صفرعلی مهدیان

Oomycete species occupy many different environments and many ecological niches. The family Saprolegniaceae from Oomycota includes widely distributed water molds which usually behave as saprophytes on plants and animal debris. Members of some species may also be pathogenic for plants and fish. Oomycete species identification based on DNA is well established, but DNA barcoding with cytochrome c oxidase subunit I (COXI) and II (COX II) are a relatively new approach. In this study, 57 isolates were obtained from water samples in mazandaran province, Iran. After morphological identification by morphological keys, ITS, COXI , and COX II gene regions of 10 representatives of the isolates were sequenced and 3 genera and 6 species (Newbya recurva, Achlya bisexualis, Dictyuchus monosporus, Saprolegnia ferax, S. bulbosa , and S. debaryana) were identified through BLASTn in NCBI gene bank. The results described in this paper were indicated that except for ITS, COXI and COXII sequencing could also be valuable resources to Saprolegniaceae identification. Except for S. ferax, other described species were new reports for oomycete biota of Iran.

Green mold (Penicillium digitatum) is one of the most important post-harvest pathogens of citrus fruits. Tens of thousands of citrus fruits are often destroyed by green mold in Iran every year. The use of chemical toxins to control the disease, in addition to negative environmental effects, leads to the selection of fungal-resistant populations and also endangers consumer health, so non-chemical control of the pathogen has become an important goal of researchers in recent years.

The essential oil components of myrtle (Myrtus communis L.) were extracted with a Clevenger apparatus and their compounds were identified with a gas chromatography apparatus with a mass spectrometer. The inhibitory effect of myrtle essential oil and the fungicides chitosan and thiabendazole on spore germination and colony growth was investigated by mixing with PDA and PDB under laboratory conditions and by impregnating the fruit surface during storage.

Thirteen compounds were identified in myrtle essential oil, which was quantitatively the highest compound 1-8 cineole. Myrtle essential oil at a concentration of 1700 ppm and chitosan at a concentration of 500 ppm inhibited 100% of fungal colony growth, as did the fungicide thiabendazole.

It is possible to use myrtle essential oil or chitosan as an alternative to the fungicide thiabendazole to control citrus green mold.

Grapevine trunk diseases (GTDs)are known as the most important factors in crop reduction and cause considerable economic problems in grapevines worldwide. During 2016 to 2018, several field surveys were conducted on numerous vineyards in Khorasan-Razavi province to study fungal species associated with grapevine trunk diseases. In this study, samples were collected from trunk and branches of trees showing yellowing, stunted growth, dieback and wood discoloration in cross sections. In this study, 258 fungal isolates were obtained and identified based on morphological characteristics and comparison of DNA sequence data (ITS-rDNA region and a part of β-tubulin gene). These isolates were identified as Phaeoacremonium minimum (75 isolates), P. parasiticum (19 isolates), P. iranianum (52 isolates), P. tuscanum (8 isolates), Fomitiporia mediterranea (56 isolates) and Seimatosporium vitis (48 isolates). Pathogenicity of the selected isolates was verified by inoculation of potted grapevines shoots under greenhouse conditions. Based on the mean length of wood discoloration in the wood, P. minimum and F. mediterranea were the most and least virulent species, respectively. Our findings indicated that known fungal trunk pathogens such as Phaeoacremonium species and F. mediterranea occur on grapevine in Khorasan-Razavi province. This study is the first report of S. vitis associated with grapevine decline in Iran.

Grapevine downy mildew caused by Plasmopara viticola is the most important factor in decreasing grape production in temperate and rainy regions. To investigate the disease progression curve in vineyards of North Khorasan province during two years of 2018 and 2019, Scoring of the target vineyards was carried out each week on a regular schedule from mid-April at the bud swelling time from the vineyard. The incidence rate and severity of the disease in 80 vineyards from four counties of Bojnourd, Maneh and Samolghan, Shirvan and Farouj were calculated. Linear regression was fitted to disease time progression curves with five population growth models as exponential, monomolecular, logistic, log-logistic and gompertz models. The model fitness was determined based on statistics as coefficient of determination (R2), standard error of estimates (SEE) and adjusted coefficient of determination (Ra2). The results showed that exponential, monomolecular, logistic, log-logistic and Gompertz models were fitted with 5, 27.5, 12.5, 17.5 and 37.5% of the disease in the studied gardens, respectively. Accordingly, Gompertz model with 96.76% coefficient of determination was selected as the most suitable model to describe disease progression in North Khorasan province. Rates of increase (rG) per unit of disease in each vineyard was 0.005 to 0.048 (with an average of 0.026). This is the first report of a study of the progression curve of grapevine downy mildew in Iran.

Grapevine are important and valuable fruits that is contaminated in different parts of Iran, especially in North Khorasan Province, by the downy mildew of grapevine (Plasmopara viticola) and its yield decreases. Investigating the relationship between the incidence and the severity of the disease is one of the important concepts in the epidemiology of plant diseases. It is easier and faster to measure the incidence of the disease, but the severity of the disease is an important indicator.

In this study, the relationship between the incidence disease and severity disease of downy mildew of grapevine in North Khorasan Province (Bojnourd, Mane and Samalghan, Shirvan and Farooj) during 2018 and 2019. Incidence and severity of disease were recorded weekly in 80 selected vineyards from early April to stop the disease progression.

The incidence of the disease was 10.27% in the first year and 51.64% in the second year. The severity of the disease in the first year was between 1.2 to 6.6% (mean 3.4%) and in the second year it was between 6.4 to 44.6% (mean 25.82%). Investigation of the relationship between incidence and severity of disease using four statistical models (power, linear, quadratic, complementary logarithmic logarithm) power model was able to express this relationship in 31 vineyards more accurately. In 24 vineyards the incidence and severity of the disease were well fitted to the data by linear model.

Final models were evaluated based on R2, SEE and Ra2 of regression analysis of raw data. Based on these criteria, final model in Bojnourd as S = (0.534) × I (1.263), in Shirvan as S = (0.684) × I (1.472), in Mane and Samalghan as S = (0.4691)× I-0.01711 and in Farooj as S = (0.3484)×I-0.0078 showed relationship between incidence and severity of disease. This is the first report to evaluate the relationship between the incidence and severity of downy mildew of grapevine in Iran.

The Phomopsis is a genus of imperfect plant pathogenic fungus whose hosts comprise several species in different regions of the world, such as grapes, soybean, acacia, hollyhock, velvetleaf, and several other plants. In this study, samples collected from hollyhock, velvetleaf, purple bauhinia, and acacia plants suspected to be infected with Phomopsis fungi. Samples were cultured and then subjected to the separation and purification steps and morphological characteristics of the obtained isolates were done. Among the isolates, five representatives (P1 to P5) from Mazandaran province selected and their DNA, extracted. TEF and ITS regions of DNA were amplified and sequenced. The ITS (4 and 5) region from ribosomal DNA and a part of TEF gene were amplified and sequenced. The nucleotide sequence of the isolates was compared with the corresponding sequences available in the Gen Bank and phylogenetic tree of the isolates was constructed. Results showed that the sequence of the isolates P1, P2, and P4 had the highest similarity with Phomopsis malvacearum species. The sequence of isolate P3 was very similar to Phomopsis loropetali, and the sequence of the isolate P5 was very similar to Phomopsis theicola. The average size of pycnidia produced on three culture media viz, CDA, CMA and PDA was measured 16 days after incubation at 20–25°C. Size were 256 × 85 in acacia, 230 × 68 in velvetleaf, 230 × 69 in hollyhock and 193 × 47 micrometers in purple bauhinia isolates, respectively. Morphological and molecular features of the identified species were matched. Identified species here are reported from Iran for the first time. Symptoms of Phomopsis infection was varied depending on different hosts and identified species.

In this research, biosynthesis of Ag nanoparticle investigated using Urtica extract. Different parameter such as temperature, pH, time and concentration of Ag salt optimize for this goal. Synthesized nanoparticle characterized by Uv-vis, XRD and TEM methods. Results show Ag nanoparticle synthesized in the size of 10 nm. In continuous, Ag nanoparticle was used for preparation of modified carbon paste electrode. And its effect investigated on electron exchange system for K4[Fe(CN6)] as a standard system. The obtained result shows that synthesized nanoparticle can be improved electrical conductivity of electron exchange in electrochemical systems.

Aflatoxins are the fungal toxins produced by Aspergillus spp. These fungal metabolites in food and oil seed have a big lifetime risk for acute and chronic disease in human and animals. In this survey for production levels of B1, B2, G1 and G2 aflatoxins in two species of Aspergillus was namely A. Alaus and A. Foctides has been investigated. These fungi were grown in Potato Dextrose Broth (PDB) medium and aflatoxins were determined using HPLC method. These species were cultured in 50 ml flask at 26ºc, with 80% humidity and dark place for 32 days. 25 ml of broth cultures were filtered and then extracted with 10 ml chloroform and evaporated the organic solvent and bring the organic solvent in 3ml methanol. After filtration, 20 µl of final solvent was injected to HPLC instrument. The result has shown that A. foetidus produced the maximum amount of B1, B2 and G1 with 8.71, 2.3 & 3.1 mg after 24 days post-inoculation and the maximum amount of G2 with 0.02 after 20 days post-inoculation per 50 ml of PDB. A. flavus produced the maximum amount of B1, B2 and G2 with 487.92, 18.46 &8.57mg after 20 days post-inoculation and the maximum amount of G1 with 126.49mg after 24 days post-inoculation per 50 ml of PDB. Overall the B1 is maximum afltoxin in A. flavus and G2 is the minimum aflatoxin in A. foetidus.

The biological approaches to synthesis of nanoparticles are better than chemical and physical procedures because of low energy expenditure. In this study, the extract of apple fruit used for biosynthesis of silver nanoparticles and the effect of these nanoparticles on pathogenic fungi of Cytosporachrysosperma, Fusariumbrachygibbosum, and Diaporthephaseolorum. To Apple fruit juice, the solution of 2 and 10 mM silver nitrate was added at room temperature and change the color from pale yellow to reddish brown was confirmed to silver nanoparticles. The formation of silver nanoparticles was confirmed by the presence of absorption peak at 450 nm using spectrophotometer. The particle size distribution and average size was measured by dynamic light scattering (DLS). Different densities of colloidal silver nanoparticles were added in PDA growth medium and the fungi were inoculated on it. The results showed that the silver nanoparticles with 10 ppm concentration were inhibited growth of hyphae of pathogenic fungi in PDA culture medium. The results of this study are green synthesis of silver nanoparticles with biological methods and without using of harmful chemical and the inhibitory effect of silver nanoparticles on some important plant pathogenic fungi.

The Botrytis cinerea is one of the most important agents of Strawberry fruit rot. In order to identify the pathogenicity potential of the isolates on fruits and the antifungal effect of Anise essence on this fungus, forty one isolates of B. cinerea was collected from different areas of Mazandaran province on strawberry showing symptoms of gray rot on fruits. Following the purification of the fungus, pathogenicity test was done on Comarosa, Parus and Gilasi varieties of strawberries. Morphological identification of isolates was done in regard to their vegetative characteristics. Molecular identification carried out using specific primer C729 and common primers ITS4 and ITS5. Inhibition rate of fungal growth was recorded by Anise oil and Iprodione- Carbendazim fungicide. The results based on morphological characteristics showed that all isolates belonge to Botrytis cinerea. Identification of isolates using specific primer C729 showed that all of them had band of 700 bp. Based on disease severity on three strawberry cultivars; isolates were graded into seven groups. The ITS region of ribosomal DNA of each group was amplified using ITS4 and ITS5 primers. After sequencing and alignment, the obtained sequences were compared with the existing sequences in Gene Bank. The results showed there is high genetic diversity among the isolates, so that and they classified into five groups with 80% similarity. The result of in vitro evaluation of fungicide and Anise essence effect, showed that with increasing of Anise oil concentration, antifungal activity is also increasing against B. cinerea. Iprodione- Carnbendazim fungicide could inhibit the growth of isolates on a culture medium.

Post- harvest rot of citrus fruits is one of the most important limiting factors that reduce the life of harvested products and are one of the most important economical diseases in world’s citrus production areas. Two most important fungi that affect the citrus fruits, are green and blue molds which are produced by Penicillium digitatum and P. italicum, respectively. The disease are mainly managed by using the synthetic fungicides, but because of environmental hazards and appearance of resistant strains of the pathogen, the biological control by the use of bacterial, fungal and yeast antagonists can be suggested. The efficiency of yeasts such as Candida guilliermondii, C. saitoan, Pichia guilliermondi and Aureobasidium pullulans; the bacteria Pseudomonas fluorescens, Bacillus subtilis, Pantoea agglomerans and the fungus Muscodor albus, in controlling the green and blue molds of citrus is reported so far. In this paper, we tried to explain the method of biological control with emphasizing on the identification of useful microorganisms and their operation.

The golden nematode، Globodera rostochiensis which was reported from Hamadan in 2008، is one of the most important pests of potatoe world wide which causes serious yield reduction. Damage to plant occures with invasion of the roots and production of specialized feeding cells. Since the nematode is fairly new for the region، its pathogenicity needs to be monitored on potato cultivars. In a preliminary test، the relation between nematode and a common potato cultivar in Hamadan was studied. Marfona was planted in microplots infested with 0. 05، 4، 9 and 15 eggs and J2/g soil and weights of plant growth parameters and final nematode density were taken after 75 days. As nematode density increased at planting، plant and tuber weights decreased. Nematode reproduction increased with increasing nematode population at planting. The highest final nematode density occurred at highest initial population.

Aflatoxins are very toxic secondary metabolites of some، Aspergilluss sp. that are produced when these fungi grow on different agricultural products under special environmental circumstances. In this study aflatoxinsB1، B2، G1 and G2 in some species of Aspergillus were investigated. These fungi included A. terreus، A. ustus، A. candidus، A. carneus، A. ostianus، A. auricomus، A. niveus، A. niger، A. fumigates، A. parasiticus، A. caespitosus، A. awamori and A. sclerotiorumthat were grown in potato dextrose broth (PDB) and aflatoxins thereof were measured using high performance liquid chromatography (HPLC) methods. Pure cultures of the aspergilli were prepared and identified to species، and then each species was cultured for 22 days in 50 ml flask containing PDB at 26 0C، 80% humidity and in darkness، conditions similar to natural habitat. Fungal exudates in the broth cultures were extracted with 10 ml chloroform، the organic solvent was evaporated and the precipitate was dissolved in 3ml methanol. After filtration through 0. 2 µm milipore filter، the final solute was injected into HPLC instrument. Maximum amount of aflatoxins was secreted by A. parasiticus while aflatoxin G1 was not produced in A. terreus، A. carneus، A. fumigatus، A. niveus، A. parasiticus، A. caespitosus، A. ostianus and A. niger. As well، A. niveus، A. ostianus، A. niger and A. sclerotiorum did not produce aflatoxin G2. No aflatoxin B2 was detected in A. sclerotiorum and A. carneus and no aflatoxin B1 was detected in A. ostianus. Among the four type of aflatoxins (B1، B2، G1 and G2)، B1 and G1 had respectively the maximum and minimum amount of secreted aflatoxins in A. parasiticus.

Blast (Magnaporthe grisea) is the most important disease of rice in Mazandaran province, north of Iran, which causes severe damages annually on susceptible cultivars. Tarom Mahalli is a local aromatic cultivar with high cooking quality and marketability, but very susceptible to blast. To protect this cultivar and similar susceptible cultivars against rice blast, farmers have to use high amounts of chemicals every year. In the present study, an attempt was done to transfer rice blast resistance genes Pi-1 and Pi-2 from near isogenic lines C101LAC and C101A51 (as male parents) to Tarom Mahalli (as femate parent) to develop a resistant cultivar with high cooking cultivar. Necessary crosses and backcrosses were accomplished between parents and hybrids developed during three years were selected based on morphological, virulence and molecular markers (RG64 and C481). Selected plants were finally exposed to a mixture of races of the pathogen prevalent in Mazandaran. Based on the results of this investigation, several plants were selected that had morphological and physiological characteristics of Tarom Mahalli and carried Pi-1 and Pi-2 resistance genes. The infection types of the hybrids were 1-2, while those of the Tarom Mahalli were 4 and 5. Although some morphological and qualitative characteristics of the progenies were slightly different from those of Tarom Mahalli, but transferance of resistance genes gave it a satisfactory protection against the disease.

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is one of the rapeseed important diseases in the world and Iran. In order to study the infection status of this disease in rapeseed fields of Mazandaran province, 120 fields in five different regions of Mazandaran (including Sari, Babolsar, Dashte Naz, Behshahr and Galogah) selected during years 2010 and 2011. From the beginning of disease symptoms appearance, weekly surveys were done from fields and amount of disease was recorded during the infection period. Based on the highest disease incidence on leaves, there were no significant differences between regions and fields in first year, but in second and combined two years, there were significant differences (P<0.001) between regions and years. The infection in first year (35%) was higher than second year (24%) and the region Galogah had the highest infection (42%) and Sari lowest infection (20.8%). Based on the final disease incidence on stems, there were significant differences between regions (P <0.001), but no significant differences between years. Based on disease severity, there were significant differences between regions (P <0.001) and years (P <0.05). Disease incidence was 21% in both two years and disease severity in first year (15%) was more than second year (11.5%). In combined two years, Galogah with disease incidence 32% and severity 21.2% had the highest infection and Sari with disease incidence 13.75% and severity 8.25 % had the lowest infection. Based on areas under disease progress curves, there were significant differences between regions and years, that these factors in first year were more than second year and in regions Galogah and Behshar were more than other regions.

In some wet areas of Iran, mancozeb is widely used for control of the downy mildew of cucumber which is harvesting shortly after spray application. Therefore residual detection of this fungicide in the cucumber fruit is important, considering the consumer's health. Residual amount of this fungicide is detecting in the randomly collected cucumber fruit samples. In this regards, fruit samples in 100 gram weight is taken and the juice extracts using N-hexane solvent in the succulent apparatus. Then the extract examine at the light with wave length of 280 nm by spectrophotometer. The relationship between amount of the light absorption by the extract and concentration of mancozeb active ingredient is determined, using the linear diagram. The maximum allowed residual level for cucumber fruit, is 2 mg/kg.

Aeluropus littoralis belong to poaceae family. It often grows in salty soils. In thisstudy reaction of A. littoralis to rice pathogens (Pyricularia grisea, Rhizoctonia solaniand Bipolaris oryzae) was investigated at greenhouse and field conditions underartificial inoculation. These three mentioned fungi were isolated from rice plants andthen propagated and separately inoculated on Aeluropus plants. The results indicatedthat R. solani and P. grisea could infect the A. littoralis and showed the typicalsymptoms on this plants. This is the first report of these fungi that infect the A. littoralisplant in northern Iran. But B. oryzae could not infect the A. littoralis, and was notshowed brown spot symptoms on plants at greenhouse and field conditions. Aeluropuscan be an alternative host for the blast and sheath blight of the rice. Therefore,eradication of this weed can reduce the inoculum sources of the two important ricepathogens. Also it can be source of resistance to rice brown spot disease. Beside, thepossibility of existence of other tentative methods for considering this disease must bestudied and researched in the future.