Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Soil Biology and Biochemistry 107728 [10 ] Phosphorus cycling Microbial loop Bacillus subtilis Pinus pinaster Hebeloma cylindrosporum Rhabditis sp 2020 fdi:010078924 ENG Soil Biology and Biochemistry 0038-0717 ISI:000523634500011 10.1016/j.soilbio.2020.107728 https://www.documentation.ird.fr/hor/fdi:010078924 https://www.documentation.ird.fr/intranet/publi/2020/04/010078924.pdf 143 Horizon (IRD) Phytate is considered a poorly available plant P source but proved to be useful for particular soil bacteria strains. In soil-free conditions, it has been shown that bacteria locked up the mineralized phosphorus from phytate whereas bacterial grazers like nematodes were able to deliver P to plants. Here, we aimed to determine if the interactions between phytate-mineralizing bacteria, bacterial grazer nematodes, and mycorrhizal fungi could increase plant P acquisition from phytate in high P-adsorbing soils. Pinus pinaster was grown in a Cambisol supplemented with phytate. Plants, whether associated or not associated with the ectomycorrhizal fungus Hebeloma cylindrosporum, were either inoculated or not inoculated with the phytase-releasing bacteria Bacillus subtilis and the bacterial-feeding nematode Rhabditis sp. After 100 days, the dual inoculation of bacteria and nematodes significantly increased net plant P accumulation. We observed that, on average, mycorrhizal plants accumulated more P in their shoots than non-mycorrhizal plants. However, the highest plant P acquisition efficiency was found when the three soil organisms were present in the P. pinaster rhizosphere. We conclude that, in a highly inorganic P-fixing soil, plant P acquisition from phytate strongly depends on the grazing of phytate-mineralizing bacteria. Our results confirm the importance of the soil microbial loop to improve plant P nutrition from phytate, which should be considered a route to improve the utilization of this source of poorly available P by plants. 068 ; 074 ; 076 UR210