Characterization of a highly repeated DNA sequence (SC1) from the arbuscular mycorrhizal fungus Scutellospora castanea and its detection in planta.

A highly repeated DNA sequence from the genome of an arbuscular mycorrhizal fungus has been isolated and characterized. This 1,202-bp sequence (SC1) represents about 0.24% of the Scutellospora castanea genome, estimated to be 1 pg by flow cytometry. The sequence was shown to be a Scutellospora-specific probe in Southern blots and dot blot hybridizations. After complete sequencing of SC1, PCR primers were generated and used to amplify a 907-bp fragment from spores of S. castanea or from colonized Allium porrum roots. No amplification products were obtained with DNA from either spores or mycorrhizal root of other species of arbuscular mycorrhizal fungi. These primers were sufficiently specific for unequivocal detection of S. castanea in planta.