Identification of some viruses causing mosaic on lettuce and characterization of Lettuce mosaic virus from Tehran province in Iran.
Lettuce mosaic virus (LMV), Cucumber mosaic virus (CMV) and Tomato spotted wilt virus (TSWV) were identified in lettuce fields in Tehran province. In this study, 452 infected lettuce plants having viral infection symptoms including, mosaic, mottling, leaf distortion, stunting defective heading, were collected from the fields throughout Tehran province. Distribution of Lettuce mosaic virus (LMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV) and Arabis mosaic virus (ArMV) were determined with DAS-ELISA. LMV, CMV and TSWV were found on lettuce in this region, but no infection by ArMV was found. Percentage of single infection by LMV, CMV or TSWV was 21, 16 and 10% respectively. Also, 16% of samples were co-infected with LMV+CMV, 8% with LMV+TSWV and 8% with CMV+TSWV. 5% of samples were infected to all of these viruses. LMV was found in 49%, CMV in 44% and TSWV in 31% of samples totally. Therefore, LMV is major agent of lettuce mosaic disease in Tehran province. This is the first report of occurrence of TSWV on lettuce in Iran and the first report of CMV and LMV in Tehran province. Three LMV infected samples were collected and their characteristics were determined. After mechanical inoculation, these isolates produced symptoms on Chenopodium quinoa, Chenopodium amaranticolor, Gomphrena globosa, Nicotiana benthamiana, Lactuca sativa cv. Mantilia and cv. Terocadero (which contains the mo11 resistance gene and susceptible respectively), but not cv. Salinas 88 (which contains the mo12 resistance gene). LMV was purified and LMV polyclonal antiserum was produced in rabbit by a series of intravenous and intramuscular injections, the titre of this antiserum was 1:1024. Gel double diffusion test (GDDT) was performed, and precipitin bands appeared. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting showed the presence of coat protein 29 kDa. In Immunocapture reverse transcription PCR (IC-RT-PCR) with a LMV specific primer pair, an aproximately 1300 bp fragment was amplified.