Arbuscular mycorrhizal (AM) fungal extraradical hyphae exude their metabolites into the soil. Root exudate metabolites are affected by plant species and P status. However, the effect of P status on AM hyphal exudate metabolites has been unknown. This study aimed to examine hyphal exudate metabolite composition of two AM fungal species and their response to P deficiency through metabolite profiling. Rhizophagus clarus and R. irregularis were grown in a two-compartment in vitro culture system of Linum usitatissimum roots on solid modified Strullu-Romand medium in combination with two P levels (3 µM (P3) and 30 µM (P30)). Hyphal exudates were collected from the hyphal compartment at 118 days after inoculation (DAI). The metabolite composition of the hyphal exudates was determined by capillary electrophoresis/time-of-flight mass spectrometry, resulting in the identification of a total of 141 metabolites at 118 DAI. In the hyphal exudates of R. clarus, the concentrations of 18 metabolites, including sugars, amino acids, and organic acids, were significantly higher (p < 0.05) under P3 than under P30 conditions. In contrast, the concentrations of 10 metabolites, including sugar and amino acids, in the hyphal exudates of R. irregularis were significantly lower (p < 0.05) under P3 than under P30 conditions. These findings suggest that the extraradical hyphae of AM fungi exude diverse metabolites of which concentrations are affected by P conditions and differ between AM fungal species.

丛枝菌根（AM）真菌根外菌丝将其代谢产物渗入土壤。根系分泌物代谢物受植物种类和磷状态的影响。但是，P状态对AM菌丝渗出物代谢产物的影响尚不清楚。这项研究的目的是检查两种AM真菌菌丝的渗出物代谢产物组成以及它们通过代谢物谱分析对磷缺乏的反应。在两室的Linum usitatissimum体外培养系统中生长了根瘤菌和不规则根瘤菌根源与两种P水平（3 µM（P3）和30 µM（P30））结合在一起的固体改良Strullu-Romand培养基。接种后118天（DAI），从菌丝室收集菌丝渗出液。通过毛细管电泳/飞行时间质谱测定菌丝渗出物的代谢物组成，从而在118 DAI下鉴定出总共141种代谢物。在克拉斯菌的菌丝渗出物中， P3条件下的18种代谢物（包括糖，氨基酸和有机酸）的浓度显着高于P30条件（p <0.05）。相反，不规则红斑菌的菌丝渗出物中10种代谢物（包括糖和氨基酸）的浓度明显较低（ 与P30条件相比，P3条件下的p <0.05）。这些发现表明，AM真菌的自由基外菌丝散布着多种代谢物，其浓度受P条件的影响，并且在AM真菌种类之间也不同。