Complete nucleotide sequence of L RNA segment of Melon yellow spot virus

Abstract

Melon yellow spot virus causes yellow spots or necrosis on melon (Cucumis melo) and cucumber (C. sativas) plants in Japan. This virus belongs to the genus Tospovirus, which has a tripartite RNA genome. The complete nucleotide sequence of the largest RNA segment (L RNA) of an MYSV isolate was determined and analyzed. The L RNA segment was 8, 918 nucleotide (nt) long and had one open reading frame (ORF) in the complementary sense. Deduced amino acid sequence of the ORF was 2, 870 amino acids and contained motifs of RNA-dependent RNA polymerase. Comparison of the nucleotide and deduced amino acid sequences with those of other tospoviruses revealed that MYSV was closer to Groundnut bud necrosis virus (71.0% identity) and Watermelon silver mottle virus (70.6% identity) than other tospoviruses. The 19-nt terminal sequences in the 5' and 3' untranslated regions were incomplete inverted complementary sequences. They were not similar to those in the S RNA of MYSV, but were similar to those of the L RNA of known tospovirus species.