Fahad Zaenab A, Bolou-Bi Emile B, Köhler Stephan J, Finlay Roger D, Mahmood Shahid
Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, SE, 750 07, Sweden.
Department of Earth Sciences, Uppsala University, Uppsala, SE, 752 36, Sweden.
Environ Microbiol Rep. 2016 Dec;8(6):956-965. doi: 10.1111/1758-2229.12459. Epub 2016 Sep 21.
Symbiotic ectomycorrhizal fungi mobilize nutrients from both organic and inorganic substrates and supply them to their host plants. Their role in mobilizing base cations and phosphorus from mineral substrates through weathering has received increasing attention in recent years but the processes involved remain to be elucidated. We grew selected ectomycorrhizal and nonmycorrhizal fungi in axenic systems containing mineral and organic substrates and examined their capacity to fractionate and assimilate stable isotopes of magnesium. The mycorrhizal fungi were significantly depleted in heavy isotopes with the lowest Δ Mg values (the difference between δ Mg in fungal tissue and δ Mg in the substrate) compared with nonmycorrhizal fungi, when grown on mineral substrates containing granite particles. The ectomycorrhizal fungi accumulated significantly higher concentrations of Mg, K and P than the nonmycorrhizal fungi. There was a highly significant statistical relationship between δ Mg tissue signature and mycelial concentration of Mg, with a clear separation between most ectomycorrhizal fungi and the nonmycorrhizal fungi. These results are consistent with the idea that ectomycorrhizal fungi have evolved efficient mechanisms to mobilize, transport and store Mg within their mycelia.
共生外生菌根真菌从有机和无机底物中获取养分并将其供应给宿主植物。近年来，它们通过风化作用从矿物底物中调动碱金属阳离子和磷的作用受到了越来越多的关注，但其中涉及的过程仍有待阐明。我们在含有矿物和有机底物的无菌系统中培养了选定的外生菌根真菌和非菌根真菌，并研究了它们对镁稳定同位素的分馏和同化能力。与非菌根真菌相比，当在含有花岗岩颗粒的矿物底物上生长时，菌根真菌的重同位素显著贫化，ΔMg值（真菌组织中的δMg与底物中的δMg之差）最低。外生菌根真菌积累的镁、钾和磷浓度显著高于非菌根真菌。δMg组织特征与菌丝体中镁的浓度之间存在高度显著的统计关系，大多数外生菌根真菌和非菌根真菌之间有明显的区分。这些结果与外生菌根真菌已经进化出在其菌丝体内调动、运输和储存镁的有效机制这一观点一致。
