Author
|
Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 4/2/2016 Publication Date: 7/20/2017 Citation: Wintermantel, W.M. 2017. Lettuce big vein. In: Subbarao, K.V., Davis, R.M., Gibertson, R.L., Raid, R.N., editors. Compendium of Lettuce Diseases and Pests. 2nd edition. St. Paul, MN: APS Press. p. 76-78. Interpretive Summary: Lettuce big-vein disease is an important soil-borne virus disease affecting lettuce production throughout the world. The most common symptom in LBV-affected lettuce plants is a clearing along the veins. When vein-clearing symptoms become intense, affected leaves pucker slightly, and the leaf margins exhibit a ruffled appearance. Lettuce plants can become severely stunted if infected at an early stage of growth, and maturity can be delayed. There are two viruses associated with big vein disease of lettuce: Mirafiori lettuce big-vein virus (MLBVV; genus Ophiovirus) and Lettuce big-vein associated virus (LBVaV; genus Varicosavirus). Although both viruses are usually found associated with big-vein disease symptoms, only MLBVV has been confirmed as a causative agent. The genome of MLBVV is composed of four RNAs; one large RNA of approximately 7.8 kb encoding proteins involved in virus replication, and three smaller RNAs. Although MLBVV can be mechanically inoculated and graft-transmitted in the laboratory, the natural mode of infection in fields is through transmission by the chytrid fungus, Olpidium brassicae. Lettuce big-vein symptoms are most prevalent in lettuce fields during the spring season, because symptom development is favored by cool temperatures and wet soils. Several accessions of Lactuca virosa, a wild relative of lettuce, have been identified with significantly high levels of resistance to MLBVV infection and big vein symptom development. This resistance has been introduced into lettuce although commercial varieties with resistance derived from L. virosa remain to be developed. Technical Abstract: Lettuce big-vein disease is an important soil-borne virus disease affecting lettuce production throughout the world. The most common symptom in LBV-affected lettuce plants is a clearing along the veins. When vein-clearing symptoms become intense, affected leaves pucker slightly, and the leaf margins exhibit a ruffled appearance. Lettuce plants can become severely stunted if infected at an early stage of growth, and maturity can be delayed. There are two viruses associated with big vein disease of lettuce: Mirafiori lettuce big-vein virus (MLBVV; genus Ophiovirus) and Lettuce big-vein associated virus (LBVaV; genus Varicosavirus). Although both viruses are usually found associated with big-vein disease symptoms, only MLBVV has been confirmed as a causative agent. The genome of MLBVV is composed of four RNAs; one large RNA of approximately 7.8 kb encoding proteins involved in virus replication, and three smaller RNAs. Although MLBVV can be mechanically inoculated and graft-transmitted in the laboratory, the natural mode of infection in fields is through transmission by the chytrid fungus, Olpidium brassicae. Lettuce big-vein symptoms are most prevalent in lettuce fields during the spring season, because symptom development is favored by cool temperatures and wet soils. Several accessions of Lactuca virosa, a wild relative of lettuce, have been identified with significantly high levels of resistance to MLBVV infection and big vein symptom development. This resistance has been introduced into lettuce although commercial varieties with resistance derived from L. virosa remain to be developed. |
