Molecular diversity of arbuscular mycorrhizal fungi colonising Hyacinthoides non-scripta (bluebell) in a seminatural woodland

Arbuscular mycorrhizal (AM) fungi form symbiotic associations with plant ro ots. Around 150 species have been described and it is becoming clear that m any of these species have different functional properties. The species dive rsity of AM fungi actively growing in roots is therefore an important compo nent of ecosystem diversity. However, it is difficult to identify AM fungi below the genus level from morphology in planta, as they possess few inform ative characters. We present here a molecular method for identifying infrag eneric sequence types that estimate the taxonomic diversity of AM fungi pre sent in actively growing roots. Bluebell roots were sampled from beneath tw o different canopy types, oak and sycamore, and DNA sequences were amplifie d from roots by the polymerase chain reaction with fungal-specific primers for part of the small subunit ribosomal RNA gene. Restriction fragment leng th polymorphism among 141 clones was assessed and 62 clones were sequenced. When aligned, discrete sequence groups emerged that cluster into the three families of AM fungi: Acaulosporaceae, Gigasporaceae and Glomaceae. The se quence variation is consistent with rRNA secondary structure. The same sequ ence types were found at both sampling times. Frequencies of Scutellospora increased in December, and Acaulospora increased in abundance in July. Site s with a sycamore canopy show a reduced abundance of Acaulospora, and those with oak showed a reduced abundance of Glomus. These distribution patterns are consistent with previous morphological studies carried out in this woo dland. The molecular method provides an alternative method of estimating th e distribution and abundance of AM fungi, and has the potential to provide greater resolution at the infrageneric level.