Homologies between the genomes of a carlavirus (lily symptomless virus) and a potexvirus (lily virus X) from lily plants

Abstract

cDNA clones complementary to the 3"-terminal regions of the genomic RNAs of the carlavirus lily symptomless virus and the potexvirus lily virus X (LVX) have been sequenced. The carlavirus RNA sequence contains five open reading frames (ORFs) coding for proteins of Mr 25 374, 11631, 6960, 32 041 (coat protein) and 16121, which are all very similar in size, amino acid sequence and relative position in the genome to proteins encoded by two different potato carlaviruses. The first four of these proteins also show considerable amino acid sequence similarity to proteins encoded by RNA of potexviruses, and the relative position of the ORFs on the carlavirus genome strongly resembles that in the potexvirus genomes. The LVX cDNA clone contains three ORFs encoding proteins of Mr 23574, 11767 and 21569 (coat protein). A small ORF immediately 5' of the coat protein ORF, which has been found in other potexvirus genomes, is not present in the LVX genome. Thus, the data confirm the close taxonomic relationship between carlaviruses and potexviruses and reveal some differences in genome organization among the potexviruses.

The nucleotide sequence of potato mop-top virus RNA 2: a novel type of genome organization for a furovirus

“…In the two viruses known to contain only two of these genes, infection or replication is less effective than that of viruses with complete triple gene blocks. For instance, lily X potexvirus lacks the third of the genes and reaches only low concentrations in plant tissue (Memelink et al, 1990). Strawberry mild yellow edgeassociated potexvirus appears to lack an initiation codon for the first triple block ORF and is confined to phloem tissue (Jelkmann et al, 1990(Jelkmann et al, , 1992.…”

Nucleotide sequence and gene organization of the 3'-terminal region of chrysanthemum virus B genomic RNA

“…They consist of multiple copies of a coat protein (Mr 37000) encapsidating the viral RNA (Hollings & Stone, 1972). Recently, there have been reports of the complete nucleotide sequence of the genomic RNA of carlavirus potato virus M (PVM) (Zavriev et al, 1991) and the 3'-terminal regions of other carlavirus genomic RNAs such as those of potato virus S (PVS), lily symptomless virus (LSV), helenium virus S (HelVS) and carnation latent virus (CLV) (MacKenzie et al, 1989;Memelink et al, 1990;Foster et al, 1990;Haylor et al, 1990). These carlaviruses have an identical genome organization, which is similar to that of potexviruses.…”

“…The long ORF1 at the beginning of the sequence ends at position 787 and encodes a polypeptide of at least Mr 30255. The next three ORFs code for the proteins of the triple gene block which is found in all carla-and potexviruses except lily virus X (Memelink et al, 1990 Analysis of the negative RNA strand of the sequence reveals only one relatively long ORF (ORF7, Fig. 1) which encodes a putative 164 residue polypeptide of Mr 16718 (17K).…”

Molecular characterization and field survey of Iranian potato virus X isolates

“…ORFs 2-4 are known as the triple gene block (TGB), encoding three polypeptides of 25, 12, and 8 kDa, respectively and are involved in viral movement [16,24]. The TGB proteins are highly conserved in members of the genera Potexvirus, Hordeivirus, Benyvirus and Carlavirus [6,15,23]. ORF5 encodes the capsid protein (CP) with an estimated molecular mass of 25 kDa and plays an significant role in cell-to-cell movement of PVX particles and translational regulation of the PVX RNA genome [10,14].…”