The <i>MAT</i> locus structure variety within the Helotiaceae.

Hymenoscyphus fraxineus and Pirottaea palmicola are heterothallic and the representative genomes used in this study possess genes associated only with the MAT1-1 idiomorph. The remaining species illustrated here are all homothallic, but exhibit different MAT locus structures which enable homothallism and thus suggest multiple, independent transitions towards self-fertility. Hymenoscyphus koreanus, Hymenoscyphus occultus, and Hymenoscyphus albidus possess the MAT1-1-1 and MAT1-2-1 genes at what is likely a single locus in the genome. However, in all three genomes, the APN2 and MAT1-2-1 genes are found on the end of one contig, while the MAT1-1-1, SLU, DNA pol and SLA genes are found on the end of a second contig. Amylocarpus encephaloides and Hymenoscyphus repandus both harbour the MAT1-1 and MAT1-2-associated genes at a single, intact locus in their genomes. In contrast, Hymenoscyphus fructigenus possesses two unlinked MAT loci, one encoding the MAT1-2-1 gene and the other encoding the MAT1-1-1 and MAT1-1-3 genes. The MAT1-1-associated genes are indicated in blue, while the MAT1-2-associated genes are indicated in green. APN2: AP endonuclease, Hyp: Hypothetical protein, SLA: cytoskeleton assembly control protein, SLU: pre-mRNA splice factor SLU7-like protein, DNA pol: DNA polymerase, AA: amino acid transporter protein. These gene diagrams are not drawn to scale, but instead aim to illustrate the similarities and differences between the locus structures of these species.