The Balance and Interplay between Asexual and Sexual Reproduction in Fungi

Abstract

This chapter discusses the balance and interplay between asexual and sexual reproduction in fungi. Whether produced mitotically or meiotically, the spores of most fungi germinate to give rise to a vegetatively growing mat, each hyphal cell dividing mitotically to produce a network of hyphae or mycelium. At some stage in the course of the vegetative growth the mycelium becomes ready for asexual sporulation, a state that is termed as “competence.” In homothallic species, that is those in which each mycelium can complete the sexual cycle on its own, sexual reproduction is triggered without fertilization between two different strains. In heterothallic species, that is those that require the interaction of two different strains to complete the life cycle, sexual reproduction is initially dependent on the availability of compatible nuclei. External factors which are known to affect the switch between the different reproductive processes include general physical and nutritional factors such as temperature, light, humidity and water availability, aeration, and pH as well as the quality and quantity of nutrients. Given that competition within and between species affects the choice of developmental strategy, it is not surprising that mycelial extracts are also effective.