Zucchini green mottle mosaic virus is a new tobamovirus; comparison of itscoat protein gene with that of kyuri green mottle mosaic virus

A novel virus we call zucchini green mottle mosaic virus (ZGMMV) was isolat ed from zucchini squash and its properties were determined. The size and sh ape of its virions, and other properties suggest that the virus is a tobamo virus. The coat protein (CP) genes of ZGMMV and kyuri green mottle mosaic v irus (KGMMV), which also infects zucchini squash plants, were cloned and th eir nucleotides sequences were determined. The CP genes of ZGMMV and KGMMV are composed of 161 amino acid residues, and they share 77.6% amino acid id entity. Western blot analysis showed that the two viruses are serologically related but not identical. Comparison of the sequences with those of sixte en other tobamoviruses revealed that the two viruses had much higher identi ty to cucumber green mottle mosaic virus (CGMMV), another tobamovirus infec tious to cucurbit plants, than other tobamoviruses. The nucleotide and amin o acid sequences of ZGMMV were from 29.5 to 78.4% and from 29.3 to 77.6% id entical, respectively, to those of other tobamoviruses. The predicted virio n assembly origins of the two tobamoviruses were located in the CP region o f the genomic RNAs, and the predicted secondary structures were more simila r to that of CGMMV than those of other tobamoviruses. The seventeen tobamo- viruses could be classified into three main subgroups based on the phylogen etic tree analysis on the CP gene, and ZGMMV and KGMMV formed a third subgr oup together with CGMMV and sunn-hemp mosaic virus (SKMV). These results sh ow that ZGMMV is a previously unknown member of the Tobamovirus genus.