Cloning and Characterization of a new tobamovirus infecting Hibiscus rosa-sinensis

A near full-length sequence of a new tobamovirus infecting Hibiscus rosa-sinensis L. was determined. The genome consists of 58 nucleotides (nt) 5' UTR, followed by a 4.9 kb ORF which methyl transferase helicase domain (128 kDa), readthrough protein RNA dependent RNA polymerase (RdRp) 185 kDa and a 52 kDa protein. The 128 kDa protein had a maximum homology of 51.4 ％ to TMGMV and amino acids (an) were 54.3 ％ identical to TMV- vulgare strain. The 185 kDa RdRp had a maximum homology of 53.5％ to TMV-Ob and KGMMV-Y and a 59.6％ homology at the an level to CGMMV-SH. The MP gene encodes 282 aa and its theoretical molecular weight is 30.4 kDa. The nt and an sequence identities of MP ranged from 38.8％ to 43.9％ and 30.9％ to 37.9％, respectively. The CP gene encodes 163 residues and with a theoretical molecular weight of 18.2 kDa The (nt) and aa sequences of the CP were 46.9 ％ to 51.6％ and 45.3％ to 57.1％ identical to other tobamoviruses, respectively. The predicted virion origin of assembly (OAS) was located in the CP gene. Phylogenetic trees generated based on the nt and as sequences of RdRp, MP and CP genes indicated that this new virus clustered with subgroup II tobamoviruses. Although the CP ORF of this virus shared a high nt and aa sequence identity with Sunn-hemp mosaic virus (SHMV), Western analysis showed that it is serologically unrelated to SHMV. We propose the name Hibiscus virus S (HVS) for this Singapore isolate. This is the first report on a near full-length sequence of a Tobamovirus that infects hibiscus.