• Neurospora crassa has lower sugar metabolic gene redundancy than Aspergillus niger • The mating type of N. crassa affects growth of sugar metabolic deletion strains • We present a strongly improved sugar metabolic model for N. crassa The filamentous fungus Neurospora crassa has been a model organism for understanding many fundamental aspects of eukaryotic biology. Here, we constructed a genome-scale model of its sugar metabolism based on the sugar metabolic model of Aspergillus niger using an orthology-based approach. To further support the model, the role of the identified genes in specific pathways was validated by evaluating their expression in transcriptome data of N. crassa from previously published studies during growth on different carbon sources, and by growth phenotypes of deletion mutants for selected genes. This data was compared to another Sordariomycete model species ( Trichoderma reesei ) and the ascomycete A. niger . The genome and orthology based sugar metabolic models revealed that N. crassa has high similarity to T. reesei at the genomic level, but a lower gene redundancy for individual pathway steps than A. niger . This was confirmed by significant growth reduction of strains in which a single gene for a pathway step was deleted, while previous studies in A. niger often required deletion of multiple genes to obtain significant growth reduction. Interestingly, there was higher similarity in the transcriptome profiles of orthologous genes from T. reesei and A. niger , while in N. crassa , different profiles were observed for genes of several pathways. This study provides a well-supported framework for metabolic studies in N. crassa and exemplifies the species-specific modification that occur in the organization of sugar metabolism in filamentous fungi.
Li et al. (Wed,) studied this question.