Arbuscular mycorrhizal fungi: Hyphal fusion and multigenomic structure (reply)

Pawlowska and Taylor reply - To challenge the hypothesis of multigenomic structure of arbuscular mycorrhizal (AM) fungi1,2, we presented three lines of evidence consistent with the homokaryotic organization of within-individual genetic variation, including distribution of polymorphic genetic markers among and within field isolates of an AM fungus, and distribution of ribosomal DNA variants among individually microdissected nuclei3. Bever and Wang suggest4 that our data can be explained equally well by heterokaryosis, proposing a model that relies on the assumption that fusions of hyphae of genetically non-identical individuals contribute to the creation and maintenance of a multigenomic status of AM fungal cells. However, we do not believe that this assumption is supported by existing biological evidence.