Content area
Full Text
Abstract. A region of the Kalanchoe latent carlavirus (KLV) genome, containing the coding capacity for the triple gene block and the coat protein, was cloned and sequenced for two isolates, the one infecting Chenopodium quinoa systemically whereas the other infects C. quinoa locally. The sequence confirmed the classification of KLV as a carlavirus. There was the highest identity in the amino acid sequences to the carlaviruses potato rough dwarf virus, lily latent virus, lily symptomless virus, blueberry scorch virus and potato virus S. The aminoacid sequences of proteins of the two KLV isolates had an identity between 86% and 91%.
Key words: carlavirus, kalanchoe latent virus, triple gene block, coat protein, kalanchoe
Introduction
Kalanchoe blosfeldiana Poelln. is an important ornamental plant which belongs to the Crassulaceae. It is a short day succulent that is vegetatively propagated. Kalanchoe latent carlavirus (KLV) is widespread in K. blosfeldiana as a latent infection. KLV is a member of the carlavirus group of positive-sense ssRNA viruses [1]. The genome structure between individual carlaviruses is very similar and consist of ORF I which codes for a putative RNA replicase of about 223 kDa, ORFs 2, 3, and 4 (the triple gene block) which code for proteins of about 25, 12, and 7 kDa, repectively. The triple gene block has been shown to be involved in cell-to-cell movement of virus [2-4]. ORF 5 codes for the coat protein (about 32 kDa), and ORF 6 codes for a protein of 12-15 kDa, which has been shown to bind nucleic acids in vitro [5]. KLV has been separated into two strains, KV-I and KV-2 [6]. KV-2 was found to infect Chenopodium quinoa systemically, whereas KV-1 infected C. quinoa locally. KV-2 was degraded by reagents such as 1% triton X-100, 5mMEDTA, and chloroform-carbon tetrachloride that did not degrade KV-1. The virions of KLV were found to be flexuous rods of 590-640 nm (KV-1) or 620-670 nm (KV-2). KV-1 and -2 were serologically closely related and also reacted strongly to antisera prepared against carnation latent, lily symptomless, potato S, and chrysantemum B viruses [6].
We have cloned and determined the nucleotide sequences corresponding to the triple gene block and the coat protein of two isolates ofKLV, the one infecting C. quinoa systemically and the other...