Identification of arbuscular mycorrhizal fungi in soils and roots of plants colonizing zinc wastes in southern Poland

Analysis of the community of arbuscular mycorrhizal (AM) fungi in roots of Fragaria vesca growing in a heavy metal contaminated site was carried out o n a Zn waste site near Chrzanow (southern Poland). The waste substratum was characterized by high contents of Pb, Zn, Cd, Cu and As, and by low levels of N, P and organic matter. Spores of Glomales were isolated by wet sievin g and DNA was isolated from individual spores, Nested polymerase chain reac tion (PCR) with taxon-specific primers was used to identify the species Glo mus mosseae, Glomus intraradices and Glomus claroideum. Spores of other fun gi were morphologically characterized and new taxon-discriminating molecula r probes were developed for two of them (Glomus sp. HM-CL4 and HM-CLS) base d on variations in the large ribosomal subunit (25S rDNA). High sequence si milarities were found between Glomus sp. HM-CL4 and Glomus gerdemanii, and between Glomus sp. HM-CL5 and Glomus occultum. The designed primers were us ed to characterize the population of AM fungi colonizing the roots of F. ve sca collected from the Zn waste site. The analysis, carried out on roots st ained with trypan blue, showed that the most effective colonizer was closel y related to G. gerdemannii. G. claroideum and the G. occultum-like fungus were slightly less common whilst frequencies of G. intraradices and G. moss eae in roots were much lower. The analysis of mycorrhiza stained with rhodi zoniate to localize heavy metal accumulation showed that the stain does not influence the PCR reaction. Seventy percent of the root samples containing positively stained fungal hyphae were found to be colonized by G. mosseae. The data obtained demonstrate the usefulness of nested PCR for studies car ried out in polluted areas. It will enable selection of AM fungi which are able to colonize plant roots under heavy metal stress conditions, as well a s the identification of fungi showing high in situ accumulation of potentia lly toxic elements.