habiballah hamzehzarghani

Aflatoxins are toxic secondary metabolites produced by speices of Aspergillus including A. flavus and A. parasiticus. Mycotoxins are potential carcinogens and reduce global trade of agricultural products. Soil and peanuts were sampled across fields located in seven important peanut production villages of Astaneh Ashrafieh to investigate the frequency of toxigenic and atoxigenic strains of A. flavus and A. parasiticus. Toxigenicity of the Flavi section strains was evaluated according to change in color of the back of colonies on coconut agar in contact with ammonium hydroxide vapor. 48 isolates of Flavi section were identified, including 20 isolates of A. flavus and 28 isolates of A. parasiticus with nine atoxigenic and 39 toxigenic isolates. Risk maps were developed based on mean toxigenicity where Lakujdeh, Mohsenabad, and Noghredeh respectively with mean toxigenicity of 2.50, 2.25 and 2.10 had the highest risk scores for peanut cultivation while parkaposht, Nubijarmahale and Nabi dehka with mean toxigenicity of 1.00, had the lowest risk scores. Peanut fields located in Dehsar with a mean toxigenicity of 1.50 were classified with moderate risk scores. The outlook of this study was based on identification of atoxigenic isolates of the fungus with potential future application in biological control of toxigenic strains of Flavi section and emphasize on their competitive ability to colonize peanuts as well as developing risk maps to plan for reducing the risk of aflatoxin production on peanuts, an important product of Guilan province, and to pave the way for increased production and export of this product.

Heterodera schachtii is the most important nematode of sugar beet worldwide. Application of organic matter can reduce populations of plant-parasitic nematodes. In this study, the inhibitory effects of creeping thistle, tall sisymbrium, liquorice, narrow-leaf plantain, wild lettuce, castor bean, French marigold, cornflower, wild safflower and arugula on sugar beet cv. Sharif and H. schachtii were investigated in two microplot experiments. The first experiment was conducted in pasteurized mixed field soil and river sand, and the second in field soil, both with an initial population of 4200 eggs/plant. Also, the effects of the treatments on nematode egg hatching and root penetration were studied in a glasshouse experiment. The results showed that adding plant powders to pasteurized soil had no significant effect on the infected sugar beet growth indices. However, except marigold, the other treatments caused a relative increase in taproot weight of 5% to 241% compared to the control. Cornflower, wild lettuce and wild safflower increased taproot weight more than twofold compared to the control. Moreover, creeping thistle, castor bean and plantain caused a relative decrease in nematode final population and reproduction factor. In field soil, castor bean, marigold, wild lettuce, cornflower and sisymbrium increased taproot weight by at least twofold, and arugula increased sugar content by 1.2-fold. The treatments had no significant effect on the nematode indices. Plantain and wild lettuce caused a relative decrease in the nematode reproduction factor. In glasshouse experiment, wild lettuce caused the greatest reduction in egg hatching and safflower reduced nematode penetration into the roots.

Identifying resistance related metabolites as biomarker for screening wheat germplasms resistant to leaf rust (Puccinia triticina) is a useful approach to increase the speed, accuracy and cost effectiveness of screening disease resistance. The relatively polar metabolites were extracted in a mixture of methanol-water from near isogenic line (NILs) of wheat susceptible (Thatcher Lr22b) or resistant (Thatcher Lr25) to leaf rust in the two leaf stage, 24 h after inoculation with the pathogen, talcum powder or sterilized distilled water, in three replications. Metabolites were analyzed using a GC/MS. ANOVA showed that abundance of 26 metabolites had significant differences among experimental factors including near isogenic lines (NILs), inoculation (I) and NILs ×I interaction. Abundance of 26 significant metabolites was subjected to canonical discriminant analysis and hierarchical cluster analysis to group observations of metabolite profiles based on similarities and differences in the investigated metabolic space. Finally 13 resistance related metabolites (RR) and 13 Pathogenesis related metabolites (PR) were identified that the majority of RR metabolites involved in induced resistance and constitutive resistance. Significant metabolites included metabolites with potential signaling and/or antimicrobial activity as well as molecules used as precursors for cell wall reinforcement, phenolic and alkaloids compounds, and accumulation of amino acids and proteins associated with resistance. Up-regulation of the number pathways upon infection of wheat to leaf rust fungus is discussed.Key words: metabolic profiling, Wheat leaf rust, screening resistance, gas chromatography/mass spectrometry.

Reducing the damage of the cyst nematode Heterodera schachtii is one of the research fields in sugar beet producing countries. Using chemical fertilizers can improve soil fertility and reduce damages of plant parasitic nematodes. In this study, the effects of ammonium sulfate, calcium sulfate, zinc sulfate, potassium sulfate, potassium nitrate, sodium silicate, triple superphosphate, iron sequesterine and sulfur on H. schachtii and growth parameters of susceptible sugar beet cultivar (cv Sharif) were investigated in two experiments. The first experiment was performed in plastic pots containing 6 kg of pasteurized field soil and river sand (1:1), and the second one in pots filled with 9 kg of field soil for four and five months, respectively, both under microplot conditions. Fertilizers were mixed with pots soils before sowing and the nematode was inoculated by adding 200 g of infested soil containing 18 cysts with 4200 eggs. The results showed that chemical fertilizers and sulfur did not have significant effects on growth of the infected sugar beet plants in pasteurized mixed or field soils, and some of them reduced it. In the pasteurized soil, zinc sulfate 50 kg/ha, iron sequestrene 5 kg/ha, sodium silicate 10 kg/ha and triple superphosphate 100 kg/ha caused a relative decrease of more than 67% in the nematode final population and reproduction factor. In the field soil, these indices in triple superphosphate 100 kg/ha and sulfur 100 and 200 kg/ha were lower than other treatments, but were at the same statistical level with the control. The third experiment was performed in small containers filled with infested soil to investigate the effects of treatments on nematode egg hatching in greenhouse. The results showed that the highest hatching was happened in the treatment of ammonium sulfate 200 kg/ha, which was statistically at the same level with triple superphosphate 100 kg/ha.

To evaluate the effect of residue of sulfonylurea herbicides and  wheat residues on the growth and yield of sunflower, a split factorial experiment was conducted based on a randomized complete block design (RCBD) with four replications at the College of Agriculture, Shiraz University, Shiraz, Iran. The treatments included with and without wheat residues from the tested farm as the main plots, and a combination of three herbicides (Total, Apirus and Atlantis) and their concentrations (recommended and 30% overdose) which were considered as subplots. No herbicide treatment was used as control. The results showed that application of all herbicides reduced sunflower height, seed number and seed weight as well as seed yield of sunflower. The highest reduction in seed yield was recorded when Total  followed by Apirus residues were applied, which caused 95% and 80.6% yield reductions, respectively. Also, the minimum reduction of seed yield (32.7%) observed in Atlantis treatment. Moreover, 30% increase in herbicides dose caused increasing adverse effects and decreasing grain and biological yield compared to the recommended dose. Wheat residues incorporated to the soil increased damage of Atlantis by maintaining it in the soil (reduced seed yield from 3932.3 to 3556.9 kg/ha) and reduced damage of Total and Apirus by further degradation of these herbicides (increased seed yield from 235.4 to 311.6 kg/ha in Total treatment, and from 996.6 to 1161.3 kg/ha in Apirus treatment). But overall, wheat residues increased seed yield (2.1%) in comparison to the removal of plant residue. Therefore, addition of wheat residues as organic matter in the soil can affect the biological changes of herbicides.

Pythium oligandrum is known as an important biological agent against plant pathogens. Isolates from different regions of Iran including Bushehr, Bakhtiari, Chaharmahal, Fars, Golestan, Ilam, Kermanshah, Kerman, West Azerbaijan and Yazd were identified based on morphological and molecular characteristics. The highest recovering frequency of isolates was observed in Kermanshah and Fars provinces. The functional diversity of isolates based on their growth temperature and biological control effect under laboratory conditions was evaluated. The antagonistic effects of native P. oligandrum isolates were evaluated against soil–borne fungal pathogens including Rhizoctonia solani, Phytophthora parasitica, Fusarium solani, F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. pisi using nonparametric statistics, and compered with commercial products of various biocontrol agents such as Clonostachys rosea, Fusarium oxysporum, P. oligandrum and Trichoderma spp. The native isolates of P. oligandrum were diverse in their growth temperature and biocontrol activities. The highest mycelial growth inhibition was found in the interaction between P. oligandrum isolates and R. solani. A significant difference between P. oligandrum isolates was found by evaluating their volatile compounds. The isolates of P. oligandrum showed maximum inhibition on P. parasitica and R. solani and minimum inhibition on F. oxysporum f. sp. lycopersici. The non–volatile compounds had the highest significant effect on P. parasitica as well. The result of this study showed that the growth characteristics and the in vitro biocontrol ability of the native isolates of P. oligandrum on various plant pathogens were different. This variety can be employed in biochemical and greenhouse screening of the isolates.

Wheat (Triticum aestivum L.) is one of the most important crops among cereals. Many factors could be responsible for low yield in wheat, but one of the major causes is weed infestation. The efficacy of any herbicide primarily depends on selectivity and the dose of application. Use of herbicides is an effective and efficient means of weed management. In many cases, there are no practical alternatives to chemical weed control methods. However, not only all kinds of weeds do not control by one type of herbicide and continuous use of that, but also lead to increase weed resistance to herbicides over the time (Hall et al. 1999). Of the many weeds that infest wheat fields across southern Iran, wild barley (Hordeum spontaneum L.), foxtail (Setaria viridis L.) and wild oat (Avena fatua L.) are the major weeds causing economic losses .Baghestani et al. (2007) reported that sulfosulfuron at 19.95 and 24.90 g a.i. ha-1 were proper application rates for broadleaf and grass weed control in wheat fields. Sij et al. (2016) reported that sulfonylurea herbicides were more efficient in terms of weed control. Lair and Redente (2004) reported that sulfonylurea herbicide application increased stability and biomass of crop as much as 43% over auxin herbicide and simultaneously reduced the grass weeds up to 71%. Golparvar et al. (2012) reported that limited doses of herbicides provided the same yield as weed free plots, therefore, this could be recommended to the farmers. The present study initiated to investigate the effect of some sulfonylurea herbicides on weed control and grain and biological yield of winter wheat under with/without wheat residue treatments. A field experiment was carried out in split-plot arrangement based on randomized complete block design with four replicates at College of Agriculture, Shiraz University, in 2014 growing season. Treatments included wheat residue at two levels (0 and 1850 kg/ha) as main plot in combination with each of the three of herbicides (Total, Apyrus and Atlantis) in two concentrations (recommended dose and 30% over the recommended dose) as Subplots. A weed infest plot (no herbicide application) was used as control. Wheat (Shiraz cultivar) planted on 5th November 2014, by Pneumatic planter at the rate of 200 kg ha-1 and maintaining 20 cm distance between crop rows. The plot size was 5m × 5m. Measurement of the effects included weed dry weight, weed density, wheat height, grain yield and its components. The data were subjected to the analysis of variance using SAS statistical software and means were compared by Duncan multiple range test (DMRT) at the 0.05 level of significance. Investigation on the effects of different application doses of Total, Apyrus and Atlantis to control weeds in wheat fields under applied wheat residue showed that the wheat residue had negative effect on the efficiency of three types of herbicides and increased weed dry weight by 41.4 percent, as compared to without wheat residue. Wheat residue incorporated to soil, reduced biological yield (from 14865.60 to 12340.40 kg ha-1) in comparison to without residue treatment. Three herbicides reduced weed biomass and the highest (43.56%) and lowest (18.7%) weed control recorded compared to weedy check. In comparison to weed infest control, Total increased wheat grain yield (from 3329.88 to 5283.19 kg ha-1), followed by Apyrus and Atlantis with 46 and 21 % increase in wheat grain yield, respectively. Application of Total, Apyrus and Atlantis herbicides, had increased wheat biological yield in comparison with weed infest control by 30.7, 26.8 and 13.6 %, respectively. Additive dose of herbicides application had better effect on weeds control and increased wheat grain and biological yield more than the recommended dose. Baghestani et al. (2007) reported that the wheat yield increased with increasing application dose of herbicide without any crop injury. Wheat grain yield for Total applied at the recommended dose was 5090.99 kg ha-1 but no significant effect was observed when an additive dose of the Apyrus herbicide was applied. This could be due to strong weed control effect of the Total herbicide at this dose. Interaction effect of herbicides and application dose indicated that Total at additive dose resulted in highest seed yield and weed control. Wheat residue had negative effect on weed control and the highest weed dry weight (~48.5%) observed when Total was applied under no residue conditions. All herbicide treatments increased wheat biological and grain yield as compared with the weed infested control. Application of Atlantis did not provide acceptable weed control in wheat. It is concluded that the most effective herbicide treatment was Total that provided maximum reduction in overall weed dry matter and obtained maximum grain yield. Atlantis had the lowest effect on weed control compared with the other herbicides (Total and Apyrus) and this could be due to poor weed control of the herbicide at both doses.

Beet necrotic yellow vein virus (BNYVV), the causal agent of rhizomania, is one of the most important viruses influencing sugar beet root in Iran and other parts of the world. A high number of studies has been done on this disease and several resistant cultivars were introduced. In the present study, the physiological changes in two resistant and two susceptible sugar beet cultivars in interaction with this virus was studied. ELISA test results showed that susceptible cultivars had significantly higher virus concentration compared with resistant cultivars. Resistant cultivars showed significantly lower variation in fresh and dry root weight, chlorophyll and antioxidant content. Resistant cultivars showed higher variation in carbohydrate content, total phenol and protein compared with control. In general, BNYVV stimulates a prompt response and more physiological changes in resitant cultivars compared with susceptible ones.

Tortrix viridana is a serious pest of oaks in the Kamfirooz oak forests.Oak bud tortricid (Tortrix viridana) has five larval instars in Kamfirooz oak forests. The pest overwinters as diaposed eggs. The first larval instar emergence coincides with tree budburst when they enter bud scales. First instar larvae appear between 10th to late march, depending on weather condition. Weather parameters such as low temperature at the time of egg hatching determine losses of the pest to the host tree. First, second, third, fourth and fifth instars of the pest take 4-7, 5-8, 5-8, 6-12 and 7-14 days respectively. Pest larvae make their feeding sites by attaching leaves in clusters through webbing. Larvae suspend themselves from a fine silken thread until they find a suitable feeding site and when there is a crowd of larvae on the some branches of the trees, larval movement between trees through hanging can be facilitated by wind. Many predators including spiders, ants, beetles and occasionally birds feed on pest larvae. The pest finishes its larval stages between 26 and 47 days (with an average 31.5 days). Pupal stage lasts 1-2 weeks. Trees can offset pest damages after pest outbreak, provided rainy winter precede, but if pest outbreak occurs in a year with low precipitation followed by a dry and hot summer, high losses due to pest will be unavoidable. Egg, larva, pupa and adult temporal distribution frequencies were 72.61, 10.14, 2.73, and 14.52 percent respectively. Direction had no significant effect on pest damage. Pest moths emerge during late April up through mid may. Moth population reaches its peak within 2-3 weeks after its appearance, and gradually disappears after its unimodal peak. Swarming as a social phenomenon may be observed during the emergence of adults. Twenty species of Aranidae belong to more than 7 families including Lycacidae, Oplinoidae, Clubionidae, Araneidae, Ulobridae, Phomicidae, Salticidae, four species of Coleoptera including Tenebrionidae (one unidentified species) and three coccinellids (Coccinellidae) as well as four species of Hymenoptera were among frequently collected natural enemies of the pest. Population dynamics of Exochomus quadripustulatus, one of the important coccinellids was also studied in sampling plots.

Food production and food security is an essential precursor to sustainable development in agriculture. Currently, more than 800 million people, generally in Africa and Asia, suffer from hunger and agriculture is considered as the main source of food for them. One of the application of nuclear technology is reducing the damages of plant pest and diseases. The application of nuclear techniques in plant pathology can be grouped in three categories including disease tracing, mutagenesis induction and radiation of crops to induce resistance and destruction of pathogens. As a new method to induce defense responses to biotic and abiotic stresses, nowadays, gamma radiation is used to improve the growth in the way to induce the plant resistance to environmental tensions and plant pathogens as well. Use of this potential, especially in management of seed and seedling diseases is very important to reduce a big portion of crop losses caused by plant pathogens in the first weeks of seedling growth.

Metabolomics or analysis of the whole cellular metabolites is a new and powerful tool that provides a quick view to the large numbers of small molecules (metabolites) within the cell and indicates dynamics of these molecules under different conditions. Quantitative and qualitative measurements of these metabolites provide some useful information on biochemical status of the cell so can be used to monitor the gene functions. Nowadays, metabolomics has a wide range of application in agriculture. Metabolomics is mainly used for the study of plant responses to a wide range of biotic or abiotic stresses including plant storage diseases as well as the resistance of plants to the pathogens. Since metabolites are final products of gene expression and all changes in gene expression is reflected in metabolite profiles, hence metabolite profiles provide a good comprehensive understanding of plant defense mechanisms against plant pathogens. This is a rapid, simple and accurate tool for identifying the metabolites associated with resistance as a biomarker for screening the resistant cultivars against plant diseases. In addition, understanding the resistance mechanisms at molecular level provide a better understanding of resistant gene function and pyramiding suitable resistant gene in elite cultivar. This is a review article on different methods of studying the plant metabolites and their administrative problems in plant pathology.