[Scientific Papers] http://www.scipapers.com    2007-11-16  

Genetic structure of TSWV isolates collected from epidemics in North Carolina (2002) and California (2003)

New SL¹, Abad JA¹, Carbone I^1,2, Kennedy GG³, Tsompana M⁴, Moyer JW¹

¹Department of Plant Pathology, North Carolina State University, Raleigh, NC.

²Center for Integrated Fungal Research, Department of Plant Pathology, North Carolina State University, Raleigh, NC

³Department of Entomology, North Carolina State University, Raleigh, NC

⁴Department of Biology, University of North Carolina-Chapel Hill, NC.

Correspondence: james_moyer@ncsu.edu

Tomato spotted wilt virus (TSWV) has been known to cause wide spread epidemics in a number of crops with increased frequency. In addition, there is constant geographic expansion of the virus. In this study, we compare and characterize the genetic structure of infected isolates obtained in epidemics of North Carolina and California. For this study, sequence of the entire nucleocapsid (N) gene and the glycoprotein precursor (GnGc) in addition to partial fragments of the non-structural protein (NsM) and the RNA-dependent-RNA-polymerase (RdRp) were generated from 15 isolates from North Carolina and seven isolates from California. Preliminary analysis for all coding regions sequenced in this study revealed the clustering of all isolates from North Carolina with previously sequenced isolates collected from the Southeastern region of the United States. California isolates clustered in at least two distinct groups. Statistical tests were used to evaluate the genetic differentiation between isolates based on host or geographic origin. The null hypothesis of no differentiation between subgroups based on host was not rejected. However, the differentiation of geographical subpopulations was supported statistically at all loci and in the analysis of the combined sequence. Additionally, synonymous changes specific to geographical subpopulations were determined from the amino acid translations. Further analysis was used to elucidate the evolutionary properties of the different geographical subpopulations.

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