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Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, is one of the most important diseases of canola (Brassica napus) in Golestan province, the leading canola producer in Iran. In order to assess the yield loss of canola caused by SSR, 80 fields were surveyed in four different regions of the province (Gorgan, Ali Abad, Kalaleh and Gonbad) during 2006-2007, and SSR intensity was recorded weekly in the fields. Study of yield loss-SSR severity relationships by linear, nonlinear and multiple regression analyses with final intensity (S_f), time to initial symptoms (t_is), Gompertz rate of disease progress (r_G), and standardized area under disease progress curve (SAUDPC) as independent variables indicate that single point and integral models were significant (P < 0.05) only in three cases. Results of multiple point models which were performed using weekly recorded SSR intensities (S₁, S₂, …), were significant in two cases and a general model for 2007 survey was developed using S₃ to S₆. Eventually, response surface models were developed for each region by integrating t_is with SSR intensity variables (S_f or SAUDPC).

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Brassica napus is an important oilseed crop and the yield loss due to fungal disease stem rot caused by Sclerotinia sclerotiorum is a serious problem in cultivation of this crop. The pathogenesis-related (PR) protein, glucanase, hydrolyzes a major cell wall component, glucan, of the pathogenic fungi and acts as a plant defense barrier. In this study, a β-1,3-glucanase (bgn13.1) gene was isolated from the biocontrol fungus Trichoderma virens-10 (showing the high β-glucanase activity) and cloned in pUC19 cloning vector. The cloned fragment was confirmed by molecular analysis and showed to contain two short introns, 52 and 57 bp and an open reading frame coding 761 amino acids. The bgn13.1 gene was over-expressed under the CaMV35S promoter in B. napus, R line Hyola 308. Transformation of cotyledonary petioles was achieved by pBIKH1 containing bgn13.1 gene via Agrobacterium tumefaciens LBA4404. The insertion of transgene was verified by the polymerase chain reaction (PCR) and genomic DNA Southern dot blotting in T0 generation. RT-PCR analysis indicated that the transgenic canola plants were able to transcribe the β-1,3 glucanase gene. Also, we used transgenic over-expression approach in order to investigate antifungal activity of expressed Bgn13.1 on S. sclerotiorum. The heterologous expressed Bgn13.1 of line # 7 and line # 10 compared with other lines showed stronger inhibition against hyphal growth of S. sclerotiorum with

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In vitro antifungal activity of silver nanoparticles, at concentrations of 6, 8, 10, 12, 14 and 16 ppm, was studied on five phytopathogenic fungi, and a biocontrol agent. Then effect of silver nanoparticle at 6 ppm (optimum concentration) was evaluated on Macrophomina phaseolina in greenhouse. For in vitro experiment, the fungal isolates were grown on potato dextrose agar medium amended with silver nanoparticles. Radial fungal growth was recorded after 1, 2, 3, 5 and 10 days and mycelial growth inhibition rates were calculated. The most sensitive fungus to nanoparticles was Pythium aphanidermatum, since all tested concentrations showed 100% inhibition during the 10 days of observation.The second most sensitive fungus was Sclerotinia sclerotiorum, since it was able to grow only at concentration of 6 ppm and M. phaseolina was the third in sensitivity since its growth was inhibited in all concentrations after three days. In greenhouse experiments, five treatments including no nanosilver-no pathogen (Negative control), no nanosilver +pathogen (Positive control), 6 ppm nanosilver– no pathogen, 6 ppm nanosilver +pathogen, Carboxin-Thiram (0.15%) +pathogen were compared. Four characters viz shoot and root fresh and dry weights were measured. Based on the greenhouse experimental results, treatments with nanosilver and fungicide gave higher yields than the positive control. The chemical control treatment had the highest measured parameters, while 6 ppm nanosilver +pathogen treatment had the same parameters as negative control. It may therefore be suggested to use nanosilver as a safer alternative to chemical fungicides for control of M. phaseolina.

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Sclerotinia Stem Rot (SSR), caused by Sclerotinia sclerotiorum, is believed as the most important disease of canola (Brassica napus) in Iran. Temporal analysis of the disease epidemics was carried out by evaluating SSR in 80 fields in four locations of: Gorgan, AliAbad, Kalaleh and Gonbad in Golestan Province during 2006 and 2007. Scouting of the fields to record disease incidence (I) and disease severity (S) was started before the end of flowering and continued weekly up to harvest time. Disease Progress Curves (DPCs) were studied using mathematical growth models and their goodness of fit determined based on such statistics as coefficient of determination (R2), standard error of estimates (SEE) and residual plots. Gompertz model with a mean R2 of 94.69% was selected as the most appropriate model for describing SSR progress in field conditions of Golestan Province. Rates of increase (rG) per unit of disease in the canola fields were 0.003 to 0.077 (with an average of 0.03). This is the first temporal study of canola SSR in Iran.

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The response of five inbred sunflower seedling lines, including AC 4122, C, HA 89, HA 410, HA 411, to inoculation with Sclerotinia sclerotiorum culture filtrate containing endogenous oxalic acid was compared with the exogenous application of synthetic oxalic acid. The reaction of seedlings was evaluated in terms of dry and fresh plant weights and the total chlorophyll concentration relative to untreated controls. The expression of shikimate dehydrogenase in cotyledons was also assessed five days after treatment. The results indicated that exogenous oxalic acid inoculation caused more deleterious effects on stem rot, eliciting photosynthesis reduction and different isoenzyme patterns of shikimate dehydrogenase. A positive correlation was found between increased oxalic acid and shikimate dehydrogenase activity in both treatments. However, the excessive toxicity of the exogenously administrated acid suggests that Sclerotinia sclerotiorum infection triggers a more complex metabolic pathway involving oxalic acid secreted by the pathogen. These observations preclude the possibility of using the synthetic acid administration as a method of screening sunflower genotypes for resistance to Sclerotinia. In addition to these findings, the reactivation of shikimate dehydrogenase was observed in both treatments. In contrast to synthetic administration, expression during the first phase of growth may serve as a tool for rapid screening and selection of sunflower genotypes resistant to Sclerotinia sclerotiorum.

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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.

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Prangos ferulacea (Apiaceae) is a perennial herb with a distribution from East Europe to Middle East and Central Asia. The plant’s leaves are used as animal fodder. Its fruits and roots possess biological traits that provide it with the potential to be used for medicinal purposes. The essential oils obtained through hydrodistillation from aerial parts of Prangos ferulacea at the vegetative and flowering stages were analyzed through GC and GC-MS. Thirty-one vs. seven compounds were identified in the vegetative and flowering stages’ oils, respectively. While the essential oil of aerial parts at vegetative stage was dominated by α- pinene (57%), the oil at flowering stage was characterized by (E)-anethol (95.5%). The latter exhibited significant phytotoxic and fungitoxic effects in lettuce and against Sclerotinia sclerotiorum, respectively.

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This study was conducted to evaluate the control efficacy of Pseudomonas chlororaphis, Erwinia herbicola, Bacillus amyloliquefaciens, and Bacillus subtilis, as well as solutions of zinc sulfate, sodium malonate, and oxalic acid against potato white mold caused by Sclerotinia sclerotiorum under field conditions during growing seasons of 2017 and 2018 in Bahar and Lalehjin, Hamedan, Iran. The results showed that strains of Bacillus subtilis as well as zinc sulfate had the highest inhibitory effect against carpogenic germination of sclerotia. The myceliogenic germination of sclerotia was inhibited by solutions of zinc sulfate and sodium malonate with statistically similar results followed by oxalic acid. In addition, activities of resistance-related enzymes including β-N-acetyl hexosaminidase, endochitinase, chitin 1,4-β-chitobiosidase, β-1,3-glucanase, phenylalanine ammonia lyase, polyphenoloxidase, and peroxidase markedly increased in potato leaves due to application of bacteria on plants. The results showed that all treatments were able to reduce significantly (P< 0.05) the number of infected and dead plants in both years. The mixtures of five bacterial biocontrol agents and solution of zinc sulfate were found to be the most effective treatments to control white mold.