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Mosaic symptoms were seen on the ornamental plantBupleurum falcatum(Apiaceae) grown in a commercial nursery in Israel. Examination by electron microscopy (EM) of samples from diseased plants revealed elongated filamentous virus particles. Here we provide evidence thatB. falcatumis an alternate host for Lettuce mosaic potyvirus (LMV). Several lines of evidence indicated thatBupleurumwas infected by LMV, including double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), immunosorbent electron microscopy, and sap and aphid transmission of LMV to lettuce and other host plants. Additionally, general primers derived from a conserved region of the 3’-terminus of the potyvirus genome were used in a reverse transcription-polymerase chain reaction (RT-PCR) assay and gave an expected amplification product of 672 bp. A similar approach was carried out to amplify the corresponding fragment from LMV-infected lettuce. The PCR product was cloned and sequenced; it encompassed an open reading frame encoding 153 amino acids and a 3’ untranslated region (UTR) of 273 nucleotides, very similar to the coat protein (CP) and the 3‵UTR nucleotide sequence, respectively, of other LMV isolates. Analysis of the amino acid sequences of the putative CP of theBupleurumisolate showed complete identity to the lettuce isolate of LMV. TheBupleurumisolate had no new nucleotide changes which have not been established in other published LMV strain sequences. It is concluded that LMV is the causal agent of the disease inB. falcatumin Israel.

Conspicuous viral symptoms were seen on Tabernaemontana divaricata, a member of the family Apocynaceae, grown in a commercial nursery, in Israel. The symptoms varied widely and included chlorotic ringspots and banding, oak-leaf patterns and mosaic. At the end of the winter, large yellow spots, which later became necrotic, appeared on fully expanded leaves. The necrotic zones later fell out, leaving "shot holes". Preliminary analysis suggested that the disease was associated with a tobamovirus. Particles typical of a tobamovirus were observed by electron microscopy only in samples taken from symptomatic leaves. Apartial segment of the 5'-terminus of the viral RNA, which comprised of 533 bp was cloned and sequenced. Comparison of the predicted amino acid sequence with those of other tobamoviruses revealed 94 identity with Tobacco mild green mosaic virus(TMGMV) genome. Primers specific to the coat protein (CP) gene of TMGMV used in a reverse transcription-polymerase chain reaction assay (RT-PCR) gave an expected amplification product of 455 bp. The amino acid composition of the cloned CP gene, which shows a complete identity to that of TMGMV, confirmed the identity of TMGMV infecting Tabernaemontana. Polyclonal antibodies prepared against the virus and used in double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) enabled specific detection of the virus in crude sap extracted from T. divaricataand mechanically inoculated indicator plants. This is the first report of TMGMV infection in Tabernaemontanaand the first incidence of the virus in Israel.

A PVY isolate which causes strong necrotic lesions in tomato was isolated and characterised. It did not infect potato and did not react with antiserum specific to the N-strain of PVY. Restriction endonuclease cleavage patterns of PCR products derived from the 5'-end of the virus genome (Hinc II and Rsa I) clearly distinguished the tomato, pepper and potato strains. Additional sequence analysis indicated that the tomato and pepper isolates were closely related, while both markedly differed from the necrotic strains of potato. Hence, it was concluded that the necrotic tomato isolate is uniquely specific for tomato.

Primus necrotic ringspot virus (PNRSV) isolates were characterised by bioassays, serotyping and restriction fragment length polymorphism (RFLP) analysis of PCR products. Based on symptoms in host trees and bioassays it was concluded that only one of the 16 tested isolates is severe. The serotyping results demonstrated that by using four different MAbs in TAS-ELISA the tested isolates could be divided into four subgroups, however, the severe isolate could not be singled out. RFLP analysis of PCR products supported the serotyping data but did not differentiate between isolates of the two main serological subgroups. A restriction map, derived from sequence analysis of the PCR products obtained from selected isolates, allowed exact location of the restriction sites within the PCR products of each isolate. A mild isolate with a unique genome structure was identified by both serological and RFLP assays. As far as we are aware, this is the first report on sub-grouping of PNRSV isolates by bioassays, serotyping with MAbs and RFLP analysis.