DNA polymorphism in morels : 1 ; PCR/RFLP analysis of the ribosomal DNA spacers and microsatellite-primed PCR

As a part of investigations on heterokaryon formation in morels, a characterisation of DNA polymorphism within this fungal group was attempted. In order to assess which discrimination level is necessary to trace nucleus populations in heterokaryons, but also in the context of the debatable species definition in morels, different taxa and strains types (monosporal and heterokaryons) were analysed with two polymerase chain reaction (PCR) techniques of distinct sensitivity: (i) PCR of the internal transcribed spacer (ITS) and the intergenic spacer (IGS) of the ribosomal nuclear DNA coupled with restriction fragment length polymorphism (RFLP) analysis, (ii) microsatellite-primed PCR. The ITS and IGS PCR/RFLP appeared at first to be adequate to assess morel systematics. The microsatellite-primed PCR with the primer (GTG)5 revealed, however, that morels exhibit less intraspecific DNA polymorphism than other ascomycetes. Based upon these results, two strategies for investigating somatic strain interactions within morels using DNA analyses are proposed.