Soybean mosaic virus (SMV) which belongs to the virus family Potyviridae, causes a disease in soybean that is present in soybean-growing areas of the world, and is widely distributed in northern Iran. Detection of SMV is very important for disease management. In the present study several serological and molecular (nucleic acid- based) methods of rapid virus detection were compared. Serological studies including DASELISA, DAC-ELISA, TPIA and DIBA were optimized and compared to identify the virus by using a polyclonal antibody. Among the serological methods, TPIA and DIBA are simple and TPIA is rapidly and easily applicable in the field. However, TPIA was found to be preferable. TPIA is time-saving, not requiring conventional sap extraction and also nitrocellulose membranes used for printing can be used in the field and stored for a long time or transported to other laboratory to be processed. RT-PCR and Immunocapture RT-PCR (IC-RT-PCR) were performed as molecular methods for detecting SMV using a pair of primers designed to amplify a fragment in the coding region of the SMV coat protein. To extract total RNA for RT-PCR, two methods including RNAWIZ and phenolchloroform were used. A part of the coat protein genome of SMV was converted to cDNA using a reverse transcription (RT) reaction. For IC-RT-PCR method, virus partial purification was carried out by solid-phase (0.2 ml microfuge tube) adsorbed polyclonal antibody, and then the RT reaction was carried out in the tube. In both methods cDNAs were amplified by PCR. Both methods amplified the expected fragment in virus-infected plants. Whereas RT-PCR requires total RNA extraction, ICRT- PCR does not have total RNA extraction problems. Our findings suggest that TPIA and IC- RT- PCR can be routinely used for SMV detection, with high efficiency.

Detection of barley yellow dwarf viruses (BYDVs) and Cereal yellow dwarf virus (CYDV) is very important for disease management. In the present study several serological and molecular methods for rapid detection of these viruses were compared. Among the serological methods that were used in this study, TPIA and cocktail-ELISA had more advantages. TPIA needs few equipments and can be used widely in the field. Cocktail-ELISA was time-saving. Both methods can differentiate and detect serotypes. By RT-PCR with degenerate primers 400 bp and 1200 bp long segments for RPV and PAV, respectively, were amplified. Segments of 700 bp and 800 bp were amplified by using RPV and PAV specific primers, respectively. In this study, regular RT-PCR was unable to detect serotypes in crude saps of the infected plants, while IC-RT-PCR by using polyclonal antibodies of these two serotypes (to trap virus particles) was able to amplify the expected segments. Our findings suggest that TPIA and IC-RT-PCR can be used routinely with high efficiency for BYDVs and CYDV detection.  

Sugarcane white leaf (SCWL) is among the most important and economical diseases of sugarcane in Asia. SCWL is reported from Khuzestan province as an emerging phytoplasmal disease of sugarcane. In addition to SCWL, Bermuda grass white leaf (BGWL) the other monocot phytoplasmal disease also is reported from this province.Rabbit has been used for rising of antiserum by injection of partially purified SCWL at 40g of infected tissue. This antiserum exhibited specificity for its homologous phytoplasma antigen in Plate-Trapped Antigen enzyme-linked immunosorbent assay (PTA-ELISA) dot immunoblotting assay (DIBA) and tissue print immuno assay (TPIA).No cross-reactions were observed in reciprocal tests between this antiserum and other tested phytoplasmas.

Two hundred and thirty one leaf samples of virus infected and mosaic and as well dwarf mosaic symptoms showing maize plants from various corn fields in Tehran province were collected during the growing season 2003. By performing serological tests of DAS-ELISA, DIBA and TPIA, using SCMV, MDMV, SrMV and JGMV antisera, only SCMV was detected in samples, with all samples reacting strongly to the SCMV antiserum. SCMV was determined as the main and prevalent potyvirus on maize in Tehran province. The virus was transmitted to sweet corn and sorghum plants using 0.1 M potassium phosphate buffer (pH 7) containing 2% Polyvinyl Pyrrolidon (PVP) for mechanical inoculation. For propagation and maintenance in greenhouse, the virus was propagated on sweet corn cv. Pars 403 and on grain sorghum cv. Kimia. The host range study with selected isolates of SCMV showed that the virus isolates were not transmitted by mechanical inoculation on Avena sativa, Panicum miliaceum, Setaria italica, Pennisetum americanum, Hordeum vulgare and Triticum aestivum. Purification of isolates was done using a minipurification method. UV absorbance spectra were obtained for purified viruses a ratio of A260/280=1.2 being calculated. Electron microscopic study using ISEM and decoration method with SCMV antiserum revealed filamentous flexuous particles of SCMV. In SDS-PAGE and western blotting tests on infected samples and purified isolates, the molecular weight of the virus coat protein was approximately 37-38 KDa. A difference among the CP of various SCMV isolates however, was not detected. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was done using SCMV F3 and SCMV R3 primers. Where amplified fragments were found of approximately 900 bp in size as expected. The study indicated that SCMV is the prevalent potyvirus and the main causal agent of mosaic and dwarf mosaic on maize plants in the province.

Soybean mosaic virus (SMV) occurs in all soybean- producing regions worldwide. The damage due to infection by SMV vary, depending on the host cultivar, strain of the virus, and environmental factors. An introduction of soybean resistant cultivars is possible through knowledge of the kind of virus strain prevalent in a region. In this study, efforts were made to detect SMV strains in Mazandaran and Golestan provinces. During June, July and August 2002, 253 samples suspected of being infected with SMV were collected from various soybean fields in these provinces. By serological tests (ELISA, Dot-Blot, and TPIA), 147 samples were found to be infected with SMV. Following biological purification, based on different kinds of symptoms, 47 isolates were selected for further studies. These isolates were classified into four groups (I, II, III, IY) based on reactions of inoculated differential soybean cultivars (Buffalo, Davis, Kwanggyo, Marshall, Ogden, and York). Group-I did not infect any of the resistant cultivars. Two cultivars (Marshall, Ogden), four cultivars (Davis, Marshall, Ogden, York), and three cultivars (Davis, York, Kwanggyo) were infected by SMV groups-II, III, and IV, respectively. Results indicated that identified groups, I, II, III and IV, belong to strains SMV-G1, G3, G4 and G5 [described by Cho and Goodman (1979)], respectively. Two primer pairs (SMV-G2, G7) to prime the amplification of a fragment in the coding region of cylindrical inclusion protein were used in RT-PCR assay for differentiation of strains. All strains produced a 277- bp using SMV-G7 primers. But no fragments were amplified from RNA extracted from any of the strains using SMV-G2 primers. RT-PCR confirmed the results of differentiation of strains based upon reactions of inoculated differential host.

Field studies were conducted in Shahre kord region, in three growing seasons from 2001 through 2004, to evaluate the effect of planting date, with and without a seed- treatment insecticide (Imidac1oprid: (1-(6-chloro- pyridin- 3- ylmethyl) -N- nitromidazolidin- 2- ylideneamine), on grain yield and yield components of winter barley (Hordeum vulgare L.) ZaJjo cultivar. The experimental design was a split plot arrangement of a randomized complete block with four replications. Main plots consisted of five planting dates, approximately 15 days apart from 22 September through 21 November. Sub plots consisted of a seed-treatment systemic insecticide application. In each of the 3 years, grain yields of plots planted in 22 September were reduced significantly by YD infection. Planting dates of 22 October and 6 November resulted in the highest grain yields and yield components in 3 years. Grain yield and yield component responses to seed-treatment insecticide, depended on planting dates, but significant yield increase (up to 377%) occurred in plots planted on 22 September compared to plots without seed-treatment. The plots of planting date 22 October with seed-treatment resulted in the highest grain yield and yield components and reduction of barley yellow dwarf disease in three years. Samples of plants from plots were tested for presence of BYDV and CYDV serotypes by tissue print immunoassay method. Infection by PAV, MAV and RPV serotypes was confirmed. Frequency of PAV, MAV and RPV serotypes were studied. The results showed 36.8% of samples infected with PAY, MAY or RPV serotypes; however PAV was the dominant serotype Mixed infections with more than one serotype was also observed. In most cases samples were co-infected with PAV and RPV.