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Title: Identifying a new causal agent of mosaic in Louisiana sugarcane

item Keizerweerd, Amber
item Warnke, Kathryn
item Grisham, Michael

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/10/2013
Publication Date: 12/23/2013
Citation: Keizerweerd, A.T., Warnke, K.Z., Grisham, M.P. 2013. Identifying a new causal agent of mosaic in Louisiana sugarcane [abstract]. Journal of the American Society of Sugar Cane Technologists. 33:75.

Interpretive Summary:

Technical Abstract: Sugarcane mosaic virus (SCMV) is a pathogen of economic concern that infects maize, sorghum, and sugarcane worldwide. It is a member of the genus Potyvirus in the family Potyviridae and contains a linear, positive sense ssRNA genome 10 kb long. It is transmitted non-persistently via aphids and causes stunting, chlorosis, and yield losses of 7 to 21% (over a three-year crop cycle) in susceptible varieties. Prior to the use of molecular techniques to characterize plant viruses, differences in cultivar response and variations in symptom expression during infection were attributed to different strains of SCMV. However, the sequence of the virus coat protein amino terminus differed between two groups of isolates. This difference was sufficient to separate the groups into two distinct species: SCMV and Sorghum mosaic virus (SrMV). Due to the widespread occurrence and ability of SCMV and SrMV to cause significant yield losses in susceptible cultivars, breeding and cultivating resistant varieties remains an important control method. Though SCMV is more widespread internationally than SrMV, ongoing research reveals that SrMV is responsible for causing the majority of mosaic symptoms seen in sugarcane in Louisiana. In recent years, strain I of SrMV has become the dominant strain isolated in Louisiana, whereas SCMV strain E remains prevalent in Florida. No nucleic acid product was amplified from a small number of samples collected in Louisiana sugarcane displaying mosaic symptoms when analyzed with SCMV- and SrMV-specific PCR primer sets. However, a product was amplified when Potyvirus-specific primers were used instead. This poses the question whether the mosaic symptoms expressed in these samples are caused by another species of Potyvirus or by a new strain of SCMV or SrMV. Consequently, gathering sequence data on these unidentified isolates is critical to the continued protection of the Louisiana sugarcane industry from this important pathogen.