Triticum aestivum shows a greater biomass response to a supply of aluminium phosphate than Lupinus albus, despite releasing fewer carboxylates into the rhizosphere.
The relationship between carboxylate release and the ability of plants to access phosphorus from AlPO4 and to detoxify aluminium was studied by comparing species with a low and high rate of carboxylate release, Triticum aestivum (wheat) and Lupinus albus (white lupin), respectively. Species were supplied with P at 10, 20, 40 or 100 mg P kg-1 sand in the form of sparingly soluble AlPO4 or soluble KH2PO4; control plants did not receive any P. Triticum aestivum was significantly better than L. albus at accessing P from AlPO4, despite accumulating fewer carboxylates in its rhizosphere. Rhizosphere pH of L. albus did not vary with form or level of P supply, while the rhizosphere pH of T. aestivum increased with the level of P supplied. Based on the evidence in the present study, a model is proposed to explain the poor performance of L. albus, whereby the release of carboxylates and associated protons reduces the chelating ability of exuded carboxylates, thus reducing P acquisition and increasing Al toxicity.
Pearse
Stuart J
SJ
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. spearse@graduate.uwa.edu.au
Veneklaas
Erik J
EJ
Cawthray
Greg
G
Bolland
Mike D A
MD
Lambers
Hans
H
D017607:Aluminum Compounds / Q000378:metabolism*; D018533:Biomass; D002264:Carboxylic Acids / Q000378:metabolism*; D031297:Lupinus / Q000254:growth & development* / Q000378:metabolism; D008954:Models, Biological; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D014908:Triticum / Q000254:growth & development* / Q000378:metabolism
D017607:Aluminum Compounds; D002264:Carboxylic Acids; D010710:Phosphates; D010758:Phosphorus; C012714:aluminum phosphate