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Samples of leaf, twig and fruit from ‘Mexican’ lime (Citrus aurantifolia) and grapefruit (Citrus paradisi) with symptoms of bacterial canker were collected from different provinces throughout Iran during spring and summers of 2010 and 2011. Yellow, gram-negative colonies were isolated from infected tissue samples. Results of pathogenicity assays indicated that some isolates incited tissue hyperplasia, hypertrophy and raised callus-like lesions typical of canker in hosts while other isolates stimulated flat necrotic and water-soaked lesions on leaves. Candidate samples of each group were identified according to morphological and physiological characteristics. Detections were also made using specific primers and partial sequencing of 16SrDNA for Pantoea group and gyrB for Xanthomonas group. Results showed that one group was characterized as the typical Xanthomonas citri subsp. citri strain while the other group containing most of the isolates was identified as Pantoea agglomerans. Samplings done frequently in different seasons revealed the presence of high populations of P. agglomerans with bacterial canker, especially in warmer and drier regions. These bacteria were able to incite canker-like symptoms on grapefruit seedlings and could be reisolated after two months.

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Ninety one monoconidial Bipolaris isolates were obtained from lesions on different parts of rice in different locations of Mazandaran province during the summer of 2009. Bipolaris species were identified using morphological features such as color and shape of colony and color and size of conidia and conidiophores. The isolates were separated into two species; 85 (93.4%) isolates belonged to Bipolaris oryzae and the remaining 6 (6.6%) isolates to Bipolaris cynodontis. Therefore B. oryzae is regarded as the major cause of rice brown spot disease in Mazandaran province. In order to analyze genetic diversity among B. oryzae isolates, 71 isolates were subjected to fingerprinting analysis by rep-PCR using BOX and REP primers. In cluster analysis, 15 clonal lineages and 54 haplotypes were identified. The largest clonal lineage contained with 36 haplotypes was the most common lineage. These results also indicate a relatively high level of genetic diversity among B. oryzae isolates. Also, pathogenicity test of a few B. oryzae isolates (12 isolates) was conducted under greenhouse condition and showed that those isolates were pathogenic to rice seedlings of cv. Tarom. All isolates produced some leaf spots 24 h after inoculation.

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A total of ten isolates of fungi with Rhizoctonia-like mycelia were obtained from infected roots and stems of Pistachio Pistacia vera grown in a commercial nursery in Rafsanjan, Iran, during the autumn of 2011. The infected seedlings showed symptoms of chlorosis that later turned to necrosis. All of the isolates were identified as binucleate Rhizoctonia on the basis of hyphal characteristics and nuclear number. They were tested for detection of the anastomosis group, optimum growth temperature, rDNA-ITS region traits and pathogenicity on pistachio seedlings in vitro and in vivo. The analysis of hyphal anastomosis reaction was carried out with the tester isolates of binucleate Rhizoctonia AG-A, AG-Ba, AG-G and AG-F as well as multinucleate Rhizoctonia AG4 as already detected on pistachio seedlings. The optimum temperature for growth of binucleate Rhizoctonia sp.was 35 °C. In in vivo test, the symptoms of root rot were observed 30 days after inoculation and mortality happened two weeks thereafter. According to molecular characteristics and anastomosis test groups, all isolates showed greatest similarity to anastomosis group AG-F. This finding is the first report of anastomosis group F (AG-F) of binucleate Rhizoctonia, as causal agent of root and stem rot disease of pistachio in the world and Iran.

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The study was conducted to determine the distribution of the common Meloidogyne species in research stations and vegetable farms in Ibadan, south-western Nigeria. Galled roots were collected from inoculum plots of four research stations and two vegetable farms. Identification of species was based on juvenile and female morphological characters and specific SCAR primers for Meloidogyne species. The pathogenicity of M. incognita and M. javanica was evaluated at different inoculum levels on tomato in a screenhouse study. M. incognita was the dominant species encountered in research plots, although it often occurred in mixed population with M. javanica and other unidentified species. Growth parameters such as plant height, number of leaves, and yield responded negatively to increasing inoculum levels for all the cultivars except Small Fry and Celebrity. Both cultivars were categorized as resistant to M. incognita and tolerant to M. javanca. The most popularly grown tomato cultivars, Ibadan Local, Roma (Roma type) and Beske were susceptible to both species of root-knot nematodes.  

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Cercospora leaf spot caused by Cercospora beticola has a great negative impact on yield and quality of sugar beet. In the present study, pathogenic and genotypic variation of 24 C. beticola isolates collected from different regions of Iran were studied using RFLP of the Internal Transcribed Spacer (ITS-RFLP), and Random Amplified Polymorphic DNA (RAPD-PCR). Pathogenic variability and genotype × isolate interaction were evaluated in greenhouse experiments on five sugar beet cultivars (FD0018, HM1836, Puma, Eudora and Monatuna). All of the 24 isolates tested were found to be pathogenic on the cultivars with significant variation in disease severity. Results of RAPD analysis showed wide DNA polymorphism among the Iranian C. beticola isolates. Restriction pattern of the internal transcribed spacer of rDNA (ITS1-5.8-ITS4) was studied using three restriction endonucleases: EcoR1, Taq1, and Busr1. The length of undigested DNA fragment of all isolates was estimated to be 500bp without rDNA polymorphism after digestion with EcoR1 (280, 270 bp), Taq1 (330 bp) and Busr1 (240, 220, 90 bp). RAPD and ITS-RFLP markers showed the highest level of genetic diversity which confirms the variation in C. beticola detection.

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The genus Paratylenchus sensu lato includes members belonging to the genera Paratylenchus sensustricto (species with 10 to 40µm long stylet), Gracilacus (species with 40-120µm long stylet), Gracilpaurus (species having cuticular punctuations) and Paratylenchoides (species having sclerotized cephalic framework). Long stylet species become swollen and feed as sedentary parasites of roots, some feed from cortex of perennial host roots, but most species feed as sedentary ectoparasites on roots. In other words, species with stylet shorter than 40µm commonly feed on epidermal cells, whilst the species with longer stylet nourish primarily in cortical tissue, without penetration into the plant tissue. In general, pin nematodes, Paratylenchus spp. are parasites of higher plants with a higher abundance in the rhizosphere of trees and perennials. In present review, an attempt is made to document published information on the pathogenicity and damage potential of the pin nematodes to plants.
 

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Biocontrol of Fusarium oxysporum f. sp. ciceris by six Bacillus species was evaluated. Also plant growth promoting potential of the bacteria was assessed. Results showed that four bacterial strains produced the chitinase and cellulase enzymes and all isolates produced indole acetic acid. Bacillus licheniformis proved to be the most productive of hydrogen cyanide and particularly, Bacillus firmus solubilized phosphorus on Pikovskaya solid and liquid media. The majority of strains were able to produce siderophore and three produced NH₃. Results showed that the Flip05-156C chickpea variety was less susceptible to Foc isolates compared to Flip93-93C and there was a clear difference in pathogenicity of the Foc isolates. Thus, Foc1 and Foc2 isolates caused 31.25% and 41.66%, plant mortality, respectively. As regards PGPR effect, results showed that B. licheniformis gave the best branching number, stem length and root weight of both chickpea varieties. However, Bacillus lentus distinctly improved the root length while Bacillus amyloliquefaciens improved weight of the vegetative parts.

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An effective in vitro approach to predict host resistance and pathogenicity of Fusarium species causing head blight (FHB) may improve resistance evaluation in wheat. The in vitro capacity of four Fusarium species to cause disease on young plant parts of six bread and durum wheat cultivars with known quantitative resistance was assessed using a coleoptile infection assay. Significant differences were detected in pathogenicity among Fusarium species and susceptibility/resistance levels among wheat cultivars. Only the resistance measured by coleoptile length (CL) was correlated with resistance criteria generated under in vitro (area under disease progress curve, r = -0.951), controlled (Type I and Type II, r = -0.813 and r = -0.907, respectively) and field (Type I during 2018/19 and 2019/20, r = -0.857 and r = -0.866, respectively) conditions. Moreover, the values of seed germination and CL components were significantly correlated with pathogenic indices obtained under several experimental conditions. CL predicts quantitative traits at the earliest and latest wheat development phases during disease invasion. Thus, CL may suggest a veritable potential of simple, quick, and trustworthy early screening of FHB resistance in wheat cultivars and the pathogenicity of Fusarium species.


 

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The fungus Ustilago maydis causes common smut disease in corn. Under favorable conditions, it can cause severe damage to corn. In this study, the genetic structure of U. maydis populations in Iran from the most corn-growing regions of seven provinces, including Ardebil, Fars, Isfahan, Kerman, Kermanshah, Khuzestan, and Qazvin, was evaluated using rep-PCR with primers; BOX, ERIC, and REP. Rep-PCR reactions with 109 isolates of U. maydis produced seven distinct clusters consistent with their geographical origin with few exceptions. The results of AMOVA revealed significant genetic differences within and between pathogen populations. The Euclidean similarity coefficient and the UPGMA algorithm indicate five distant clusters based on the disease severity index. The mean comparison of the disease severity index grouped target isolates into 18 clades using the Tukey test. Our findings showed that the pathogenicity assay-based grouping was not consistent with those of the geographical origin of the isolates nor their genetic similarity.

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During 2007-2008, 58 strains of P. syringae pv. syringae (Pss) were isolated from various Prunus species and other hosts such as sugar beet, pear, quince, oat, millet, wheat, barley, and rice in Fars, Isfahan, Kohgiloye and Boyer Ahmad, Chahar Mahal-o-Bakhtiari provinces of Iran. The strains were tested for pathogenicity, the presence of the syrB gene and BOX PCR (BOX A1R primer). All tested Pss strains were pathogenic on peach seedlings regardless of their original hosts. A total of 58 isolates of the Pss and Pss IVIA 773-1 amplified a 752-bp fragment with the syrB primers. The results of analysis of the BOX fingerprints from P. syringae pv. syringae strains showed that the strains isolated from stone fruits, graminous hosts and pome fruits formed a relatively distinct cluster, which were separable from the strains isolated from the other hosts. Results of this study indicate the existence of a relative degree of host specialization within the heterogeneous pathovar Pss.

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Fusarium oxysporum f. sp. albedinis (Foa) is a soil borne fungus causing the most serious disease of date palm (Phoenix dactylifera L.) called “Bayoud”. In the present study, five medicinal plants from the Algerian Sahara (Southwest of Algeria): Limoniastrum feei (aerial part, roots), Launeae arborescens (Batt.) Murb. (aerial part, roots), Fredolia aretioides Moq. et Coss. (aerial part, roots), Asteriscus graveolens (Forsk) (leaves, stems) and Acacia raddiana (leaves, bark), were used to evaluate their extracts for antifungal activity against Foa. Two parts from each plant were used for extraction by four solvents: methanol, ethyl acetate, dichloromethane and hexane. The antifungal test was conducted using disc diffusion technique and relative virulence (RV) test (on potato tuber tissue). For both tests, four extract quantities were used (200, 400, 800 and 1,600g). The relative virulence was presented as necrotic tissue weight (mg) of potato tuber tissue. Among all solvents, methanol had the best extraction yield (mean: 6.35%, minimum: 2.27%, maximum: 9.80%). The highest frequency of antifungal effect on Foa was presented by ethyl acetate extracts (32.50% of detectable effect). The best effect was observed for ethyl acetate extract of Limoniastrum feei (aerial part). The virulence test showed a decrease in RV up to 30% for ethyl acetate extract of Launea arborescens aerial part. The increase in RV was observed mostly for hexanic extract from Fredolia aretioides reflecting its high toxicity compared to the other extracts.

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Fusarium solani wasisolated from diseased roots of common bean (Phaseolus vulgaris) grown in fields which were severely infected with Fusarium root rot of bean in Markazi Province of Iran. Specific PCR primer pairs were used for the identification and verification of F. solani (Mart.) f.sp. phaseoli (Burkholder) W.C. Snyder and N.H. Hans. Spore suspensions of F. solani f.sp. phaseoli were subjected to gamma irradiation at 130 Gy using Cobalt-60, and 700 mutants were generated. All 700 mutagenized colonies were tested in the greenhouse for reduced pathogenicity. One mutant (M23) showed the best expected reduction of Fusarium root rot and was chosen to be tested as a biocontrol agent in field experiments. Different concentrations of avirulent mutant (avr-M23) were used against Fusarium root rot in the infested field and their effects on the yield of bean plants were evaluated. The biocontrol effect of avr-M23 on Fusarium root rot was significantly improved with increasing its concentration from 10³ to 10⁹ conidia ml^-1. Best yields (no. of pods per plant and 100-seed weight) were obtained at concentrations of 10⁶ and 10⁹ conidia ml^-1. This study confirms that avr-M23 can be used as a biocontrol agent to protect bean plants from Fusarium root rot under field conditions.

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During 2004-2007, a field survey was conducted in different vineyards to determine the fungal pathogens associated with grapevine decline in different provinces of Iran including Fars,Hamedan,Isfahan, and Kohgiluyeh and Boirahmad. Twenty-seven isolates of Botryosphaeriaceae were recovered from vines showing decline and dieback symptoms only in Fars Province. Based on morphological and cultural characters along with molecular analysis [partial sequences of the nuclear ribosomal internal transcribed spacer (ITS), beta-tubulin (BT), and elongation factor 1-a (EF)], two species of Botryosphaeriaceae, namely, Diplodia seriata and Neofusicoccum parvum were identified. Both species were pathogenic on rooted cuttings of cv. Cabernet Sauvignon and caused the dieback and drying-out of leaves as well as extended lesions on the shoots 4 months after inoculation. Results showed that N. parvum isolates were the most virulent and produced significantly longer lesions than those caused by D. seriata. Both species were reisolated from the margin of the lesions completing Koch’s postulates.

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Newcastle disease virus (NDV) causes one of the most dangerous infections in birds. High economic losses and high mortality are outcomes of this virus, which does not have any immediate cure. The natural reservoir of this virus can remain among bird and non-bird animals like farm animals. In Iran, this virus has reached a steady situation. Also, it should be mentioned that migrating birds can transfer the virus. The F protein of the virus is essential in pathogenicity and determination of pathogenic strain of NDVs, which has the regions that are essential in pathogenicity, immunogenicity, cell fusibility, and tissue necrosis. In this study, with computational analysis of this protein, some features related to this protein such as protein cleavage site, the conserved region in immunogenicity, infected species in Middle Eastern countries, and physicochemical properties of protein were determined. Results showed that the F protein of NDV consists of highly conserved regions that show a high rate of similarity and identity. Despite the majority of strains characterized as pathogenic, there were still non-pathogenic strains circulating in the Middle East. In this comprehensive study, protein regions essential in immunogenicity and epitope formation were identified, which may be used in the development of recombinant vaccines against this virus.
 

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Non-ionizing ultraviolet (UV) radiation is a kind of electromagnetic radiation that has been shown to be harmful to microorganisms such as bacteria, viruses, and fungus. The goal of this study is to evaluate the effective and hazardous features of this type of radiation in three regions (UVA, UVB, and UVC), using the approach of biological properties and applications in disinfection and sterilizing. In this research study, in order to be effective on microorganisms in the ultraviolet spectrum and its surroundings near the visible area, two test samples with commercial UVC and blue-LED lamps were used. In this study, the effect of ultraviolet C radiation on pathogenic microorganisms of Staphylococcus aureus and Pseudomonas aeruginosa in liquid environment and solid surface culture, the effect of ultraviolet C radiation on the total count (total count) of microorganisms on paper and mobile surfaces, and finally to The effect of UV LED on the total number of oral microbes attached to the toothbrush after brushing was investigated. In two tests performed with radiation in the ultraviolet region and near it in the visible region, the lethal effect on bacteria and microorganisms was concluded with more than 90% effectiveness and destruction of bacteria. Which indicates the effectiveness of such radiation in disinfecting, disinfecting and sterilizing equipment. Spectroscopic investigations of UV commercial lamps, as well as their efficacy on microbes, demonstrate the use of this sort of radiation, in addition to its biological hazards, which necessitate careful consideration of how it is utilized. In comparison to alternative sterilizing methods, the use of UV radiation in business and medicine is a cool, dry, easy, effective, and economical technique that produces no ionized radiation.

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Citrus Viroid V (CVdV) is a member of the genus Apscaviroid, in the Pospiviroidae family. It is restricted to citrus species naturally. The herbaceous host range of CVdV was determined using the viroid infectious clone. Several herbaceous plants from the Cucurbitaceae, Solanaceae, Fabaceae, and Asteraceae families were found to be susceptible to CVdV. Also, CVdV could be transmitted to these hosts through rubbing of monomeric DNA plasmids and through mechanical inoculation of infected sap. The accumulation of CVdV in the tomato was monitored up to 28 days after inoculation and a further 56-fold increase of viroid titer was observed. Analysis of sequences of the viroid progenies from herbaceous plants revealed several nucleotide substitutions, which mostly concentrated in the pathogenicity domain on the secondary structure of the viroids.
 

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Recently, special attention has been paid to enterococci for use as probiotics in dairy products. All these desirable features are a stimulus for the producers of dairy products to use enterococci isolated from dairy products such as Liqvan cheese. Despite having all these features, enterococci are not recognized as GRAS and their presence in food products is a sign of fecal contamination. The purpose of this research is to investigate enterococci isolated from Liqvan and Koze cheese in terms of having pathogenic indicators in order to confirm that they are safe for consumers and finally to investigate the possibility of using them as starters or starter aids in dairy products. Especially cheeses. Based on this, 57 isolates of Enterococcus faecium from traditional Iranian cheeses were examined for the presence of pathogenic genes, and finally 23 isolates did not have any pathogenic genes. Then the technological properties of these isolates such as acidification, proteolytic, lipolytic, autolytic, heat and acid resistance and exopolysaccharide production were investigated. The results showed that among the 23 investigated strains, 19 isolates had antimicrobial activity against pathogenic bacteria, 16 strains were able to produce exopolysaccharide and 20 isolates had moderate acidification properties. The highest proteolytic and lipolytic activity was related to strains c18 and c16, respectively, and strain LR78 showed the highest acid and heat resistance.

 

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Escherichia coli and Staphylococcus aureus are pathogens that have the ability to form biofilms and cause disease in food products. Due to the fact that the enterotoxins produced by these two pathogens remain in a wide range of temperature, pH and saline conditions, they cause severe infections in humans. Melittin is a natural peptide derived from bee venom that can show its antimicrobial and anti-biofilm potential through disrupting the membrane of bacterial cells. For this purpose, in this study, the antimicrobial effect of this peptide on Gram positive and negative bacteria was investigated and its minimum inhibitory concentration (MIC) was determined as 100 µg/mL and 300 µg/mL, respectively. Also, the scanning electron microscope images confirmed the antimicrobial effect of the peptide on these two bacteria. Peptide melittin caused wrinkling, deformation and creation of holes in the cell membrane of treated bacteria, compared to the control sample. On the other hand, the results of the biofilm inhibition test showed that the addition of the peptide at a concentration of 2MIC completely prevented the biofilm formation of S. aureus prevented, while this value was equal to 91.00 ± 2.82 in E. coli bacteria. Also, the increase in peptide concentration caused an increase in the destruction of adult biofilms of both bacteria. On the other hand, this peptide decreased the invasion and adhesion of these two bacteria to HT-29 and Caco-2 cells by reducing the mobility of pathogens. Therefore, according to the obtained results, melittin peptide can be a suitable alternative to chemical disinfectants that are harmful to the environment.