Assessment of arbuscular mycorrhizal fungi diversity in the rhizosphere ofViola calaminaria and effect of these fungi on heavy metal uptake by clover

The ability of arbuscular mycorrhizal (AM) fungi from a metal-tolerant plan t (Viola calaminaria, violet) to colonise and reduce metal uptake by a nont olerant plant (Trifolium subterraneum, subterranean clover) in comparison t o a metal-tolerant AM fungus isolated from a non-tolerant plant was studied . AM spores from the violet rhizosphere and from violet roots were characte rised by polymerase chain reaction (PCR) amplification of the SSU rDNA, and sequencing. Subterranean clover was grown in pots containing a soil supple mented with Cd and Zn salts and inoculated either with a mixture of spores extracted from the violet rhizosphere or with spores of a Cd-tolerant Glomu s mosseae P2 (BEG 69), or non-inoculated. The diversity of fungi, including AM fungi, colonising clover roots was assessed and analysed using terminal -restriction fragment length polymorphism. At least four different Glomus s pecies were found in the violet rhizosphere. After 8 weeks in a growth cham ber, colonisation of clover roots with spores from the violet rhizosphere i ncreased Cd and Zn concentrations in clover roots without significantly aff ecting the concentrations of metals in the shoot and plant growth. G. mosse ae P2 reduced plant growth and slightly increased the Cd concentration. Onl y one AM fungus (Glomus b) from the violet rhizosphere colonised clover roo ts, but other fungi were present. AM fungi from heavy metal-contaminated so ils and associated with metal-tolerant plants may be effective in accumulat ing heavy metals in roots in a non-toxic form.