 DNA damage can be caused by a variety of stresses such as nutrient limitation.The sexual part of the life cycle commences when two hyphal structures mate.In the case of "homothallic" species, mating is enabled between hyphae of the same fungal clone, whereas in "heterothallic" species, the two hyphae must originate from fungal clones that differ genetically, i.e., those that are of a different mating type.