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RESEARCH PRODUCT

Bacillus consortium positively impacts arbuscular mycorrhizal fungi community, plant phosphate nutrition and potato yield in Solanum tuberosum cv. Jazzy

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Many agricultural soils are naturally poor in plant available phosphorus (P), although total P stocks can exceed plant requirements by more than 100-fold. The reason for such apparent contradiction is that P is complexed under organic and inorganic forms, but only free inorganic orthophosphate (Pi) ions are available to plants and soil organisms. The high immobility of Pi in soil, the low soil solution circulation associated with a rapid root absorption lead to the development of a depletion zone around the roots. As a consequence, P is frequently a limiting factor for plant growth and development.Arbuscular mycorrhizal (AM) fungi are estimated to colonize the vast majority of crop plants and can provide up to 90% of the P required by plants. The hyphae produced by AM fungi and emanating from the roots forms an extremely dense hyphal network. Although those hyphae are efficient to translocate phosphate to their host, they can only absorb Pi from soil solution but are less able to degrade P complexes, contrary to P-degrading bacteria that are effective in the degradation of inorganic (i.e. Phosphate-solubilising bacteria) and organic (i.e. Phosphate-moblizsing bacteria) P. In this context, the synergetic interaction between P-degrading bacteria and AMF should allow AM fungi to take-up and translocate P to their host plants to promote their growth. Using Solanum tuberosum cv. Jazzy, we have investigated the impact of bacterial inoculation on AMF community, plant phosphate nutrition and potato yield. We have developed and characterized in-vitro an inoculum composed of two Bacillus species for their PGPR capacity. In non-sterile soil, we have shown that the inoculation with those 2 strains improves indigenous mycorrhizal colonization, plant P nutrition and potato yield. Taken together our results suggest that the bacterial inoculum synergically interacts with AMF community to improve plant nutrition and yield.