Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Nanjing, China.
Institute of Crop Germplasm Resources, Shandong Academy of Agricultural Sciences (SAAS), Jinan, China.
Microbiol Spectr. 2023 Aug 17;11(4):e0016223. doi: 10.1128/spectrum.00162-23. Epub 2023 Jul 5.
Ectomycorrhizal fungi play an irreplaceable role in phosphorus cycling. However, ectomycorrhizal fungi have a limited ability to dissolve chelated inorganic phosphorus, which is the main component of soil phosphorus. Endofungal bacteria in ectomycorrhizal fruiting bodies are always closely related to the ecological function of ectomycorrhizal fungi. In this study, we explore endofungal bacteria in the fruiting body of and their function during the absorption of chelated inorganic phosphorus by host pine through the ectomycorrhizal system. The results showed that the endofungal bacterial microbiota in the fruiting body of might be related to the dissolution of chelated inorganic phosphorus in soil. The soluble phosphorus content in the combined system of and endofungal bacteria sp. strain B5 was five times higher than the sum of -only treatment and sp. strain B5-only treatment in the dissolution experiment of chelated inorganic phosphorus. The results showed that not only promoted the proliferation of sp. strain B5 in the combined system but also improved the expression of genes related to organic acid metabolism, as assesed by transcriptomic analysis. Lactic acid content was five times higher in the combined system than the sum of -only treatment and sp. strain B5-only treatment. Two essential genes related to lactate metabolism of sp. strain B5, and , were significantly upregulated. Finally, in a pot experiment, we verified that and sp. strain B5 could synergistically promote the absorption of chelated inorganic phosphorus by in a ternary symbiotic system. Ectomycorrhizal fungi (ECMF) have a limited ability to dissolve chelated inorganic phosphorus, which is the main component of soil phosphorus. In the natural environment, the extraradical hyphae of ECMF alone may not satisfy the phosphorus demand of the plant ectomycorrhizal system. In this study, our results innovatively show that the ectomycorrhizal system might be a ternary symbiont in which ectomycorrhizal fungi might recruit endofungal bacteria that could synergistically promote the mineralization of chelated inorganic phosphorus, which ultimately promotes plant phosphorus absorption by the ectomycorrhizal system.
外生菌根真菌在磷循环中起着不可替代的作用。然而，外生菌根真菌溶解螯合态无机磷的能力有限，而螯合态无机磷是土壤磷的主要组成部分。外生菌根真菌子实体中的内生真菌总是与其生态功能密切相关。在这项研究中，我们通过外生菌根系统研究了与宿主松吸收螯合态无机磷相关的子实体中的内生真菌，并探索了其功能。结果表明， 子实体中的内生细菌微生物群可能与土壤中螯合态无机磷的溶解有关。在螯合态无机磷溶解实验中， 与内生真菌 sp. strain B5 的组合系统中的可溶性磷含量是 -only 处理和 sp. strain B5-only 处理总和的五倍。结果表明， 不仅促进了组合系统中 sp. strain B5 的增殖，而且通过转录组分析评估，还提高了与有机酸代谢相关的基因的表达。在组合系统中，乳酸含量是 -only 处理和 sp. strain B5-only 处理总和的五倍。 sp. strain B5 与乳酸代谢相关的两个必需基因 和 显著上调。最后，在盆栽实验中，我们验证了 和 sp. strain B5 可以在三元共生系统中协同促进 对螯合态无机磷的吸收。外生菌根真菌（ECMF）溶解螯合态无机磷的能力有限，而螯合态无机磷是土壤磷的主要组成部分。在自然环境中，外生菌根真菌的根外菌丝可能无法满足植物外生菌根系统对磷的需求。在这项研究中，我们的结果创新性地表明，外生菌根系统可能是一个三元共生体，外生菌根真菌可能会招募内生真菌，这些内生真菌可以协同促进螯合态无机磷的矿化，最终促进外生菌根系统对植物磷的吸收。
