Mycorrhizal bioremediation

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Mycorrhizal amelioration of heavy metals or pollutants is a process by which mycorrhizal fungi in a mutualistic relationship with plants can sequester toxic compounds from the environment, as a form of bioremediation. [1] [2] [3]

Contents

Mycorrhizae-plant partners

These symbiotic relationships are generally between plants and arbuscular mycorrhizae in the Glomeromycota clade of fungi. [3] [4] Other types of fungi have been documented. For example, there is a case where zinc phytoextraction from willows was increased after the Basidiomycete fungus Paxillus involutus was inoculated in the soil. [5]

Mechanisms of the symbiosis

The mycorrhizae allow the plants to increase their biomass, which increases their tolerance to heavy metals. The fungi also stimulate the uptake of heavy metals (such as manganese and cadmium) with the enzymes and organic acids (such as acetic acid and malic acid) that they excrete into their surroundings in order to digest them. [5] [6]

Mycorrhizae on plant toleration

The fungi can prevent heavy metals from traveling past the roots of the plant. [6] They can also store heavy metals in their vacuoles. However, in some cases, the fungi do not decrease the uptake of heavy metals by plants but increase their tolerance. In some cases, this is done by increasing the overall biomass of the plant so that there is a lower concentration of metals. They can also modify the response of the plant to heavy metals at the level of plant transcription and translation. [3] [7]

Colonization of barren soil

Mycorrhizae remain functional underground following extreme conditions, such as a forest fire. Researchers believe that this allows them to obtain minerals and nutrients that are released during a fire before they are leached out of the soil. This likely increases the ability to recover quickly after forest fires. [8]

Serpentine soils are in part characterized by a low calcium-to-magnesium ratio. Studies indicate that arbuscular mycorrhiza helps plants increase their magnesium uptake in soils with low amounts of magnesium. However, plants in serpentine soils inoculated with fungus either showed no effect on magnesium concentration or decreased magnesium uptake. [9]

Resistance to toxicity

Studies show that mycorrhizal symbionts of poplar seedlings are capable of preventing heavy metals reaching vulnerable parts of the plant by keeping the toxins in the rhizosphere. [10] Another study demonstrates that Arctostaphylos uva-ursi plants in symbiotic relationships were more resistant to toxins because the fungi helped the plants grow below toxic layers of soil. [11]

Application in bioremediation

In China's provinces of Guizhou, Yunnan and Guangxi, rocky desertification is expanding and is not well controlled. This area is characterized by soil depletion, soil erosion and droughts. It is very difficult for plants to grow in this region, and it is mostly filled with drought-resistant plants, lithophytes and calciphilopteris plants. Morus alba, commonly known as a mulberry, is a drought-resistant tree that can tolerate barren soils. It has been found that mulberry inoculated with arbuscular mycorrhiza has increased survivability in karst desert areas and, therefore, an increased rate of soil improvement and reduced erosion. [12]

In 1993, artist Mel Chin collaborated with USDA agronomist Dr. Rufus Chaney in an effort to detoxify Pigs Eye Landfill, a superfund site in Saint Paul, Minnesota. The team planted Thlaspi, which had been selected for increased uptake and sequestration of heavy metals. Analysis showed elevated cadmium concentrations in Thlaspi biomass. [13] It has been found that Thlaspi has a significant arbuscular mycorrhiza association.[ citation needed ]

Slovakia has many heavy metal mines, which have caused significant regional soil contamination. Samples of Thlaspi harvested in Slovakia from contaminated soils near a lead mine showed increased levels of cadmium, lead, and zinc. Furthermore, Thlaspi growing in contaminated regions had higher rates of certain arbuscular mycorrhizal fungi when compared to non-contaminated Thlaspi. [14] Since manual clean-up is usually inefficient and expensive, mycorrhiza colonized Thlaspi may be useful in bioremediation efforts.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Mycorrhiza</span> Fungus-plant symbiotic association

A mycorrhiza is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play important roles in plant nutrition, soil biology, and soil chemistry.

<span class="mw-page-title-main">Phytoremediation</span> Decontamination technique using living plants

Phytoremediation technologies use living plants to clean up soil, air and water contaminated with hazardous contaminants. It is defined as "the use of green plants and the associated microorganisms, along with proper soil amendments and agronomic techniques to either contain, remove or render toxic environmental contaminants harmless". The term is an amalgam of the Greek phyto (plant) and Latin remedium. Although attractive for its cost, phytoremediation has not been demonstrated to redress any significant environmental challenge to the extent that contaminated space has been reclaimed.

<span class="mw-page-title-main">Arbuscular mycorrhiza</span> Symbiotic penetrative association between a fungus and the roots of a vascular plant

An arbuscular mycorrhiza (AM) is a type of mycorrhiza in which the symbiont fungus penetrates the cortical cells of the roots of a vascular plant forming arbuscules. Arbuscular mycorrhiza is a type of endomycorrhiza along with ericoid mycorrhiza and orchid mycorrhiza. They are characterized by the formation of unique tree-like structures, the arbuscules. In addition, globular storage structures called vesicles are often encountered.

<span class="mw-page-title-main">Mycoremediation</span> Process of using fungi to degrade or sequester contaminants in the environment

Mycoremediation is a form of bioremediation in which fungi-based remediation methods are used to decontaminate the environment. Fungi have been proven to be a cheap, effective and environmentally sound way for removing a wide array of contaminants from damaged environments or wastewater. These contaminants include heavy metals, organic pollutants, textile dyes, leather tanning chemicals and wastewater, petroleum fuels, polycyclic aromatic hydrocarbons, pharmaceuticals and personal care products, pesticides and herbicides in land, fresh water, and marine environments.

<span class="mw-page-title-main">Hyperaccumulator</span>

A hyperaccumulator is a plant capable of growing in soil or water with high concentrations of metals, absorbing these metals through their roots, and concentrating extremely high levels of metals in their tissues. The metals are concentrated at levels that are toxic to closely related species not adapted to growing on the metalliferous soils. Compared to non-hyperaccumulating species, hyperaccumulator roots extract the metal from the soil at a higher rate, transfer it more quickly to their shoots, and store large amounts in leaves and roots. The ability to hyperaccumulate toxic metals compared to related species has been shown to be due to differential gene expression and regulation of the same genes in both plants.

Glomus aggregatum is an arbuscular mycorrhizal fungus used as a soil inoculant in agriculture and horticulture. Like other species in this phylum it forms obligate symbioses with plant roots, where it obtains carbon (photosynthate) from the host plant in exchange for nutrients and other benefits.

This list covers hyperaccumulators, plant species which accumulate, or are tolerant of radionuclides, hydrocarbons and organic solvents, and inorganic compounds.

Microbial inoculants, also known as soil inoculants or bioinoculants, are agricultural amendments that use beneficial rhizosphericic or endophytic microbes to promote plant health. Many of the microbes involved form symbiotic relationships with the target crops where both parties benefit (mutualism). While microbial inoculants are applied to improve plant nutrition, they can also be used to promote plant growth by stimulating plant hormone production. Although bacterial and fungal inoculants are common, inoculation with archaea to promote plant growth is being increasingly studied.

Acaulospora mellea is a species of fungus in the family Acaulosporaceae. It forms arbuscular mycorrhiza and vesicles in roots.

James Wessell Gerdemann was an American mycologist. He was known for his contributions to the taxonomy of the Glomeromycota, and expertise in arbuscular mycorrhizae. He earned his bachelor and master's degrees in botany at the University of Missouri. His PhD dissertation, titled "The resistance of two tomato varieties to formae of Fusarium oxysporum", was obtained in 1949 at the University of California at Berkeley. The Gerdemann Botanic Preserve in Yachats, Oregon is named after him.

The mycorrhizosphere is the region around a mycorrhizal fungus in which nutrients released from the fungus increase the microbial population and its activities. The roots of most terrestrial plants, including most crop plants and almost all woody plants, are colonized by mycorrhiza-forming symbiotic fungi. In this relationship, the plant roots are infected by a fungus, but the rest of the fungal mycelium continues to grow through the soil, digesting and absorbing nutrients and water and sharing these with its plant host. The fungus in turn benefits by receiving photosynthetic sugars from its host. The mycorrhizosphere consists of roots, hyphae of the directly connected mycorrhizal fungi, associated microorganisms, and the soil in their direct influence.

<span class="mw-page-title-main">Mycorrhizal network</span> Underground fungal networks that connect individual plants together

Mycorrhizal associations have profoundly impacted the evolution of plant life on Earth ever since the initial adaptation of plant life to land. In evolutionary biology, mycorrhizal symbiosis has prompted inquiries into the possibility that symbiosis, not competition, is the main driver of evolution.

<span class="mw-page-title-main">Ectomycorrhiza</span> Non-penetrative symbiotic association between a fungus and the roots of a vascular plant

An ectomycorrhiza is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobiont, and the roots of various plant species. The mycobiont is often from the phyla Basidiomycota and Ascomycota, and more rarely from the Zygomycota. Ectomycorrhizas form on the roots of around 2% of plant species, usually woody plants, including species from the birch, dipterocarp, myrtle, beech, willow, pine and rose families. Research on ectomycorrhizas is increasingly important in areas such as ecosystem management and restoration, forestry and agriculture.

<i>Rhizophagus irregularis</i> Arbuscular mycorrhizal fungus used as a soil inoculant

Rhizophagus irregularis is an arbuscular mycorrhizal fungus used as a soil inoculant in agriculture and horticulture. Rhizophagus irregularis is also commonly used in scientific studies of the effects of arbuscular mycorrhizal fungi on plant and soil improvement. Until 2001, the species was known and widely marketed as Glomus intraradices, but molecular analysis of ribosomal DNA led to the reclassification of all arbuscular fungi from Zygomycota phylum to the Glomeromycota phylum.

Orchid mycorrhizae are endomycorrhizal fungi which develop symbiotic relationships with the roots and seeds of plants of the family Orchidaceae. Nearly all orchids are myco-heterotrophic at some point in their life cycle. Orchid mycorrhizae are critically important during orchid germination, as an orchid seed has virtually no energy reserve and obtains its carbon from the fungal symbiont.

<span class="mw-page-title-main">Mycorrhiza helper bacteria</span> Group of organisms

Mycorrhiza helper bacteria (MHB) are a group of organisms that form symbiotic associations with both ectomycorrhiza and arbuscular mycorrhiza. MHBs are diverse and belong to a wide variety of bacterial phyla including both Gram-negative and Gram-positive bacteria. Some of the most common MHBs observed in studies belong to the phylas Pseudomonas and Streptomyces. MHBs have been seen to have extremely specific interactions with their fungal hosts at times, but this specificity is lost with plants. MHBs enhance mycorrhizal function, growth, nutrient uptake to the fungus and plant, improve soil conductance, aid against certain pathogens, and help promote defense mechanisms. These bacteria are naturally present in the soil, and form these complex interactions with fungi as plant root development starts to take shape. The mechanisms through which these interactions take shape are not well-understood and needs further study.

Nancy Collins Johnson is an American earth scientist who is the Regents’ Professor and Director of the School of Earth Sciences & Environmental Sustainability at Northern Arizona University. Her work considers soil microbial ecology and the study of mycorrhizal fungi. She was elected a Fellow of the American Association for the Advancement of Science in 2020.

Dr. Mohamed Hijri is a biologist who studies arbuscular mycorrhizal fungi (AMF). He is a professor of biology and research at the Institut de recherche en biologie végétale at the University of Montreal.

<i>Funneliformis mosseae</i> Species of fungus

Funneliformis mosseae is a species of fungus in the family Glomeraceae, which is an arbuscular mycorrhizal (AM) fungi that forms symbiotic relationships with plant roots. Funneliformis mosseae has a wide distribution worldwide, and can be found in North America, South America, Europe, Africa, Asia and Australia. Funneliformis are characterized by having an easily visible septum in the area of the spore base and are often cylindrical or funnel-shaped. Funneliformis mosseae similarly resembles Glomus caledonium, however the spore wall of Funneliformis mosseae contains three layers, whereas Gl. caledonium spore walls are composed of four layers. Funneliformis is an easily cultivated species which multiplies well in trap culture, along with its high distribution, F. mosseae is not considered endangered and is often used for experimental purposes when combined with another host.

The International Collection of (Vesicular) Arbuscular Mycorrhizal Fungi (INVAM) is the largest collection of living arbuscular mycorrhizal fungi (AMF) and includes Glomeromycotan species from 6 continents. Curators of INVAM acquire, grow, identify, and elucidate the biology, taxonomy, and ecology of a diversity AMF with the mission to expand availability and knowledge of these symbiotic fungi. Culturing AMF presents difficulty as these fungi are obligate biotrophs that must complete their life cycle while in association with their plant hosts, while resting spores outside of the host are vulnerable to predation and degradation. Curators of INVAM have thus developed methods to overcome these challenges to increase the availability of AMF spores. The inception of this living collection of germplasm occurred in the 1980s and it takes the form of fungi growing in association with plant symbionts in the greenhouse, with spores preserved in cold storage within their associated rhizosphere. AMF spores acquired from INVAM have been used extensively in both basic and applied research projects in the fields of ecology, evolutionary biology, agroecology, and in restoration. INVAM is umbrellaed under the Kansas Biological Survey at The University of Kansas, an R1 Research Institution. The Kansas Biological Survey is also home to the well-known organization Monarch Watch. INVAM is currently located within the tallgrass prairie ecoregion, and many collaborators and researchers associated with INVAM study the role of AMF in the mediation of prairie biodiversity. James Bever and Peggy Schultz are the Curator and Director of Operation team, with Elizabeth Koziol and Terra Lubin as Associate Curators.

References

  1. ↑ Hildebrandt, Ulrich; Regvar, Marjana; Bothe, Hermann (January 2007). "Arbuscular mycorrhiza and heavy metal tolerance". Phytochemistry. 68 (1): 139–146. Bibcode:2007PChem..68..139H. doi:10.1016/j.phytochem.2006.09.023. PMID   17078985.
  2. ↑ Luo, Zhi-Bin; Wu, Chenhan; Zhang, Chao; Li, Hong; Lipka, Ulrike; Polle, Andrea (2014). "The role of ectomycorrhizas in heavy metal stress tolerance of host plants". Environmental and Experimental Botany. 108: 47–62. Bibcode:2014EnvEB.108...47L. doi:10.1016/j.envexpbot.2013.10.018.
  3. 1 2 3 Ferrol, Nuria; Tamayo, Elisabeth; Vargas, Paola (December 2016). "The heavy metal paradox in arbuscular mycorrhizas: from mechanisms to biotechnological applications". Journal of Experimental Botany. 67 (22): 6253–6265. doi: 10.1093/jxb/erw403 . PMID   27799283.
  4. ↑ Vangronsveld, J; Colpaert, JV; Van Tichelen, KK (1996). "Reclamation of a bare industrial area contaminated by non-ferrous metals: physico-chemical and biological evaluation of the durability of soil treatment and revegetation". Environmental Pollution. 94 (2): 131–40. doi:10.1016/S0269-7491(96)00082-6. PMID   15093499.
  5. 1 2 SHEORAN, Vimla; SHEORAN, Attar Singh; POONIA, Poonam (April 2016). "Factors Affecting Phytoextraction: A Review". Pedosphere. 26 (2): 148–166. doi:10.1016/S1002-0160(15)60032-7.
  6. 1 2 Rajkumar, M.; Sandhya, S.; Prasad, M.N.V.; Freitas, H. (November 2012). "Perspectives of plant-associated microbes in heavy metal phytoremediation". Biotechnology Advances. 30 (6): 1562–1574. doi:10.1016/j.biotechadv.2012.04.011. PMID   22580219.
  7. ↑ Meharg, Andrew A. (November 2003). "The Mechanistic Basis of Interactions Between Mycorrhizal Associations and Toxic Metal Cations". Mycological Research. 107 (11): 1253–1265. doi:10.1017/S0953756203008608. PMID   15000228.
  8. ↑ Buchholz, Kenneth; Motto, Harry (1981). "Abundances and Vertical Distributions of Mycorrhizae in Plains and Barrens Forest Soils from the New Jersey Pine Barrens". Bulletin of the Torrey Botanical Club. 108 (2): 268–271. doi:10.2307/2484905. JSTOR   2484905.
  9. ↑ Doubková, Pavla; Suda, Jan; Sudová, Radka (2011-08-01). "Arbuscular mycorrhizal symbiosis on serpentine soils: the effect of native fungal communities on different Knautia arvensis ecotypes". Plant and Soil. 345 (1–2): 325–338. Bibcode:2011PlSoi.345..325D. doi:10.1007/s11104-011-0785-z. ISSN   0032-079X. S2CID   29085114.
  10. ↑ Lux, Heidi B.; Cumming, Jonathan R. (n.d.). "Mycorrhizae Confer Aluminum Resistance to Tulip-Poplar Seedlings". Canadian Journal of Forest Research. 31 (4): 694–702. doi:10.1139/x01-004.
  11. ↑ Salemaa, Maija; Monni, Satu (2003). "Copper resistance of the evergreen dwarf shrub Arctostaphylos uva-ursi: an experimental exposure". Environmental Pollution. 126 (3): 435–443. Bibcode:2003EPoll.126..435S. doi:10.1016/s0269-7491(03)00235-5. PMID   12963307.
  12. ↑ Xing, Dan; et al. (November 2014). "Research of Ecological Restoration of Mycorrhizal Mulberry in Karst Rocky Desertification Area". Agricultural Science & Technology. 15 (11): 1998–2002 – via EBSCOhost.
  13. ↑ "USDA ARS Online Magazine Vol. 43, No. 11". United States Department of Agriculture AgResearch Magazine. 1995. Retrieved May 9, 2020.
  14. ↑ Vogel-Mikuš, Katarina; Drobne, Damjana; Regvar, Marjana (2005). "Zn, Cd and Pb accumulation and arbuscular mycorrhizal colonisation of pennycress Thlaspi praecox Wulf. (Brassicaceae) from the vicinity of a lead mine and smelter in Slovenia". Environmental Pollution. 133 (2): 233–242. Bibcode:2005EPoll.133..233V. doi:10.1016/j.envpol.2004.06.021. PMID   15519454.
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