Fig. 2

The rDNA locus. a Organization of the rDNA locus. The top panel illustrates the nine tandem “head-to-tail” repeats revealed by the PacBio RSII platform. Each repeat contains an 18S-5.8S-26S rRNA gene cluster and a full-length non-transcribed intergenic spacer (IGS). The bottom panel shows the five repeats in the HiC draft genome. Each repeat has an 18S-5.8S-26S rRNA gene cluster and two truncated IGSs (IGS-5′Δ and IGS-3′Δ). The locations of restriction enzymes XbaI (X) and NheI (N) are indicted. b Southern hybridization. Genomic DNA (1 μg) was isolated from three different wild-isolate strains: QM6a, CBS999.97(1-1) and CBS999.97(1-2). After digestion with XbaI (X) or NheI (N), the genomic DNA was subjected to agarose gel electrophoresis, Southern blotting, and hybridization with a 28S rDNA probe (a) or a mus53 probe (as the DNA loading control). The mus53 gene encodes the DNA ligase IV protein, and there is only one copy of the mus53 gene in the Trichoderma reesei genome [78]