A paper in Current Genetics describes the discovery of Repeat Induced Polymorphism (RIP) in two Euriotiales fungi. RIP has been extensively studied in Neurospora crassa and has been identified in other Sordariomycete fungi Magnaporthe, Fusiarium. This is not the first Aspergillus species to have RIP described as it was demonstrated in the biotech workhorse Aspergillus oryzae. However, I think this study is the first to describe RIP in a putatively asexual fungus. The evidence for RIP is only found in transposon sequences in the Aspergillus and Penicillium. A really interesting aspect of this discovery is RIP is thought to only occur during sexual stage, but a sexual state has never been observed for these fungi.
The authors discuss this evidence as to whether or not there is a cryptic sexual state that hasn’t been observed or sex has only been lost for a short time in these fungi (the RIP evidence suggests the transposons were RIPed relatively recently). The mating genes are still present in the genome of A. niger but whether its actively able to complete a sexual cycle (or enough of it to allow for RIPing) still needs to be investigated.
Braumann, I., Berg, M., Kempken, F. (2008). Repeat induced point mutation in two asexual fungi, Aspergillus niger and Penicillium chrysogenum. Current Genetics DOI: 10.1007/s00294-008-0185-y