Ribosomal RNA gene sequence diversity in arbuscular mycorrhizal fungi (Glomeromycota)
*Present address and correspondence: Alia Rodriguez, Institut für Pflanzenbau und Günland (340), Universität Hohenheim, D-70593 Stuttgart, Germany (fax +49 711 459 2297; e-mail email@example.com).
- 1The existence of multiple rRNA sequences within AMF single spores and the high levels of variability found in these symbionts for highly conserved genes with low copy numbers have provoked intense controversy over the genetic structure of the Glomeromycota. Lately, two hypotheses have been proposed to explain the source of such a variation, mainly either at internuclear (multigenomic) or intranuclear (polyploidy) levels.
- 2Evidence reported by numerous authors suggests that the magnitude of sequence variation, and the presence in single spores of sequences from apparently unrelated taxa within the Glomeromycota, makes the use of one, or very few sequences, from only one or two isolates of AMF insufficient for taxonomic purposes in some species groups.
- 3A large-scale, collaborative study on genetic variation in AMF across different genes could help to address fundamental questions on the biology and genetic structure of these important symbionts.