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Managing arbuscular mycorrhizal fungi for bioprotection: Mn

toxicity ( Soil Biology and Biochemistry 68:78–84,DOI 10.1016/j.soilbio.2013.09.018)

We investigated whether an intact extraradical mycelium (ERM) is more effective than other forms of propagule from indigenous arbuscular mycorrhizal fungi (AMF) in providing protection against stress to a host plant. The response of wheat (Triticum aestivum L.) to Mn toxicity was studied in a two-phase greenhouse experiment. In Phase 1, four Mn tolerant species from the natural vegetation, ranging from strongly mycotrophic to non- or weakly mycotrophic, were grown to develop different amounts of ERM. Wheat was then planted (Phase 2) with the ERM fragmented by sieving (Disturbed Treatment) or kept intact with no prior soil disturbance (Undisturbed Treatment). The growth of wheat was doubled by earlier and faster mycorrhizal colonization (AC) in the presence of an intact ERM at planting. There was a positive correlation between plant growth and the reduction of Mn and enhancement of P and S uptake into shoots. However, the growth of plants in undisturbed soil was significantly affected by the ERM developer species, which was not explained by differences in AC. Colonization starting from an intact ERM greatly enhanced the potential of AMF for protection against Mn toxicity. However, the degree of protection depended on the plant previously grown to develop the ERM, suggesting that there may be functional diversity within the ERM developed by mycotrophic plants of the natural vegetation.

Beneficial role of plant growth promoting bacteria and arbuscular mycorrhizal fungi on plant responses to heavy metal stress https://doi.org/10.1139/W09-010

Heavy metal pollution is a major worldwide environmental concern that has recently motivated researchers to develop a variety of novel approaches towards its cleanup. As an alternative to traditional physical and chemical methods of environmental cleanup, scientists have developed phytoremediation approaches that include the use of plants to remove or render harmless a range of compounds. Both plant growth promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) can be used to facilitate the process of phytoremediation and the growth of plants in metal-contaminated soils. This review focuses on the recent literature dealing with the effects of plant growth-promoting bacteria and AM fungi on the response of plants to heavy metal stress and points the way to strategies that may facilitate the practical realization of this technology.

AMF produces siderophore , which chelates cations, so there is competition in the soil for metals and pathogen can not grow without essential cation, this is one of mechanism.

There are several mechanisms involved in the AMF induced cleaning of heavy metals; 1. dilution of the metal by promoting the growth of plants 2. synthesis of organic acids by the roots that prevents the entry of the heavy metals under the host 3. Selective action of the plasma membrane 4. chelation of the heavy metal ions by the metallothionin or by 5. immobilization and retention of the meal ions by the hyphae or the roots.

The mechanisms are just being understood and Basu S, Rabara R and Negi S, they have discussed recently.

Please >> Doi: 10.1016/j.pmpp.2017.11.007

Well responded Ruben. Its a range of mechanisms involved comprising chelation , solubilisation , complexation, ixidation - reduction, hydrolysis and all these deruved through hyphal network producing a great variety of siderophores facilitating AMs , one of the most dynamic soil inhabiting microbial communities ...