Submitted to: Virus Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/6/2006
Publication Date: 10/8/2006
Citation: Tzanetakis, I.E., Postman, J.D., Gergerich, R.C., Martin, R.R. 2006. A virus between families: nucleotide sequence and evolution of Strawberry latent ringspot virus. Virus Research. 121:199-204. Interpretive Summary: Golden ginger mint (Mentha × gracilis, ‘Variegata’) is sold as an ornamental mint because it exhibits a bright yellow veinbanding symptom. It was discovered that the veinbanding symptom is caused by infection with three viruses, one of which is Strawberry latent ringspot virus (SLRSV). This virus has long been considered a European nepovirus that was not established in North America. The virus was purified and then sequenced to confirm its identity. Surprisingly, the sequence showed that the virus has similarities to a number of different virus genera in several virus families and that it is not closely related to the Nepoviruses. Since SLRSV was related to genera with beetle and aphid vectors, studies were undertaken to determine if this virus may have multiple vectors which would be very unusual for a plant virus. All transmission attempts with the mint aphid and the cucumber beetle failed. If the virus is only transmitted by the nematode Xiphinema diversicaudatum, which occurs in Europe but not in North America, it is not surprising that it has not become a serious pathogen in North America.
Technical Abstract: Several clones of golden ginger mint (Mentha × gracilis, ‘Variegata’)were found infected with Strawberry latent ringspot virus (SLRSV). The virus was purified and cloned and the complete nucleotide sequence of a mint isolate was obtained. RNA 1 consists of 7496 nucleotides excluding the poly A tail and encodes a polyprotein with signature enzymatic motifs found in other picorna-like plant viruses. RNA 2 consists of 3842 nucleotides excluding the poly A tail, coding for a polyprotein that is processed to a putative movement protein and the two coat proteins of the virus. A satellite RNA of 1117 nucleotides was found associated with this isolate encoding for a putative protein of 31 kDa. Phylogenetic analysis revealed that SLRSV shares characteristics with members of the Cheravirus, Fabavirus, Comovirus and Sadwavirus genera indicative of the uniqueness of SLRSV. The close relationship of SLRSV with these genera led to the examination of aphid and beetle transmission of the virus with, however, negative results.