جستجوی مقالات مرتبط با کلیدواژه « گلومالین » در نشریات گروه « آب و خاک »

In the recent decades, the industrial revolution resulted in contamination of the biosphere by heavy metals and mycorrhizal fungi could affect the metals uptake by the plant. This research was carried out using Zea mays with three levels of soil Cd cotamination (0, 50 mg kg-1 using Polymer (Poly-hydroxybutanamide) – Cd, and 50 mg kg-1 using Cd-nitrate) and two levels of mycorrhizal (inoculanted with Glomus Caledonium and non-inoculanted) with three replications in a factorial experiment as a completely randomized design in greenhouse conditions. Cadmium pollution caused a significant reduction (P≥0.05) in shoot dry weight (from 31.05 to 26.34 and 27.10 g pot-1), shoot phosphorus concentration (from 0.37 to 0.36 and 0.36 g kg-1), soil carbohydrate (from 12.67 to 10.40 and 9.81 mg g-1) and also resulted an increases in soil glomalin (from 458.56 to 600.37 and 635 µg g-1) from control to polymer-Cd and nitrate-Cd respectively. Inoculation with mycorrhizal fungi reduced Cd uptake by the Zea mays, increased the soil glomalin content and improved the soil biological parameters. The results of this study showed that glomalin is an important protein in response to stress condition of Cd contamination. Poly-hydroxybutanamide polymer (a non-toxic compound) increased Cd availability and Cd uptake by plant (34.91 mg kg-1) compared to nitrate-Cd (19.83 mg kg-1) and it could be recommended to improve phytoremediation.

Glomalin is a glycoprotein which has been identified in cell walls of hyphae and spores of Glomerale fungi. Glomalin is a glue produced by fungal hyphae and deposites on soil particles which leads to the formation and stabilization of soil aggregates. Water deficit stress by affecting mycorrizal symbiosis can modify glomalin production. This study was conducted as a factorial experiment arranged in a completely randomized design (CRD) with four replications using corn (Zea mays L. Single cross 704) under greenhouse conditions. The first factor was three levels of moisture in the soil: 10-30% depletion of available water (W0), 35-55% depletion of available water (W1), 60-90% depletion of available water (W2) and the second factor was three species of mycorrhizal fungi, Glomus versiforme (Gv), Glomus intraradices (Gi), Glomus etunicatum (Ge) and non mycorrhizal control (NM). At the end of the vegetative growth, easily extractable glomalin (EEG) and total glomalin (TG) were measured using the Bradford method after extraction from soil. Shoot and root dry weights and root colonization declined by reducing soil moisture level. Water deficit significantly increased the amount of EEG and TG in soil. Also, a significant increase in glomalin production was observed at W2 level in all three fungal species compared to the W0 and W1 moisture levels. Moreover, by enhancing water deficit stress and decreasing root colonization, glomalin production per unit of root colonization was significantly increased.

Root stabilization of heavy metals (HMs) by glomalin is one of the protective mechanisms of mycorrhizal fungi in response to metal stress. Considering this hypothesize, the contribution of Rhizophagus irregularis in symbiosis with white clover (Trifolium repens L.) to root stabilization of Cd, glomalin production by the fungus, and Cd sequestration was investigated. A pot culture experiment was conducted as completely randomized block design by two factors including arbuscular mycorrhizal fungus (inoculated with R. irregularis and non-inoculated) and four levels of Cd (0, 15, 30 and 45 µM) with five replications. The results showed that the root colonization by R. irregularis improved phosphorus nutrition, shoot and root dry weights compared to the non-mycorrhizal plants. With increasing of Cd concentration, plant uptake and extraction efficiency of Cd increased but Cd translocation efficiency decreased. Uptake efficiency of Cd in mycorrhizal plants was higher than non-mycorrhizal ones. Translocation efficiency of Cd in mycorrhizal plants was lower than non-mycorrhizal ones, although this factor showed no significant difference between mycorrhizal and non-mycorrhizal plants. Moreover, Cd uptake by roots was higher than shoots and this portion in mycorrhizal plants was higher than non-mycorrhizal ones. Therefore, mycorrhizal clover plants had higher contribution to root stabilization of Cd. Glomalin production and its Cd sequestration capacity was significantly increased as Cd concentration increased. As a result, higher contribution of mycorrhizal roots to Cd uptake can be due to sequestration of Cd in fungal structures inside the roots. Consequently, glomalin could be considered as an induced-stress protein as well as a vital and effective component of spore and hyphal cell wall of the fungus. Glomalin as a heat shock protein, has important role in Cd root stabilization via protection of host plant from toxic effects of Cd and reduction of the Cd bioavailability.

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.
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.
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.
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.

Arbuscular mycorrhizal fungi (AMF) are widespread endosymbionts in terrestrial ecosystems and their exudates have important effects on soil properties. A greenhouse experiment was conducted with six AMF treatments including four exotic species inoculums (Funneliformis mosseae، Claroideoglomus claroideum and Rhizophagus irregularis and a mixed isolate of three species)، one mixed native AMF species treatment and a sterilized soil (control) with four salinity levels (1، 5، 10 and 15 dS m-1). AMF increased the soil (EEG) and total (TG) extractable glomalin، and also the hot water (HWC) and diluted acid (DAC) extractable carbohydrates compared to control treatment in all salinity levels. The native AMF species had the greatest effects on EEG، TG، HWC and DAC at 10 and 15 dS m-1. Soil EEG and TG concentrations were higher in the mixed exotic AMF treatment than in each AMF species. The greatest glomalin concentration was related to F. mosseae at 1، 5 and 15 dS m-1 but at 10 dS m-1 the greatest glomalin concentration was related to C. claroideum. The greatest carbohydrate concentration was related to F. mosseae at 1 and 5 dS m-1 but at 15 dS m-1 significant differences were observed among the three AMF species. Our results showed that there is an interaction between salinity and different AMF species، and a combination of them determines the function of AMF.

Glomalin is a specific glycoprotein that is produced by a fungi belonging to the order Glomerales in phylum Glomeromycota. Noting the widespread symbiotic relation of these fungi with a large number of plants، considerable amounts of glomalin are entered into the soil ecosystems، annually. Heavy metals can influence the both symbionts physiology and hence glomalin production by the fungi. In this study، the effects of Cu levels were investigated on mycorrhizal establishment in corn plants inoculated by either Glomus mosseae or G. intraradices as well as glomalin production by the system. Copper levels of 0، 250 and 500 mg Cu. kg-1 soil (as CuSO4. 5H2O) were applied to the pots before plant culture. Non-mycorrhizal treatment was left un-inoculated as control. Easily extractable glomalin (EEG) and total glomalin (TG) were determined by the Bradford method after extraction from soil. With increasing Cu concentration in soil، shoot and root fresh and dry weights، P and K concentrations in shoot and root، root colonization، EEG and TG decreased and proline concentration in leaves، Cu concentration in shoot and root increased. The results showed that، glomalin levels in fungal treatments significantly increased compared to the non-mycorrhizal control. The results also showed a positive correlation between the measured glomalin and the percent of root colonization.

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