Complete genome sequences and recombination analysis of three divergent Satsuma dwarf virus isolates

Abstract

Citrus mosaic virus (CiMV) and navel orange infectious mottling virus (NIMV) are considered strains of satsuma dwarf virus (SDV). To understand the distribution of different isolates of SDV in China, a field survey was conducted, which allowed for the detection of CiMV and NIMV in citrus plants in Zhejiang and Sichuan provinces, respectively. In the present work, two CiMV isolates, including one named CiMV-GTC1 from Goutoucheng sour orange and one named CiMV-SE1 from Setoka tangor, as well as one NIMV isolate named NIMV-EH1 from Ehime-ken No. 38 tangor were, for the first time, fully sequenced. Among the isolates, CiMV-SE1 and CiMV-GTC1 were closely associated with the partial genomes of known CiMV isolates, while NIMV-EH1 was markedly different from known NIMV isolate. Sequence analysis demonstrated that CiMV, NIMV, and SDV shared similar genome organization and high nucleotide identities at the genome level. In addition, phylogenetic reconstruction of the three viruses also suggested a close relationship. Furthermore, recombination analysis provided evidence for their common co-occurrence in nature. These findings contribute significantly to our understanding of the natural evolution of SDV populations and can provide a basis for preventing the spread of different SDV isolates in the main citrus production regions.