Zymoseptoria tritici

Zymoseptoria tritici
Zymoseptoria tritici on leaves of wheat
Scientific classification
Kingdom:	Fungi
Phylum:	Ascomycota
Class:	Dothideomycetes
Subclass:	Dothideomycetidae
Order:	Capnodiales
Family:	Mycosphaerellaceae
Genus:	Zymoseptoria
Species:	Z. tritici
Binomial name
Zymoseptoria tritici (Roberge ex Desm.) Quaedvl. & Crous, (2011)
Synonyms
Septoria curtisiana Sacc., (1884)[1] Septoria graminum Desm., (1843) Septoria tritici Desm., 1842[2] Septoria tritici Berk. & M.A. Curtis, (1874)[3] Septoria tritici var. lolicola R. Sprague & Aar. G. Johnson, (1944)[4] Sphaeria graminicola Fuckel, (1865)[5] Sphaerella graminicola Fuckel, (1870)[6] Mycosphaerella graminicola ( Fuckel) J. Schröt., (1894)[7]

Zymoseptoria tritici, synonyms Septoria tritici, Mycosphaerella graminicola, is a species of

This fungus causes septoria tritici blotch of wheat, a disease characterized by necrotic blotches on the foliage.

• 
  Light stimulates yeast-like growth of Zymoseptoria tritici.^[13] Close-up of yeast-like growth of Zymoseptoria tritici in vitro on V8 agar.
• 
  In vitro production of asexual fructifications (

  pycnidia

  ; arrow) of Zymoseptoria tritici on wheat leaf extract agar.
• 
  Penetration of a wheat leaf stoma (arrow) by a pycnidiospore germ tube of Zymoseptoria tritici.
• 
  Colonization of the mesophyll tissue by an intercellular hypha (arrows) of Zymoseptoria tritici during the symptomless biotrophic phase of pathogenesis.
• 
  Initiation (arrow head) of a pycnidium of Zymoseptoria tritici in the substomatal cavity of a wheat leaf.

Sexual state (

Zymoseptoria tritici represents an intriguing model for fundamental genetic studies of plant-pathogenic fungi.

Primary inoculum requires wet conditions and cool temperatures of 50-68 °F.[19] Under appropriate environmental conditions, lesions are able to develop on infected leaves, and soon pycnidia begin to develop on the lesions.^[19] The pycnidia appear as small dark dots on the lesions. From the pycnidia, conidiospores, the asexual spores of the fungus, are released. These asexual spores are dispersed via rain splash and are response for the secondary inoculum of this polycyclic disease cycle.^[17] When the conidiospores are splashed onto leaves, they act similarly to ascospores and cause the development of foliar lesions. In addition to pycnidia, pseudothecia also develop within these lesions. Pycnidia and pseudothecia are the structures in which the fungus overwinters, and the cycle begins again.^{[citation needed]}

Disease Management

Zymoseptoria tritici is a difficult fungus to

There are also cultural management strategies that may be effective, including regular rotation of crops, deep plowing, and late planting.[15] More specifically, rotating a recently infected field to any non-host crop can be useful in minimizing the amount of fungus present in the field. Planting winter wheat after the first ascospore flights in September is a way to reduce primary inoculum of winter wheat.^[22]

Fungicide use often simply is not economical for Septoria Leaf Blotch. The rapid evolution of pathogen resistance to fungicides is a major barrier. Zymoseptoria tritici has

The last method of control for Zymoseptoria tritici is biological control using bacteria. Bacillus megaterium has been shown to cause about an 80% decrease in disease development in the trials done so far.^[17] Pseudomonads are also a promising bacterial control option. A benefit to using pseudomonads or bacillus is that they are not harmed by most fungicides, so they can be used in combination with chemical controls.^[17] However, resistant cultivars and cultural control methods for Zymoseptoria tritici are generally favored over chemical or biological control methods, mainly because of the high costs associated with biological control.^{[citation needed]}

Disease Importance

The ascomycete fungus Zymoseptoria tritici causes septoria tritici blotch, a foliar disease of

Different areas of the world are currently trying different management strategies. For example, in the Nordic-Baltic region, one of the largest wheat-producing regions of the world, the use of fungicides has substantially increased wheat yields.[25] The fungicides that have been shown to be effective include quinone outside inhibitors (QoIs), which, like most fungicides, are expensive to apply in large quantities. As climate change begins to increase temperatures around the globe, Zymoseptoria tritici, along with many other fungal pathogens, is likely to show increased overwintering survival and therefore more substantial primary inocula.^[26] The need for effective management techniques will become even more important as the prevalence of Septoria leaf blotch increases with climate change.^{[citation needed]}

• 
  Typical infection caused by Zymoseptoria tritici of the primary leaf of a resistant

  hyphae

  .
• 
  (upper image) Typical symptoms of Zymoseptoria tritici on a primary seedling leaf of a highly susceptible wheat cultivar. (lower image) Typical response to Zymoseptoria tritici on a primary leaf of a highly resistant wheat cultivar.
• 
  Symptoms of Zymoseptoria tritici on a naturally infected adult plant flag leaf of wheat.

References

This article incorporates CC-BY-2.5 text from references^{[8][11][13][23]}

External links

Wikimedia Commons has media related to Mycosphaerella graminicola.

• USDA ARS Fungal Database
• van Ginkel, M.; A. McNab; J. Krupinsky (1999). Septoria and stagonospora diseases of cereals: A compilation of global research (PDF). CIMMYT. p. 186pp. Archived from the original (PDF) on 2003-10-29.

• Orton E. S., Sian Deller S. & Brown J. K. M. (2011). "Mycosphaerella graminicola: from genomics to disease control".
  doi:10.1111/j.1364-3703.2010.00688.x
  .