|Eastwell, K - WASHINGTON STATE UNIV.|
|Grau, C - UNIVERSITY OF WISCONSIN|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 14, 2008
Publication Date: July 1, 2008
Citation: Larsen, R. C., Miklas, P. N., Eastwell, K. C., and Grau, C. R. 2008. A strain of Clover yellow vein virus that causes severe pod necrosis disease in snap bean. Plant Dis. 92:1026-1032. Interpretive Summary: Since the introduction of the soybean aphid (Aphis glycines) in 2000, widespread virus epidemics have occurred in snap bean crops in the upper Midwest and Northeastern States. Among the viruses detected by our lab, the potyvirus Clover yellow vein virus (ClYVV) has been determined to cause serious pod necrosis in the beans, rendering them unmarketable. Producers over these years have suffered multi-million dollar losses due to this virus. Initial identification has been problematic because the strain escaped detection using a potyvirus group-specific antiserum reported to easily detect the virus. However, using biological assays, and a molecular technique to clone and sequence the viral RNA, the virus was successfully identified as ClYVV and not the very closely related Bean yellow mosaic virus. Coat protein sequence comparison with a known strain of ClYVV detectable by the antiserum used in our experiments was 98% identical at the amino acid level and 100% identical at the site on the protein detectable by the antiserum. Forty-seven commercial snap bean lines were screened using three different strains of ClYVV for resistance to the virus. All entries were found to be highly susceptible except Roma 442 that was determined to be tolerant to the virus under greenhouse conditions. When selected common bean cultivars screened over a two-year period for potential resistance to ClYVV, results indicated that all genotypes with the bc-3 gene for resistance to Bean common mosaic necrosis virus were resistant to ClYVV. Introgression of the bc-3 resistance gene into snap bean lines may offer a high level of resistance to ClYVV.
Technical Abstract: Since 2000, the soybean aphid (Aphis glycines) has been associated with severe virus epidemics in snap bean (Phaseolus vulgaris) in the upper Midwestern states, New York, and Ontario, Canada. The causal agent of a disease causing severe mosaic, apical necrosis stunting and extensive pod necrosis was identified as Clover yellow vein virus. The virus could not be detected by the potyvirus broad spectrum reacting PTY-1 monoclonal antibody. The putative coat protein amino acid sequence from clones of amplicons generated by reverse transcription polymerase chain reaction was 98% identical with ClYVV strain No. 30 and 92% identical with strain P180. The closely related Bean yellow mosaic virus was not detected as a single infection by RT-PCR in any pods with necrosis symptoms. Forty-seven snap bean varieties were screened for resistance to ClYVV and all were highly susceptible except Roma 442 which was determined to be tolerant to the virus. Selected common bean cultivars screened for potential resistance to ClYVV indicated that all genotypes with the bc-3 gene for resistance to Bean common mosaic necrosis virus were resistant to ClYVV. Introgression of the bc-3 resistance gene into snap bean lines may offer a high level of resistance to ClYVV.