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United States Department of Agriculture

Agricultural Research Service

Research Project: Biology, Epidemiology and Management of Vector-Borne Viruses of Sugarbeet and Vegetable Crops

Location: Crop Improvement and Protection Research

Title: Molecular Detection of Tobacco rattle virus in Bleeding Heart [Dicentra spectabilis (L.) Lem.] Growing in Alaska

Author
item Robertson, Nancy

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2012
Publication Date: February 27, 2013
Citation: Robertson, N.L. 2013. Molecular detection of Tobacco rattle virus in Bleeding Heart [Dicentra spectabilis (L.) Lem.] growing in Alaska. Plant Health Progress. doi: 10.1094/PHP-2013-0227-01-BR.

Interpretive Summary: Tobacco rattle virus (TRV) was detected in Dicentra spectabilis (L.) Lem. (Papaveraceae) from South Central Alaskan home gardens in 2010-11. The common name for these cold-hardy perennials, bleeding heart, is derived from their gracefully stalked heart-shaped flowers. Bleeding heart plants were found with noticeable ringspots and oak-leaf patterns on the foliage, and overall severe stunting. Tobacco rattle virus (TRV) is a plant virus that in nature may occur as an M-type isolate with RNA1 and RNA2, or NM-type isolates with only RNA1 and is found throughout the world in a variety of plants that include vegetables, weeds, and ornamentals. TRV was confirmed from four symptomatic bleeding heart plants by reverse transcription (RT)-PCR polymerase chain reaction using specific sets of primers for TRV RNA1. By incorporating additional protein, serological, and virus transmission assays, TRV M-type isolates were confirmed to exist in two of the diseased bleeding heart plants, while two other plants contained NM-type isolates. RNA1 was sequenced from one of the bleeding heart M-type isolates, and when compared with six TRV isolates from potato, spinach, and alstroemeria, the nucleotide identity ranged from 91% to 94%. Interestingly, the TRV isolate from bleeding heart was most closely related to the TRV isolate from another ornamental plant, alstroemeria. This is the first detection of TRV from D. spectabilis in Alaska, and the first TRV molecular characterization from bleeding-heart. It is also the first time that M- and NM- type isolates have been distinguished from bleeding heart plants. The significance of these findings is that even though TRV infected plants containing NM-type isolates probably will not be spread to other plants by its specific nematode vector, vegetative propagated roots from TRV infected plants of either type of isolates will continue to be a source of diseased plants to home gardeners.

Technical Abstract: Tobacco rattle virus (TRV) is a single-stranded positive RNA plant virus that in nature may occur as M-type isolates with RNA1 and RNA2, or as NM-type isolates with only RNA1. RNA1 is responsible for viral replication and transmission, while the formation of the coat protein (CP) is dependent on RNA2. TRV has a wide plant host range and causes disease in vegetables, weeds, and ornamentals throughout the world. In 2010-2011, Tobacco rattle virus (TRV) was detected in an ornamental perennial, Dicentra spectabilis (L.) Lem. (Papaveraceae) growing in Alaska from several home gardens. Commonly named bleeding heart, several plants contained virus-like symptoms of noticeable ringspots and oak-leaf patterns on the foliage. TRV was confirmed from four symptomatic bleeding heart plants by reverse transcription (RT)-PCR polymerase chain reaction using specific sets of primers for TRV RNA1. Coat protein detection by western blot assays and mechanical sap transmission of TRV to three indicator test species were confirmed from only two of the diseased bleeding plants and not the other two plants. This infers that TRV M-type isolates were confirmed to exist in two of the diseased bleeding heart plants, while the other two plants contained NM-type isolates. RNA1 was sequenced from one of the bleeding heart M-type isolates with over-lapping PCR segments that spanned the genome, and identified as TRV-1AKBH. When compared with six TRV isolates from potato, spinach, and alstroemeria, TRV-1AKBH nucleotide identity ranged from 91% to 94%. Interestingly, the bleeding heart TRV isolate clustered with another ornamental plant, alstroemeria, in a phylogenetic tree. This is the first detection of TRV from D. spectabilis in Alaska, and the first TRV molecular characterization from bleeding-heart. It is also the first time that M- and NM- type isolates have been distinguished from bleeding heart plants. The significance of these findings is that even though TRV infected plants containing NM-type isolates probably will not be spread to other plants by its specific nematode vector, vegetative propagated roots from TRV infected plants of either type of isolates will continue to be a source of diseased plants to home gardeners.

Last Modified: 8/21/2014
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