Identification of Three Strains of Bean common mosaic necrosis virus in Common Bean from Iran.

Bean common mosaic virus (BCMV; genus Potyvirus) has been recognized as a major constraint on bean production in Iran. BCMV and Bean common mosaic necrosis virus (BCMNV) have been reported from bean-growing regions of Iran (2,3), but no attempts were made to differentiate strains of BCMNV. During the early growing seasons of 2003 and 2004, 141 bean leaf samples suspected of BCMV infection were collected from the main bean-producing regions in Tehran Province (Varamin, Damavand, Boein Zahra, Hashtgerd, and Karaj). Symptoms included mild and severe mosaic, leaf curling, malformation, vein-banding, vein-clearing, mottle, and blister on the leaves. In addition, seeds of green bean and Chiti bean (300 each) were obtained from seed lots in Tabriz (East Azarbaijan) and Miyando-Âb (West Azarbaijan) and planted in the greenhouse. Emerging seedlings were subsequently screened for BCMV infection by ELISA and sodium dodecyl sulfate-Ouchterlony double diffusion test. Anti-BCMV polyclonal antisera used in this study included those raised specifically against NL-1, NL-3, NL-4, NL-6, NL-5, NL-8, and NY-15 strains. Seedborne viral infection on newly emerged seedlings varied (2 to 5%) depending on the province and bean cultivar. Seedborne symptoms were characterized as leaf curling, malformation, and necrosis. Among indicator plants used for host range determination, symptom characterization, and biological purification of BCMV, only Chenopodium quinoa, C. amaranticolor, and Phaseolus vulgaris L. cv. Red Kidney developed chlorotic local lesions in response to the BCMV inoculation. Further, P. vulgaris L. cvs. Bountiful, Red Kidney, and Stringless Green Refugee developed leaf mosaic and malformation as a systemic reaction to the inoculation. Of 172 isolates of BCMV investigated, seven representative strains, designated as A (37.2%), B (11%), C (9.3%), D (7.5%), E (12.2%), M (7.5%), and N (15.1%), were selected on the basis of symptom development on the indicator plants and serological tests with strain-specific polyclonal antisera. Thermal inactivation point, dilution end point, and longevity in vitro of the selected BCMNV strains were in the range of 60 to 65°C, -3-(-4), and 3 to 4 days, respectively. Pathogenicity groups of the selected strains were determined by symptom response (sensitive or resistance) at 26 and 32°C in the bean differential host range (1). The designated strains B and E from Tehran Province were assigned to standard strain NL-3 or pathotype VIa, strains A, C, and D from Tehran Province were assigned to standard strain NL-5 or pathotype VIb, and strains M and N from Azarbaijan Province were assigned to standard strain NL-8 or pathotype III. Western immunoblot analysis of viral capsid protein revealed that unlike NL-8, the BCMNV strains NL-3 and NL-5 had the apparent molecular mass of 32 kDa, which was slightly less than that of reference strain NL-8 (33 kDa), thus further confirming that these strains belong to serotype A of BCMV (e.g., BCMNV). Electron microscopy study showed that the virion particles were flexuous, filamentous, and unenveloped. To our knowledge, this is the first report of the differentiation of BCMNV strains from Iran. References: (1) E. Drijfhout. Page 1 in: Agriculture Research Report 872. Centre for Agriculture 46 Publishing and Documentation. Wageningen, the Netherlands, 1978. (2) W. J. Kaiser and G. H. Mossahebi. Phytopathology 64:1209, 1974. (3) N. Shahraeen et al. Plant Dis. 89:1012, 2005.

Characterisation of lettuce virus X, a new potexvirus infecting lettuce in Iran.

A virus with flexuous rod-shaped particle morphology was found in samples from lettuce during a survey of viruses infecting lettuce in Tehran province in Iran. This virus was subjected to a complete analysis of its biological and molecular features. The entire nucleotide sequence of the virus was determined, revealing a polyadenylated ssRNA genome consisting of 7,212 nucleotides [without poly (A) tail] and possessing an organization typical for potexviruses. Comparative genome analysis showed that the lettuce virus is closely related to Alstroemeria virus X, narcissus mosaic virus and asparagus virus 3. Based on particle morphology, physico-chemical properties and the complete genome sequence, this virus is a member of a new species in the genus Potexvirus, for which the name lettuce virus X (LeVX) is proposed. Biological assays using an infectious cDNA clone and a wild-type isolate of LeVX revealed that the virus, despite reaching high concentrations in all lettuce cultivars tested, does not cause symptoms in lettuce.

Determination of the races of potato virus X and its host rang in Karaj, Damavand and Ardabil, Iran.

Potato virus x (PVX) is found commonly in potato-growing areas, worldwide. It is an economically important virus which causes losses in tuber yield of approximate 5 to 15 percent. In a 2 year survey, potato leaf and tuber samples were collected from various fields in Damavand and Karaj. The initial isolations from potato were made by mechanical inoculation first to Gomphrena globosa L. and later to Dartura stramonium L. It was not transmitted by 2 species of Cuscuta but transmitted mechamically. The isolates were inoculated to Nicotiana glutinosa L. in which they were maintained throughout the work. Sap from infected N. glutinosa was ineffective after dilution to 10-6, after 10 minutes at 70 degrees C and after 10 weeks at room temperature. The virus had filamentous and slightly flexuous particles with a normal length of about 490-500 nm and 12 nm width. According to the symptoms, TIP results and serological comparisons, the compared isolates showed no difference and they belong to XN group. In order to estimate disease incidence, 773 tubers from Damavand area were tested and compared with that in Ardabil area. Disease incidence in Damavand ranged from 1.1-20.9 percent and was lower than disease incidence in Ardabil. In 8 genera of collected weeds from fields of potato and tomato samples by using test plants and serological methods, they didn't show existence of the potato virus x.

Occurrence and distribution of lettuce mosaic disease in Tehran province from Iran.

Lettuce mosaic virus (LMV) Cucumber mosaic virus (CMV) and Tomato spotted wilt virus (TSWV) were identified in fields of Tehran province. In this study 452 leaf samples were collected from the fields throughout the Tehran province during 2002 and 2003. Distribution of Lettuce mosaic virus (LMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV)and Arabis mosaic virus (ArMV) was determined with DAS-ELISA. Percentage of single Infection to LMV. CMV or TSWV was 20.58, 15.93 and 9.96% respectively. Also 15.28% of samples were co- infected with LMV+CMV, 8.19% with LMV+TSMV and 7.74% with CMV+TSWV. 4.65% of samples were Infected to all of these three viruses. LMV was found in 48.69%, CMV in 43.59% and TSWV in 30.54% of samples totally. Therefore LMV is major dominant agent of lettuce mosaic disease in Tehran province. This is the first report of occurrence of TSWV on lettuce in Iran and first report of CMV and LMV in Tehran province.

Biological and molecular characterization of lettuce mosaic virus from Tehran province in Iran.

In this study, lettuce samples having LMV infection symptoms were collected from Tehran fields during 2003. Samples tested for LMV infection by immuno printing. Three positive samples in immuno printing collected and their characteristics were determined. In mechanical inoculation, these Isolates produced symptoms on Chenopodium quinoa, C. amaranticolor, Gomphrena globosa, Nicotiana benthamiana, Lactuca sativa cv. Mantilia and cv. Terocadero (which contains the mol1 resistance gene and susceptible respectively), but not cv. Salinas 88 (which contains the mol2 resistance gene). LMV was purified and LMV polyclonal antiserum was produced in rabbit by a series of intravenous and intramuscular injections, the precipitin titre of this antiserum was 1:1024. Gel double diffusion test (GDDT) was performed, and precipitin bands appeared. SDS-PAGE and western blotting showed the presence of coat protein 29 kDa. In IC-RT-PCR with on LMV specific primer pair, an approximately 1300 bp fragment was amplified.