Pheromone expression reveals putative mechanism of unisexuality in a saprobic ascomycete fungus

Homothallism (self-fertility) describes a wide variety of sexual strategies that enable a fungus to reproduce in the absence of a mating partner. Unisexual reproduction, a form of homothallism, is a process whereby a fungus can progress through sexual reproduction in the absence of mating genes previously considered essential for self-fertility. In this study, we consider the molecular mechanisms that allow for this unique sexual behaviour in the saprotrophic ascomycete; Huntiella moniliformis. These molecular mechanisms are also compared to the underlying mechanisms that control sex in Huntiella omanensis, a closely related, but self-sterile, species. The main finding was that H. omanensis displayed mating-type dependent expression of the a- and α-pheromones. This was in contrast to H. moniliformis where both pheromones were co-expressed during vegetative growth and sexual development. Furthermore, H. moniliformis also expressed the receptors of both pheromones. Consequently, this fungus is likely able to recognize and respond to the endogenously produced pheromones, allowing for self-fertility in the absence of other key mating genes. Overall, these results are concomitant with those reported for other unisexual species, but represent the first detailed study considering the unisexual behaviour of a filamentous fungus.Data are available on the NCBI SRA database under the following accession number: SRP108437. All cultures are available from the Culture Collection of Michael Wingfield (CMW) at the Forestry & Agricultural Biotechnology Institute (FABI) at the University of Pretoria (UP) and at the Westerdijk Fungal Biodiversity Institute, The Netherlands.The University of Pretoria and the Department of Science and Technology (DST)/National Research Foundation (NRF) Centre of Excellence in Tree Health Biotechnology (CTHB). This work is based on the research supported in part by a number of grants from the National Research Foundation of South Africa (including Grant specific unique reference number, UID 83924). This research was also funded in part by Prof Brenda Wingfield’s SARCHi grant.http://www.plosone.orgForestry and Agricultural Biotechnology Institute (FABI)Genetic