Tomato infectious chlorosis virus has a bipartite genome and induces phloem-limited inclusions characteristic of the closteroviruses

Tomato infectious chlorosis virus (TICV) is a newly described closterovirus. Virions purified from TICV-infected plants contained two single-stranded (ss) RNAs, one of approximately 7,800 (RNA 1) and the other 7,400 (RNA 2) nucleotides. Double-stranded (ds) RNA analysis showed two prominent dsRNAs of approximately 7,800 and 7,400 bp, as well as several smaller dsRNAs. The TICV virion ssRNAs were used for cDNA cloning. Of 200 cDNA clones analyzed, 10 clones containing cDNAs ranging in size from about 900 to 1,500 nucleotides were used to generate digoxigenin-UTP-labeled transcripts. These transcripts hybridized with the TICV ssRNAs in Northern blot hybridization analyses and were used in dot-blot analyses to confirm TICV infection in several host plants including tomato, potato, Physalis wrightii, Nicotiana clevelandii, and artichoke. None of the probes reacted with any uninfected host plant tested or with plants infected with four other clostero- or clostero-like viruses including lettuce infectious yellows closterovirus, lettuce chlorosis virus, cucurbit yellow stunting disorder virus, and beet pseudo yellows virus. Northern blot hybridization analyses using selected riboprobes showed no detectable homology between TICV dsRNA 1 and 2, or between subsets of smaller dsRNAs. Inclusion bodies, characteristic of the closteroviruses, were consistently associated with the phloem of TICV-infected N. clevelandii.