“…However, increasing evidence supports a critical importance of AM for plant nitrogen (N) nutrition. AMF transfer N to host plants (Johansen et al ., 1994; Hawkins et al ., 2000; Mäder et al ., 2000; Leigh et al ., 2009; Herman et al ., 2012; Ngwene et al ., 2013; Thirkell et al ., 2016; Seck‐Mbengue et al ., 2017; Bukovská et al ., 2018), the amounts transferred are considerable (Frey et al ., 1994; Mäder et al ., 2000; Tanaka & Yano, 2005; Karagiannidis et al ., 2007; Leigh et al ., 2009), and N transport may play a critical role in the formation, maintenance and nutrient efficiency of AM symbioses (Bonneau et al ., 2013; Corrêa et al ., 2014; Hodge & Storer, 2014; Bücking & Kafle, 2015; Mensah et al ., 2015; Jach‐Smith & Jackson, 2018). Furthermore, several genes encoding enzymes from plant and fungal N assimilation pathways are co‐regulated in AM roots, suggesting partner interdependence in the mycorrhizal N uptake pathway (Koegel et al ., 2015).…”