Suvarna Garge (Editor)

Bremia lactucae

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Domain
  
Eukaryota

Family
  
Scientific name
  
Bremia lactucae

Rank
  
Species

Superphylum
  
Heterokonta

Genus
  
Bremia

Higher classification
  
Bremia

Bremia lactucae httpsuploadwikimediaorgwikipediacommonsff

Similar
  
Bremia, Lettuce, Pseudoperonospora cubensis, Pseudoperonospora, Peronospora destructor

Downy mildew of lettuce bremia lactucae


Bremia lactucae is a plant pathogen. This microorganism causes a disease of lettuce (Lactuca sativa) denominated as downy mildew. Some other strains can be found on 36 genera of Asteraceae including Senecio and Sonchus. Experiments using sporangia from hosts do not infect lettuce and it is concluded that the fungus exists as a quantity of host-specific strains (formae speciales). Wild species, such as Lactuca serriola, or varieties of Lactuca can hold strains that infect lettuce, but these pathogens are not sufficiently common to infect seriously the plant.

Contents

Bremia lactucae IgtBremia lactucaeltIgt Regel x lettuce

The damage to caused by Bremia to lettuce may not in itself be serious, but infected plants are susceptible to secondary infection by the more severe mould, Botrytis cinerea. The plant can suffer systemic infections. Metalaxyl is effective against this microorganism.

Bremia lactucae downy mildew Bremia lactucae on lettuce Lactuca sativa 1571022

Description

Bremia lactucae downy mildew Bremia lactucae on lettuce Lactuca sativa 1571028
  • Coarse intercellular mycelium.
  • Haustoria are sac-shaped, many times they are present in each host cell.
  • Sporangiophores emerge singly or in small groups through the stomata and branch dichotomously.
  • Tip of each branch expands to form a cup-shaped disc bearing short cylindrical sterigmata at the margin and occasionally in the centre, and from these the hyaline sporangia arise.
  • Germination of the sporangia is usually by means of a germ tube which forms an appressorium to penetrate epidermal cells or it enters through a stoma.
  • Zoospore formation has been reported but not confirmed.
  • Sexual reproduction is usually heterothallic, but homothallic strains also exist.
  • Oospores are formed in leaf tissue and remain viable for 12 months.
  • Bremia lactucae Agrosava

    Bremia lactucae downy mildew Bremia lactucae on lettuce Lactuca sativa 1571026

    Bremia lactucae downy mildew Bremia lactucae Regel

    References

    Bremia lactucae Wikipedia