Ourmia melon virus (OuMV), Epirus cherry virus (EpCV) and Cassava virus C (CsVC) are three species placed in the genus Ourmiavirus. We cloned and sequenced their RNA genomes. The sizes of the three genomic RNAs of OuMV, the type member of the genus, were 2814, 1064 and 974 nt and each had one open reading frame. RNA1 potentially encoded a 97.5 kDa protein carrying the GDD motif typical of RNA-dependent RNA polymerases (RdRps). The putative RdRps of ourmiaviruses are distantly related to known viral RdRps, with the closest similarity and phylogenetic affinity observed with fungal viruses of the genus Narnaviridae. RNA2 encoded a 31.6 kDa protein which, expressed in bacteria as a His-tag fusion protein and in plants through agroinfiltration, reacted specifically with antibodies made against tubular structures found in the cytoplasm. The ORF2 product is significantly similar to movement proteins of the genus Tombusviridae, and phylogenetic analysis supported this evolutionary relationship. The product of OuMV ORF3 is a 23.8 kDa protein. This protein was also expressed in bacteria and plants, and reacted specifically with antisera against the OuMV coat protein. The sequence of the ORF3 protein showed limited but significant similarity to capsid proteins of several plant and animal viruses, although phylogenetic analysis failed to reveal its most likely origin. Taken together, these results indicate that ourmiaviruses comprise a unique group of plant viruses that might have evolved by reassortment of genomic segments of RNA viruses infecting hosts belonging to different eukaryotic kingdoms, in particular, fungi and plants.

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Almond witchesÕ broom (AlmWB) is a destructive disease in several provinces in Iran. Association of phytoplasma with the disease has been established previously. In the present work two phytoplasmas from Khafr (KAlmWB) and Neyriz (NAlmWB) in the Fars Province were compared by biological and molecular analysis. Both infected bitter almond, wild almond, peach and nectarine but not apple and pear, by grafting. In bitter almond the symptoms induced by KAlmWB consisted of severe proliferation, internode shortening and leaf size reduction. In contrast, NAl-mWB caused leaf necrosis, dieback and death. KAlmWB was transmitted to periwinkle and eggplant and from experimentally infected periwinkle to almond by dodder. It was also transmitted from eggplant to eggplant, ornamental eggplant and tomato by grafting. Under similar test conditions, NAlmWB was not transmitted to herbaceous plants by dodder. Phylogenetic analysis of 16S-23S rDNA spacer region (SR) sequences placed both strains in the pigeon pea wit-chesÕ broom (PPWB) group. However, based on phylogenetic and putative restriction site analyses and sequence homology, NAlmWB was identical with the Lebanese AlmWB phytoplasma, while KAlmWB was closer to the Knautia arvensis phyllody (KAP) agent. Clustering of KAlmWB with KAP was confirmed by analysis of full length 16S rDNA sequence. On the basis of host range, dodder transmission, host range, symptomatology and molecular analyses of 16S rDNA and SR, two different phytoplasmas related to PPWB group were associated with AlmWB disease in Iran. KAlmWB phytoplasma is being reported as a new phytoplasma of AlmWB disease. Graft inoculationOne-year-old seedlings of fruit trees and 8-week-old herbaceous plants were used as test indicators and grafted with small auxillary shoots from infected or www.blackwell-synergy.com

Phyllody is a destructive disease of sesame (Sesamum indicum L.) in Iran. The major symptoms of the disease are floral virescence, phyllody and proliferation. Other symptoms which sometimes accompany the disease are yellowing, cracking of seed capsules, germination of seeds in the capsules and formation of dark exudates on the foliage. Light microscopy of hand‐cut sections of sesame and colza (Brassica napus L. cv. Oro) stems treated with Dienes' stain showed blue areas in the phloem region of phyllody infected plants. Mycoplasma‐like bodies were found in the sieve cells of infected sesame stems when thin sections were examined m an electron microscope. Sesame phyllody was successfully transmitted from sesame to sesame by grafting. Among various leafhoppers collected in sesame fields only Neoaliturus haematoceps transmitted the disease. This is the first report on the identification of a Mycoplasma‐like organism (MLO) as the cause of sesame phyllody and N. haematoceps as an MLO vector in Iran. In host range studies using the leafhopper vector, only B. napus cv. Oro, Lepidium sativum, Catharanthus roseus, Lactuca sp. and Portulaca oleracea, but not 17 other species, developed symptoms. The species of vector and host range of MLO indicate that sesame phyllody in Iran is different from that reported in India and Upper Volta.

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