Abstract：Somatic incompatibility (SI) commonly occurs among intraspecific heterokaryons of basidiomycetes with different genotype, preventing plasmogamy and exchange of genetic information among them, controlled by SI loci. It is unclear whether the SI loci expression in the monokaryon strains. Dikaryon strains DK13×3 was bred by mating monokaryons MK13 and MK3, which were from the basidiospores of Pleurotus ostreatus TD300. Using RNA-Seq, the transcriptomes of the 3 strains were obtained. 76 unigenes in the transcriptomes involved in SI, and categorized of heterokaryon incompatibility gene (het) het-e, het-6, tol (tolerant), NACHT (nucleoside-triphosphatase domain)/WD40 (ligand-binding domain; approximately 40 amino acids terminating with tryptophan and aspartic acid residues) gene homologues, respectively. 61.8% of the unigenes were all expressed in the 3 strains, 23.7% were expressed only in MK13 and DK13×3, 11.8% were expressed only in MK3 and DK13×3, 1.3% were expressed only in DK13×3 or only in MK13 and MK3. Four of these unigenes were selected and their expression levels were verified by quantitative reverse transcription-polymerase chain reaction (RT-PCR). The quantitative RT-PCR results were consistent with RNA-Seq. These results showed that almost all unigenes involved in SI were expressed in the dikaryon strains and more than 70% were expressed in the 2 monokaryons strains, suggesting that these genes may be involved in self/non-recognition in ho-ho crosses and he-ho crosses in basidiomycetes. This study suggests that somatic incompatibility genes in basidiomycetes may affect the success rate of hybridization and the fertility of hybrid progeny.
