Research progress of synergistic interactions between ectomycorrhizal fungi and mycorrhizal helper bacteria in phosphorus solubilization

Abstract:

Plants require a large amount of phosphorus for metabolic processes. However, the available phosphorus in the soil is typically less than 0.1% of total phosphorus, which is difficult to meet the growth and development of plants. The symbiosis system of ectomycorrhizal fungi and mycorrhizal helper bacteria can significantly improve the availability of soil phosphorus and promote the efficient uptake of phosphorus by plants. In this review, we discussed the solubilization and mineralization of chelated inorganic phosphorus, soluble organic phosphorus, and chelated organic phosphorus by ectomycorrhizal fungi and mycorrhizal helper bacteria. Ectomycorrhizal fungi mainly promote the solubilization of chelated inorganic phosphorus by regulating the organic acid and proton metabolism of mycorrhizal helper bacteria. They accelerate the mineralization of soluble organic phosphorus by enhancing the activities of related phosphatases in themselves and in mycorrhizal helper bacteria. Ectomycorrhizal fungi may first stimulate the mycorrhizal helper bacteria to secrete organic acids for solubilizing chelated organic phosphorus into soluble phosphorus before mineralization. Moreover, we explored the molecular mechanisms of metabolite signal exchange and secretion in the symbiosis system and outlined the prospects for studying the interactions between ectomycorrhizal fungi and mycorrhizal helper bacteria in promoting plant phosphorus uptake.