Molecular Research on two Orthotospoviruses Infecting Important Legumes in Alabama.

Abstract

Peanut (Arachis hypogaea. L) is a major crop in the United States, especially in Georgia, Florida, and Alabama, where they produce two-thirds of the peanut total production in the US. Soybean (Glycine max (L.) Merrill) is the fourth most popular crop produced in the state. In Alabama, Tomato spotted wilt virus (TSWV) and Soybean vein necrosis virus (SVNV), can be found in peanuts (TSWV) and soybean (TSWV and SVNV). These viruses are both in the genus Orthotospovirus in the family bunyviridae and have an ambisense ssRNA genome. To understand the sequences of TSWV in AL, a total of 126 symptomatic peanut samples were collected from three locations in AL over two years, and a protein alignment was conducted. This alignment revealed five compared to the MT2 strain (X61799.1) and seven mutations compared to BR-O1 GenBank strain (NC_002051.1). Eight samples were selected for microscopy and a difference in aggregation speed between samples was described. Although unlikely the cause of rising levels of TSWV, these differences reveal new insights into TSWV-N protein function. SVNV proteins have never been localized in plant cells. The five ORFs of SVNV (N, NSs, NSm, GN, and GC) were localized, and the images revealed that NSs and N proteins localize to the cell periphery and to the nucleus. NSm causes cell death and the glycoproteins GN and GC localize to the cell membrane and accumulate around the nucleus. To further our work, the genes of SVNV from the field were sequenced and a protein alignment and a phylogeny tree were constructed for each of SVNV's three genes. This revealed mutations in the SVNV of AL compared to the SVNV reference genome (GCF_004789395.1). This is essential to understand the diversity and the distribution of SVNV in AL which will further our understanding of this new emergent orthotospoviurs infecting soybean fields in the southern states of the US.