Arbuscular mycorrhizal fungi alleviate the heavy metal toxicity on sunflower (Helianthus annuus L.) plants cultivated on a heavily contaminated field soil at a WEEE-recycling site.

An 8-week pot experiment was conducted to investigate the growth and responses of sunflower (Helianthus annuus L.) to arbuscular mycorrhizal (AM) fungal inoculations on a heavily heavy metal (HM)-contaminated (H) soil and a lightly HM-enriched (L) soil, both of which were collected from a waste electrical and electronic equipment (WEEE)-recycling site. Compared with the L soil, the H soil induced significantly larger (P<0.05) concentrations of Cd, Cu, Pb, Cr, Zn and Ni in sunflower (except for root Cr and shoot Ni), which impaired the thylakoid lamellar folds in leaves. The biomasses and P concentrations of shoots and roots, as well as the total P acquisitions per pot were all significantly decreased (P<0.05). Both Funneliformis mosseae (Fm) and F. caledonium (Fc) inoculation significantly increased (P<0.05) root mycorrhizal colonization. For the L soil, AM fungal inoculations had no significant effects on the soil-plant system, except for a decrease of soil pH and increases of soil available P and DTPA-extractable Zn concentrations with the Fm-inoculated treatment. For the H soil, however, AM fungal inoculations significantly increased (P<0.05) the biomasses and P concentrations of shoots and roots, as well as the total P acquisitions per pot, and significantly reduced (P<0.05) the concentrations of HMs in shoots (except for Cu and Pb with Fm- and Fc- inoculated treatments, respectively) and alleviated the toxicity symptoms of HMs in thylakoid structure of leaves. AM fungal inoculations in the H soil also significantly increased (P<0.05) the shoot uptake of HMs (except for Cr), and tended to decrease the total concentrations of HMs in soils. This suggests the potential application of AM fungi for both reducing HM stress and promoting phytoextraction of HM-contaminated soils caused by WEEE recycling.

Zhang Y ，Hu J ，Bai J ，Wang J ，Yin R ，Wang J ，Lin X ... -  《-》

Intercropping with sunflower and inoculation with arbuscular mycorrhizal fungi promotes growth of garlic chive in metal-contaminated soil at a WEEE-recycling site.

Heavy metal (HM) pollution in agricultural soils due to the recycling of waste electrical and electronic equipment (WEEE) has become a serious concern, but most farmers cannot afford the economic losses of fallow land during remediation. Thus, it is imperative to produce low-HM crops while remediating the contaminated soils. A 17-week pot experiment was conducted to investigate the growth and HM (Cd, Cu, Pb, Cr, Zn, and Ni) acquisition of garlic chives (Allium tuberosum Rottl. ex Spreng.) intercropped with sunflower (Helianthus annuus L.) and inoculated with (I+M) or without (I-M) the arbuscular mycorrhizal (AM) fungus Funneliformis caledonium on a severely HM-contaminated soil that was collected from a WEEE-recycling site. Compared with the monoculture control, the I-M treatment significantly (P < 0.05) decreased Cd, Cu, Cr, Zn, and Ni concentrations in the shoots of chives through rhizosphere competition and HM (except Cr) transfer from the root to the shoot of chives, and increased the average shoot fresh weight (i.e., yield) of chives by 794% by alleviating HM toxicity. Compared with the I-M treatment, the I+M treatment significantly increased soil phosphatase activity as well as root mycorrhizal colonization of both sunflower and chives. The I+M treatment had no effect on the tissue P concentration of sunflower but elevated the average dry biomass (shoot plus root) and P acquisition level of sunflower by 179% and 121%, respectively. In addition, the I+M treatment significantly increased the P concentration in the root rather than in the shoot of chives and significantly increased the level of P acquisition by chives, increasing the average yield of chives by 229%. Simultaneously, the I+M treatment significantly increased the level of HM (except Cd) acquisition by sunflower, enhancing the rhizosphere competition by sunflower over chives, and further reducing the transfer of all six HMs from root to shoot in the chives, and inducing significant decreases in chive shoot HM concentrations compared with the monoculture control. Furthermore, the I+M treatment decreased the average total concentrations and increased the average DTPA-extractable concentrations of soil HMs. The results demonstrate the multifunctional role of AM fungi in the intercropping system for both vegetable production and phytoremediation on HM-contaminated soils.

Zhang Y ，Hu J ，Bai J ，Qin H ，Wang J ，Wang J ，Lin X ... -  《-》

Effect of arbuscular mycorrhizal fungal inoculation on heavy metal accumulation of maize grown in a naturally contaminated soil.

Wang FY ，Lin XG ，Yin R 《INTERNATIONAL JOURNAL OF PHYTOREMEDIATION》

Effect of arbuscular mycorrhizal fungi on trace metal uptake by sunflower plants grown on cadmium contaminated soil.

Trace metal (TM) pollution of soil is a worldwide problem that threatens the quality of human and environmental health. Phytoremediation using plants and their associated microbes has been increasingly used as a green technology for cleaning up TM-polluted soils. In this study, we investigated the effect of inoculating two arbuscular mycorrhizal fungal isolates, Rhizophagus irregularis and Funneliformis mosseae, on trace metal uptake by sunflower plants grown in soils contaminated with three different Cd concentrations in a greenhouse trial. Root colonization, plant dry mass, and plant tissue cadmium (Cd), zinc (Zn), and copper (Cu) concentrations in roots and shoots were determined after sunflower harvesting. We found that root mycorrhizal colonization rates were not significantly affected by Cd treatments. At low soil Cd concentration, R. irregularis-inoculated plants had significantly higher shoot Cd and Zn concentrations than plants inoculated with F. mosseae and non-inoculated plants. However, at high soil Cd concentrations, F. mosseae-inoculated plants had significantly lower shoot Cd and Zn concentrations and biological concentration factor (BCF) values than plants inoculated with R. irregularis and non-inoculated plants. Cadmium was mainly translocated in shoot tissues of R. irregularis-inoculated plants and sequestered in the rhizosphere of F. mosseae-inoculated plants. The results indicate that these AMF strains mediate different tolerance strategies to alleviate TM toxicity in their host plants and that inoculation with the R. irregularis strain can be used for Cd phytoextraction, whereas this F. mosseae strain can be useful for Cd and Zn phytostabilization of contaminated soil.

Hassan SE ，Hijri M ，St-Arnaud M 《-》

[Effects of Arbuscular Mycorrhizal Fungi on the Growth and Uptake of La and Pb by Maize Grown in La and Pb-Contaminated Soil].

Chang Q ，Guo W ，Pan L ，Wang QF ，Zhou XN ，Yang L ，Li E ... -  《-》