Mycorrhizal fungi exhibit the exceptional feature of dwelling partly inside as well as outside the plant roots. The term mycorrhizae comes from the Greek word ‘mykes’ and ‘rhiza’, meaning ‘fungus’ and ‘root’ respectively, which was first applied to the association of trees with fungal symbionts. Mycorrhizal fungi, which are members of Glomeromycota, are common on the landscape and associate with over 80% of plants in a diversity of managed (agricultural) and unmanaged (natural) ecosystems. Mycorrhization benefits plants by up-regulating the catalytic activities of soil enzymes (such as phosphatases, dehydrogenase, nitrogenase, etc.), assisting in the breakdown of complex organic compounds of soil, and positively influencing other microbes present in the rhizosphere for improved nutrients uptake. Activation of these mechanisms, in turn, provides the ability to withstand drought stress, alleviate salinity, helps with micronutrient absorption and better water absorption, and defense systems in the plants. Owing to these benefits, mycorrhizae have gained a lot of consideration towards multidisciplinary research and have huge applications in agriculture as bio-fertilizers, in fuel production due to the increased plant biomass, and in soil rehabilitation, phytoextraction, and phytoremediation, etc.
Sr. No. | Mineral | Mycorrhizal sp. | Plant sp. | Host Plant Transporters | Effect of Mycorrhizal Symbiosis | Reference |
---|---|---|---|---|---|---|
1. | Phosphate | Claroideoglomus etunicatum | Camellia sinensis | CsPT1 & CsPT4 | AMF up-regulated root CsPT1 expression, while down-regulated the CsPT4 expression. AMF inoculation significantly promoted P acquisition capacity of tea plants, especially in roots through improving root growth and enhancing soil acid phosphatase activity and root CsPT1 expression. | [23] |
Rhizophagus irregularis | Zea mays | ZmPht1;6 & ZmPht1;11 | AMF improved plant growth and Pi assimilation, AMF colonization strongly improved the nutritional status of the plants and increased the internal P concentration. ZmPht1;6 over expression at a high level in AMF-colonized roots. While less expressed ZmPht1;11 also stimulated by AMF colonization. | [24] | ||
2. | Gigaspora margarita or Funnelliformis mosseae | Lotus japonicus | LjPT4 | LjPT4 affects proper arbuscule formation on the fungal side and for improved Pi uptake on the plant side. | [25] | |
3. | Sulfur | Rhizophagus irregularis | Zea mays | ZmSULTR1.2a, ZmSULTR2.1, ZmSULTR3.5 | Upregulation of ZmSULTR1.2a & ZmSULTR2.1 in sulfur deprived conditions while downregulation of ZmSULTR3.5 in mycorrhized plants. | [26] |
4. | Copper | Rhizophagus irregularis | Medicago truncatula | MtCOPT2 | Preferential expression of MtCOPT2 during mycorrhizal symbiosis. | [27] |
Nitrate | Rhizophagus irregularis | Oryza sativa, Zea mays, Sorghum bicolor, Medicago truncatula | OsNPF4.5, ZmNPF4.5, SbNPF4.5, MtNPF4.5 | Myc-symbiosis resulted in efficient up-regulation of OsNPF4.5, ZmNPF4.5 and SbNPF4.5, while slight induction of MtNPF4.5. | [28] | |
Rhizophagus irregularis | Oryza sativa | OsNPF genes: NPF2.2/ PTR2, NPF1.3, NPF6.4 and NPF4.12 | Enhanced expression of nitrate transporter genes in mycorrhizal roots in nutrient dependent manner. | [29] | ||
5. | Ammonium | Rhizophagus irregularis | Oryza sativa | OsAM1, OsAM10, OsAM20, OsAM25 | Significant upregulation in roots via AMF symbiosis. | [29] |
Rhizophagus irregularis | Oryza sativa | OsAMT3.1 | Up-regulation of OsAMT3.1 in rice mycorrhizal roots | [28] | ||
6. | Zinc | Rhizophagus irregularis | Medicago truncatula | MtZIP5, MtZIP2 | AMF symbiosis caused higher expression of MtZIP5 in poor rhizospheric Zn condition and reduction in MtZIP2 at elevated soil Zn concentration. | [30] |
Rhizophagus irregularis/mock-inoculated | Hordeum vulgare | HvZIP3, HvZIP7, HvZIP8, HvZIP10, HvZI13 | Out of five transporters, HvZI13 found most significantly upregulated, HvZI3 & 8 upregulated also in Zn deficient conditions, while HvZI7 & 10 downregulated. | [31] | ||
7. | Potassium | Rhizophagus irregularis | Lycium barbarum Solanum lycopersicum | LbKT1, LbSKOR SlHAK10 |
Regulated expression of LbKT1 and LbSKOR for varying water & potassium availability | [32][33] |
Pollutant | Mycorrhizal Species | Plant Species | Possible Mechanism | Literature Cited |
---|---|---|---|---|
Chromium (Cr) | Rhizophagus irregularis | Daucuscarota | Reduced translocation, and immobilization of Cr6+ through EPS (extracellular polymers) production. distribution of Cr in roots | [48] |
Rhizophagus irregularis | bermudagrass [Cynodondactylon (Linn.) | Cr absorption and immobilization by AM roots, Reduction of Cr6+ to Cr3+ within fungal structures, inhibited Cr flow from roots to shoots, | [49] | |
Rhizophagus irregularis | Taraxacum platypecidum | Cr absorption and immobilization by AM roots, inhibit Cr translocation from roots to shoots, promoted plant growth | [49] | |
Glomus deserticola | Prosopisjuli flora-velutina | Accumulation of Cr in vascular tissue and decreased the translocation of Cr into shoots | [50] | |
Zinc (Zn) | Glomus mosseae & G. intraradices | Vetiver grass | Increased P uptake by the plant and improved overall growth (G. intraradices showed more rehabilitation capacity) | [51] |
Glomu smosseae | Trifolium pratense | Zn accumulation in roots which decreases in shoots as the Zn conc. rises to its maximum, improved P sustenance | [52] | |
Glomus deserticola | Eucalyptus globulus | Increased root to shoot metal accumulation, high metabolic activity, symbiotic effect of saprophytic fungal sp. on mycoremediation process | [53] | |
Lead (Pb) | Glomus mosseae& G. intraradices | Vetiver grass | Increased P uptake by the plant and improved overall growth (G. mosseae showed more rehabilitation capacity) | [51] |
Glomus mosseae and G. deserticola | Eucalyptus globulus | Promoted overall growth, mineral nutrition, chlorophyll production and enzymatic performances (which further increased due to synergistic effect of G. deserticola and T. koningii), enhanced Pb accumulation | [54] | |
Aluminium | Pisolithus sp. | Schinusmolle | Phytoextraction or phytostbilization, Glomalin production supported chelation, rise in photochemical efficacy | [55] |
Copper (Cu) | R. irregularis | Zea mays | Increased accumulation of total phytochelating content in shoots | [56] |
Funneliformis mosseae; R. intraradices | Capsicum annuum | Cu Higher total dry weight and the leaf | [57] | |
Arbascular Mycorrhizal Fungi (AMF) | Elsholtzia splendens | Increase in germination rate and the germination index of the seeds as well as the fresh weights of hypocotyl and radicle | [58] | |
Claroideoglomus claroideum | Oenothera picensis | Protect plant from metal toxicity, enhance both plant establishment and nutrition | [59] | |
R. irregularis | Phragmites australis | Stress tolerance via up-regulating photo systems membrane complexes, improved plant growth. | [60] | |
Rhizoglomus clarum | Canavalia ensiformis | Alleviated amounts of Cu due to phytoextraction in addition to earthworms | [61] | |
Rhizophagus clarus | Canavalia ensiformis | Alleviated amounts of Cu due to phytoextraction & phytostabilization in addition to bovine | [62] | |
Claroideo glomu sclaroideum and | Oenothera picensis | Cu chelation with AM-secreted glomalin protein | [63] | |
Mercury (Hg) | Glomussp.,Gigaspora sp. &Skutelespora sp. | Cyperus kyllingia, Lindernia crustacea, Paspalum conjugatum | P. conjugatum resulted maximum phytoextraction, while C.kyllingia exhibited maximum (Hg) tolerance | [64] |
Native AM fungal morphotypes | Axonopus compressus, and Erato polymnioides | A. compressus ensued phythoextracting; Eratopolymnioides–Hg phytostabilization | [65] | |
AMF | Lolium perenne | Decreased shoot:root (St:Rt) (Hg conc.), increased metal assimilation in roots | [66] | |
Nickel (Ni) | Funneliformis mosseae (also named as Glomus mosseae) | Festuca arundinacea | Enhance expression of ABC transporters and metallothione induced metal intoxication, decreased metal translocation | [67] |
Acaulospora sp. (indigenous) | Canavalia ensiformis | [68] | ||
Arsenic (As) | AMF mix | Lens culinaris | Alleviated uptake by roots and shoots as an effect of mycorrhizal association | [69] |
Rhizophagus intraradices (formerly named G. intraradices) | Plantago lanceolata | Down-regulating phosphate/arsenate transporters could assist plants to enhance the As tolerance | [70] | |
Rhizoglomus intraradices & Glomus etunicatum | Triticum aestivum | Regulated P/As ratio, enhanced antioxidant production, holding As into non-toxic forms via increased production of biopolymers | [4] | |
Rhizoglomus intraradices | Robiniapseudoacacia | Induced changes in root morphology, increased shoot-root dry weights, controlled phyto-hormone concentration etc. | [4] | |
Acaulospora scrobiculata | Anadenantheraperegrina | Promoted P uptake lead to higher growth rates, As concentrations in the roots and shoots. | [5] | |
Cadmium (Cd) | Funelliformis mosseae and Piriformos poraindica | T. aestivum | Biomass uplift, imposed catalytic activities for G-SH transferase, catalase, peroxidase etc., and antioxidant genes upregulation | [71] |
Glomus intraradices | Zea mays | Mycorrhizae in association with biochar resulted alleviation in Cd accumulation in plant and restricted mobilization, soil rehabiliation | [72] | |
Glomus monosporum, G. clarum, Gigaspora nigra, and Acaulospora laevis | Trigonella foenum-graecum | Decreased St: Rt Cd ratio, enhanced antioxidant activities | [73] | |
Rhizophagus irregularis | Phragmites australis | Immobilization of Cd in roots, increased mineral uptake (Mn& P mainly) to survive Cd-toxicity | [74] | |
Glomus intraradices, Glomus mosseae, Glomus claroideum, and Glomus geosporum | Nicotiana tabacum | Phyto stabilization of lead via immobilization in extraradical mycelial network | [75] | |
Glomusmosseae | Cajanus ajan | Diminished oxidative disturbances (free radicle formation), high non-protein thiols (-SH) production and high antioxidant activities | [76] | |
Claroideoglomus etunicatum | Sorghum bicolor | Increased the glomalin content for improved soil, Cd stabilization in mycorrhizal roots &phytoextraction (by shoots), high nutrient uptake | [77] |
This entry is adapted from the peer-reviewed paper 10.3390/su141610220