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To investigate the infection of carnations (Dianthus caryophillus) to common viruses, a total of 130 samples showing suspected viral disease symptoms were collected from 10 commercial greenhouses located in Mahallat City, Markazi Province. Total DNA and RNA were extracted and amplified by PCR and RT-PCR methods, respectively, using generic primers for the genera Potyvirus and Orthotospovirus and also specific primers of Carnation mottle virus (CarMV), Carnation necrotic fleck virus (CNFV), Carnation etched ring virus (CERV), Carnation latent virus (CLV), Carnation vein mottle virus (CVMV) and Cucumber mosaic virus (CMV). Results revealed that the estimated rates of infection in the collected samples for different viruses in decreasing order were for CarMV, CNFV, CERV, CMV and CVMV, while CLV and species of genus Orthotospovirus were not detected. Mixed viral infections were also investigated and among all of the 130 collected samples, 3.1% showed mixed infections with CarMV, CNFV, CVMV, CERV and CMV, 32% with CarMV, CNFV, and CERV, 20% with CarMV and CNFV, and 9% with CarMV and CERV. For phylogenetical assays, NIb-CP fragment of the CVMV genome was amplified, cloned, and sequenced. Phylogenetic trees of two isolates of this virus revealed that the two Iranian isolates of CVMV (IBR and RCM) were phylogenetically divergent. Mechanical inoculation of CVMV on 16 different indicator plant species showed specific symptoms on six of the indicators that were confirmed by RT-PCR. To the best of our knowledge, this is the first report of CMV and first partial genome sequencing of CVMV from a carnation plant in Iran. [ABSTRACT FROM AUTHOR]

Differential induction of genes in wheat (cv. Chamran) in response to Mycosphaerella graminicola was studied using cDNA-AFLP analysis. The three weeks old wheat seedlings were inoculated by the fungal pathogen, then the samples were collected at six time points (0, 12, 24, 48, 72, 96 hours) after inoculation with pathogen. By comparing the expression patterns of induced (infected) with non-induced (uninfected) plants, 276 differentially expressed fragments were identified and sequenced. Blast search of wheat genes assigned these sequences to different functional categories including defense, metabolism, energy, transcription, transport, signal transduction, stress response, secondary metabolism, and unknown sequences. Eight defense-related genes including lipoxygenase, peroxidase (PR 9), chitinase (PR 2, 4, 8), PR-1, thaumatin-like protein (PR5), Phenylalanine Ammonia Lyase (PAL), β-1-3 glucanase (PR3), disulfide isomerase, and methionine sulfoxide reductase were induced 12 to 24 hours after inoculation in this cultivar of wheat. Induction of glucosyltransferase, Catalase, and putative xylanase inhibitor genes were observed around 48 h after inoculation with pathogen. Expression patterns of the other three genes, i.e., chalcone synthase, EXECUTER 1 protein, and nonspecific lipid transfer protein showed that these genes were induced later after inoculation (72-96 hours). Our data showed that expression of the PR- proteins were enhanced 24 h after inoculation, suggesting that they may play a role in the defense against M. graminicola. Expression of lipoxygenase, glycosyltransferase, thaumatin like protein, putative xylanase inhibitor, EXECUTER 1 protein and Nonspecific lipid transfer protein are reported for the first time in this interaction. [ABSTRACT FROM AUTHOR]

The Severe strain of Beet Curly Top Virus (BCTV-Svr) and Beet Curly Top Iran Virus (BCTIV) are considered as the main causal agents of sugar beet curly top disease in Iran and mixed infections of BCTV-Svr and BCTIV usually occur in nature. As the use of resistant cultivars is the safer and stable tool for management of the disease, the objective of current work was to identify sugar beet genotypes resistant to both agents. To this end, the reaction of thirty-eight sugar beet genotypes to infection by each of BCTV-Svr and BCTIV was separately evaluated using their infectious clones under the greenhouse condition. Incubation period, recovery, and disease severity index were considered for selection of resistant genotypes. As a result, ten and seven sugar beet genotypes resistant to, respectively, BCTV-Svr and BCTIV were selected. To evaluate the resistant genotypes, the experiments were repeated under greenhouse condition. In the field experiment with natural infection of viruses, the resistant genotypes were assessed and six sugar beet genotypes (S1 91019, S1 91022, S1 91023, S1 91028, S1 91029, and S1-91041) resistant to BCTV-Svr and BCTIV were identified; which could be used in future breeding programs. [ABSTRACT FROM AUTHOR]

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is one of the most important diseases of wheat with devastating epidemics in Iran and the world. In this study, we evaluated some Iranian wheat landraces in a greenhouse at the seedling stage against a new pathotype related to Ug99 of Pgt, which was collected from Iran and designated as TTSSK. Marker analysis was done on resistant landraces. Molecular markers for detecting some Sr genes were used. The results showed that Sr22, Sr35 and SrWeb provided resistance against TTSSK in the resistant landraces. In addition, some of the susceptible landraces that were resistant at adult stage were used for Sr2 analysis. The results showed that some of these landraces were carrying other adult plant resistance gene/genes except Sr2. To evaluate the defence gene expression in compatible and incompatible interactions, cv. Morocco (susceptible) and KC-440 landrace (resistant) were used. Sampling was done at 0, 12, 18, 24, and 72 hours post inoculation (hpi) with stem rust isolate and water as mock treatment. β-1,3 glucanase gene expressions were studied using qGLU-S and qGLU-AS primers. Also, 18srRNA, β-tubulin and EF1-α genes were used as internal control. The results showed that in incompatible interactions, the defence gene expression was increased at 24 hpi, but in compatible interactions, expression level reached the peak at 12 hpi and it significantly decreased at 18 hpi. The results revealed that the expression of defence genes such as β-1,3 glucanase was earlier in compatible interactions than in incompatible interactions, but the quantity of expressed gene was less than in incompatible interactions. [ABSTRACT FROM AUTHOR]

Trichoderma species are known as effective agents used for biological control of plant pathogenic fungi. The Trichoderma harzianum and its mutant isolates were cultured and their traits including, mycelial growth, antagonistic activity and extracellular proteins and enzymes production (Chitinase and Cellulase) were investigated to select the most effective mutant isolates against plant pathogenic fungus Rhizoctonia solani. Also, the purity and composition of enzyme-rich protein samples were evaluated under denaturing gel electrophoresis. This study clearly showed the possibility of improving mycelia growth rate (from 1.18 to 1.33 cm d-1), the antagonistic capability of Trichoderma (from 54.9% growth inhibition of R. solani to 66%), extracellular proteins and enzymes production for biological control of plant diseases through mutation with γ-radiation. Also, compared to wild type strain, protein production in the mutant isolates increased. Moreover, the highest specific chitinase enzyme activities were observed in mutant isolates T. h M8 (42.48 U mg-1) and T. h M15 (38.25 U mg-1). Trichoderma mutant of T. h M8 maintained higher mycelia growth rate and higher ability to inhibit growth of R. solani. The SDSPAGE profiles had several enzyme protein bands such as CelloBioHydrolases (CBHs), EndoGlucanases (EGs), β-Glucosidases (BGLs), endochitinases, and β-(1, 4)-N-acetyl glucoaminidases. SDS-PAGE analysis indicated the presence of different protein bands in the range of 10.5 to 245 KDa. Interestingly, expression of chitinase in 95 percent of mutants was higher than wild type of T. harzianum. The results showed that gamma mutation could increase the efficiency and amount of enzymes in T. harzianum, while these enzymes are involved in antagonistic properties of T. harzianum. [ABSTRACT FROM AUTHOR]

Seventy five bacterial strains were isolated from cucurbits rhizosphere and examined for antagonistic activities against Macrophomina phaseolina isolate 44, the causal agent of melon charcoal root rot disease. The results of screening strains including B2, B11, B12 and BKN showed high potential of antagonistic activities against the pathogen in laboratory experiments. Inhibition of mycelial growth varied from 54.3 to 62.22%, 39.43 to 54.82%, 78.52 to 100%, and 64.45 to 88.89% in dual culture, volatile metabolite, antibiotic production, and cell free culture tests, respectively. In greenhouse experiment, seed treatment with strain B2 significantly (P= 0.01) controlled the disease by increasing plant growth indices including height, shoot and root fresh weight, shoot and root dry weight by 37.98, 36.27, 32.97, 34.44, and 30.39%, respectively, as compared to the control. The biochemical and physiological tests as well as gyrA sequence confirmed these four strains as Bacillus amyloliquefaciens. Results indicated that strain B2 could be an important new biological control agent for charcoal root rot disease of melon. [ABSTRACT FROM AUTHOR]

Abstract: Members of the genus Serratia are known for their abilities to infect insects. In this study, a red‐pigmented S. marcescens was isolated and characterized from the infected larvae of Polyphylla olivieri using bacterial cultivation, phylogenetic analysis as well as bioassays against larvae of the two insect pests, Plodia interpunctella and Ephestia kuehniella. Comparative 16S rRNA and groEL gene sequence BLAST analyses strongly suggested that the isolated strain should be placed in the genus Serratia, sharing high sequence similarities with several strain of S. marcescens associated with insects. Phylogenetic analysis placed the isolated bacterium with other S. marcescens bacteria in a clade with high bootstrapping values. To assess pathogenicity of the S. marcescens isolate, the bacterial cells were either injected into the haemolymph of the fifth‐instar larvae or added to the diets of insects. Survival curves of the control insects and those challenged with six different concentrations of S. marcescens showed that the S. marcescens isolate significantly reduced survival rates of the larvae. The LC50s of the bacterium on P. interpunctella and E. kuehniella were 1992.26 and 1.09 × 104 (CFU/μl) for injection bioassays at 6 h post‐injection, and 4.48 × 104 and 1.96 × 105 (CFU/10 μl) for feeding bioassays at 24 h post‐feeding, respectively. Injection of the bacterial culture supernatant into the larvae led to continuous bleeding from the site of injection, while injection of heat‐treated culture supernatant of the bacterium did not cause continuous bleeding. Together, our results showed the possibility of using this S. marcescens isolate in microbial control of the insect pests after addressing the safety concerns. Moreover, it might be considered as a source of useful bioactive molecules and genes with application in insect control and biotechnology via developing insect‐resistant plants. [ABSTRACT FROM AUTHOR]

Apple Stem Pitting Virus (ASPV) is one of the most common viruses of apple and pear trees. During 2012 to 2013, a total of 1053 symptomatic and asymptomatic leaf samples were collected from orchards in nine provinces of Iran. ASPV infection was detected by DAS-ELISA and PCR in 54 samples (5.12%) from seven provinces. Based on the geographical origin, 22 representative isolates were selected for phylogenetic analysis. Twenty-two amplicons with a size of about 370 base pair (bp) comprising partial sequence of the Coat Protein (CP) coding regions of the viral genome were sequenced. Sequence data analysis, showed that the identities of 3'-terminal region of CP gene at both nucleotide and amino acid levels among the Iranian isolates were 95-100% and these isolates were closer to the Asian ASPV isolates than to the other isolates. Constructed phylogenetic tree by Neighbor-joining on the basis of the 3'-terminal region of CP gene sequences showed that the Iranian isolates were categorized into two major groups. Furthermore, phylogenetic and population genetic analysis were carried out on the basis of 3'-terminal region of CP gene which revealed that ASPV isolates were not geographically resolved. Also, all values in the GABranch analysis showed a ratio of substitution rates at Non-synonymous and Synonymous sites (dN/dS) below one, suggesting strong negative selection forces during C-terminal region of the ASPV CP gene history. To the best of our knowledge, this is the first report of distribution and partial genome sequence analysis of the ASPV in Iran. [ABSTRACT FROM AUTHOR]

Surfactin secreted by bacilli has biological functions in plant. Surfactin C14 and C15 have the highest effect on inducing hydrogen peroxide species release in the plant. Surfactin production in the two Bacillus strains ACCT21332 and FKR3 were analysed by HPLC and the phytotoxicity of the Bacilli-derived surfactins was determined in Tobacco cell culture. Surfactin C14 and C15 were detected in ACCT21332 but not in FKR3 strain. Extracellular hydrogen peroxide produced by tobacco cell culture cells exposed to ATCC21332 and FKR3 strains increased compared to untreated ones. The Agrobacterium mediated transformation rate of tobacco cells drops from 4% transformed cells to 0.8 and 1.2% when pretreated with ATCC21332 or FKR3 strain, respectively. The strong drop in transformation rate of plant cell culture after FKR3 strain pre-treatment indicates that Surfactin C14 and C15 are not the major or the only cause in protecting plant cells from Agrobacterial infection and transformation. [ABSTRACT FROM AUTHOR]

Macrophomina phaseolina is an important soil-borne pathogen causing charcoal rot in many important crop plants including sesame, in Iran. A total of 60 isolates of M. phaseolina were collected from the main sesame producing regions in ten provinces of Iran. The genetic diversity among M. phaseolina populations was estimated using InterSimple Sequence Repeat (ISSR), focusing particularly on geographic differentiation. Five ISSR primers generated 105 discernible DNA bands, of which 85 (77.11%) were polymorphic. The greatest value of variability (PPB: 60.00%; H: 0.185; I: 0.284) was estimated for Fars population, whereas the least variability (PPB: 9.52%; H: 0.042; I: 0.060) was estimated for Kerman population. Total gene diversity exhibited high levels of variability (HT = 0.186). Analysis of molecular variance indicated a large proportion of genetic variability within populations. [ABSTRACT FROM AUTHOR]

A survey for the presence ofApple chlorotic leaf spot virus(ACLSV) in apple (Malus pumila), pear (Pyrus communis) and quince (Cydonia oblonga) was conducted in the provinces of Tehran, Isfahan, Khorasan, East and West Azerbaijan, the main pome fruit growing areas in Iran. Samples were taken from 1078 apple, 92 pear and 23 quince trees and tested by double antibody sandwich-ELISA for the presence of ACLSV using commercial kits (Bioreba, Switzerland). ACLSV was detected in 200 apple samples (18.55%) but in none of the other samples. Some of the positive samples came from trees bearing small and malformed leaves with necrotic lesions, whereas others were from symptomless plants. The highest incidence of ACLSV was in the province of Isfahan (30.9%), followed by West Azerbaijan (17.78%), Tehran (14.1%) and East Azerbaijan (11.68%). To confirm virus identification, total RNA was extracted from leaf samples and subjected to reverse transcription polymerase chain reaction using primers specific for a region of the ACLSV genome that encodes part of the coat protein (CP). A 358 bp DNA fragment corresponding to a fragment of the ACLSV CP gene was amplified from extracts of infected trees but not from those of healthy trees. [ABSTRACT FROM AUTHOR]

Bacterial leaf streak (BLS) caused by Xanthomonas translucens pv. cerealis (Xtc) is an important disease of wheat (Triticum aestivum L.) worldwide. The management methods presently in practice are insufficient to meet current safety and/or efficacy standards. Therefore, use of resistant genotypes is the best approach to manage BLS. The present study was undertaken to identify possible sources of resistance to Xtc in cereal cultivars and germplasm. Twelve strains of Xtc were isolated from symptomatic leaves in several regions in Kerman province. Out of twelve, nine strains produced the expected Xtcspecific 120 bp fragment using PCR and the primer pairs PABr/PBf. Six strains produced water-soaked streaks covered with exudates on wheat cultivars, whereas the three remaining strains incited only chlorotic streaks with no water-soaking on leaves. A highly virulent strain that caused conspicuous water-soaking and necrosis was used for inoculation of 645 winter and spring wheat, barley, and rye accessions to identify possible sources of resistance to BLS. The fourth leaves of test plants were infiltrated with bacterial suspension and scored after seven to ten days. Among all the accessions evaluated, only two rye accessions, namely, 4538 and 4794, were resistant to BLS. These two rye accessions can potentially be used in breeding rye and triticale cultivars for resistance to BLS. [ABSTRACT FROM AUTHOR]

To study molecular evolutionary characteristics and genetics of beet necrotic yellow vein virus (BNYVV) isolates population from Iran, nucleotide sequences of p25 and coat protein (CP) were determined and the amino acids sequences thus deduced were analyzed using phylogenetic and population genetics methods. A survey of BNYVV in Iran indicated the infection of 288 collected samples out of 392 samples in most beet growing areas and that most of the isolates (92%) were of the A-type and the rest of isolates (8%) were P-type. Our molecular evolutionary analysis showed that CP was highly conserved but allowed to assign all isolates to three distinct groups. Different parts of p25 coding regions were under different evolutionary constraints. The most positive selection was detected at the position 68, the second amino acid of the tetrad motif. Iranian isolates were found to cluster with European isolates into three distinct clusters based on p25 sequences. Population genetics analysis revealed that BNYVV populations have low differentiation (Kt= 3.97145) and low diversity (πT= 0.006, Hd= 0.860) with frequent gene flow indicating lack of phylogeographic structure between populations. [ABSTRACT FROM AUTHOR]

Angular leaf spots of sleepy mallow Malvaviscus penduliflorus have been observed in some areas of Mazandaran and Golestan provinces. The spots were angular, brown and necrotic. A levan positive and oxidase negative pseudomonad was isolated from the symptomatic leaves. The biochemical and physiological characteristics and profile of fatty acid methyl esters of the causal bacterium was very similar to Pseudomonas syringae pv. syringae. Pathogenicity of selected strains was confirmed by inoculation of sleepy mallow with bacterial suspension of several strains. PCR amplification using the syrB specific primer pairs yielded the expected 720 bp fragment from all strains. In rep-PCR, the fingerprints of the strains from sleepy mallow showed 28% similarity to those of the standard strains of P. s. pv. syringae. However, on the bases of difference in host specifity, some genotypic properties, sequencing of some highly conserved genes (rpoD and gyrB), the strains isolated from angular leaf spot on sleepy mallow just were similar to Pss but were genetically distinct from other groups and may represent a new pathovar of P. syringae belonged to another genemospecies. [ABSTRACT FROM AUTHOR]

Tomato yellow leaf curl virus (TYLCV) is destructive pathogen of tomato (Solanum lycopercicum) and causes annual damage in tomato crops of many tropical and subtropical regions worldwide. Due to distribution of this pathogen in Iran, detection of this virus is necessary for controlling the damages caused by this pathogen. As enzyme-linked immunosorbent assay (ELISA) is a convenient method for the detection of viruses, preparing a source of antigen for immunization process is essential. In this study, the movement protein gene of TYLCV-Ir2 was amplified by polymerase chain reaction (PCR) and cloned in the expression vector pET26. It was transformed into Escherchia coli BL21 competent cells. The identity of the clone and the fidelity of the PCR product were verified by sequence analysis. The expression of recombinant TYLCV movement protein was induced by IPTG. The results indicated that the TYLCV movement protein gene was expressed in Escherchia coli and can be used as a source of antigen for producing antibodies against it. [ABSTRACT FROM AUTHOR]

Grapevine fanleaf virus (GFLV) is one of the most destructive grapevine viruses worldwide. The best strategy to control the virus is to cultivate virus free plant material in non-infested soils. Therefore, detection of the virus plays a key role in control of GFLV. To establish a reliable and sensitive technique for detection of GFLV in the stock grapevines or in preparation of virus free grapevines, samples from different vineyards of Iran were collected in 2009 and their infection by GFLV was assessed by DAS-ELISA. Fourteen ELISA positive samples were subjected to RT-PCR using GFLV published primers and the primers designed in this study. Most of the primers available in literature failed to detect GFLV in all 14 tested samples, whereas the primers designed in this study detected the virus in all mentioned samples. The efficacy of the designed primers in this study was confirmed by detection of the virus in further 35 ELISA positive samples collected from other provinces in 2010. Moreover, GFLV infectivity of grapevines for the first time was confirmed by green grafting. The results revealed that the combination of the green-grafting with RT-PCR method, using the introduced primers in this study, offers a reliable method for detection of GFLV isolates. [ABSTRACT FROM AUTHOR]

Genetic structure and pathogenic diversity of Sclerotinia sclerotiorum, the causal agent of canola white stem rot, were assessed through Mycalial Compatibility Groupings (MCGs), a comparison and comparing of isolate virulence. Fifty-seven isolates from three different regions in Golestan Province were selected for mycelial compatibility and as well for virulence tests. Within the 57 tested isolates, 35 MCGs were identified, 42.86% of which being constituted of single isolate specimens, were all collected from Ali Abad region. The observed MCGs differed within the three regions. From among the 35 MCGs, 25.71%, 28.57% and 45.72% belonged to Kalaleh, Hashem Abad and Ali Abad, respectively. In Kalaleh, nine MCGs were identified all of which fell into two isolates. Ten MCGs were identified within the Hashem Abad region, eight of which represented two isolates and the remaining were constituted from three isolates. Sixteen MCGs were detected in Ali Abad for which, except one MCG which was constituted of two isolates, the rest belonged to one isolate. Moreover, no MCG was identified as common among these regions. Shannon diversity index (Ho) of MCGs for the whole regions found to be was 0.86 (Htot). Partition of total diversity (Htot) showed that 95.45% corresponded to a variation in diversity within S. sclerotiorum populations. Variation in isolate virulence was tested using a petiole inoculation technique under greenhouse conditions. Isolate virulence varied within the three regions. Moreover, in most cases the differences in virulence of isolates within MCGs were significant. The data indicated that populations of S. sclerotiorum obtained from the studied regions were composed of a heterogeneous mix of MCGs, therefore the population structure of this pathogen as well as variations in virulence of isolates must be considered in disease management systems in these regions. [ABSTRACT FROM AUTHOR]

A total of 363 isolates were collected from all over Iran. They were isolated from apple, arum lily, briar rose, bride wort, broad bean, camellia, canola, carnation, cucumber, egg plant, feijoa, geranium, gerbera, gladiolus, grape, guilder rose, hibiscus, iris, kiwifruit, oleander, onion, orange, pear, pomegranate, primrose, quince, redbud, robinia, rose, rubber plant, sow thiste, spathe flower, strawberry, tomato, violet, wall flower and wheat. To identify the species, morphological characters such as conidiophore length, conidial and sclerotial dimensions were measured. According to morphological and cultural characters, eight Botrytis species were identified: B. aclada sensu lato, B. cinerea, B. fabae, B. convoluta, B. gladiolorum, B. paeoniae, B. pelargonii and B. porri. As far as we are aware, this is the first report of the last five species from Iran. These species were examined by polymerase chain reaction (PCR) using necrosis and ethylene-inducing protein (NEP2) and C729 primers. A 835 bp band was amplified in B. cinerea, B. fabae and B. pelargonii, using NEP2, but not in others. However, C729 primers amplified a 700 bp band in B. cinerea and B. pelargonii and a 600 bp in B. fabae. [ABSTRACT FROM AUTHOR]

Various viral pathogens infect Cucurbitaceae and cause economic losses. The aim of the present study was to detect plant viral pathogens including Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), Zucchini yellow mosaic virus (ZYMV), Cucurbit yellow stunting disorder virus (CYSDV) and Cucurbit chlorotic yellows virus (CCYV) in Lorestan province, in western Iran, and also to determine CMV genetic diversity in Iranian populations. A total of 569 symptomatic leaf samples were collected in 2013 and 2014 from cucurbits growing regions in Lorestan province. The collected samples were assessed for viral diseases by ELISA. The results showed virus incidences in most regions. Then, the infection of 40 samples to CMV was confirmed by RT-PCR. Moreover, to distinguish between the two groups (I and II) of CMV, PCR products were digested by two restriction enzymes XhoI and EcoRI. Results of the digestion showed that the isolates of Lorestan belonged to group I. The CMV-coat protein gene of eight isolates from different regions and hosts was sequenced and phylogenetic analysis was performed. Subsequent analyses showed even more genetic variation among Lorestan isolates. The phylogenetic tree revealed that Lorestan province isolates belonged to two IA and IB subgroups and could be classified together with East Azerbaijan province isolates. The results of the present study indicate a wide distribution of CMV, ZYMV, CGMMV, CYSDV and CCYV viruses in cucurbits fields of Lorestan province and for the first time subgroup IB of CMV was reported on melon from Iran.

Fig mosaic virus (FMV) and Fig badnavirus-1 (FBV-1) are two of the most important fig infecting viruses. The incidence and distribution of FBV-1 and FMV were determined by testing in PCR 138 asymptomatic and symptomatic samples. These samples were collected from 60 fig gardens and agricultural fields in three provinces of Iran. The fig infecting viruses FBV-1 and FMV, respectively, were detected in 92 (66.6%) and 34 (24.6%) samples collected from all the surveyed fields. Overall, 24 out of 138 (17.3%) samples showed mixed infections. The sequence analysis of a genomic fragment of 922 nt, comprising the entire ORF-2 and part of the 5’ termini of the ORF-3 of 10 selected FBV-1 Iranian isolates from different provinces, and of the type member from GenBank (Acc. No: JF411989), showed a variation ranging from 1 to 3% at nucleotide level and 1% at the amino acid level. The phylogenetic analysis grouped the FBV-1 isolates into two groups, with the Iranian isolates clustered in two distinct subgroups of group I, according to their geographical origin. In our research, the prevalence and sequence analysis of FBV-1 as the only identified DNA virus infecting fig trees, was studied for the first time in Iran.

Cucurbit yellow stunting disorder virus (CYSDV), a member of the genus Crinivirus (family Closteroviridae), causes considerable losses in cucurbits. Using of the resistant cultivars is a potential option for control of the disease induced by CYSDV. In this research twenty five accessions of Cucumis melo, including local melons, collected from different regions in Iran, were evaluated under controlled conditions for their reaction to Iranian CYSDV isolate, (Bushehr). Inoculations were made at first true leaf-stage with Bemisia tabaci. Assays included mean of disease severity index 6 weeks after inoculation, time of symptoms development (infection percentages 20 days after inoculation) and virus concentration in plant (mean ELISA value 8 weeks after inoculation). Only two accessions Chorook zard and Til zard showed delay in symptom development, low disease severity index and low concentration of the virus. They were considered resistant to the virus and tolerant to the disease. The accessions Zard khareji, Zard moshabbak dorosht, Zard talaee and Sefid because of low concentration of the virus in ELISA and Sirjan and Kashefi because of delay in symptoms development were resistant to virus. Yazdi, Zard talaee, Sirjan, Zard moattar and Sefid had low disease severity index and rated tolerant. Other accessions were highly sensitive to the virus. [ABSTRACT FROM AUTHOR]

The shallow bark canker of Persian walnut (Juglans regia L.) trees incited by the bacterium Brenneria nigrifluens affects the bark of trunk and scaffold branches. Fifty-nine isolates of bacterium were isolated on the basis of disease symptoms from 114 plant samples, collected from Mazandaran, Golestan, Kerman and Kermanshah provinces. Furthermore, 10 isolates from Fars province, one isolate from Kohgiluyeh-va-Boyerahmad province and one isolate from Kurdistan province were received. Based on physiological and biochemical characters, bacterial isolates were divided into two groups and identified as Brenneria nigrifluens or strains close to B. nigrifluens. The electrophoretic profile of the strains cell proteins also confirmed this grouping. Isolates were assessed by polymerase chain reaction (PCR) using a specific primer pair for B. nigrifluens. Twenty four isolates produced the expected band of approximately 255 bp and were named PCR+ strains. Pathogenicity tests performed with one PCR+ isolate and three PCR- isolates showed that only PCR+ isolate was able to cause cankers in walnut seedlings. Eight weeks after inoculation of PCR+ isolates on Persian walnut seedlings, water-soaked cankers appeared around the inoculation sites. The bacterium was reisolated from the bark lesions of the inoculated seedling on EMB-agar medium. To investigate the certitude of the primer pair, one PCR+ isolate and three PCR isolates from different geographic locations were analyzed by sequencing 16S rDNA. The results revealed that PCR+ isolates were Brenneria nigrifluens. On the basis of this study, it can be concluded that general phenotypic tests are not reliable enough to identify B. nigrifluens isolates and that specific detection of the pathogen with pathogenicity test or PCR is necessary. [ABSTRACT FROM AUTHOR]

RNA directed RNA polymerase 1 (RDR1) expression is induced by virus infection and appears to be involved in resistance to infection by some viruses. In the present study, reactions of two transgenic tobacco (Nicotiana tabacum cv. Samsun NN) lines in which the expression of their RDR1 gene was silenced were assessed against several plant viruses under greenhouse conditions. Silencing the RDRI gene in tobacco led to no change in the response to virus infection but in others, as expected, an enhanced susceptibility to tobacco mosaic virus was observed. By contrast, lines of tobacco with silenced RDR1 gene showed enhanced resistance to infection by several viruses, viz., tobacco rattle virus (genus Tobravirus) and tomato bushy stunt virus (genus Tombusvirus). These results suggest that complex interactions occur between the innate resistance pathways, so inhibiting one component involved in resistance may show effects on other aspects of innate resistance. Nevertheless, suppressing RDRI gene expression may provide novel, broad-spectrum resistance to a range of viruses. [ABSTRACT FROM AUTHOR]