Given that the ANT1-like aromatic and neutral amino acid transporters (ANT)28 are known to translocate arginine (Arg), which is a key component in nitrogen translocation in arbuscular mycorrhizal fungi29, it seems likely that Arg in G. elata is related to mycoheterotrophic symbiosis (Fig. 3a, Supplementary Table 41). It is known that arginases can hydrolyze Arg into urea in mycelia, which is further hydrolyzed to ammonium and carbonic acid by ureases30. Although P. equestris, D. officinale, A. comosus and A. thaliana have only one copy of glutamate N-acetyltransferase (ArgJ), an enzyme of the arginine biosynthesis pathway31, G. elata has three copies (Supplementary Fig. 11 and Supplementary Table 41). The number of genes encoding ureases is drastically expanded in G. elata (9 genes) compared with P. equestris (2 genes), D. officinale (2 genes), A. comosus (1 gene), and A. thaliana (1 gene) (Supplementary Table 41). This suggests that urea metabolism might be an important source of nitrogen for G. elata (Fig. 3a).