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United States Department of Agriculture

Agricultural Research Service

Title: Biology and Genetics of Lettuce Dieback Disease and Lettuce Necrotic Stunt Virus.

Authors
item Wintermantel, William
item Grube, Rebecca - UNIV. NEW HAMPSHIRE
item Anchieta, Amy

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 30, 2006
Publication Date: July 1, 2006
Citation: Wintermantel, W.M., Grube, R.C., Anchieta, A.G. 2006. Biology and Genetics of Lettuce Dieback Disease and Lettuce Necrotic Stunt Virus. Phytopathology. 96:S124.

Interpretive Summary: Lettuce dieback, a new soil-borne disease of lettuce, emerged in the 1990s to cause severe losses for lettuce production in the western United States. The disease is caused by Tomato bushy stunt virus (TBSV) and the recently described tombusvirus, Lettuce necrotic stunt virus (LNSV). The complete genome of LNSV was sequenced, compared with genomes of other tombusviruses, and was found to be related to but distinct from TBSV. Both LNSV and TBSV can infect lettuce through the soil in the absence of fungal vectors. Fields with high disease incidence are usually poorly drained, and field and greenhouse tests determined that elevated soil salinity, as measured by electrical conductivity led to increased frequency of diseased plants. Neither virus appears to be transmissible through seed embryos, however, seed coat transmission occurred at low levels when plants were tested as seedlings for the presence of virus. The ability to detect virus in seedlings, however, does not always lead to development of disease symptoms. Resistance based on a single dominant gene, Tvr1, is widespread among commercial crisphead lettuce cultivars, and resistance has also been identified for other lettuce types. LNSV and TBSV can accumulate in seedlings of both resistant and susceptible cultivars based on ELISA, but resistant varieties do not develop disease symptoms, and virus accumulation is rarely detectable in resistant plants from the field.

Technical Abstract: Lettuce dieback, a new soil-borne disease of lettuce, emerged in the 1990s to cause severe losses for lettuce production in the western United States. The disease is caused by Tomato bushy stunt virus (TBSV) and the recently described tombusvirus, Lettuce necrotic stunt virus (LNSV). The complete genome of LNSV was sequenced, compared with genomes of other tombusviruses, and was found to be related to but distinct from TBSV. Both LNSV and TBSV can infect lettuce through the soil in the absence of fungal vectors. Fields with high disease incidence are usually poorly drained, and field and greenhouse tests determined that elevated soil salinity, as measured by electrical conductivity led to increased frequency of diseased plants. Neither virus appears to be transmissible through seed embryos, however, seed coat transmission occurred at low levels when plants were tested as seedlings for the presence of virus. The ability to detect virus in seedlings, however, does not always lead to development of disease symptoms. Resistance based on a single dominant gene, Tvr1, is widespread among commercial crisphead lettuce cultivars, and resistance has also been identified for other lettuce types. LNSV and TBSV can accumulate in seedlings of both resistant and susceptible cultivars based on ELISA, but resistant varieties do not develop disease symptoms, and virus accumulation is rarely detectable in resistant plants from the field.

Last Modified: 9/10/2014
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