Genetic diversity of viruses causing mosaic in Louisiana sugarcane

Authors: Keizerweerd, Amber; Warnke, Kathryn; Grisham, Michael

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/18/2013
Publication Date: 6/1/2013
Citation: Keizerweerd, A.T., Warnke, K.Z., Grisham, M.P. 2013. Genetic diversity of viruses causing mosaic in Louisiana sugarcane. Phytopathology. (Suppl. 2):S2.158.

Interpretive Summary:

Technical Abstract: Mosaic caused by Sugarcane mosaic virus (SCMV) contributed to the near collapse of Louisiana’s sugarcane industry in the early 20th Century. By the 1950s, the cultivation of resistant cultivars eliminated mosaic as a major disease problem; however, new strains arose among previously resistant cultivars. These new strains were placed in a new taxon, Sorghum mosaic virus (SrMV), on the basis of molecular studies conducted in the 1990s. Between 1978 and 1995, over 90% of the virus isolates from plants with mosaic symptoms in Louisiana were identified as SrMV strain H. A reverse transcriptase-polymerase chain reaction (RT-PCR)-based restriction fragment length polymorphism (RFLP) analysis was used to determine that 67% of isolates collected between 2000 and 2003 were identified as SrMV strain I, representing a shift from strain H as the predominant strain causing mosaic. Among isolates collected from 2005 to the present, SrMV strain I remains the predominant virus and strain recovered from sugarcane with mosaic symptoms. However, for the first time since the 1950s, isolates of SCMV were also identified. In approximately 8% of the samples from plants with mosaic symptoms, the causal agent has not been identified. Due to the economical threat posed by these viruses, an awareness of their genetic diversity is needed by pathologists and breeders when screening new germplasm in search of new sources of resistance to mosaic.