JXB Advance Access originally published online on March 31, 2003
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Journal of Experimental Botany, Vol. 54, No. 386, pp. 1447-1459,
May 1, 2003
© 2003 Oxford University Press
Arbuscular mycorrhizal fungi enhance aluminium resistance of broomsedge (Andropogon virginicus L.)
Received 30 October 2002; Accepted 12 February 2003
Department of Biology, West Virginia University, Morgantown, WV 26506 USA
2 Present address: Delaware Biotechnology Institute, Newark, DE 19711, USA.
In the eastern United States, broomsedge (Andropogon virginicus L.) is found growing on abandoned coal-mined lands that have extremely acidic soils with high residual aluminium (Al) concentrations. Broomsedge may be inherently metal-resistant and nutrient-efficient or may rely on the arbuscular mycorrhizal (AM) fungal association to overcome limitations on such sites. Broomsedge plants were grown with and without an acidic ecotype AM fungal consortium and exposed to controlled levels of Al in two experiments. The AM fungal consortium conferred Al resistance to broomsedge. Arbuscular mycorrhizal fungi reduced Al uptake and translocation in host plants, potentially reflecting measured reductions in inorganic Al availability in the rhizosphere of mycorrhizal plants. Mycorrhizal plants exhibited lower shoot P concentrations, higher phosphorus use efficiency, and lower root acid phosphatase rates than non-mycorrhizal plants. Aluminium significantly reduced calcium (Ca) and magnesium (Mg) tissue concentrations in both mycorrhizal and non-mycorrhizal plants. However, plant response to any change in nutrient acquisition was substantially less pronounced in mycorrhizal plants. The exclusion of Al and greater stability of tissue biomass accretiontissue nutrient relationships in mycorrhizal broomsedge plants exposed to Al may be important mechanisms that allow broomsedge to grow on unfavourable acidic soils.
Key words: Acidic soils, calcium, magnesium, nutrient homeostasis, phosphorus.