Evidence for specificity to Glomus group Ab in two Asian mycoheterotrophic Burmannia species

Nonphotosynthetic mycorrhizal plants, so-called mycoheterotrophic plants, have long attracted the curiosity of botanists and mycologists. Recent advances in molecular methods based on fungal-specific PCR amplification have dramatically enhanced the identification of their host mycorrhizal fungi. However, studies investigating the fungal hosts of arbuscular mycorrhizae-forming mycoheterotrophs are still limited in Asia, which is known as one of the diversity hot spots of mycoheterotrophs that parasitize arbuscular mycorrhizae (AM). Therefore, we aimed to reveal the mycorrhizal associations of two Asian, fully mycoheterotrophic Burmannia species by molecular identification. Sequences of the small subunit ribosomal DNA showed that both Burmannia species are associated with several distinct lineages of Glomus group Ab. Because Glomus group Ab fungi have been confirmed as fungal hosts of various mycoheterotrophic plants in Africa and South America, we suggest they are widely exploited by AM-forming mycoheterotrophs globally.