Diverse interactions mediate asymmetric incompatibility by the het-6 supergene complex in Neurospora crassa

► Gene interactions identified that control het-6 heterokaryon incompatibility. ► Both allelic (un-24) and nonallelic (un-24 with het-6) interactions are characterized. ► Bases revealed for asymmetric incompatibility of the het-6 locus. ► vib-1 partially suppresses het-6 locus allelic and nonallelic incompatibility. ► vib-1 differentially controls het-6 allele transcription and nonallelic incompatibility.