ABSTRACT: Purpose: We utilised high-throughput genomic approache to investigate transcriptional changes in two Neurospora strains (74A [wild-type] and mutant Δmus-52), under different phosphate availability conditions to evaluate the effects of mus-52 deletion in gene transcriptional modulation, and thus, infer its influence regarding metabolic response to changing extracellular levels of inorganic phosphate (Pi). Methods: All N. crassa strains were maintained on Vogel’s minimal medium, pH 5.8, at 30°C. Conidia from each strain were germinated for 5 h at 30°C in an orbital shaker (200 rpm), in low-Pi (10µM) and high-Pi (10mM) media. Total RNA was isolated from both strains and a total of 4 cDNA libraries were sequenced, with their respective biological triplicates corresponding to the paired libraries, using an Illumina HiSeq2000 sequencer, to generate 100 bp paired-end reads. FastQC software was used to visualize the library quality before and after trimming. For quality and sequence filtering, a Phred score lower than 20 was employed to remove sequencing bases from the read ends. Filtered reads were mapped onto the N. crassa genome using Bowtie2 software. The reads count values were obtained and used to calculate the expression variation of the transcripts from different conditions, considering the statistical significance of the differential gene expression. qRT–PCR validation was performed using SYBR Green assays. Results: extracellular Pi availability influenced the expression of genes involved in several biological functions. The main affected gene groups were those associated with integral components of the membrane, such as transport, regulation, and cell signalling pathways, as well as genes involved with the nucleolus and protein synthesis. The absence of mus-52 affected global gene transcription in all conditions tested, highlighting the expression of some specific gene groups, such as transcription factors, kinase proteins, circadian clock-related genes, oxi-reduction balance, phosphate pathways, and general metabolism. Conclusions: The consequences of N. crassa mus-52 disruption to the cell may be deeper than the obvious phenotypic aspect. It may affect canonical and non-canonical pathways, leading to alternative adaptive processes, altering the perception and response to the environmental changes.
