Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 176 (2), 345-55

Convergence of a Specialized Root Trait in Plants From Nutrient-Impoverished Soils: Phosphorus-Acquisition Strategy in a Nonmycorrhizal Cactus

Affiliations

Convergence of a Specialized Root Trait in Plants From Nutrient-Impoverished Soils: Phosphorus-Acquisition Strategy in a Nonmycorrhizal Cactus

A Abrahão et al. Oecologia.

Abstract

In old, phosphorus (P)-impoverished habitats, root specializations such as cluster roots efficiently mobilize and acquire P by releasing large amounts of carboxylates in the rhizosphere. These specialized roots are rarely mycorrhizal. We investigated whether Discocactus placentiformis (Cactaceae), a common species in nutrient-poor campos rupestres over white sands, operates in the same way as other root specializations. Discocactus placentiformis showed no mycorrhizal colonization, but exhibited a sand-binding root specialization with rhizosheath formation. We first provide circumstantial evidence for carboxylate exudation in field material, based on its very high shoot manganese (Mn) concentrations, and then firm evidence, based on exudate analysis. We identified predominantly oxalic acid, but also malic, citric, lactic, succinic, fumaric, and malonic acids. When grown in nutrient solution with P concentrations ranging from 0 to 100 μM, we observed an increase in total carboxylate exudation with decreasing P supply, showing that P deficiency stimulated carboxylate release. Additionally, we tested P solubilization by citric, malic and oxalic acids, and found that they solubilized P from the strongly P-sorbing soil in its native habitat, when the acids were added in combination and in relatively low concentrations. We conclude that the sand-binding root specialization in this nonmycorrhizal cactus functions similar to that of cluster roots, which efficiently enhance P acquisition in other habitats with very low P availability.

Similar articles

See all similar articles

Cited by 2 articles

References

    1. New Phytol. 2005 Mar;165(3):887-98 - PubMed
    1. Trends Plant Sci. 2002 Apr;7(4):162-7 - PubMed
    1. Plant Physiol. 1999 Jul;120(3):705-16 - PubMed
    1. Nature. 2000 Feb 24;403(6772):853-8 - PubMed
    1. Plant Physiol. 1998 Jul;117(3):745-51 - PubMed

Publication types

LinkOut - more resources

Feedback