Mycorrhizal colonization affects the elemental distribution in roots of Ni-hyperaccumulator Berkheya coddii Roessler El _ zbieta Or1owska a, * , 2 , Wojciech Przyby1owicz a,1 , Dariusz Orlowski a, 3 , Nametso P. Mongwaketsi a , Katarzyna Turnau b , Jolanta Mesjasz-Przyby1owicz a a Materials Research Department, iThemba LABS, PO Box 722, Somerset West 7129, South Africa b Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland article info Article history: Received 16 September 2012 Received in revised form 19 December 2012 Accepted 21 December 2012 Keywords: Arbuscular mycorrhiza Elemental distribution Ni-hyperaccumulation Root X-ray microanalysis abstract The effect of arbuscular mycorrhizal fungi (AMF) on the distribution and concentration of elements in roots of Ni-hyperaccumulating plant Berkheya coddii was studied. Micro-PIXE (particle-induced X-ray emission) analysis revealed significant differences between AMF-inoculated and non-inoculated plants as well as between main and lateral roots. The accumulation of P, K, Mn and Zn in the cortical layer of lateral roots of inoculated plants confirmed the important role of AMF in uptake and accumulation of these elements. Higher concentration of P, K, Fe, Ni, Cu and Zn in the vascular stele in roots of AMF- inoculated plants than in the non-inoculated ones indicates more efficient translocation of these ele- ments to the aboveground parts of the plant. These findings indicate the necessity of including the in- fluence of AMF in studies on the uptake of elements by plants and in industrial use of B. coddii for Ni extraction from polluted soils. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, plants hyperaccumulating metals have received a lot of attention (Rascio and Navari-Izzo, 2011), not only due to their unique ecological and physiological properties, but also because of their commercial potential in mining metals (phyto- mining) from low-grade surface ores or mineralized soils that are too metal-poor for conventional mining (Brooks et al., 1998; Chaney et al., 2007 , 2000, 1997; Nicks and Chambers, 1998; Sheoran et al., 2009). Since in hyperaccumulators most accumulated metals are translocated to the aboveground parts of the plant, most research has focused on the aboveground organs. However, roots are the prime site of metals’ uptake and therefore merit extensive study in the context of hyperaccumulation. Most previous studies on the roots of hyperaccumulators focused on the root physical characteristics, metal transporters in the roots or on the root exudates and their influence on metals’ availability and uptake (reviewed by Alford et al., 2010). Although the role of rhizosphere microorganisms in metal up- take by hyperaccumulating plants has recently been gaining recognition, studies of microorganisms in the roots and rhizo- sphere, as reviewed by Alford et al. (2010), have been conducted for only less than 10% of known hyperaccumulators. Most studies concerned the rhizospheric bacteria and their effect on metal hyperaccumulation (Abou-Shanab et al., 2003a, 2003b; Belimov and Dietz, 2000; Belimov et al., 2001; Li et al., 2007; Pal et al., 2007). Arbuscular mycorrhizal fungi (AMF), which are the most common symbiotic soil microorganisms, have gained less attention mainly due to the conviction that hyperaccumulating plants do not form mycorrhizal symbiosis. Since 2003, when the presence of AMF in hyperaccumulators has been for the first time reported in four Ni hyperaccumulating plant species from South Africa (Turnau and Mesjasz-Przybylowicz, 2003), an expansion of research on these remarkable interactions took place (Al Agely et al., 2005; Liu et al., 2005; Or1owska et al., 2011; Trotta et al., 2006; Vogel-Mikus et al., 2006; Wu et al., 2009). The present study focuses on the Ni-hyperaccumulating plant Berkheya coddii which, due to high biomass and high Ni accumu- lation ability, has high potential in economical Ni phytomining (Brooks et al., 1998; Brooks and Robinson, 1998; Harris et al., 2009; Keeling et al., 2003; Robinson et al., 1999, 1997). B. coddii forms * Corresponding author. E-mail addresses: ez.orlowska@gmail.com, elo@mb.au.dk (E. Or1owska). 1 On leave from AGH University of Science and Technology, Faculty of Physics & Applied Computer Science, al. A. Mickiewicza 30, 30-059 Krakow, Poland. 2 Present address: Department of Molecular Biology and Genetics, Aarhus Uni- versity, Gustav Wieds Vej 10, 8000 Aarhus C, Denmark. 3 Present address: Department of Biomedicine, Aarhus University, Wilhelm Meyers Alle 3, Building 1233/1234, 8000 Aarhus C, Denmark. Contents lists available at SciVerse ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.envpol.2012.12.028 Environmental Pollution 175 (2013) 100e109