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United States Department of Agriculture

Agricultural Research Service

Research Project: ARCTIC AND SUBARCTIC PLANT GENETIC RESOURCES CONSERVATION, RESEARCH, AND INFORMATION MANAGEMENT Title: First Report of Bean Yellow Mosaic Virus in Alaska from Clover (Trifolium spp.)

Authors
item Robertson, Nancy
item Brown, Kathryn

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 23, 2009
Publication Date: March 20, 2010
Citation: Robertson, N.L., Brown, K.L. 2010. First Report of Bean Yellow Mosaic Virus in Alaska from Clover (Trifolium spp.). Plant Disease. 94(3):372.

Interpretive Summary: Bean yellow mosaic virus (BYMV) was confirmed for the first time in Alaska in 2008. A cluster of white clover, Trifolium repens L., growing on a lawn in Palmer, Alaska contained leaves with virus-like symptoms (mosaic). Leaves were collected and processed for virus extraction and purification. Serological assays determined that the virus belonged to a large group of plant potyviruses. Subsequent reverse transcription (RT)-polymerase chain reaction (PCR) and genomic sequencing determined that the virus was Bean yellow mosaic virus. Although BYMV occurs worldwide and has a wide host range in dictoyledonous and monocotyledonous plants, this is the first report of a natural occurrence of BYMV in Alaska. White clover has been reported in western Oregon to act as a reservoir for BYMV which is subsequently vectored by several aphid species into bean crops causing economical losses. Since BYMV may be transmitted by seed and to other plant species by aphids, BYMV's presence in Alaska is significant. The incidence and distribution of BYMV in white clover or other horticultural and native plant species are not known in Alaska.

Technical Abstract: During mid-June 2008, distinct mosaic leaves were observed on a cluster of white clover, Trifolium repens L., growing at the edge of a lawn in Palmer, Alaska. Virus minipurification from leaves of affected clover and polyacrylamide electrophoresis implicated a ~35 kDa putative coat protein (CP). Subsequent western blots and ELISA (enzyme-linked immunosorbent assay) using a universal potyvirus antiserum (Agdia Inc., IN) confirmed potyvirus identity. Total RNA extracts (RNeasy Plant Mini Kit, Qiagen Inc., CA) from the same leaves were used for reverse transcription (RT) –PCR. Two sets of degenerate primers that targeted potyvirus-specific genes, HC-Pro (helper component protease) and CI (cylindrical inclusion protein) produced the expected PCR segments (~0.7 kbp) on 1% agarose gels (1). Direct sequencing of the HP and CI segments revealed 98% and 97% nucleotide identities (no gaps), respectively, to Bean yellow mosaic virus (family Potyviridae, genus Potyvirus), Accession No. AB373203 (strain CS). Other BYMV percent identity comparisons were considerably less, and the next closest in the Genbank database decreased to 79% for HP (Accession No. DQ641248), and 79% for CI (Accession No. U47033). Interestingly, the Alaskan strain of BYMV from clover appears to resemble the CS strain that was originally isolated from peas, Pisum sativum L., in Japan, which was designated in the polytypic “Pea” group of BYMV (4) with a seed-borne propensity, and likely BYMV distribution in the international seed trade industry. Mechanical inoculations of purified preparations produced local lesions on Chenopodium amaranticolor and C. quinoa, and mosaic on Nicotiana benthamiana. BYMV was confirmed on tester plants by RT-PCR, western blots, and ELISA as described previously. Although BYMV occurs worldwide and has a wide host range in dictoyledonous and monocotyledonous plants, this is the first report of a natural occurrence of BYMV in Alaska. White clover has been reported in western Oregon to act as a reservoir for BYMV which is subsequently vectored by several aphid species into bean crops causing economical losses. The incidence and distribution of BYMV in white clover are not known in Alaska.

Last Modified: 4/23/2014
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