Partial mycoheterotrophy in green plants forming Paris-type arbuscular mycorrhiza requires a thorough investigation

Recently, many green plants forming Paris-type arbuscular mycorrhiza (AM) have been suggested to receive fungal carbon (Giesemann et al. 2020b, 2021). Whereas the enrichment of natural abundance of heavy stable isotopes (particularly 13C) has been considered as strong evidence for this ‘partial mycoheterotrophy,’ we show our own data on isotopic abundances and mycorrhizal colonization in Japanese plants and argue that the 13C-enrichment may not always be the result of acquiring carbon from AM fungi.