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Transcriptome during shift of Trichoderma reesei from mycelial growth to asexual sporulation

ABSTRACT: The asexual spore or conidium plays a critical role in the life cycle of many filamentous fungi, being the primary means for dispersion in the environment. To investigate the transcriptional changes taking place during the sporulation phase in T. reesei, which culminates with the production of the conidiospores, microarray experiments were performed. Among the 1,994 distinct genes displaying >90 % confidence , a total of 900 were classified as differentially expressed, relative to time zero of sporulation, at at least one of the time points analyzed. The main functional categories (FunCat) overrepresented among upregulated genes were those involving solute transport, metabolism, transcriptional regulation, secondary metabolite synthesis, lipases, proteases and particularly cellulases and hemicellulases. Categories overrepresented among downregulated genes were especially those associated with ribosomal and mitochondrial functions. The upregulation of cellulase and hemicellulase genes was depending on the function of the positive transcriptional regulator XYR1, but the latter exerted no influence on sporulation itself. At least 20 % of the significantly regulated genes occured non-randomly distributed within the T. reesei genome suggesting an epigenetic component in the regulation of conidiation. The significant upregulation of cellulases and hemicellulases during conidiation, and thus cellulase and hemicelulase content in the spores of T. reesei lend to hypothesize that the ability to hydrolyse plant biomass is a major trait of this fungus to break dormancy and reinitiate vegetative growth after a period of facing unfavorable conditions

ORGANISM(S): Trichoderma reesei

PROVIDER: GSE27471 | GEO | 2011/12/08

SECONDARY ACCESSION(S): PRJNA138443

REPOSITORIES: GEO

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Project description:The filamentous fungus Trichoderma reesei is the main industrial cellulytic enzymes producer. Several strains have been developed in the past using random mutagenesis, and despite impressive performance enhancements, the pressure for low-cost cellulases has stimulated continuous research in the field. In this context, comparative study of the lower and higher producer strains obtained through random mutagenesis using systems biology tools (genome sequencing, transcriptome) can shed light on the mechanisms of cellulase production and help identify genes linked to performance. Previously, our group published comparative genome sequencing of the lower and higher producer strains NG14 and RUTM-BM- C30. In this follow-up work, we examined how these mutations affect phenotype at the level of the transcriptome and cultivation behavior.M-BM- We performed kinetic transcriptome analysis of the NG14 and RUTM-BM- C30 strains of early cellulase production induced by lactose using bioreactor cultivations close to industrial conditions. RUTM-BM- C30 exhibited both earlier onset of cellulase production and higher steady-state productivity. A rather lowM-BM- number of genes were regulated, most of them being specific to the NG14 strains. Clustering of these genes highlighted similar behavior for some functional categories, and allowed to distinguish between induction-related genes and productivity-related genes. The lower number of genes regulated in RUTM-BM- C30 could not formally be linked to the relief in catabolic repression that is characteristic of this strain. Cross-comparison of our transcriptome data with mutations previously identified revealed that most genes from our dataset have not been mutated. Interestingly, the few mutated genes belong to the same clusters, suggesting these clusters contain genes playing a role in strain performance. This is the first kinetic transcriptome study carried out in industry-relevant conditions with two related strains of T. reesei showing distinctive performances. Our study sheds some light on some of the events occurring in these strains following induction by lactose. The fact that few regulated genes have been affected by mutagenesis suggest that the induction mechanism is essentially intact and that there is room for further improvement of T. reesei. We also provide some potential target for further genetic improvement of these strains. Two biological pool by condition in dye switch. For the two biological replicates on each four experiments we apply on the pretreated results the linear modeling approach implemented by lmFit and the empirical Bayes statistics implemented by eBayes from the limma R package (Smyth 2004). We select the list of statistically regulated genes using a 5% significance threshold.

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Transcriptome during shift of Trichoderma reesei from mycelial growth to asexual sporulation

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