Influence of arbuscular mycorrhizae on heavy metal (Zn and Pb) uptake and growth of Lygeum spartum and Anthyllis cytisoides

Abstract

The influence of arbuscular mycorrhizae (AM) on plant growth and Zn and Pb uptake by Lygeum spartum and Anthyllis cytisoides was studied in soils with different levels of these heavy metals. A. cytisoides is highly dependent on AM for optimal growth, while L. spartum is a facultative mycotroph.Mycorrhizal and nonmycorrhizal plants were grown in soil supplemented with 0, 10, 100 and 1000 mg of Zn kg -l soil or 0, 100 and 1000 mg of Pb kg -1 soil. Two different mycorrhizal fungi were separately studied: Glomus macrocarpum isolated from a non contaminated site and a strain of Glomus mosseae isolated from a soil contaminated with these metals. The infectivity of the fungi was not affected by the presence of Zn or Pb in the soil. In unamended soil, both fungi were equally effective in promoting plant growth, but when Zn or Pb were added to soils, G. mosseae was more efficient than G. macrocarpum in stimulating plant growth of A. cytisoides. A. cytisoides was unable to grow unless mycorrhizal. Metal addition to the soil induced a reduction in the biomass of L. spartum and of mycorrhizal A. cytisoides, and a decrease in shoot P concentration of mycorrhizal plants. The concentration of metals in the plants varied according to the amount added to the soil and to the inoculation treatment: at low doses, mycorrhizal plants showed equal or higher concentration of Zn or Pb than nonmycorrhizal ones; at higher doses, however, metal concentrations in the plants inoculated with G. mosseae were lower than those found in the corresponding controls, while the plants inoculated with G. macrocarpum showed similar (L. spartum) or even higher (A. cytisoides) levels than the controls.

Co-inoculations of arbuscular mycorrhizal fungi and rhizobia under salinity in alfalfa

“…In line with our results, other researchers also reported that inoculation of plants with AMF increased uptake of N, P, K, Zn, Fe, Cu, Mg and Ca (Tinker and Gildon 1983;Díaz et al 1996). The results are also supported by the results reported by Aziz and Khan (2001), which showed that coinoculation of alfalfa with Glomus mosseae and Sinorhizobium meliloti increased N and P contents in the plant tissues.…”

The role of arbuscular mycorrhiza in zinc uptake by red clover growing in a calcareous soil spiked with various quantities of zinc

“…High levels of colonization by AM fungi were observed both in mine spoils heavily polluted with metals by Diaz et al (1996) and in agricultural soils contaminated with metals of different origins by Weissenhorn et al (1995a,b). This leads to the conclusion that metal tolerance has developed naturally in the soil microorganisms.…”

Arsenic phytoextraction and hyperaccumulation by fern species

“…The presence of mycorrhizae also seems to be related to the formation of thiol like glutathione (Schutzendubel & Andrea, 2002), a phenolic defense system. It is hypothesized that the production of thiols by P. vittata, induced by the increased arsenic concentration, alleviates the toxicity of arsenic and the plant can readily retain arsenic with the aid of mycorrhizas (Diaz et al, 1996). Therefore, it is possible that P. vittata may derive some benefit from the symbiosis by forming low molecular weight thiols.…”