In followup to the Aspergillus RIP paper discussion, Jo Anne posted in the comments that her paper published in FGB about RIP in another asexual species of fungi also found that evidence for the meiosis-specific process of Repeat Induced Point-mutations (RIP).
So what is going on? Is meiosis occurring cryptically in nature without any evidence for this in the lab Certainly we have evidence for recombination among species (Coccidiodies, Aspergillus fumigatus, Batrachochytrium) that don’t appear to have a defined sexual cycle (no teleomorphic stage). Maybe there is some small amount of hybridization and meiosis among these species despite best efforts to induce it in the lab?
It seems likely that RIP is dependent on aspects of the mating process, and another article from Arnaise et al (that Jo Anne also pointed in the same issue of FGB), shows a reduction in RIP efficiency dependent on mutations in mating genes.
CROUCH, J., GLASHEEN, B., GIUNTA, M., CLARKE, B., HILLMAN, B. (2008). The evolution of transposon repeat-induced point mutation in the genome of Colletotrichum cereale: Reconciling sex, recombination and homoplasy in an asexual pathogen. Fungal Genetics and Biology, 45(3), 190-206. DOI: 10.1016/j.fgb.2007.08.004
ARNAISE, S., ZICKLER, D., BOURDAIS, A., DEQUARDCHABLAT, M., DEBUCHY, R. (2008). Mutations in mating-type genes greatly decrease repeat-induced point mutation process in the fungus Podospora anserina. Fungal Genetics and Biology, 45(3), 207-220. DOI: 10.1016/j.fgb.2007.09.010