Transposition of a non-autonomous element into the Gβ gene of Schizophyllum commune causes the streak mutation

Streak mutants of Schizophyllum commune are characterized by ropy, hyperbranching hyphae, suppressed aerial hyphae formation, and the production of pigments. Additionally, these mutants dikaryotize unilaterally, with the mutant fertilizing its compatible mating partner, but not accepting its nucleus. Here we show that a 512 bp non-autonomous transposable element had integrated in the G_β protein of a streak mutant of S. commune. This element has the same 50 bp inverted repeat as an autonomous element, dubbed Bike transposon. Its transposase has homologues in various Agaricomycetes. Introducing the G_β gene in the streak mutant restored the wild-type phenotype showing that the integration of the 512 bp element in the G_β gene is responsible for the streak phenotype.