Soil science
Vahideh Dinmohammadi; N. Aliasgharzad; Leili Aghebati-Maleki
Abstract
Introduction
Recent studies show that most crops and horticultural plants can form symbiosis with the arbuscular mycorrhizal fungi (AMF) and the endophytic Serendepita indica, simultaneously. The endophytic fungus plays an important role in alleviating environmental stresses in plants. It has also been ...
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Introduction
Recent studies show that most crops and horticultural plants can form symbiosis with the arbuscular mycorrhizal fungi (AMF) and the endophytic Serendepita indica, simultaneously. The endophytic fungus plays an important role in alleviating environmental stresses in plants. It has also been shown that excessive available phosphorus in soil limits the root colonization by arbuscular mycorrhizal fungi. No information is available on how soil phosphorus affects the establishment of endophytic fungus in root. Barley roots can be colonized by both mycorrhizal fungi and the endophytic fungus Serendipita indica. The objective of this study was to evaluate the effects of single or dual inoculation with Rhizophagus irregularis and Serendipita indica on barley roots under different phosphorus (P) levels. The researchers utilized a monoclonal antibody called MAb32B11 to assess the presence of glomalin, a signature molecule of arbuscular mycorrhizal (AM) fungi, in the roots. The glomalin content was quantified using the enzyme-linked immunosorbent assay (ELISA) method with the MAb32B11 antibody.
Materials and Methods
In this experiment, barley plants were inoculated with Rhizaphagus irregularis (AMF) and Serendepita indica (endophytic fungus) with three levels of phosphorus from triple super phosphate source. At the end of the vegetative growth period (about three months), the plants were harvested and phosphorus concentration in the plant were measured. A subsample from roots was stored in -20 ºC for determination of glomalin content. The glomalin content in the roots was analyzed using the monoclonal antibody MAb32B11. This antibody was employed to differentiate between the two fungi present in the roots and to quantify the abundance of arbuscular mycorrhizal fungi (AMF) specifically in plants treated with Rhizophagus irregularis. Additionally, the content of glomalin in the soil was determined at the end of the experiment using the same method as described above. The experiment was designed as a factorial completely randomized design (CRD) with three replications.
Results and Discussion
The results showed that the fresh and dry weights of shoot and root increased significantly in dual inoculation. At zero phosphorus level, shoot and root phosphorus concentrations were significantly higher in treatments with R. irregularis than in those without fungus (control). Under individual inoculation with R. irregularis, or S. indica as well as their dual inoculations, increasing level of phosphorus had no significant effect on shoot and root phosphorus concentration. In dual inoculation, the percentage of total colonization (88%) was significantly higher than that of individual inoculation treatment (68%) but the contribution of each fungus in root colonization under dual inoculation was significantly reduced as estimated by glomalin content of root and determination of total colonization. It was found that with increasing phosphorus level, total colonization percentage significantly decreased and the highest percentage of colonization (61%) was observed at zero level of phosphorus. By increasing phosphorus level, the percentage of root colonization was significantly decreased in individual inoculation by R. irregularis, or S. indica as well as dual inoculation. Results of glomalin assay in soil showed that the glomalin content was high in treatments of R. irregularis but control treatments without fungus and individual inoculation with S. indica had low glomalin. Antibody-reactive root glomalin was less in the dual inoculation treatment (1006.9 µg.g-1) than in the R. irregularis treatment alone (1924.5 µg.g-1) indicating that the presence of S. indica, in root inhibits, root colonization by R. irregularis. Moreover, the increasing of phosphorus level, significantly decreased root glomalin.
Conclusion
The increase of available phosphorus concentration in the soil caused to limit the expansion of the symbiosis of R. irregularis and S. indica, and this limitation was more for R. irregularis. In the case of dual inoculation with both Rhizophagus irregularis and Serendipita indica, the negative impact of phosphorus on colonization percentage was observed to be less compared to single inoculation. Although the percentage of colonization by each fungus decreased in the dual inoculation treatment compared to their individual inoculation, the overall colonization percentage increased significantly. It appears that in the dual inoculation scenario, while the total root colonization percentage increases, the presence of S. indica leads to a decrease in the colonization percentage specifically with R. irregularis. But in general, growth and nutrient absorption in the case of dual inoculation was better than the inoculation of each of them individually. It was also found that increasing the concentration of phosphorus in the soil caused a decrease in root colonization for both fungi, although the negative effect of phosphorus on the colonization of R. irregularis was more than that of S. indica. The measurement of glomalin in soil and root showed that the inhibitory effect of S. indica fungus on R. irregularis is less in soil than in root.
Nosratollah Najafi; Rashed Ahmadinezhad; Naser Aliasgharzad; Shahin Oustan
Abstract
Introduction: Chemical fertilizers can supply all the nutrients required by plants, but their high consumptions cause environmental pollution and increased agricultural production costs. Organic fertilizers can improve the biological, physical, and chemical properties of soil and improve soil fertility ...
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Introduction: Chemical fertilizers can supply all the nutrients required by plants, but their high consumptions cause environmental pollution and increased agricultural production costs. Organic fertilizers can improve the biological, physical, and chemical properties of soil and improve soil fertility and productivity. However, these fertilizers alone cannot provide all the requirements of plants for different nutrients. In addition, these fertilizers are not sufficiently available to farmers everywhere. So, in order to increase effectiveness of organic and chemical fertilizers, to decrease environmental pollutions and to achieve sustainable agriculture, integrated application of organic and chemical fertilizers is recommended. Nitrogen (N), phosphorus (P) and potassium (K) are essential elements for plant nutrition and growth. Wheat as a strategic crop is the most important cereal and plays a very important role in human and animal nutrition and health. The deficiencies of N, P and K in the most agricultural soils often reduce the growth and yield of wheat. Therefore, the appropriate concentrations of these nutrients in wheat seed, leaf and stem are important not only for the optimum growth of the wheat plant and its quality improvement but also for the health of humans and animals.
Materials and Methods: This research work was carried out to study the effects of combining farmyard manure (FYM), municipal solid waste compost (MSWC) and municipal sewage sludge compost (MSSC) with different levels of urea on seed, leaf and stem yields of wheat (Triticum aestivum L.) cultivar Alvand and concentrations of N, P and K in seed, leaf and stem in a randomized complete blocks design with 15 treatments and three replications under field conditions at Khalatposhan Agricultural Research Station, University of Tabriz, Tabriz, Iran. The treatments included were: 1) control (without fertilizers), 2) 150 kg urea/ha, 3) 300 kg urea/ha, 4) 30 ton MSWC/ha, 5) 30 ton MSWC/ha + 150 kg urea/ha, 6) 60 ton MSWC/ha, 7) 60 ton MSWC/ha + 150 kg urea/ha, 8) 30 ton MSSC/ha, 9) 30 ton MSSC/ha + 150 kg urea/ha, 10) 60 ton MSSC/ha, 11) 60 ton MSSC/ha + 150 kg urea/ha, 12) 30 ton FYM/ha, 13) 30 ton FYM/ha + 150 kg urea/ha, 14) 60 ton FYM/ha, 15) 60 ton FYM/ha + 150 kg urea/ha. The size of each plot was 2.0m × 1.9m. At the end of growth period, the plants were harvested and different sections of wheat plant (seed, leaf and stem) were separated and the yield of each section was determined. The concentration of N in seed, leaf and stem were then measured by Kjeldahl method. After dry ashing of the seed, leaf and stem samples, the concentrations of P and K in their extracts were measured by spectrophotometer and flame photometer instruments, respectively.
Results and Discussion: The results showed that application of 300 kg urea/ha increased the wheat grain yield and concentrations of N, P and K in seed, leaf and stem but it decreased the stem yield. Application of 150 kg urea/ha had no significant effect on the leaf yield but its integration with 60 ton MSWC/ha significantly increased the leaf yield of wheat. The combining of 150 kg urea with 30 and 60 ton FYM, MSWC and MSSC per hectare increased yields of wheat stem and seed and their N and P concentrations as compared with the control and application of solely organic fertilizers. The use of FYM, MSWC and MSSC significantly increased the wheat grain yield and concentrations of N, P and K in seed, leaf and stem relative to the control but their effects on yields of leaf and stem depended on the type and rate of organic fertilizer. The highest yields of grain, stem and leaf and the highest concentrations of N, P and K in wheat grain, stem and leaf were observed under combined application of 150 kg urea and 60 ton FYM, MSWC and MSSC per hectare. The minimum yields of seed, leaf and stem and the minimum concentrations of N, P and K in different organs of wheat plant were observed in the control treatment. The average wheat yield component was in the order of seed > stem > leaf. The mean concentrations of N, P and K in different sections of wheat were in the order of seed > leaf > stem, seed > leaf > stem and stem > leaf > seed, respectively. The grain yield of wheat had positive and significant correlations (p<0.01) with concentrations of N, P and K in different organs of wheat, which indicates the role of N, P and K nutrition of wheat plant in increasing its seed yield.
Conclusions: The wheat seed had higher concentrations of N and P and lower concentration of K compared to leaf and stem. In general, in order to decrease nitrogen fertilizers use, enhance N, P and K nutrition of wheat plant, improve wheat seed quality, decline environmental pollution and increase wheat yield, application of 150 kg urea and 60 ton manure per hectare is recommended. However, if there is not enough manure, 150 kg urea and 60 ton municipal solid waste compost or municipal sewage sludge compost per hectare can be applied at similar conditions.
vahideh Shaabani Zenoozagh; Nasser Aliasgharzad; Jaffar Majidi; Roghaieh Hajiboland; Behzad Baradaran; Leili Aghebati-Maleki
Abstract
Introduction: Glomalin is a specific glycoprotein produced by the fungi belonging to phylum Glomeromycota and plays a key role in soil carbon and nitrogen storage. This also has a significant role in the stable aggregates formation and establishment of microbial communities in soil. Assimilated plant ...
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Introduction: Glomalin is a specific glycoprotein produced by the fungi belonging to phylum Glomeromycota and plays a key role in soil carbon and nitrogen storage. This also has a significant role in the stable aggregates formation and establishment of microbial communities in soil. Assimilated plant C which is allocated to the mycorrhizal fungus, appears as a recalcitrant glycoprotein (glomalin) in cell walls of hyphae and spores. Considering global warming due to increasing greenhouse gases, this phenomenon cab be important in carbon sequestration and reducing CO2 in atmosphere. Chemical fertilizers can affect symbiotic relations of these fungi, which in turn affect glomalin production.
Materials and Methods: In a factorial completely randomized design with three replication, clover plants (Trifolium repense L.) were included with Rhizophagus irregularis and/or Rhizobium leguminosarum bv. Trifolii. Four levels of nitrogen (0, 2, 6 and 10 mM as nitrate) in Newman & Romheld nutrient solution were applied to the pots containing 1.5 kg sterile sand. The pots were daily irrigated with nutrient solution containing the above-mentioned levels of nitrogen. Clover plants were excised after 12 weeks of growth. Fine roots were cleaned with %10 KOH and then stained using lactoglycerol trypan blue. Root colonization percentage was determined by grid line intersections method (GLM) described by Norrif et al (1992). For glomalin extraction, hyphal or root samples were autoclaved at 121 ⁰C with 50 mM sodium citrate buffer for 60 min in three cycles. Sand glomalin (SG) and root glomalin (RG) were measured by Bradford method after extraction. Nitrogen concentration in shoot and root was measured according to the standard method.
Results and Discussion: By increasing nitrogen level, the SG significantly decreased (p < 0.01), and at 2 mM, a 63.5 % decrease in SG was observed with relative to the nitrogen-free control. In the rhizobial treated pots, SG production increased by fungal inoculation (p < 0.01). The interaction between bacteria and AM was also significant in production of SG. At the presence of rhizobium bacteria, glomalin production by AM fungi increased significantly. The changes of glomalin content were not impacted by the presence of bacteria in the uninoculated pots with fungi. The highest amount of SG was recorded in the co-inoculated plants with nitrogen-free level. The amount of RG enhanced by increasing nitrogen concentration in nutrient solution. At 10 mM, RG increased by 12.90 %, 11.91 % and 1.44 % compared to the levels of 0, 2 and 6 mM, respectively. As the nitrogen level increased, the percentage of root colonization increased with respect to the control. Nitrogen concentration in shoot and root was enhanced by N increment to 10mM.
Conclusion: Carbon sequestration via glomali synthase by AM fungi is an important pathway for capturing CO2 from atmosphere. Field management measures help AM development of glomalin production. Based on our results, co-inoculated plants with AM and rhizobuim seem to positively affect the production of this glycoprotein. On the other hand, SG decreased significantly by increasing nitrogen concentrations in the nutrient solution. RG, however, increased significantly as a result of increased nitrogen in both fungal inoculations. The highest amount of RG was recorded in the co-inoculated plants with 10mM level. Glomalin synthesis by the fungi is positively affected by the soil nitrogen availability. Nitrogen is the main constituent of this glycoprotein. Plant photosynthates are translocated to the fungal organs via roots and mainly utilized for glomalin synthesis in hyphal and spore cell walls. During this process, nitrogen plays an important role as a constituent of the glycoprotein. The Bradford method was used for glomalin determination in this study. The method is not specific for glomalin and can also measure other glomalin related proteins and glycoproteins. Other proteins increased by N fertilization can hence be measured based on Bradford method. Once plant assimilates are translocated to the fungi, they may be transformed to the nitrogenous compounds if sufficient nitrogen sources are available. Accordingly, a considerable amount of fixed carbon is assimilated in fungal organs and soil particles. It can be concluded that carbon sequestration by arbuscular mycorrhizal symbiosis in terrestrial ecosystems can be improved by N fertilization at optimum level. In addition, the presence of rhizobium bacteria can meet the nitrogen requirement of plants through biological stabilization of nitrogen.
Sheyda Kaboodi; farzin shahbazi; Nasser Aliasgharzad; nosratola najafi; naser davatgar
Abstract
Introduction: Understanding soil biology and ecology is increasingly important for renewing and sustainability of ecosystems. In all ecosystems, soil microbes play an important role in organic matter turnover, nutrient cycling and availability of nutrients for plants. Different scenarios of land use ...
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Introduction: Understanding soil biology and ecology is increasingly important for renewing and sustainability of ecosystems. In all ecosystems, soil microbes play an important role in organic matter turnover, nutrient cycling and availability of nutrients for plants. Different scenarios of land use may affect soil biological properties. Advanced information technologies in modern software tools such as spatial geostatistics and geographical information system (GIS) enable the integration of large and complex databases, models, tools and techniques, and are proposed to improve the process of soil quality and sustainability. Spatial distribution of chemical and biological properties under three scenarios of land use was assessed.
Materials and Methods: This study was carried out in Mirabad area located in the western part of Souldoz plain surrounded by Urmieh, Miandoab, Piranshahr and Naghadeh cities in the west Azerbaijan province with latitude and longitude of 36°59′N and 45°18′E, respectively. The altitude varies from 1310 to 1345 with average of 1325 m above sea level. The monthly average temperature ranges from -1.4 °C in January to 24.6 °C in July and monthly precipitation ranges from 0.9 mm in July to 106.6 mm in March. Apple orchard, crop production field and rich pasture are three selected scenarios in this research work. Soil samples were systematically collected at 65 sampling points (0-30 cm) on mid July 2010. Soil chemical and biological properties i.e. microbial community, organic carbon and calcium carbonate equivalent were determined. The ArcGIS Geostatistical Analyst tool was applied for assessing and mapping the spatial variability of measured properties. The experimental design was randomized complete blocks design (RCBD) with five replications. Two widely applied methods i.e. Kriging and Inverse Distance Weighed (IDW) were employed for interpolation. According to the ratio of nugget variance to sill of the best variogram model three following spatial dependence conditions for the soil properties can be considered: (I) if this ratio is less than 25%, then the variable has strong spatial dependence; (II) if the ratio is between 25% and 75%, the variable has moderate spatial dependence; and (III) otherwise, the variable has weak spatial dependence. Data were also integrated with GIS for creating digital soil biological maps after testing analysis and interpolating the mentioned properties.
Results and Discussion: Spherical model was the best isotropic model fitted to variograms of all examined properties. The value of statistics (R2 and reduced sum of squares (RSS)) revealed that IDW method estimated calcium carbonate equivalent more reliably while organic carbon and microbial community was estimated more accurately by Kriging method. The minimum effective range (6110 m) was found for microbial community which had the strong spatial dependence [(Co/Co+C)
Elham Malekzadeh; Jafar Majidi; Nasser Aliasgharzad; Jalal Abdolalizadeh
Abstract
Introduction: Glomalin is known as a specific fungal glycoprotein belonging to the order Glomerales in phylum Glomeromycota and has been introduced as a heat shock protein. We hypothesised that increasing the level of Pb would lead to increase in glomalin production. Glomalin is usually determined by ...
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Introduction: Glomalin is known as a specific fungal glycoprotein belonging to the order Glomerales in phylum Glomeromycota and has been introduced as a heat shock protein. We hypothesised that increasing the level of Pb would lead to increase in glomalin production. Glomalin is usually determined by two methods, the Bradford protein dye-binding assay and the enzyme-linked immunosorbent assay (ELISA). Since many laboratories are not equipped to carry out the ELISA assay, many studies have measured glomalin-related soil protein using the Bradford colorimetric total protein assay. While, the ELISA method specifically measures glomalin by using monoclonal antibody MAb32B11.
Materials and Methods: The pot experiment was conducted in the sterile free-glomalin sand with Trifolium repens L. mycorrhized by Rhizophagus irregularis fungus and treated with the Pb levels of 0, 150, 300 and 450 µM. Thus, in vitro experiment was performed in two-compartments plates containing of the transformed carrot roots (Daucus carota L.) mycorrhized with the same fungus in root compartment and hyphal compartment treated with the Pb levels of 0, 0.01, 0.1 and 1 mM as Pb(NO3)2. For glomalin extraction, hyphal or root samples were autoclaved at 121 ⁰C with 50 mM sodium citrate buffer for 60 min in three cycles. Protein concentrations in the extracted samples were determined using a modified Bradford protein assay. Also, glomalin content in the samples were determined by indirect ELISA using monoclonal antibody MAb32B11. The percentages of the total root length were colonised by mycorrhizal fungi in pot culture and both hyphal and spore densities in the metal-containing hyphal compartment were determined.
Results and Discussion: In the in vitro culture the percentage of total hyphae and spore frequency decreased, while Bradford reactive total hyphal protein (BRHP) and Immunoreactive hyphal protein (IRHP) in hyphal compartment increased as the concentrations of Pb increased. Also, there was positive and significant correlation between immunoreactive hyphal protein (IRHP) and Bradford reactive total hyphal protein (BRHP) in hyphal compartment of in vitro culture (r= 0.941**). In the pot culture, the percentage of the total mycorrhized root length in all the treatments increased compared to the unleaded control as the concentrations of Pb raised. In general, Bradford reactive total protein and Immunoreactive protein in both the hyphal and root compartments of pot culture increased with increasing the Pb levels. Also, there were positive and significant correlations between immunoreactive hyphal protein (IRHP) with Bradford reactive total hyphal protein (BRHP) (r= 0.845 **) and immunoreactive root protein (IRRP) with Bradford reactive total root protein (BRRP) (r= 0.706 **) in pot experiment. Some previously researches had reported correlation between ELISA with Bradford contents, whether, Bradford and ELISA values were nearly the same, this means that the extraction process mostly separates glomalin. The results of non-mycorrhizal roots indicated that a small proportion of root protein is cross-reactive with the MAb32B11 antibody. There are some evidences that MAb32B11 is slightly cross-reactive with plant compounds, non-AMF species, and non-target proteins present in large concentration, such as BSA. Additionally, we found the increasing of BRRP contents of AMF-colonized root compared to the non-mycorhizal roots. This may be as a result of uptake and storage of arginine within AMF intraradical hyphae. Considering IRHP to BRHP ratio indicates that immunoreactivity percentage enhances by rising Pb levels. Immunoreactivity indicates a molecular configuration similar to the configuration of glomalin on hyphae. Our findings are in agreement with previous observations confirming that the toxicity-induced stress by metals may be enhancing glomalin production by AMF. The sequence of the glomalin gene revealed that is likely a 60-KDa heat-shock protein (Hsp) homolog. Glomalin relation with the heat shock proteins clarifies how stress is imposed by heavy metals may rapidly increase glomalin production by AMF and its concentrations in polluted soils.
Conclusion: The high contents of glomalin along with the increasing of Pb concentrations may be explained by the overexpression of this protein. This suggests that under Pb-induced stress and the toxic effect of Pb, the fungus exerts a protective mechanism against toxicant. Therefore, glomalin as a heat shock protein can involve in the reduction of possible cytosolic damages and the transfiguration of proteins under Pb toxicity. We can conclude that glomalin may reduce toxic elements availability via their stabilization and decrease their toxicity risk to other microorganisms and plants in heavy metal polluted sites.
samaneh ahmadi gheshlaghi
Abstract
Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and is a major component of soil organic matter, which plays an important role in soil aggregation and carbon sequestration. Glomalin is produced only by the AM fungi. On the other hand, stressful environments such as salinity ...
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Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and is a major component of soil organic matter, which plays an important role in soil aggregation and carbon sequestration. Glomalin is produced only by the AM fungi. On the other hand, stressful environments such as salinity can affect the AM fungi .The purpose of this study was to investigate the effect of NaCl salinity on glomalin production by Glomerales in symbiosis with corn plant. A factorial experiment was conducted in completely-randomized design (CRD) with four replications in a greenhouse. Factors were NaCl salinity with three levels (S0: 1.34, S1:4 and S2: 8 dS/m) and mycorrhizal fungi with four levels (non mycorrhizal, Glomus versiforme, G. intraradices, G. etunicatum). The results showed that the interaction of salinity and mycorrhizal fungi on plant dry weight, leaf proline, root colonization percentage, EEG and TG was significant at p
