Beet curly top Iran virus (BCTIV) ( Becurtovirus , Geminiviridae ) is a destructive virus in crop growing farms in Iran. In this study, BCTIV infected eggplant and chili and bell pepper plants showing typical geminivirus symptoms were collected in north-eastern Iran and investigated. PCR and sequence of the resulting amplicons showed that the samples are infected with the BCTIV. A bell pepper isolate was chosen and BCTIV full-length genome was amplified using rolling circle amplification (RCA) method. An infectious clone containing a partial dimer of the BCTIV genome was constructed and used for agroinoculation tests. Results indicated that inoculated eggplant and bell pepper seedlings with BCTIV infectious construct are efficiently infected and resulted in 60 and 47% infection. Based on the results of this study, eggplant and chili and bell peppers are the BCTIV hosts in north-eastern Iran and therefore, eggplant is reported as new natural host of BCTIV. This finding confirms broad host range of the virus.

This study aimed at controlling the common fungi causing postharvest Aspergillus rot of cv. Thompson seedless table grape (Vitis vinifera L.) via application of epiphytic biocontrol agents. Antagonistic yeasts and bacteria were isolated from the epiphytic flora associated with grape berries and leaves from five vineyards in Iran. A total of 130 yeast and bacterial isolates from grapevine surfaces were screened for antagonism against Aspergillus flavus, A. niger and A. ochraceus, the main species responsible for the accumulation of aflatoxin and ochratoxin A in grape berries. Seven yeast and bacterial isolates were selected based on their inhibitory effects on Aspergillus spp. and assayed by an in vitro nutritional competition test for their antagonistic capability. These isolates showed obvious antifungal activity against three different species of Aspergillus. Five yeast isolates were identified based on ITS region sequences as Candida membranifasciens (isolates Ka15 and Kh69) and Meyerozyma guilliermondii (Ka21, Kh59 and Kh60). Two bacterial isolates were identified based on the 16S rRNA gene sequences as Bacillus sp. (Ka3 and A10). Finally, the effect of antagonistic isolates on inoculated grape berries for their ability to inhibit infection by Aspergillus spp. was also investigated. All isolates showed antagonistic properties against the pathogens assayed at 25 °C and significantly reduced the disease progress on grape berries. Our data demonstrated that application of antagonistic microorganisms could be a promising alternative to fungicide treatments for controlling postharvest diseases of grapevine.

The objective of this study was to identify grapevine epiphytic yeasts and bacteria for biocontrol of Botrytis cinerea on grapes. Antagonistic yeasts and bacteria were isolated from the epiphytic flora associated with grape berries and leaves cv. 'Thompson seedless' from vineyards in Iran and identified by sequencing the conserved genomic regions. A total of 130 yeast and bacterial isolates from the surface of grapevine were screened in vitro for determining their antagonistic effect against B. cinerea and used to control postharvest gray mold. Among the 130 isolates, five yeasts and four bacterial isolates showed the greatest antagonistic activity in vitro against B. cinerea. Two yeasts species including Meyerozyma guilliermondii and Candida membranifaciens had high antagonistic capability against the pathogen. Also, 4 bacterial isolates belonging to Bacillus sp. and Ralstonia sp. showed significant biocontrol effect against B. cinerea. The isolates were capable of producing volatile and non-volatile substances, which suppressed the pathogen growth. The antagonistic activity of selected yeasts and bacteria against the pathogen was investigated on wounded berries of 'Thompson seedless'. On small clusters with intact berries, all of the antagonistic isolates considerably reduced the decay on grape berries and inhibition of gray mold incidence on fruits treated by these isolates was less than 50%, except for the isolate N1, which had higher capability in inhibiting the disease incidence. These results suggest that antagonist yeasts and bacteria with potential to control B. cinerea on grape can be found in the microflora of grape berries and leaves.

Viroids are pathogenic RNAs in plants without protein encoding capacity. Seven viroids belonging to four genera in the Pospiviroidae family have been reported from citrus species. By constructing the infectious clones of citrus viroids, it was possible to carried out their pathogenicity test. Full-length genome of CEVd, HSVd, CBCVd, CDVd, CVdV and CBLVd was separately amplified in RT-PCR using total RNA extracted from a Moro blood orange plant and resulting PCR products were sequenced. The full-length genome of each viroid was inserted under the control of cauliflower mosaic virus 35S promoter in a pBin62SK binary vector. Pathogenicity of viroids was tested by agroinoculation of their infectious clones to cucumber (Cucumis sativus), tomato (Solanum lycopersicum) and trifoliate orange (Poncirus trifoliata). Three weeks after inoculation, viroids were detected in newly grown leaves of inoculated plants by RT-PCR using specific primers and by dot blot hybridization using viroid specific probes. Five weeks after inoculation, symptoms including little leaf, mottling and epinasty by CVdV and CBCVd, mottling by CDVd, and epinasty and leaf deformation by CEVd, HSVd and CBLVd in tomato leaves were observed. Mechanical inoculation of infected sap of infected tomato plants induced similar symptoms in healthy tomato plants. Identification of the viroids in newly grown leaves of inoculated plants indicated the infectiousness of the generated constructs. Infectious clones of CEVd, HSVd and CBCVd were previously made, but it is the first report of the construction of the infectious clone for CDVd, CBLVd and CVdV.

The potato virus M (PVM), belonging to the genus Carlavirus, is a worldwide endemic pathogen in potato fields. p11 is an 11–16 kDa protein encoded by the last open reading frame of PVM which contains cysteine rich proteins (CRPs) motif. CRPs have been identified as suppressors of gene silencing. In this study the p11 gene from 28 PVM isolates, including 16 new isolates from Iran, were used to determine the global genetic structure of PVM populations. Pairwise nucleotide sequence identity scores showed that global PVM CRP sequence similarity was between 69.3 and 100 %. This genetic diversity divided the 28 isolates into two main divergent phylogenetic clades. The rate of genetic diversity and non-synonymous to synonymous mutations (dN/dS) were significantly different between these two clades. Analysis showed that PVM CP is under significant negative selection pressure with the global ω value of 0.260.

To investigate the genetic diversity of potato virus M (PVM; genus Carlavirus, family Betaflexiviridae), the complete nucleotide sequence of the coat protein gene of 30 PVM isolates from a major potato-growing region in Iran were determined. Phylogenetic analysis of these Iranian PVM isolates together with those available in the GenBank database suggested two divergent evolutionary lineages that did not reflect the origin of the isolates, and these were designated as PVM-o and PVM-d. Examination of the genetic variability of the coat protein of Iranian isolates and their counterparts whose sequences are available in the Genbank database revealed 16 genotype groups in the PVM population. Analysis of the synonymous-to-nonsynonymous ratio showed strong purifying selection in the CP gene in the genotype groups of divergent clades.

During March and April of 2011, 436 samples showing viral disease symptoms were collected from canola fields in the Khorasan Razavi province. The samples were tested by double-antibody sandwich (DAS)-enzyme linked immunosorbent assay (ELISA) for the presence of Turnip mosaic virus (TuMV). Among the 436 samples, 117 samples were found to be infected with TuMV. One of the infected samples from Govareshk region (TuMV-IRN GSK) was selected for biological purification. Total RNA of this isolate were extracted and reverse transcriptase (RT)-PCR was performed with specific primers according to the coat protein gene. PCR products (986 bp) was first purified and then directly sequenced. Phylogenetic analyses based on ClustalW multiple alignments with previously reported 33 isolates indicated 88 to 98% similarity in nucleotide and 94 to 99% in amino acid levels among isolates. TuMV-IRN GSK represented the highest identity to another Iranian isolate (IRN TRa6). Phylogenetic tree clustered all sequences into four groups and IRN GSK fell into the basal-B group. Nucleotide and amino acid distances between IRN GSK and other isolates in the basal-B group showed that this isolate was closely related to another Iranian isolate IRN TRa6, and distinct from other isolates in the basal-B group. These results indicate that TuMV is a common pathogen of canola crops in the Khorasan Razavi province. Key words : Turnip mosaic virus (TuMV), canola, reverse-transcription polymerase chain reaction (RT-PCR), coat protein gene, sequence analysis.

Alstroemeria cv. Ovation plants with virus-like necrotic spots and streaks on leaves and petals were observed in greenhouses in Khorasan Razavi (Mashhad) and Markazi (Mahallat) provinces, Iran. Samples with virus-like symptoms reacted positively in enzyme-linked immunosorbent assay with a polyclonal antibody raised against Tomato yellow ring virus (TYRV) nucleocapsid (N) protein. TYRV-specific primers were used in a reverse transcription-polymerase chain reaction to amplify the N gene. The deduced amino acid sequences of the obtained amplicon revealed 99% identity to the N protein of an isolate of TYRV isolated from tomato (TYRV-t).

Apple scar skin viroid (ASSVd) is one of the most destructive viroids of pome fruit. We report 12 new sequence variants of ASSVd from apple and pear trees in north-eastern Iran. The Iranian variants ranged in size from 329 to 334 nucleotides. They formed a cluster distinct from other reported ASSVd isolates, and showed sequence variations in specific regions of the viroid RNA. This is the first report of the identification and molecular characterization of ASSVd in Iran.

Peach latent mosaic viroid isolates from peach and plum in Iran have been compared with an Australian isolate from nectarine. Thirteen sequence variants 336-338 nt in size were obtained. All variants clustered phylogenetically with variants reported from several hosts and countries. A total nucleic acid extract, a slightly longer than full-length RT-PCR amplicon, and a recombinant plasmid clone from the Australian isolate were all infectious to, and symptomatic in, mechanically inoculated peach seedlings. The infectious clone generated two progeny viroid molecules, which each showed 10 different mutations compared with the parent clone inoculated 30 days previously.