外生菌根真菌及其助手细菌联合解磷的研究进展

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

摘要:

植物的各项新陈代谢活动需要大量磷素，然而土壤中有效磷含量往往不到全磷的0.1%，难以满足植物的生长发育。外生菌根真菌与菌根助手细菌二者联合体系能够显著提高土壤磷的植物有效性，促进外生菌根体系对磷的高效吸收。本文分类讨论了外生菌根真菌与菌根助手细菌二者联合对难溶性无机磷、可溶性有机磷和难溶性有机磷这3种主要土壤磷源的溶解矿化能力及其机制。其中，对于难溶性无机磷，外生菌根真菌主要通过调控菌根助手细菌的有机酸和质子代谢促进其溶解；对于可溶性有机磷，外生菌根真菌主要是提高自身及菌根助手细菌相关磷酸酶的活性，以加速其矿化；而对于难溶性有机磷，外生菌根真菌首先通过刺激菌根助手细菌分泌有机酸，将其溶解为可溶态有机磷，然后再对其进行有效矿化。此外，本文还对联合体系中分泌相关代谢物与启动信号交换的分子机制进行了讨论，展望了联合体系解磷在未来的研究前景。

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.