Gene expression associated with intersterility in Heterobasidion

Intersterility (IS) is thought to prevent mating compatibility between homokaryons that belong to different species. Although IS in Heterobasidion is regulated by the genes located at the IS loci, it is not yet known how the IS genes influence sexual compatibility and heterokaryon formation. To increase our understanding of the molecular events underlying IS, we studied mRNA abundance changes during IS compatible and incompatible interactions over time. The clustering of the transcripts into expression profiles, followed by the application of Gene Ontology (GO) enrichment pathway analysis of each of the clusters, allowed inference of biological processes participating in IS. These analyses identified events involved in mating and sexual development (i.e., linked with IS compatibility), which included processes associated with cell-cell adhesion and recognition, cell cycle control and signal transduction. We also identified events potentially involved in overriding mating between individuals belonging to different species (i.e., linked with IS incompatibility), which included reactive oxygen species (ROS) production, responses to stress (especially to oxidative stress), signal transduction and metabolic biosynthesis. Our findings thus enabled detection and characterization of gene expression changes associated with IS in Heterobasidion, as well as identification of important processes and pathways associated with this phenomenon. Overall, the results of this study increase current knowledge regarding the molecular mechanisms underpinning IS in Heterobasidion and allowed for the establishment of a vital baseline for further studies.