Arbuscular mycorrhizal fungi (AMF) live in symbiosis with plant roots, facilitating mineral nutrient transfer from soil to hosts through large networks of extraradical hyphae. Limited data are available on the fungal structures (appressoria) connecting soil- to root-based mycelium, in relation to plant nutrition. Two in vivo systems were set up using three AMF, Funneliformis mosseae, Funneliformis coronatus and Rhizoglomus irregulare, grown in symbiosis with Cichorium intybus. The assessment of plant P content, number of appressoria, diameter of their subtending hyphae and length of colonized roots allowed calculation of the total cross-section area of appressorium-subtending hyphae, which differed among the three AMF and was correlated with plant P contents and with extraradical mycelium density. A conservative evaluation of P fluxes from soil- to plant-based hyphae occurring through appressoria gave values ranging from 1.7 to 4.2 × 10⁻⁸ mol cm⁻² s⁻¹ (moles per total cross-section area of the appressorium subtending hyphae per time elapsed), depending on AMF identity. This work suggests that, beyond intraradical colonization and extraradical mycelium extent, connections between extraradical and intraradical fungal mycelium through appressoria are important for mycorrhizal plant nutrition, as appressorium structural traits and density can be related to P transfer mediated by AMF.

中文翻译：

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菌根植物中的Appressoria和磷通量：基于土壤和植物的菌丝之间的联系。

丛枝菌根真菌（AMF）与植物根共生，通过大量的根外菌丝网络促进矿物质营养素从土壤向宿主的转移。关于将土壤与根系菌丝连接的真菌结构（appressoria），有关植物营养的数据有限。两个体内系统共设置了使用三个AMF，Funneliformis霉，Funneliformis冠斑和Rhizoglomus不规则型，在共生生长与菊苣。通过对植物P含量，附子数，对接菌丝的直径和定植根的长度进行评估，可以计算出对服ress菌丝的总横截面积，这在三个AMF之间有所不同，并且与植物P含量和根外菌丝密度高。对通过食欲发生的从土壤菌丝到植物菌丝的P通量的保守评估得出的值范围为1.7至4.2×10 ^-8  mol cm ^-2  s ^-1（每隔一段时间，菌丝每单位内膜的总横截面面积都与菌丝相对），这取决于AMF的身份。这项工作表明，除了根内定植和根外菌丝体范围之外，根外和根内真菌菌丝体之间通过附着力之间的联系对于菌根植物营养也很重要，因为附着力结构性状和密度可能与AMF介导的P转移有关。