Arbuscular mycorrhiza confers Pb tolerance in Calopogonium mucunoides

Abstract

Heavy metals (HMs) are environmental pollutants of great concern to humans because of their high potential toxicity. Lead is a HM that is present in the soil in very small amounts, but anthropogenic activities have increased its content in some locations, which can make these areas unproductive or inappropriate for crop production. However, there are some plants that can grow in contaminated soils and, thus, can be useful for the removal or stabilisation of such contaminants. In addition, plants that are not able to tolerate high concentrations of HMs in the soil can become tolerant or increase their performance when associated with arbuscular mycorrhizal (AM) fungi. Accordingly, this study was carried out to verify whether the inoculation of Glomus etunicatum, an AM fungus species, in Calopogonium mucunoides would influence plant tolerance to increasing concentrations of Pb in the soil. The experimental design was completely randomised, in a 2 9 4 factorial design, and the treatments consisted of inoculation (or not) with the AM fungus, G. etunicatum, and the addition of four Pb concentrations (0, 250, 500 or 1,000 mg kg -1 ) to the soil. The results showed that the association of C. mucunoides with G. etunicatum promoted biomass production, and nutrient uptake (P, S and Fe) was also positively influenced by mycorrhization. The malondialdehyde content was higher in non-mycorrhizal leaves, suggesting a reduction in the damage to membranes by lipid peroxidation in plants associated with mycorrhizae. However, the Pb concentration in the shoots did not differ between the mycorrhizal and non-mycorrhizal plants. The results of our study suggest that the AM symbiosis can be considered very effective in contributing to the tolerance of C. mucunoides to Pb.

Lead tolerance and phytoremediation potential of Brazilian leguminous tree species at the seedling stage

“…In M. caesalpiniaefolia leaves, the Pb concentrations were below 30 mg kg À1 , at levels considered non-toxic to plants for some authors (Kramer, 2010;Kabata-Pendias and Pendias, 2001). In previous work with the herbaceous leguminous plant Calopogonium mucunoides Souza et al (2012) observed that this plant accumulated up to 90 mg kg À1 Pb in their shoots when growing in a soil with similar available Pb concentrations (520 mg kg À1 Pb-DTPA) as the ones in this study. C. mucunoides even accumulating relatively high Pb concentrations was able to yield the same biomass than plants growing in control soil without Pb addition.…”

Use of non-hyperaccumulator plant species for the phytoextraction of heavy metals using chelating agents

“…Not only crop plant species should be considered, but non-hyperaccumulator woody plant species, such willow, poplar (Zacchini et al, 2009) and Brazilian leguminous trees (Mimosa caesalpiniaefolia, Erythrina speciosa and Schizolobium parahyba) (de Souza et al, 2012a), should also be investigated. These woody species has been studied with special attention to their phytoremediation capability in the recovery of areas contaminated with lead (Pb) (de Souza et al, 2012a).…”

“…These woody species has been studied with special attention to their phytoremediation capability in the recovery of areas contaminated with lead (Pb) (de Souza et al, 2012a). Such plant species possess an enormous plant biomass, and the accumulation of heavy metals taken up from the soil in such a large biomass would be significant and warrant the immobilisation of metal in the aboveground parts of the tree.…”

Essential oil content and chemical composition of Cymbopogon citratus inoculated with arbuscular mycorrhizal fungi under different levels of lead

“…Soil contamination caused by HMs has increased mainly as a result of mining and manufacturing activities, the use of sewage sludge and the application of fertilizers or pesticides in rural areas. In addition to reducing plant productivity, the accumulation of HMs in soils can indirectly affect both human and the animal health (Souza et al, 2012;Sá et al, 2015).…”