First report of Eggplant Mottled Crinkle Virus in Geranium in Iran

During a survey in a commercial greenhouse in Shiraz, Iran, in September 2006, ring spots and chlorotic spots were observed on the leaves of geranium (Pelargonium hortorum). Disease symptoms appeared as small chlorotic spots on young leaves, then expanded and changed into rings and necrotic spots as the leaves aged. Sap was extracted from infected leaf samples in 0.1 M potassium phosphate buffer, pH 7, and mechanically inoculated onto test plants. Symptomatic geranium leaves were also used for electron microscopy and total RNA extraction. RT-PCR amplification was carried out using a primer pair designed on sequences that flank the coat protein gene (CP) of Pear latent virus (PeLV) (Melgarejo et al., 2003). The PCR product was ligated into pTZ57R/T vector (Fermentas), cloned in E. coli strain DH5α and sequenced.

Among mechanically inoculated test plants, Chenopodium amaranticolar, C. quinoa, Datura stramonium, Nicotiana tabacum var. Turkish, Osimum basilicum, Phaseolus vulgaris and Vigna unguiculata reacted to the virus by producing local lesions on inoculated leaves. Cucumis sativus, C. melo, Cucurbita pepo, Datura metel, Gossypium hirsutum, Lycopersicon esculentum, N. glutinosa, N. rustica and Solanum melongena did not exhibit any symptoms after inoculation. Electron microscopy of infected geranium leaves showed the presence of many isometric particles and RT-PCR amplification produced a fragment of approximately 1200 bp. These results were verified from mechanically inoculated cowpea leaves showing necrotic local lesions. A search of the GenBank database revealed 89%, 88% and 87-88% amino acid sequence identity between the CP gene (388 aa) of the geranium virus (accession no EF140907) and Lisianthus necrosis virus (LNV), Eggplant mottled crinkle virus (EMCV) and PeLV, respectively. LNV (Chen et al., 2006) and PeLV (Melgarejo et al., 2003) share high amino acid sequence identity with EMCV and should be regarded as strains of this virus (Koenig et al., 2004). These results indicate that the tombusvirus inducing ring spots and chlorotic spots in geranium plants in Shiraz is a strain of EMCV.

Since geranium has not previously been reported as natural host of EMCV, this is both the first report of EMCV naturally infecting geranium plants and of EMCV in Iran.