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Journal of Botany
Volume 2010 (2010), Article ID 268540, 11 pages
Research Article

Determining the Impact of the AM-Mycorrhizosphere on “Dwarf” Sunflower Zn Uptake and Soil-Zn Bioavailability

1Department of Biology, Ottawa-Carleton Institute of Biology, University of Ottawa, 30 Marie Curie Priv., Ottawa, ON, Canada K1N 6N5
2Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, University of Queensland, St. Lucia Campus, Brisbane, QLD, 4072, Australia

Received 16 June 2010; Revised 13 August 2010; Accepted 15 October 2010

Academic Editor: Andrea Polle

Copyright © 2010 Patrick Audet and Christiane Charest. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An in vivo compartmental pot greenhouse experiment involving “dwarf” sunflower and an arbuscular mycorrhizal (AM) fungus was designed to assess the contribution of non-AM roots (rhizosphere), AM roots and extraradical hyphae (mycorrhizosphere), or strictly extraradical hyphae (hyphosphere) on plant growth, plant metal uptake, and soil parameters using the micronutrient zinc (Zn) as a typical metal contaminant. We observed that, at high soil-Zn concentrations, the mycorrhizosphere treatments had lower Zn concentrations (especially in shoots and flowers) and a lower incidence of leaf chlorosis than the rhizosphere treatments. These phytoprotective effects are believed to be related to AM-induced biosorption processes that reduce soil metal bioavailability to delay the onset of plant metal toxicity. We also observed that the presence of extraradical hyphae causes a slight alkalinisation of the proximal soil environment whereas roots tended to acidify it, this having significant consequences toward metal bioavailability. Altogether, the AM symbiosis is considered to be a key component of ecosystem function involved in buffering plant growth conditions due to the processes of metal biosorption and hyphal alkalinisation which could contribute in enhancing the soil's resiliency.