title: Legume nodules from nutrient-poor soils exhibit high plasticity of cellular phosphorus recycling and conservation during variable phosphorus supply.
abstract: Nitrogen fixing legumes rely on phosphorus for nodule formation, nodule function and the energy costs of fixation. Phosphorus is however very limited in soils, especially in ancient sandstone-derived soils such as those in the Cape Floristic Region of South Africa. Plants growing in such areas have evolved the ability to tolerate phosphorus stress by eliciting an array of physiological and biochemical responses. In this study we investigated the effects of phosphorus limitation on N2 fixation and phosphorus recycling in the nodules of Virgilia divaricata (Adamson), a legume native to the Cape Floristic Region. In particular, we focused on nutrient acquisition efficiencies, phosphorus fractions and the exudation and accumulation of phosphatases. Our finding indicate that during low phosphorus supply, V. divaricata internally recycles phosphorus and has a lower uptake rate of phosphorus, as well as lower levels adenylates but greater levels of phosphohydrolase exudation suggesting it engages in recycling internal nodule phosphorus pools and making use of alternate bypass routes in order to conserve phosphorus.
authors.affiliation: Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Waafeka
authors.initials: W
authors.lastname: Vardien
authors.affiliation: Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa.
authors.forename: Emma T
authors.initials: ET
authors.lastname: Steenkamp
authors.affiliation: Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa. Electronic address: alexvalentine@mac.com.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Valentine
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D018533:Biomass; D007887:Fabaceae / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D055442:Metabolome; D008903:Minerals / Q000378:metabolism; D009586:Nitrogen Fixation; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D053204:Root Nodules, Plant / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D014532:Uridine Diphosphate Glucose / Q000378:metabolism
chemical_list: D008903:Minerals; D012987:Soil; D010758:Phosphorus; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000135:Acid Phosphatase; D010744:Phosphoric Monoester Hydrolases; D014532:Uridine Diphosphate Glucose
keywords: Adenylates; Nitrogen fixation; Nodules; Phosphohydrolases; Virgilia divaricata