LOCATION AND DIRECTION OF TRANSCRIPTION OF THE 5S RIBOSOMAL-RNA GENE IN ARMILLARIA

For possible use as a phylogenetic character, the location and direction of transcription of the 18S rRNA gene relative to the 18S RNA gene in Armillaria has been determined. Genomic DNAs of 33 isolates of Armillaria from 18 North American, European and Australasian species were digested with Bgl II and denatured with NaOH. Southern blots were probed with three end-labelled synthetic oligodeoxynucleotides complementary to the 5S rRNA, the 18S rRNA or the coding strand of the 18S rRNA cistron respectively. For all 33 Armillaria isolates, the oligonucleotides complementary to the 5S rRNA and the 18S rRNA both hybridized to the same DNA strand whereas the oligonucleotide complementary to the DNA strand coding for the 18S RNA gene hybridized to the other DNA strand. The direction of transcription of the 5S rRNA cistron in Armillaria is therefore, the same as that of the 18S rRNA cistron and is consistent across this genus for all the isolates investigated. © 1990, British Mycological Society. All rights reserved.