© 2007 Heron Publishing—Victoria, Canada
Variations in organic acid exudation and aluminum resistance among arbuscular mycorrhizal species colonizing Liriodendron tulipifera
Katrina R. Klugh (1, 2) and Jonathan R. Cumming (1)
1. Department of Biology, West Virginia University, 53 Campus Dr., P.O. Box 6057, Morgantown, WV 26506, USA / 2. Corresponding author (kklugh@mix.wvu.edu) / Received May 23, 2006; accepted October 12, 2006; published online May 1, 2007
Summary
Aluminum (Al) in acidic soils is toxic to plants, affecting growth, water uptake and nutrient assimilation. Aluminum resistance
in some plant species and genotypes has been ascribed to organic acid exudation from roots and arbuscular mycorrhizal (AM)
fungal symbiosis. We investigated variation among several AM species in altering Al resistance of Liriodendron tulipifera L. and evaluated AM influence on organic acid production as a potential Al resistance mechanism. Growth, nutritional responses
and rhizosphere organic acid profiles were assessed for seedlings in association with Acaulospora morrowiae Spain & Schenck, Glomus claroideum Schenck & Smith, G. clarum Nicol. & Schenck or Paraglomus brasilianum (Spain & Miranda) Morton & Redecker and non-mycorrhizal seedlings exposed to 0, 50 or 200 µM Al. Plants colonized by G. clarum had the greatest biomass, least Al and most phosphorus (P) in leaf tissues and exuded malate and citrate into the rhizosphere
at rates that complexed 99% of delivered Al in all treatments. Other AM fungi did not confer significant Al resistance on
L. tulipifera and did not maintain citrate and malate exudation in response to Al exposure. This study illustrates functional diversity
among AM fungal species in conferred Al resistance to plants and highlights the potential importance of fungal diversity in
ecosystem responses to environmental stresses.
Keywords:
Acaulospora morrowiae, AM fungi, Glomus claroideum, Glomus clarum, Paraglomus brasilianum, phosphorus.
