How (post-)genomic insights can provide new leads for improvements of mushroom cultivation

The economically important edible basidiomycete mushroom Agaricus bisporus thrives on decaying plant material in forests and grasslands of North America and Europe. It degrades forest litter and contributes to global carbon recycling, depolymerizing (hemi-)cellulose and lignin in plant biomass. Relatively little is known about how A. bisporus degrades compost in the controlled environment in commercial production facilities and utilizes this substrate to produce mushrooms. Using transcriptomics and proteomics linked to analysis of the compositional changes in the compost, we showed that changes in plant biomass degradation by A. bisporus occur throughout its life cycle. Lignin degradation appears to only occur during the spawning stage. In contrast, (hemi-)cellulolytic genes were highly expressed at the first flush, whereas low expression was observed at the second flush. The essential role for many highly expressed plant biomass degrading genes was supported by exo-proteome analysis, demonstrating the presence of these enzymes during specific stages. The out-of-phase enzyme production in the second flush may explain the reduction in the number of mushrooms during the second flush. Combined with other data generated in our lab we have now generated the first detailed model of the genes and enzymes involved in compost degradation and utilization by A. bisporus, which has provided many leads for a better understanding and improvement of the commercial mushroom cultivation