Pyrenophora tritici-repentis

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Pyrenophora tritici-repentis
Drechslera tritici-repentis (01).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Dothideomycetes
Order: Pleosporales
Family: Pleosporaceae
Genus: Pyrenophora
Species:
P. tritici-repentis
Binomial name
Pyrenophora tritici-repentis
(Died.) Drechsler, (1923)
Synonyms

Drechslera tritici-repentis
Drechslera tritici-vulgaris
Helminthosporium gramineum f.sp. tritici-repentis
Helminthosporium tritici-repentis
Helminthosporium tritici-vulgaris
Pleospora culmorum
Pleospora sarcocystis
Pleospora trichostoma
Pyrenophora tritici-vulgaris
Pyrenophora sarcocystis
Pyrenophora trichostoma
Pyrenophora tritici-vulgaris
Sphaeria culmorum
Sphaeria sarcocystis
Sphaeria trichostoma

Contents

Pyrenophora tritici-repentis (teleomorph) and Drechslera tritici-repentis (anamorph) is a necrotrophic plant pathogen of fungal origin, phylum Ascomycota. [1] The pathogen causes a disease originally named yellow spot but now commonly called tan spot, yellow leaf spot, yellow leaf blotch or helminthosporiosis. [2] [3] At least eight races of the pathogen are known to occur based on their virulence on a wheat differential set. [4]

The tan (yellow) spot fungus was first described by Nisikado in 1923 in Japan. [5] and was later identified in Europe, Australia and the US, in the mid 1900s. [6] The disease is one of the most important fungal disease on wheat and the fungal pathogen is found to infect in all parts of the world wherever wheat and other susceptible host crops are found. [4] P. tritici-repentis overwinters on stubble, and due to recent heavily no-till/residue retention cultural practices, increased incidence and yield loss of up to 49% has been witnessed if ideal conditions occur. [6] It forms characteristic, dark, oval-shaped spots of necrotic tissue surrounded by a yellow ring. [7] It is responsible for losses that account for up to 30% of the crop, [8] due to its effects reducing photosynthesis. Pathogenesis and toxicity in P. tritici-repentis is controlled by a single gene, transformations of this gene cause the pathogen to become benign when interacting with wheat. [9] This has major implications for those in agriculture seeking to combat the effects of this fungus.

Hosts and symptoms

Tan spot is found primarily on wheat, but is also found to infect other cereals and grasses including triticale, barley, and rye, but are less frequently affected. [2] Other grass species affected by the pathogen include Siberian wheat grass, sand bluestem, meadow brome, sheep fescue, June grass, little bluestem, green foxtail, needle and thread, and tall wheatgrass. [10] While these are not necessarily agriculture crop hosts such as wheat, the pathogen is able to form and survive on many grass hosts, which can eventually venture into wheat fields. Other important grass susceptible hosts include smooth brome which can be found in pastures, as well as quack grass that is found in the environment and considered a weed in many agricultural crops. Lesions typically appear on both upper and lower leaf surfaces, and initially are tan to brown specks. Eventually, the tan to brown specks expand to larger irregular, oval, lens-shaped, ellipse, tan blotches with a yellow ring around them. The yellow ring is often referred to as a halo, yellow discoloration as chlorosis, and browning/death of leaf tissue as necrosis. The development of a dark brown to black spot in the center the lesion is characteristic of the disease. [11] If warmer temperatures and moist conditions persist, spores known as conidia will move up plant as secondary inoculum and can also infect head/spikes. Symptoms on the head are indistinct, but can cause brownish glumes, and grains can have a reddish appearance similar to the pathogen Fusarium. [11]

Disease cycle

P. tritici-repentis survives and overwinters as pseudothecia on stubble from the previous year's infected crop. The pseudothecia contain ascospores (sexual spores). Such ascospores produced are large and typically dispersed by wind, but do not travel far due to their size. The ascospores land on leaf surfaces and begin to produce lesions by infection from appressorium and infection peg. The lesions initially formed by ascospores, known as condo, form atop of conidiophores, and can serve as primary inoculum to new plant/host via long distance wind dispersal. Condo can also serve as primary inoculum via rain splash to further more up primary host and re-infect. During and after maturation of the wheat crop, fungus can grow saprophytically as mycelium from the infected leaf blade, down the leaf sheath, and on to the stem where it will later form a pseudothecia. [12] The disease develops over a wide temperature range, but is favored by warmer temperatures along with or followed by long rains, dew, or irrigation. [12]

Environment

The fungus requires 6-24+ hours of moisture to infect a leaf. This means that rain, significant dew or high canopy humidity are factors that can lead to infection. Optimal temperatures for symptom development range from 60–82 °F (16–28 °C). [13] [14]

Control

Since this disease can cause considerable yield loss, effective control is very important. The most effective method of long term control is crop rotation. [15] [14] There is a considerable difference in the fungal population after one year of rotation. Examples of non-host crops include mustard, flax, and soybean. [12] [13] Some other control options include tillage. Foliar fungicides can also be used as control methods. [12] [16] Since the top two leaves contribute the most to yield, it is important to protect them. Some effective fungicides include, but are not limited to, Headline, Quilt, and Stratego. There are however, resistant varieties that make most methods of control unnecessary. [17] There is research to suggest that plant height may also influence the amount of disease able to form due to the pathogen. It suggests that shorter plants will have a lowered chance of infection. [18] This research has only been conducted in Canada however, and should lead to more research before being used as a control technique.

Out of all wheat pathogens, Ptr is among the best studied. [19] Among all necrotrophic pathogen of this crop, Ptr's and Parastagonospora nodorum 's effectors have become the best studied. [19]

Host resistance

Some resistance genes – especially against races 1 and 5, the most problematic in Kazakhstan – have been identified. [20] [21]

Importance

This disease is considered to be a very important one. According to the University of Nebraska, losses of 50 percent have been documented. This negatively impacts the profitability a farmer can hope to achieve within one year. Tan spot is recognized as "one of the major constraints of wheat production. [17] This is also a very significant disease in Canada, creating similar yield losses annually. Tan spot is important enough and causing large enough yield losses to continually prompt new research. [18] P. t-r. has caused serious epidemics in Kazakhstan since the 1980s with nearly half the national harvest being lost when there is an epidemic. [21]

Related Research Articles

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Magnaporthe grisea, also known as rice blast fungus, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, Johnson spot, neck blast, wheat blast and Imochi (稲熱), is a plant-pathogenic fungus and model organism that causes a serious disease affecting rice. It is now known that M. grisea consists of a cryptic species complex containing at least two biological species that have clear genetic differences and do not interbreed. Complex members isolated from Digitaria have been more narrowly defined as M. grisea. The remaining members of the complex isolated from rice and a variety of other hosts have been renamed Magnaporthe oryzae, within the same M. grisea complex. Confusion on which of these two names to use for the rice blast pathogen remains, as both are now used by different authors.

Pyrenophora teres is a necrotrophic fungal pathogen of some plant species, the most significant of which are economically important agricultural crops such as barley. Toxins include aspergillomarasmine A and related compounds.

The cereal grain wheat is subject to numerous wheat diseases, including bacterial, viral and fungal diseases, as well as parasitic infestations.

<span class="mw-page-title-main">Wheat leaf rust</span> Fungal disease of wheat, most prevalent

Wheat leaf rust is a fungal disease that affects wheat, barley, rye stems, leaves and grains. In temperate zones it is destructive on winter wheat because the pathogen overwinters. Infections can lead up to 20% yield loss. The pathogen is a Puccinia rust fungus. It is the most prevalent of all the wheat rust diseases, occurring in most wheat-growing regions. It causes serious epidemics in North America, Mexico and South America and is a devastating seasonal disease in India. P. triticina is heteroecious, requiring two distinct hosts.

<i>Blumeria graminis</i> Fungal pathogen of grasses

Blumeria graminis is a fungus that causes powdery mildew on grasses, including cereals. It is the only species in the genus Blumeria. It has also been called Erysiphe graminis and Oidium monilioides or Oidium tritici.

<span class="mw-page-title-main">Eyespot (wheat)</span> Fungal disease of wheat

Eyespot is an important fungal disease of wheat caused by the necrotrophic fungus Tapesia yallundae and Tapesia acuformis. It is also called Strawbreaker. Eyespot is more severe where wheat is grown continuously and when the weather is cool and moist. Treating crops against eyespot with fungicide costs millions to farmers and is complicated by the pathogen becoming resistant to the more commonly used fungicides. Severe cases of the disease can reduce yield by up to 40%. It is most common in temperate regions such as North and South America, Europe, Australia, New Zealand and Africa.

<span class="mw-page-title-main">Take-all</span> Fungal plant disease

Take-all is a plant disease affecting the roots of grass and cereal plants in temperate climates caused by the fungus Gaeumannomyces tritici. All varieties of wheat and barley are susceptible. It is an important disease in winter wheat in Western Europe particularly, and is favoured by conditions of intensive production and monoculture.

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

Phomopsis cane and leaf spot occurs wherever grapes are grown. Phomopsis cane and leaf spot is more severe in grape-growing regions characterized by a humid temperate climate through the growing season. Crop losses up to 30% have been reported to be caused by Phomopsis cane and leaf spot.

<i>Cochliobolus sativus</i> Species of fungus

The fungus Cochliobolus sativus is the teleomorph of Bipolaris sorokiniana (anamorph) which is the causal agent of a wide variety of cereal diseases. The pathogen can infect and cause disease on roots, leaf and stem, and head tissue. C. sativus is extremely rare in nature and thus it is the asexual or anamorphic stage which causes infections. The two most common diseases caused by B. sorokiniana are spot blotch and common root rot, mainly on wheat and barley crops.

Spot blotch is a leaf disease of wheat caused by Cochliobolus sativus. Cochliobolus sativus also infects other plant parts and in conjunction with other pathogens causes common root rot and black point.

<i>Fusarium culmorum</i> Fungal disease, head blight of wheat

Fusarium culmorum is a fungal plant pathogen and the causal agent of seedling blight, foot rot, ear blight, stalk rot, common root rot and other diseases of cereals, grasses, and a wide variety of monocots and dicots. In coastal dunegrass, F. culmorum is a nonpathogenic symbiont conferring both salt and drought tolerance to the plant.

<i>Pseudocercosporella capsellae</i> Species of fungus

Pseudocercosporella capsellae is a plant pathogen infecting crucifers. P. capsellae is the causal pathogen of white leaf spot disease, which is an economically significant disease in global agriculture. P. capsellae has a significant affect on crop yields on agricultural products, such as canola seed and rapeseed. Researchers are working hard to find effective methods of controlling this plant pathogen, using cultural control, genetic resistance, and chemical control practices. Due to its rapidly changing genome, P. capsellae is a rapidly emerging plant pathogen that is beginning to spread globally and affect farmers around the world.

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>Zymoseptoria tritici</i> Species of fungus

Zymoseptoria tritici, synonyms Septoria tritici, Mycosphaerella graminicola, is a species of filamentous fungus, an ascomycete in the family Mycosphaerellaceae. It is a wheat plant pathogen causing septoria leaf blotch that is difficult to control due to resistance to multiple fungicides. The pathogen today causes one of the most important diseases of wheat.

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<i>Ascochyta</i> Genus of fungi

Ascochyta is a genus of ascomycete fungi, containing several species that are pathogenic to plants, particularly cereal crops. The taxonomy of this genus is still incomplete. The genus was first described in 1830 by Marie-Anne Libert, who regarded the spores as minute asci and the cell contents as spherical spores. Numerous revisions to the members of the genus and its description were made for the next several years. Species that are plant pathogenic on cereals include, A. hordei, A. graminea, A. sorghi, A. tritici. Symptoms are usually elliptical spots that are initially chlorotic and later become a necrotic brown. Management includes fungicide applications and sanitation of diseased plant tissue debris.

<i>Ascochyta sorghi</i> Species of fungus

Ascochyta sorghi is a fungal plant pathogen. It causes Ascochyta leaf spot on barley that can also be caused by the related fungi Ascochyta hordei, Ascochyta graminea and Ascochyta tritici. It is considered a minor disease of barley.

<i>Cercospora sojina</i> Species of fungus

Cercospora sojina is a fungal plant pathogen which causes frogeye leaf spot of soybeans. Frog eye leaf spot is a major disease on soybeans in the southern U.S. and has recently started to expand into the northern U.S. where soybeans are grown. The disease is also found in other soybean production areas of the world.

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Wheat yellow rust, also known as wheat stripe rust, is one of the three major wheat rust diseases, along with stem rust of wheat and leaf rust.

Necrotic ring spot is a common disease of turf caused by soil borne fungi that mainly infects roots (4). It is an important disease as it destroys the appearance of turfgrasses on park, playing fields and golf courses. Necrotic Ring Spot is caused by a fungal pathogen that is an ascomycete that produces ascospores in an ascocarp (6). They survive over winter, or any unfavorable condition as sclerotia. Most infection occurs in spring and fall when the temperature is about 13 to 28 °C (5). The primary hosts of this disease are cool-season grasses such as Kentucky bluegrass and annual bluegrass (6). Once turf is infected with O. korrae, it kills turf roots and crowns. Symptoms of the disease are quite noticeable since they appear as large yellow ring-shaped patches of dead turf. Management of the disease is often uneasy and requires application of multiple controls. The disease can be controlled by many different kind of controls including chemicals and cultural.

References

  1. ↑ Aboukhaddour, Reem; Turkington, T. Kelly; Strelkov, Stephen E. (April 2013). "Race structure of Pyrenophora tritici-repentis (tan spot of wheat) in Alberta, Canada". Canadian Journal of Plant Pathology . 35 (2): 256–268. Bibcode:2013CaJPP..35..256A. doi:10.1080/07060661.2013.782470. S2CID   85882209.
  2. 1 2 Prescott, J. M.; Burnett, P. A.; Saari, E. E.; Ranson, J.; Bowman, J.; De Milliano, W.; Singh, R. P.; Bekele, G. "Guide to Wheat Disease and Pests". wheat.pw.usda.gov. CIMMYT. Archived from the original on 20 March 2017. Retrieved 4 December 2014.
  3. ↑ Duveiller, Etienne; Dubin, H.J.; Reeves, J.; McNab, A. (9–14 February 1997). Written at El Batan, Mexico. Helminthosporium Blights of Wheat: Spot Blotch and Tan Spot. CIMMYT . México, D.F., México. pp. viii+376. hdl:10883/1229. ISBN   970-648-001-3. OCLC   39500836. S2CID   82752566. CABI ISC# 20001003003.
  4. 1 2 Gamba, Fernanda M.; Strelkov, Stephen E.; Lamari, Lakhdar (October 2012). "Virulence of Pyrenophora tritici-repentis in the Southern Cone Region of South America". Canadian Journal of Plant Pathology . 34 (4): 545–550. Bibcode:2012CaJPP..34..545G. doi:10.1080/07060661.2012.695750. S2CID   84067227.
  5. ↑ Nisikado, Yosikazu (1928). "Preliminary notes on yellow spot diseases of wheat caused by Helminthosporium tritici-vulgaris". Inst Agric Biol . 4: 103–109.
  6. 1 2 Faris, Justin D.; Liu, Zhaohui; Xu, Steven S. (25 July 2013). "Genetics of tan spot resistance in wheat". Theoretical and Applied Genetics . 126 (9): 2197–2217. doi:10.1007/s00122-013-2157-y. PMID   23884599. S2CID   1652404.
  7. ↑ eumedia.es – Control de enfermedades en cereales de invierno. Web consulted 6 June 2008.
  8. ↑ Manejo de las enfermedades del trigo. Pérez Fernández, Jesús & Corro Molas, Andrés. Web consulted 1 June 2008.
  9. ↑ "A single gene encodes a selective toxin causal to the development of tan spot of wheat". Archived from the original on 9 November 2014.
  10. ↑ Krupinsky, J. M. (1992). "Grass Hosts of Pyrenophora tritci-repentis" (PDF). Plant Disease . 76 (1). American Phytopathological Society (APS): 92–95. doi:10.1094/pd-76-0092 . Retrieved 4 December 2014.
  11. 1 2 "Cereals Disease Encyclopedia". archive.hgca.com. Archived from the original on 23 October 2014. Retrieved 4 December 2014.
  12. 1 2 3 4 Wegulo, S. N. "Tan Spot of Cereals". apsnet.org. Archived from the original on 20 May 2014. Retrieved 4 December 2014.
  13. 1 2 De Wolf, Erick "Tan Spot." Kansas State Plant Pathology (n.d):n.pag. Kansas State Extension, Apr. 2008. Web.
  14. 1 2 Burrows Mary, Grey William, and Olmstead Jeannie. "Fungal, Bacterial and Physiological Leaf Diseases of Cereal Crops (wheat, Durum, Barley)." Fungal, Bacterial and Physiological Leaf Diseases of Cereal Crops (wheat, Durum, Barley)." (n.d.): n. pag. Montana State University. Web.
  15. ↑ Bockus, W.W., and M.M. Claassen. 1992. Effects of crop rotation and residue management practices on severity of tan spot of winter wheat. Plant Disease 76:633–636.
  16. ↑ Carigano, M., S.A. Staggenborg, and J.P. Shroyer. 2008. Management practices to minimize tan spot in a continuous wheat rotation. Agronomy Journal 100:145–153.
  17. 1 2 Wegulo, Stephen N. Tan Spot of Wheat (2012): n. pag. University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources. University of Nebraska-Lincoln, Dec. 2012. Web.
  18. 1 2 "The Effect of Plant Height on Tan Spot on Durum Wheat in Southern Saskatchewan." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web.
  19. 1 2 McDonald, Megan; Solomon, Peter (2018). "Just the surface: advances in the discovery and characterization of necrotrophic wheat effectors". Current Opinion in Microbiology . 46: 14–18. doi:10.1016/j.mib.2018.01.019. PMID   29452845. S2CID   3374561.
  20. ↑ Dahm, Madeline (29 July 2021). "Genome-wide association study puts tan spot-resistant genes in the spotlight". CIMMYT . Retrieved 21 August 2021.
  21. 1 2 Dahm, Madeline. "Genome-wide association study puts tan spot-resistant genes in the spotlight". WHEAT . Archived from the original on 22 September 2021. Retrieved 28 July 2021.
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