Detection of arbuscular mycorrhizal fungi (Glomales) in roots by nested PCR and SSCP (Single Stranded Conformation Polymorphism)

PCR amplification of a region of the large subunit ribosomal DNA sequence with Glomus specific primers was used to detect arbuscular mycorrhizal fungi in root tissue of four plant species. The primers were specific to Glomus mosseae, Glomus caledonium, Glomus geosporum, Glomus coronatum, Glomus fragilistratum and Glomus constrictum, and did not recognise sequences from Glomus claroideum. Sequence differences between isolates were detected by Single Stranded Conformation Polymorphisms (SSCPs) in polyacrylamide gels under non-denaturing conditions. Isolates of G. mosseae, G. caledonium and G. coronatum could be separated by their SSCP patterns, while three isolates of G. geosporum showed no variation. Specific SSCP patterns from isolates of G. mosseae and G. caledonium allowed detection of both fungi in the same root segment. Sequence differences leading to variations in SSCP patterns were confirmed by direct sequencing.