Verticillium dahliae

from Wikipedia, the free encyclopedia
Verticillium dahliae
Symptoms of Verticillium wilt on a sunflower

Symptoms of Verticillium wilt on a sunflower

Systematics
Class : Sordariomycetes
Subclass : Hypocreomycetidae
Order : Glomerellales
Family : Plectosphaerellaceae
Genre : Verticillium
Type : Verticillium dahliae
Scientific name
Verticillium dahliae
Glue , (1913)

Verticillium dahliae is a hose fungus from the family of the Plectosphaerellaceae . The plant pathogen causes verticillium wilt in many plant species, which is accompanied by leaf curling and discoloration. Over 400 species of plants can beinfectedby species of the genus Verticillium .

Hosts and Symptoms

There are many strains of Verticillium dahliae , which are summarized in "Vegetative Compatibility Groups " ( English vegetative compatibility groups , VCG). These groups unite tribes that can exchange genetic material through structures called anastomoses . Each VCG affects a few hosts or only a single one, the virulence of the pathogen varying depending on the host.

While individual strains of V. dahliae are relatively host-specific, the host range of the species is large. This includes over 300 types and varieties of plants such as Brussels sprouts , cabbage , eggplant , cucumber , mint , peppers , potatoes , pumpkins , spinach , tomatoes , water , honey and cantaloupe melons . Among these, there are resistant or tolerant varieties in tomatoes, potatoes and aubergines.

Symptoms of the disease can be seen throughout the plant. The leaves become abnormally colored, have necrotic areas, wither and / or fall off the plant. The stem axis can have discolored vessels, rosettes can be formed or it is altogether stunted. Premature aging or death can also occur.

Micro- sclerotic structures using a magnifying glass as small black objects living in the vessels or dead plants are found. This property can be used to differentiate V. dahliae from V. albo-atrum , another pathogenic Verticillium species.

Life cycle

Verticillium dahliae attacks the host plant through natural wounds or through penetration of the root tissue. The fungus then enters the xylem , with the help of which conidia are spread over the entire host. The plant responds by tyloses ( cellulose - derivatives ) produced that block the xylem, resulting in a limited water supply and associated disruption of wilting. When the plant dies, V. dahliae survives with mycelia in the dead tissue, as a long-term dormant stage in the form of microsclerotic spores or saprobiont in the soil. The spores can be spread by wind and rain, so that pathogen-free fields are infected beforehand. In addition, the fungus can spread locally via the root systems, survive in the vessels of some resistant species or be spread by the wind from living leaves.

Due to the ability of the species to survive saprobiont or in the form of dormant stages for more than a decade, a site once infected will most likely never become Verticillium- free again .

management

Verticillium dahliae has a broad host range and can survive in the soil for several years over long periods of time, so that control via crop rotation will generally have little success. The exception is a crop rotation with broccoli , which reduced the severity of the consequences in cauliflower fields. This is possibly due to the production of allyl isothiocyanate in broccoli, which can inhibit the growth of phytopathogenic fungi.

Seed selection can reduce the spread of the fungus. Buying seeds from certified Verticillium -free seed farms or using resistant or partially resistant varieties can reduce the risk of disease. But even resistant varieties can develop symptoms in the field if the abundance of the fungi is high enough that the choice of location is also essential to minimize the risk of infection.

Highly nitrogenous fertilizers and excessive irrigation of crops, especially in spring, can increase the risk of infection, so appropriate fertilization and drip irrigation are recommended. Burning off the residue after harvesting can reduce the amount of Verticillium spores that can penetrate the soil and overwinter.

Recombination

Verticillium dahliae has a strictly clonal population structure. There were recombinations between different clonal lines and - less often - also within the lines. Two types of mating have been identified. In the genome of V. dahliae are homologues of eight meiosis proven -specific genes. These findings suggest that the ability to meiose in the clonal lines of V. dahliae has survived adaptively and can be expressed as a recombination of genetic markers if necessary . Perhaps, as suggested by Wallen & Perlin (2018), it is generally true of ascap fungi that, as with V. dahliae, homologous recombination during sexual reproduction ensures the repair of DNA damage, especially under stressful conditions.

Taxonomy

The following synonyms are known:

  • Verticillium albo-atrum var. Dahliae (adhesive) R. Nelson
  • Verticillium tracheiphilum Curzi
  • Verticillium ovatum GH Berk. & AB Jacks.
  • Verticillium albo-atrum f. angustum Wollenw.
  • Verticillium dahliae f. angustum (Wollenw.) JFH Beyma
  • Verticillium albo-atrum var. Chlamydosporale Wollenw.
  • Verticillium dahliae f. chlamydosporale (Wollenw.) JFH Beyma
  • Verticillium albo-atrum var. Medium wool.
  • Verticillium dahliae f. medium (Wollenw.) JFH Beyma
  • Verticillium dahliae f. cerebriform JFH Beyma
  • Verticillium dahliae f. zonatum JFH Beyma

Web links

Individual evidence

  1. ↑ Verticillium wilt . 2005. Retrieved January 18, 2016.
  2. ↑ a b c d e Verticillium wilt . American Phytopathological Society. doi : 10.1094 / phi-i-2000-0801-01 . Retrieved September 5, 2019.
  3. ^ S. Douglas: Verticillium Wilt of Vegetables and Herbaceous Ornamentals . 2008. Accessed December 9, 2018.
  4. ↑ Verticillium dahliae (verticillium wilt) . Retrieved December 9, 2018.
  5. ^ University of Illinois Extension: Verticillium Wilt Disease . 1997. Retrieved December 9, 2018.
  6. ↑ a b N. Brazee: Verticillium Wilt . March 6, 2015. Accessed December 9, 2018.
  7. ↑ K. Subbarao, S. Koike: Broccoli residues can control Verticillium wilt of cauliflower . In: California Agriculture . 54, No. 3, May 1, 2000, ISSN  0008-0845 , pp. 30-33. doi : 10.3733 / ca.v054n03p30 .
  8. ↑ Hilary Mayton: Correlation of Fungicidal Activity ofBrassicaSpecies with allyl isothiocyanate Production in macerated leaf tissue . In: Phytopathology . 86, No. 3, 1996, ISSN  0031-949X , p. 267. doi : 10.1094 / phyto-86-267 .
  9. ^ UC Pest Management Guidelines: Verticillum Wilt . University of California Agriculture & Natural Resources. 2018. Retrieved September 5, 2019.
  10. ↑ MG Milgroom, M. Jiménez-Gasco Mdel, C. Olivares García, MT Drott, RM Jiménez-Díaz: Recombination between clonal lineages of the asexual fungus Verticillium dahliae detected by genotyping by sequencing . In: PLoS One . 9, No. 9, September 2, 2014, p. E106740. doi : 10.1371 / journal.pone.0106740 .
  11. ↑ RM Wallen, MH Perlin: An Overview of the Function and Maintenance of Sexual Reproduction in Dikaryotic Fungi . In: Front Microbiol . 9, 2018, p. 503. doi : 10.3389 / fmicb.2018.00503 .
  12. ↑ Verticillium dahliae Kleb., Mykol. Zentbl. 3:66 (1913) . In: Index Fungorum . Retrieved on September 5, 2019: "GSD Species Synonymy"