Effects of inoculation with Glomus intraradices on lead uptake by Zea mays L. and Agrostis capillaris L.

Abstract

An inhibitory effect of lead (Pb) on hyphal growth of Glomus intraradices was observed after the incubation of colonised root segments in the media containing Pb concentrations higher than 0.01 mM. The comparison of two G. intraradices isolates that originated either in Pb-contaminated or non-contaminated soil suggests higher Pb tolerance of the native isolate from Pb-contaminated soil in comparison to the reference isolate from non-contaminated soil. The role of both isolates in Pb accumulation by two plant species with different tolerance to heavy metals—common bent grass ( Agrostis capillaris) from a Pb-contaminated site and maize ( Zea mays)—was investigated in a sand-based hydroponic experiment with simulated Pb stress. Increased Pb concentrations influenced neither the growth of host plants nor the development of AM fungi (root colonisation, ERM length and NADH-diaphorase activity). In spite of low Pb toxicity, mycorrhizal inoculation substantially influenced Pb accumulation by the plants and the translocation into their shoots, but its effect differed considerably between plant species. When maize plants were treated with 0.01 mM Pb, mycorrhizal inoculation with both G. intraradices isolates resulted in decreased Pb concentrations in both shoots and roots in comparison with non-inoculated plants. At a higher Pb level (0.1 mM), the inoculation decreased Pb concentrations in maize roots, but not shoots, when compared to non-inoculated plants. For the common bent, shoot Pb concentrations were not influenced by the inoculation in either Pb treatment. At a lower Pb level, the G. intraradices isolate from contaminated soil increased Pb concentrations in the roots of Agrostis plants in comparison with control plants or plants inoculated with the isolate from non-contaminated soil. No significant differences in Pb concentrations in Agrostis roots were found between the inoculation treatments at the higher Pb level.