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In the present study, rice seedlings were exposed to a range of Cd concentrations (0.1μM, 1μM, 10μM, 100μM and 1mM) for 15 days and a combination of different molecular approaches were used to evidence Cd effects and to assess the plants’ ability to counteract metal toxicity. At a macroscopical level, only the highest Cd concentration (1mM) caused a complete plant growth inhibition, whereas the lowest concentrations seemed to stimulate growth. At genome level, the amplified fragment length polymorphism (AFLP) technique was applied to detect DNA sequence changes in root cells, showing that all the Cd concentrations induced significant DNA polymorphisms in a dose-dependent manner. Data also evidenced the absence of preferential mutation sites. Plant responses were analysed by measuring the levels of gluthatione (GSH) and phytochelatins (PCs), the thiol-peptides involved in heavy metal tolerance mechanisms. Results showed a progressive increase of GSH up to 10μM of Cd treatment, whereas a significant induction only of PC3 was detected in roots of plants exposed to 100μM of Cd. As suggested by the proteome analysis of root tissues, this last concentration strongly induced the expression of regulatory proteins and some metabolic enzymes. Furthermore, the treatment with 10μM of Cd induced changes in metabolic enzymes, but it mainly activated defence mechanisms by the induction of transporters and proteins involved in the degradation of oxidatively modified proteins. [Copyright &y& Elsevier]

Assesses soil genotoxicity based on biomolecular tools and plant bioindicators. Challenges in research to prevent environmental alteration and human disease; Application of biomonitoring for soil genotoxicity; Use of amplified fragment length polymorphism and flow cytometry to detect DNA damage induced by heavy metals in the soil.

Abstract: The effect of arbuscular mycorrhiza on heavy metal uptake and translocation was investigated in Cannabis sativa. Hemp was grown in the presence and absence of 100μgg−1 Cd and Ni and 300μgg−1 Cr(VI), and inoculated or not with the arbuscular mycorrhizal fungus Glomus mosseae. In our experimental condition, hemp growth was reduced in inoculated plants and the reduction was related to the degree of mycorrhization. The percentage of mycorrhizal colonisation was 42% and 9% in plants grown in non-contaminated and contaminated soil, suggesting a significant negative effect of high metal concentrations on plant infection by G. mosseae. Soil pH, metal bioavailability and plant metal uptake were not influenced by mycorrhization. The organ metal concentrations were not statistically different between inoculated and non-inoculated plants, apart from Ni which concentration was significantly higher in stem and leaf of inoculated plants grown in contaminated soil. The distribution of absorbed metals inside plant was related to the soil heavy metal concentrations: in plant grown in non-contaminated soil the greater part of absorbed Cr and Ni was found in shoots and no significant difference was determined between inoculated and non-inoculated plants. On the contrary, plants grown in artificially contaminated soil accumulated most metal in root organ. In this soil, mycorrhization significantly enhanced the translocation of all the three metals from root to shoot. The possibility to increase metal accumulation in shoot is very interesting for phytoextraction purpose, since most high producing biomass plants, such as non-mycorrhized hemp, retain most heavy metals in roots, limiting their application. [Copyright &y& Elsevier]