title: Aluminium-phosphate interactions in the rhizosphere of two bean species: Phaseolus lunatus L. and Phaseolus vulgaris L.
abstract: BACKGROUND
  Plants differ in their response to high aluminium (Al) concentrations, which typically cause toxicity in plants grown on acidic soils. The response depends on plant species and environmental conditions such as substrate and cultivation system. The present study aimed to assess Al-phosphate (P) dynamics in the rhizosphere of two bean species, Phaseolus vulgaris L. var. Red Kidney and Phaseolus lunatus L., in rhizobox experiments.
  
  
  RESULTS
  Root activity of the bean species induced up to a sevenfold increase in exchangeable Al and up to a 30-fold decrease in extractable P. High soluble Al concentrations triggered the release of plant-specific carboxylates, which differed between soil type and plant species. The results suggest that P. vulgaris L. mitigates Al stress by an internal defence mechanism and P. lunatus L. by an external one, both mechanisms involving organic acids.
  
  
  CONCLUSIONS
  Rhizosphere mechanisms involved in Al detoxification were found to be different for P. vulgaris L. and P. lunatus L., suggesting that these processes are plant species-specific. Phaseolus vulgaris L. accumulates Al in the shoots (internal tolerance mechanism), while P. lunatus L. prevents Al uptake by releasing organic acids (exclusion mechanism) into the growth media.
authors.affiliation: Faculty of Science and Technology, Free University of Bolzano, Piazza Università 5, I-39100, Bolzano, Italy.
authors.forename: Tanja
authors.initials: T
authors.lastname: Mimmo
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Ghizzi
authors.forename: Stefano
authors.initials: S
authors.lastname: Cesco
authors.forename: Nicola
authors.initials: N
authors.lastname: Tomasi
authors.forename: Roberto
authors.initials: R
authors.lastname: Pinton
authors.forename: Markus
authors.initials: M
authors.lastname: Puschenreiter
mesh_terms: D000222:Adaptation, Physiological; D000535:Aluminum / Q000378:metabolism*; D017607:Aluminum Compounds / Q000378:metabolism*; D002264:Carboxylic Acids / Q000378:metabolism; D027805:Phaseolus / Q000145:classification / Q000382:microbiology*; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism; D058441:Rhizosphere; D012987:Soil; D013045:Species Specificity; D013312:Stress, Physiological
chemical_list: D017607:Aluminum Compounds; D002264:Carboxylic Acids; D010710:Phosphates; D012987:Soil; D010758:Phosphorus; D000535:Aluminum; C012714:aluminum phosphate
keywords: Phaseolus; aluminium; organic acids; phosphate; rhizosphere