Identification of the dry rot fungus, Serpula lacrymans, and the wild merulius, S-himantioides, by amplified ribosomal DNA restriction analysis (ARDRA)

Isolates of the dry rot fungus, Serpula lacrymans, and of the morphological ly similar wild merulius, S. himantioides, were investigated by amplified r ibosomal DNA restriction analysis (ARDRA) of the internal transcribed space r (ITS) region to prove this method as diagnosis tool for the economically important indoor rot fungi. The technique uses the polymerase chain reactio n (PCR) to amplify the relatively variable sequences of the ITS region arra nged between the highly conserved portions of the 18S and 28S RNA genes of the nuclear ribosomal DNA (rDNA) repeat unit. Subsequent digestion of the a mplicon with restriction endonucleases may exhibit differences at species a nd subspecies level. Using the universal ITS 1/ITS 4 primer combination, th e ITS region of all isolates of S. lacrymans and S. himantioides was amplif ied. The size of the amplified products was about 630 bp in both species, a s estimated from agarose gel electrophoresis. Digestion of the amplicon wit h the endonuclease pairs AluI/HhaI and AvaII/MboII, respectively, revealed identical rDNA-ITS fragments for the isolates of both species, indicating t heir genetic relationship. On the other hand, digestion with BglI/HinfI and HaeIII/TaqI, respectively, separated the fungi by means of different fragm ent patterns. Thus, ARDRA-ITS proved to be suited for the identification of both fungi.