSTOR   4454171. PMID   3326127.
  2. ↑ "Alternaria alternata". www.thermofisher.com. Retrieved 2024-10-19.
  3. ↑ "Collar Rot and Alternaria Stem Canker of Tomato | NC State Extension Publications". content.ces.ncsu.edu. Retrieved 2024-10-19.
  4. 1 2 3 "Tomato Alternaria Cankers - Causes, Symptoms, Treatments & Control". Tomato Disease Help. 2010-11-02. Archived from the original on 2017-10-25. Retrieved 2017-12-12.
  5. ↑ K.P., Akhtar; M.Y., Saleem; M., Asghar; M.A., Haq (2004-07-30). "New report of Alternaria alternata causing leaf blight of tomato in Pakistan". New Disease Reports . 9. ISSN   2044-0588.
  6. ↑ Jia, Chengguo; Zhang, Liping; Liu, Lihong; Wang, Jiansheng; Li, Chuanyou; Wang, Qiaomei (2013-01-01). "Multiple phytohormone signalling pathways modulate susceptibility of tomato plants to Alternaria alternata f. sp. lycopersici". Journal of Experimental Botany. 64 (2): 637–650. doi:10.1093/jxb/ers360. PMC   3542053 . PMID   23264518.
  7. 1 2 "UC IPM: UC Management Guidelines for Alternaria Leaf Spot on Almond". University of California Statewide IPM Program . Retrieved 2017-12-12.
  8. 1 2 3 Yang, Jiali; Sun, Cui; Zhang, Yangyang; Fu, Da; Zheng, Xiaodong; Yu, Ting (2017). "Induced resistance in tomato fruit by γ-aminobutyric acid for the control of alternaria rot caused by Alternaria alternata". Food Chemistry . 221: 1014–1020. doi:10.1016/j.foodchem.2016.11.061. PMID   27979053.
  9. 1 2 "Alternaria alternata on MycoBank".
  10. 1 2 3 4 Timmer, Lavern W.; Peever, Tobin L.; Solel, Zvi; Akimitsu, Kazuya (2003). "Alternaria diseases of citrus – Novel pathosystems". Phytopathologia Mediterranea . 42 (2): 99–112. doi:10.14601/Phytopathol_Mediterr-1710 (inactive 2024-09-12).{{cite journal}}: CS1 maint: DOI inactive as of September 2024 (link)
  11. 1 2 Dewdney, M. M. "Alternaria Brown Spot1." EDIS New Publications RSS. Web. 22 October 2015. Archived 2020-08-15 at the Wayback Machine
  12. ↑ Wang, Yifei; Bao, Yihong; Shen, Danhong; Feng, Wu; Yu, Ting; Zhang, Jia; Zheng, Xiao Dong (2008-04-30). "Biocontrol of Alternaria alternata on cherry tomato fruit by use of marine yeast Rhodosporidium paludigenum Fell & Tallman". International Journal of Food Microbiology . 123 (3): 234–239. doi:10.1016/j.ijfoodmicro.2008.02.002. PMID   18378348.
  13. ↑ Brandwagt, Bas F. (January 3, 2000). "A longevity assurance gene homolog of tomato mediates resistance to Alternaria alternata f. sp. lycopersici toxins and fumonisin B1". Proceedings of the National Academy of Sciences. 97 (9): 4961–4966. Bibcode:2000PNAS...97.4961B. doi: 10.1073/pnas.97.9.4961 . PMC   18340 . PMID   10781105.
  14. ↑ Gilchrist, D. G. (19 August 1975). "Production and Nature of a Host-Specific Toxin from Alternaria alternata f. sp. lycopersici". Phytopathology . 66 (2): 165–171. doi:10.1094/phyto-66-165.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.