Phosphorus acquisition from phytate depends on efficient bacterial grazing, irrespective of the mycorrhizal status of Pinus pinaster

• Published in: Plant and soil Vol. 358; no. 1/2; pp. 155 - 168
• Main Authors: Irshad, Usman, Brauman, Alain, Villenave, Cécile, Plassard, Claude
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01-09-2012; Springer Netherlands; Springer Nature B.V; Springer Verlag
• Subjects: Acid soils; Acrobeloides; Bacillus subtilis; Bacteria; Basidiomycetes; Biomedical and Life Sciences; Ecology; Forest soils; Fungi; Grazing; Hebeloma cylindrosporum; Inoculation; Life Sciences; Mineralization; Nematoda; Nematodes; Organic phosphorus; Organic soils; Phosphorus; Pine trees; Pinus pinaster; Plant biology; Plant nutrition; Plant Physiology; Plant roots; Plant Sciences; Plants; RESEARCH ARTICLE; Rhabditis; Rhizosphere; Seedlings; Soil nematodes; Soil Science & Conservation; Trophic relationships; Phytase; Ectomycorrhiza; Cephalobidae; Root architecture; Rhabditidae; cephalobidae
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-012-1161-3

Background and aims Phosphorus from phytate, although constituting the main proportion of organic soil P, is unavailable to plants. Despite the well-known effects of rhizosphere trophic relationships on N mineralization, no work has been done yet on P mineralization. We hypothesized that the interactions between phytate-mineralizing bacteria, mycorrhizal fungi and bacterial grazer nematodes are able to improve plant P use from phytate. Methods We tested this hypothesis by growing Pinus pinaster seedlings in agar containing phytate as P source. The plants, whether or not ectomycorrhizal with the basidiomycete Hebeloma cylindrosporum, were grown alone or with a phytase-producing bacteria Bacillus subtilis and two bacterial-feeder nematodes, Rhabditis sp. and Acrobeloides sp. The bacteria and the nematodes were isolated from ectomycorrhizal roots and soil from P. pinaster plantations. Results Only the grazing of bacteria by nematodes enhanced plant P accumulation. Although plants increased the density of phytase-producing bacteria, these bacteria alone did not improve plant P nutrition. The seedlings, whether ectomycorrhizal or not, displayed a low capacity to use P from phytate. Conclusions In this experiment, the bacteria locked up the phosphorus, which was delivered to plant only by bacterial grazers like nematodes. Our results open an alternative route for better utilization of poorly available organic P by plants.