Image Credit: Susan Whitfield

The vast majority of basidiomycetes are difficult to cultivate in the laboratory.  Coprinopsis cinerea is a notable exception, in that it can complete its life cycle on artificial media in just two weeks.  Furthermore, development is synchronous and regulated by light.  Our goal is to compile a complete inventory of genes that are under developmental control, to understand “how to build a mushroom”, and also provide a valuable point of comparison to fungi with alternative life styles.  The AmutBmut #326 strain provides a huge technical advantage towards this goal.  The mutations in the A and B mating factors in this strain allow the production of homokaryotic fruit bodies that derive from a single haploid nucleus.  Thus, alignment of RNA-seq data to the reference genome is very straightforward.  In addition, haploid AmutBmut nuclei can be further mutagenized and desired mutants (including recessive mutants) with defects in fruit body development (including defects in the meiotic process) can be identified.   These strains can be mated to compatible strains with conventional mating types, and if the new mutation is recessive, the cross will result in the production of normal fruit bodies.  Then the new mutation can be recovered in the conventional genetic background for backcrossing and complementation analysis.  
The C. cinerea genome is well-characterized, and both forward and reverse genetic approaches are now standard, allowing enormous scope for experimental manipulation in this system.   The  availability of this second sequenced strain will enable comparative studies of transposon stability, including a family of DNA transposons that encode genes that oxidize 5-methylcytosine and contribute to changing chromatin dynamics and epigenetic marks during mushroom development and meiosis.  We anticipate that our findings will be highly relevant to optimizing gene expression and stability in genetically engineered basidiomycetes, information which is essential to the fundamental goals of manipulating these systems to contribute to DOE critical missions.