AraR plays a more dominant role than XlnR in plant biomass conversion in Penicillium subrubescens

Penicillium subrubescens is a promising candidate for industrial applications as its plant cell wall-degrading enzyme production levels and saccharification abilities are similar to that of the well-established industrial species Aspergillus niger. Interestingly, it has an expanded repertoire of hemicellulases, pectinases and inulinases in its genome compared to other Penicillia, that may enable a more targeted degradation of the corresponding polysaccharides. The transcriptional factor XlnR is essential for the expression of xylanolytic genes and is commonly found in genomes of filamentous ascomycete fungi. AraR (a homolog of XlnR) controls the arabinanolytic system as well as L-arabinose catabolism in Eurotiomycetes. In this study, we generated P. subrubescens ΔxlnR, ΔaraR and ΔxlnRΔaraR mutants and analyzed the transcriptional response of these strains to the monosaccharides D-xylose and L-arabinose, and the polysaccharide wheat arabinoxylan to identify the genes and pathways regulated by these TFs in P. subrubescens. Transcriptomic data revealed that AraR plays a more dominant role in plant biomass conversion in P. subrubescens than XlnR.