Intraspecific ITS polymorphism in Scutellospora castanea (Glomales, Zygomycota) is structured within multinucleate spores

Polymorphism of the internal transcribed spacers (ITS) of the ribosomal DNA in Scutellospora castanea (Glomales, Zygomycota) and its organization amon g spores were evaluated. Polymerase chain reaction (PCR) amplification with ITS1/ITS4 primers yielded several fragments of different lengths, even fro m single spores. Fragments produced from multisporal DNA were cloned and gr ouped into 6 ITS types by PCR-RFLP and sequence analysis. Five type-specifi c primers were designed. Spores were then analyzed by PCR and amplification profiles revealed that they were qualitatively different one from another due to the presence or absence of some ITS types. Intrasporal segregation o f ITS variant length types was also shown, by PCR experiments, utilizing di luted fractions of nuclear suspensions from single spores. The results demo nstrate the mainly multikaryotic condition of the spores of S. castanea. (C ) 1999 Academic Press.