Phosphate solubilization and mobilization: bacteria–mycorrhiza interactions
Tobi Moriaque Akplo, Félix Kouelo Alladassi, Mahougnon Charlotte Carmelle Zoundji, Aliou Faye, Marcela Hernández, Pierrot Lionel Yemadje, Adélaïde Hinhami Fagnibo, Pascal Houngnandan
Abstract
Phosphorus (P) is an essential macronutrient for plant growth and development. However, most of the P in the Earth's crust is insoluble, making it inaccessible to plants. This review examines the ability of phosphate-solubilizing microorganisms (PSMs) to convert these insoluble forms of P into plant-accessible forms, highlighting their potential use as biofertilizers. PSMs mainly consist of phosphate-solubilizing bacteria and fungi, which play crucial roles in the soil P cycle. The mechanisms of P solubilization encompass not only the key components of the soil P cycle but also relate to PSM species and the presence of phosphatase/phosphohydrolysis-related genes. Organic P are mineralized by enzymatic activity, while inorganic P, such as iron-phosphate, aluminium-phosphate, and calcium-phosphate are solubilized through organic acid production, proton extrusion, siderophore secretion, and exopolysaccharide production. Additionally, arbuscular mycorrhizal fungi are among the PSMs that effectively enhance P uptake in plants. Using PSM inoculants as biofertilizers has shown promise in improving soil P availability. However, further research is needed to determine the optimal application conditions, including timing, inoculum forms, and dosages, to maximize their effectiveness.