Role of Inorganic Phosphate Solubilizing Bacilli Isolated from Moroccan Phosphate Rock Mine and Rhizosphere Soils in Wheat (Triticum aestivum L) Phosphorus Uptake.

This work aimed to assess the ability of plant growth-promoting Bacilli isolated from wheat rhizosphere and rock phosphate mine soils to convert inorganic phosphate (Pi) from Moroccan natural phosphate (NP) to soluble forms. The effect of these bacteria on wheat plants in order to increase their phosphorus (P) uptake in vitro was also investigated. Bacteria were isolated from wheat rhizosphere and natural rock phosphate soils and screened for their ability to solubilize Tri-Calcium Phosphate (TCP) and Natural Rock Phosphate (NP), to produce indole-3-acetic acid (IAA), siderophores and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Isolates were identified by 16S rRNA sequencing and tested for their capacity to increase wheat plants growth and their phosphorus uptake.Twenty-four strains belonging to Bacillus genus isolated from both biotopes were screened for their ability to solubilize Pi. The highest NP solubilization was showed by strains isolated from wheat rhizosphere. Solubilization of Pi was accompanied by organic acid production. Strains produce IAA, siderophore and ACC deaminase. Inoculation assays using efficient NP-solubilizing bacilli strains from both sources showed the ability of these isolates to increase wheat growth and the phosphorus uptake under in vitro conditions. Bacilli strains isolated from rhizosphere soil and natural rock phosphorus soil showed effective solubilization of Pi from rock phosphate. Phosphate solubilizing Bacilli were evaluated for their plant growth promotion under in vitro conditions. Results revealed the positive effect of all strains on biometric parameters and P content of wheat seedlings.