Effects of the arbuscular mycorrhizal symbiosis on protein expression in the leaves of an elite poplar clone grown on heavy metal polluted soil (original) (raw)
Related papers
Ecology, 2012
Investigating how arbuscular mycorrhizal fungi (AMF)-plant interactions vary with edaphic conditions provides an opportunity to test the context-dependency of interspecific interactions. The relationship between AMF and their host plants in the context of other soil microbes was studied along a gradient of heavy metal contamination originating at the site of zinc smelters that operated for a century. The site is currently under restoration. Native C 3 grasses have reestablished, and C 4 grasses native to the region but not the site were introduced. Interactions involving the native mycorrhizal fungi, non-mycorrhizal soil microbes, soil, one C 3 grass (Deschampsia flexuosa), and one C 4 grass (Sorghastrum nutans) were investigated using soils from the two extremes of the contamination gradient in a full factorial greenhouse experiment. After 12 weeks, plant biomass and root colonization by AMF and non-mycorrhizal microbes were measured. Plants from both species grew much larger in soil from low-contaminated (LC) origin than high-contaminated (HC) origin. For S. nutans, the addition of a non-AMF soil microbial wash of either origin increased the efficacy of AMF from LC soils but decreased the efficacy of AMF from HC soils in promoting plant growth. Furthermore, there was high mortality of S. nutans in HC soil, where plants with AMF from HC died sooner. For D. flexuosa, plant biomass did not vary with AMF source or the microbial wash treatment or their interaction. While AMF origin did not affect root colonization of D. flexuosa by AMF, the presence and origin of AMF did affect the number of non-mycorrhizal (NMF) morphotypes and NMF root colonization. Adding non-AMF soil biota reduced Zn concentrations in shoots of D. flexuosa. Thus the non-AMF biotic context affected heavy metal sequestration and associated NMF in D. flexuosa, and it interacted with AMF to affect plant biomass in S. nutans. Our results should be useful for improving our basic ecological understanding of the context-dependency of plant-soil interactions and are potentially important in restoration of heavy-metal-contaminated sites.
PLoS ONE, 2012
Some plants can tolerate and even detoxify soils contaminated with heavy metals. This detoxification ability may depend on what chemical forms of metals are taken up by plants and how the plants distribute the toxins in their tissues. This, in turn, may have an important impact on phytoremediation. We investigated the impact of arbuscular mycorrhizal (AM) fungus, Glomus intraradices, on the subcellular distribution and chemical forms of cadmium (Cd) in alfalfa (Medicago sativa L.) that were grown in Cd-added soils. The fungus significantly colonized alfalfa roots by day 25 after planting. Colonization of alfalfa by G. intraradices in soils contaminated with Cd ranged from 17% to 69% after 25-60 days and then decreased to 43%. The biomass of plant shoots with AM fungi showed significant 1.7-fold increases compared to no AM fungi addition under the treatment of 20 mg?kg 21 Cd. Concentrations of Cd in the shoots of alfalfa under 0.5, 5, and 20 mg?kg 21 Cd without AM fungal inoculation are 1.87, 2.92, and 2.38 times higher, respectively, than those of fungi-inoculated plants. Fungal inoculation increased Cd (37.2-80.5%) in the cell walls of roots and shoots and decreased in membranes after 80 days of incubation compared to untreated plants. The proportion of the inactive forms of Cd in roots was higher in fungitreated plants than in controls. Furthermore, although fungi-treated plants had less overall Cd in subcellular fragments in shoots, they had more inactive Cd in shoots than did control plants. These results provide a basis for further research on plant-microbe symbioses in soils contaminated with heavy metals, which may potentially help us develop management regimes for phytoremediation.
Journal of Trace Elements in Medicine and Biology, 2005
This article reviews recent developments in in situ bioremediation of trace metal contaminated soils, with particular reference to the microbial dynamics in the rhizospheres of plants growing on such soils and their significance in phytoremediation. In non-agricultural conditions, the natural role of plant growth promoting rhizobacteria (PGPR), Psolubilizing bacteria, mycorrhizal-helping bacteria (MHB) and arbuscular mycorrhizal fungi (AMF) in maintaining soil fertility is more important than in conventional agriculture, horticulture, and forestry where higher use of agrochemicals minimize their significance. These microbes initiate a concerted action when a particular population density is achieved, i.e. quorum sensing. AMF also recognize their host by signals released by host roots, allowing a functional symbiosis. AM fungi produce an insoluble glycoprotein, glomalin, which sequester trace elements and it should be considered for biostabilization leading to remediation of contaminated soils. Conclusions drawn from studies of metal uptake kinetics in solution cultures may not be valid for more complex field conditions and use of some combination of glasshouse and field experiments with organisms that occur within the same plant community is suggested. Phytoextraction strategies, such as inoculation of plants to be used for phytoremediation with appropriate heavy metal adapted rhizobial microflora, cocropping system involving a non-mycorrhizal hyperaccumulator plant and a non-accumulator but mycorrhizal with appropriate AMF, or pre-cropping with mycotrophic crop systems to optimize phytoremediation processes, merit further field level investigations. There is also a need to improve our understanding of the mechanisms involved in transfer and mobilization of trace elements by rhizosphere microbiota and to conduct research on selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes. This is necessary if we are to improve the chances of successful phytoremediation.
Enhanced phytoremediation: A study of mycorrhizoremediation of heavy metal–contaminated soil
Remediation Journal, 2006
Arbuscular mycorrhizal fungi (AMF) are microscopic fungi that occur naturally in soil and form a symbiosis with plant roots. By colonizing the roots, the fungus increases plant growth by making soil essential elements like zinc and phosphorus more accessible. AMF can play a role in the phytoremediation of heavy metal–contaminated soil (mycorrhizoremediation). Two research experiments were conducted to evaluate the impact of AMF on the extraction of different heavy metals (arsenic, cadmium, lead, selenium, and zinc) in contaminated soil. A grass mixture composed of Festuca rubra, Festuca eliator, Agropyron repens, and Trifolium repens was used in the experiments, and four different types of AMF were investigated: Glomus intraradices, Glomus mosseae, Glomus etunicatum, and Gigaspora gigantea. The results of the study showed that heavy metal extraction by Glomus intraradices colonized plants was the highest of all four AMF tested and was generally higher than nonmycorrhizal plants, depending on the heavy metal concentration in soil and whether it interacted with other metals in soil. However, metal extraction by AMF colonized grasses reached a plateau after an approximately two-month period showing no further phytoaccumulation. © 2006 Wiley Periodicals, Inc.
Role of mycorrhizal fungi and bacteria in phytoremediation of heavy metals
Indian journal of Ecology, 2022
Understanding the specific functions of mycorrhizal fungi (AMF) and Bacillus subtillus in plant interaction is important for effective phytoremediation, and how mycorrhiza and bacterial abundance contribute to plant metal solubility is crucial. This study was conducted in the sewage treatment plant in Al-Maimira in Babylon city in the spring season 2020-2021 in soil contaminated with heavy metals cadmium (Cd) and Lead (Pb). The research aimed to employ soil microbes and sunflowers in the remediation of lead and cadmium. The study was carried out using six combinations (mycorrhiza, Bacillus 10ml, Bacillus 100ml, mycorrhiza + Bacillus 10ml, mycorrhiza + Bacillus 100ml and control). The results showed that the mycorrhiza + Bacillus 10 ml had significantly higher microbial respiration rates and polysaccharides content in the soil (2.09 mg CO2 gm-1 in dry soil, 0.71 mg respectively). The results showed also the highest rate of mycorrhiza infection was at the mycorrhiza + Bacillus 100ml treatment (93.30%) suggest that Bacillus subtillus and plant alleviate the environmental stress on mycorrhizal fungi. It was found that the highest value of the translocation factor (TF) of cadmium was at the Bacillus 100 ml treatment (1.68), while the lowest value of TF was at the control treatment (0.13). Furthermore, it was found that the highest value of the accumulation factor (BAF) of cadmium was at Bacillus 100 ml (154.53). Regarding lead, the highest value of TF was at Bacillus 100 ml (4.03), whereas, it was found that the highest value of BAF was in the mycorrhiza + Bacillus 100 ml treatment (4.38). However, untreated sunflower did not translocate cadmium and accumulate lead in the plant as the TF and BAF were less than 1, implying that the role of microbes in the lead- cadmium contaminated soils must be well taken into consideration. More importantly, the highest concentration of cadmium was in the vegetative part (stem and leaves) at Bacillus 100 ml treatment (13.282 mg kg-1), while it was found that the highest concentration of lead was in the vegetative part (stem and leaves) at mycorrhiza + Bacillus 100 ml (117.07 mg kg-1). In conclusion, we found a novel insight that enhanced heavy metal remediation by increasing the abundance of soil bacterial cells and CO2 release in combination with mycorrhizal fungi using sunflower as a good candidate for phytoremediation in the arid land ecosystem.
Mycorrhiza, 2009
Toxic metal accumulation in soils of agricultural interest is a serious problem needing more attention, and investigations on soil–plant metal transfer must be pursued to better understand the processes involved in metal uptake. Arbuscular mycorrhizal (AM) fungi are known to influence metal transfer in plants by increasing plant biomass and reducing metal toxicity to plants even if diverging results were reported. The effects of five AM fungi isolated from metal contaminated or non-contaminated soils on metal (Cd, Zn) uptake by plant and transfer to leachates was assessed with Medicago truncatula grown in a multimetallic contaminated agricultural soil. Fungi isolated from metal-contaminated soils were more effective to reduce shoot Cd concentration. Metal uptake capacity differed between AM fungi and depended on the origin of the isolate. Not only fungal tolerance and ability to reduce metal concentrations in plant but also interactions with rhizobacteria affected heavy metal transfer and plant growth. Indeed, thanks to association with nodulating rhizobacteria, one Glomus intraradices inoculum increased particularly plant biomass which allowed exporting twofold more Cd and Zn in shoots as compared to non-mycorrhizal treatment. Cd concentrations in leachates were variable among fungal treatments, but can be significantly influenced by AM inoculation. The differential strategies of AM fungal colonisation in metal stress conditions are also discussed.
Applied Soil Ecology, 2009
a b s t r a c t The plant growth, nutrient acquisition, metal translocation and antioxidant activities [ascorbate peroxidase (APX), glutatione reductase (GR), superoxide dismutase (SOD) and catalase (CAT)] were measured in plants growing in a heavy-metal (HM) multicontaminated soil inoculated with selected autochthonous microorganisms [arbuscular mycorrhizal (AM) fungus and/or plant growth promoting bacteria (PGPB)] and/or amended with an Aspergillus nigertreated agrowaste. The treated agrowaste on its own increased root growth by 296% and shoot growth by 504% compared with non-treated control plants. Both chemical and biological treatments, particularly when combined, enhanced plant shoot and root development. The stimulation effect on plant biomass was concomitant with increased AM colonization, P and K assimilation, and reduced metal translocation from soil to plant shoot. The treated residue, particularly through interactions with AM inoculation, produced the expected bioremediation effect, leading to enhanced plant development and successful rehabilitation of contaminated soil. The enhancement of CAT, APX and GR activities caused by AM inoculation suggests that AM colonization helped plants to limit oxidative damage to biomolecules in response to metal stress. The response of the plant's antioxidant activities to the amendment appears to be related to enhanced plant biomass production. The application of amendments and/or microbial inoculations to enhance plant growth and reduce metal translocation in multicontaminated soil could be a promising strategy for remediating HM pollution. (R. Azcó n). a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m journal homepage: www.elsevier.com/locate/apsoil 0929-1393/$ -see front matter #
Phytoremediation Mechanisms of Heavy Metal Contaminated Soils: A Review
Open Journal of Ecology, 2015
Phytoremediation is a green emerging technology used to remove pollutants from environment components. Mechanisms used to remediate soils contaminated by heavy metal are: phytoextraction, phytostabilisation, phytovolatilization and rhizofiltration. The two first mechanisms are the most reliable. Many factors influence the choice of the suitable phytoremediation strategy for soil decontamination. It depends on soil properties, heavy metal levels and characteristics, plant species and climatic conditions. The present review discusses factors affecting heavy metals uptake by plant species, the different phytoremediation strategies of heavy metal contaminated soils and the advantages and disadvantages of phytoremediation and each of its mechanisms.