Rhizophagus irregularis · Atlas of Contaminated Sites

How it works

Mechanisms: mycorrhizal supportphytostabilisation

Contaminants

Contaminant	Evidence	What was shown
Copper	greenhouse	White poplar cuttings (Populus alba, clone AL35) pre-inoculated with G. intraradices or G. mosseae and grown in pots on soil from a Cu- and Zn-polluted site: mycorrhiza restored biomass to normal despite higher Cu and Zn accumulation in plant organs, especially roots, with induction of foliar metallothionein and polyamine biosynthesis genes. Cicatelli et al. (2010) Arbuscular mycorrhizal fungi restore normal growth in a white poplar clone grown on heavy metal-contaminated soil. Ann Bot 106:791-802, 2010
Zinc	greenhouse	Same trial: more zinc in the roots of mycorrhizal plants and growth restored; the authors conclude that the capacity to stabilise soil metals is increased. Cicatelli et al. (2010) Ann Bot 106:791-802, 2010
Uranium	laboratory	Transformed carrot root cultures in two-compartment plates, with 0.1 µM 233U in the hyphae-only compartment: the mycelium takes up uranium and translocates it towards the roots, to an extent strongly dependent on pH. In a glasshouse, on mine-impacted soil with 111 mg/kg U, colonisation of Pteris vittata raised the U transfer factor to roots from 7 to 14, with less than 2% translocated to fronds. Rufyikiri et al. (2002) Uranium uptake and translocation by the arbuscular mycorrhizal fungus, Glomus intraradices, under root-organ culture conditions. New Phytol 156:275-281, 2002 Chen, Zhu & Smith (2006) Effects of arbuscular mycorrhizal inoculation on uranium and arsenic accumulation by Chinese brake fern (Pteris vittata L.) from a uranium mining-impacted soil. Chemosphere 62:1464-1473, 2006

Contaminant

Evidence

What was shown

greenhouse

White poplar cuttings (Populus alba, clone AL35) pre-inoculated with G. intraradices or G. mosseae and grown in pots on soil from a Cu- and Zn-polluted site: mycorrhiza restored biomass to normal despite higher Cu and Zn accumulation in plant organs, especially roots, with induction of foliar metallothionein and polyamine biosynthesis genes.

Cicatelli et al. (2010) Arbuscular mycorrhizal fungi restore normal growth in a white poplar clone grown on heavy metal-contaminated soil. Ann Bot 106:791-802, 2010

Zinc

greenhouse

Same trial: more zinc in the roots of mycorrhizal plants and growth restored; the authors conclude that the capacity to stabilise soil metals is increased.

Cicatelli et al. (2010) Ann Bot 106:791-802, 2010

Uranium

laboratory

Transformed carrot root cultures in two-compartment plates, with 0.1 µM 233U in the hyphae-only compartment: the mycelium takes up uranium and translocates it towards the roots, to an extent strongly dependent on pH. In a glasshouse, on mine-impacted soil with 111 mg/kg U, colonisation of Pteris vittata raised the U transfer factor to roots from 7 to 14, with less than 2% translocated to fronds.

Limits

The effect is stabilisation in roots, not extraction: the metal stays on site. With Pteris vittata colonisation depressed fern growth, particularly early on, and did not change tissue arsenic (Chen et al. 2006). An obligate symbiont: it cannot be grown without a host plant. The trials consulted are pot or in vitro experiments.

Where it has been tried

Sito metallurgico dismesso dell'Italia nord-occidentale (arsenico)

PhytoremediationField scale, 2014–2017

Pteris vittata, Rhizophagus spp., Funneliformis spp.

The University of Eastern Piedmont (Cantamessa, Massa, Gamalero, Berta) grew the fern Pteris vittata, inoculated or not with arbuscular mycorrhizal fungi, first for two years in a greenhouse on soil from the site and then for three years on the site itself, from March 2014, measuring arsenic at two depths.

Outcome In the greenhouse soil arsenic fell from 170 to 49 mg/kg with mycorrhizal ferns. In the field, by the third year, nearly all sub-areas were below 50 mg/kg in the 0–0.2 m layer (one stayed above the limit); fronds held 835 mg/kg of As on average. Between 0.2 and 0.4 m the decline was slower, which the authors put down to cadmium toxicity.