Construction of infectious clones of lychnis ringspot virus and evaluation of its relationship with barley stripe mosaic virus by reassortment of genomic RNA segments.

Lychnis ringspot virus (LRSV, genus Hordeivirus) was first isolated in 1959, and has been shown to infect several dicot plants in nature. However, due to the lack of infectious cDNA clones, the biological properties and mechanisms underlying LRSV infection are obscure. In this work, we constructed infectious cDNA clones of LRSV and have compiled the complete LRSV genomic (g) RNA sequence. Comparison of nucleotide and amino acid sequences between LRSV and barley stripe mosaic virus (BSMV), the type member of genus Hordeivirus, reveals that despite belonging to the same genus, and replicating in chloroplasts, the viruses are only distantly related. This could be further indicated by the failure of different LRSV/BSMV reassortants to infect N. benthamiana. LRSV infectious cDNA clones provide a useful tool for studies of biological diversity among hordeiviruses, and also may contribute to the understanding of seed transmission in dicot plants.

The complete nucleotide sequence and genome organization of lychnis mottle virus.

The complete genomic sequence of lychnis mottle virus (LycMoV) from a Lychnis cognata plant was determined. LycMoV has a bipartite genome consisting of RNA1 (7,428 nt) and RNA2 (3,734 nt). Species in the family Secoviridae are demarcated based on their amino acid similarities in the protease-polymerase and coat protein. In LycMoV, these proteins share 90% and 63% sequence similarity, respectively, with the most closely related virus, strawberry latent ringspot virus, which is a member of the family Secoviridae but has not been assigned to a genus. Therefore, LycMoV is a tentative new virus of the family Secoviridae.