Project description:Fungal species are typically either fully self-fertile or self-sterile, but some filamentous ascomycetes can transition from self-fertility to self-sterility through unidirectional mating-type switching. In these fungi, the structure of the mating-type (MAT1) locus governs sexual behaviour: MAT-2 self-fertile individuals retain both MAT1-1 and MAT1-2 genes, while MAT-1 self-sterile isolates lose MAT1-2 genes during switching. A third type of isolate morphology also occurs under laboratory conditions: these are self-sterile isolates that retain both MAT1-1 and MAT1-2, but are unable to switch mating type. They are commonly referred to as MAT-2 self-sterile isolates. Two of the mating-type (MAT) genes, one of which is deleted during switching, encode transcription factors known to regulate not only the sexual cycle but also genes unrelated to mating. To test how MAT1 structural variations affects gene expression, we studied Ceratocystis albifundus, a species that switches mating type. To minimise variability caused by intraspecific genetic differences, two self-sterile isolates (MAT-1 and MAT-2 self-steriles) were derived from the same MAT-2 self-fertile parent, making all three isolates genetically identical, except at the MAT1 locus. Comparative transcriptomic analyses revealed that the MAT-2 self-fertile, MAT-1 self-sterile and MAT-2 self-sterile isolates all exhibited distinct expression patterns, including differences in MAT genes, the pheromone–receptor pathway, and other genes not directly linked to mating. The results show that MAT1 locus structure influences gene expression more broadly than those only related to the sexual cycle.
Project description:Recombination suppression on fungal mating-type chromosomes without mating-type loci linkage and with loss of function of HD mating-type genes
Project description:Abstract BACKGROUND: Mating-type loci in yeasts and ascomycotan filamentous fungi (Pezizomycotina) encode master transcriptional factors that play a critical role in sexual development. Genome-wide analyses of mating-type-specification circuits and mating-type target genes are available in Saccharomyces cerevisiae and Schizosaccharomyces pombe; however, no such analyses have been performed in heterothallic (self-incompatible) Pezizomycotina. The heterothallic fungus Podospora anserina serves as a model for understanding the basic features of mating-type control. Its mat+ and mat- mating types are determined by dissimilar allelic sequences. The mat- sequence contains three genes, designated FMR1, SMR1 and SMR2, while the mat+ sequence contains one gene, FPR1. FMR1 and FPR1 are the major regulators of fertilization, and this study presents a genome-wide view of their target genes and analyzes their target gene regulation. METHODOLOGY/PRINCIPAL FINDINGS: The transcriptomic profiles of the mat+ and mat- strains revealed 157 differentially transcribed genes, and transcriptomic analysis of fmr1(-) and fpr1(-) mutant strains was used to determine the regulatory actions exerted by FMR1 and FPR1 on these differentially transcribed genes. All possible combinations of transcription repression and/or activation by FMR1 and/or FPR1 were observed. Furthermore, 10 additional mating-type target genes were identified that were up- or down-regulated to the same level in mat+ and mat- strains. Of the 167 genes identified, 32 genes were selected for deletion, which resulted in the identification of two genes essential for the sexual cycle. Interspecies comparisons of mating-type target genes revealed significant numbers of orthologous pairs, although transcriptional profiles were not conserved between species. CONCLUSIONS/SIGNIFICANCE: This study represents the first comprehensive genome-wide analysis of mating-type direct and indirect target genes in a heterothallic filamentous fungus. Mating-type transcription factors have many more target genes than are found in yeasts and exert a much greater diversity of regulatory actions on target genes, most of which are not directly related to mating.
Project description:So as to compare fungal mating-type chromosomes across a range of Microbotryum species, comparative genomics analyses were conducted, and were informed by RNASeq data. In this instance, different stages of the lifecycle of M. violaceum infecting D. pavonius were compared via RNASeq.
Project description:Neurospora tetrasperma is a pseudohomothallic filamentous ascomycete with a large (~ 7 Mbp) region of suppressed recombination surrounding its mating-type (mat) locus. The suppressed recombination has lead to sequence divergence between the two mating-type chromosomes of wild-type heterokaryotic strains, while the remaining genome is largely homoallelic. In this study, we use microarray technology to manifest expression divergence linked to mating type in N. tetrasperma. N. tetrasperma and N. crassa, were grown on agar regimes inducing sexual growth (Synthetic Crossing medium) and vegetative growth (Vogel's Medium), respectively.
