Comparative Genomics Analysis of Trichoderma reesei Strains

Trichoderma reesei is a key fungus for industrial production of lignocellulolytic enzymes. The genome sequences of the T. reesei hyper-cellulolytic strain RUT-C30 and its parental strain QM6a were compared at the nucleotide level. Approximately 97% of the 87 genomic-sequence scaffolds of T. reesei QM6a (33Mb) were found to have the corresponding nucleotide in the 182 genome-sequence scaffolds of RUT-C30 (32Mb). There are 455 loci within the QM6 sequence not detected in the RUT-C30 sequence. Regions at the termini of QM6a scaffolds as well as 14 small scaffolds do not have corresponding regions in RUT-C30 genomic scaffolds. Seventy-eight protein-encoding genes are included within these regions. Mutated nucleotide(s) in 2,371 positions, including short insertion/deletions (indels), were detected in the aligned regions. The predicted protein-coding regions of 97 gene models contain mutations, 34 of which were not previously described. Twenty-seven out of 34 newly discovered genes were found to have mutations in the peptide amino acid sequence. This is in addition to 63 genes described in a previous study based on low coverage sequencing of RUT-C30. These newly identified proteins are involved in signal transduction, transcription, RNA processing and modification, and post-translational modification according to their annotations. Similar distributions of eukaryotic orthologous group (KOG) categories between the mutated and all other proteins suggest random mutation. The roles of the mutated genes and potential regulatory regions in the observed phenotype of RUT-C30 remain to be explored in a targeted fashion.