Genetic linkage map for Amylostereum areolatum reveals an association between vegetative growth and sexual and self-recognition

Amylostereum areolatum is a filamentous fungus that grows through tip extension, branching and hyphal fusion. In the homokaryotic phase, the hyphae of different individuals are capable of fusing followed by heterokaryon formation, only if they have dissimilar allelic specificities at their mating-type (mat) loci. In turn, hyphal fusion between heterokaryons persists only when they share the same alleles at all of their heterokaryon incompatibility (het) loci. In this study we present the first genetic linkage map for A. areolatum, onto which the mat and het loci, as well as quantitative trait loci (QTLs) for mycelial growth rate are mapped. The recognition loci (mat-A and het-A) are positioned near QTLs associated with mycelial growth, suggesting that the genetic determinants influencing recognition and growth rate in A. areolatum are closely associated. This was confirmed when isolates associated with specific mat and het loci displayed significantly different mycelial growth rates. Although the link between growth and sexual recognition has previously been observed in other fungi, this is the first time that an association between growth and self-recognition has been shown.