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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #375841

Research Project: Epidemiology, Vector-Host Plant Interactions, and Biology of Vegetable and Cucurbit Viruses

Location: Crop Improvement and Protection Research

Title: Lettuce dieback associated virus, a putative member of the Phenuiviridae and likely causative agent of lettuce dieback disease

item Wintermantel, William - Bill
item Hladky, Laura
item CAMELO, VIVIANA - Us Forest Service (FS)
item KOIKE, STEVEN - Trical Inc
item Mollov, Dimitre

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Lettuce dieback disease (LDD) causes foliar necrosis, stunting, and death of lettuce plants throughout all western U.S. lettuce production regions. The disease is more prevalent in poorly drained soils and was traditionally believed to be caused by either of two viruses from the genus Tombusvirus: Tomato bushy stunt virus (TBSV) and Moroccan pepper virus (MPV). However, in recent years, neither tombusvirus has been found in symptomatic plants collected from the field, nor have degenerate primers detected any divergent tombusviruses from diseased lettuce. To identify additional viruses that may be associated with LDD, lettuce samples were collected from symptomatic fields and leaves were used to mechanically passage infectious agents to an array of test plants, resulting in symptoms in N. benthamiana distinct from those caused by TBSV or MPV. High throughput sequencing of RNA extracts from symptomatic lettuce field samples and Nicotiana benthamiana test plants consistently identified a previously unknown ssRNA virus with a tripartite RNA genome distantly related to others in the family Phenuiviridae, order Bunyavirales. RT-PCR using primers designed to a portion of the polymerase gene identified the new virus in nearly all symptomatic field samples and in archived diseased lettuce samples dating to 1999. The new virus, lettuce dieback associated virus (LDaV) has been reintroduced from infected N. benthamiana to lettuce and reproduced LDD symptoms, but additional experiments are needed for validation that LDaV causes LDD, and to clarify its relationship with MPV and TBSV.