DISTRIBUTION, BIOLOGICAL PROPERTIES and GENETIC DIVERSITY OF IRANIAN Tomato mosaic virus ISOLATES

Tomato mosaic virus (ToMV) with wide host range is one the most important viruses in tomato plants. A survey was conducted to analyse incidence, host range and genetic diversity of the virus during 2006 until 2008. Symptomatic samples were collected from tomato, pepper, Kidney bean and weeds in Yazd, Kerman, Hamedan and Hormozgane provinces and checked by double antibody sandwich ELISA (DAS-ELISA). Of 434 leaf samples from tomato, pepper, Kidney bean and weed species, 27 samples were ELISA positive. Among the weed species tested Common lLambsquarters (Chenopodium amaranticolour) and Black night shade (Solanum nigrum) were found to be infected with ToMV. Based on the geographical location and host range, 10 ToMV isolates were selected for molecular and biological characterization. The full-length coat protein (CP) gene from 10 isolates was PCR amplified, cloned and sequenced. Phylogenetic analysis showed that these isolates fell into three groups I, II and III. Two weeds- and one pepper isolates were clustered in group I and the rest of isolates in group III. The lowest percent nucleotide sequence identity (84.4%) was between Iranian isolate Jir.Che.4 in group I and other four isolates collected from Kerman and Hamadan provinces in group III. Inoculation of 10 Iranian ToMV isolates on test plants induced different symptoms on tobacco. This is the first report of Kidney bean as the natural host of the virus in Iran. Study of genetic diversity (π) showed a remarkable variation in the ToMV isolates in the Iran and Brazil. This value was about twice for Iranian ToMV isolates in compared to the reported isolates in the world.