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:Phytophthora infestans is a filamentous plant pathogen. It belongs to the class Oomycota within the Stramenopiles. Despite the importance of sexual reproduction in P. infestans, many aspects of the mating process remain unknown. In this study we are investigating its mating mechanisms using different molecular techniques. Isolates with A1 and A2 mating types from Sweden, the Netherlands and the UK, were used for this purpose because mating frequencies are known to differ among European countries. RNA was prepared from the “mating-zone” between the 4 Swedish, 1 Dutch and 1 British pairs. RNA-seq analysis was performed on an Illumina HiSeq 2500 platform and data normalized to parental isolates growing individually.
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.
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: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:Modes of sexual reproduction in eukaryotic organisms are highly diversified. The human fungal pathogen Candida albicans undergoes a phenotypic switch from the white to the opaque phase in order to become mating-competent. In this study, we report that functionally and morphologically differentiated white and opaque cells show a coordinating behavior in the process of mating. Although white cells are mating-incompetent, they are induced to produce sexual pheromones when treated with opposite pheromones or interacted with opaque cells of an opposite mating type. In a co-culture system, pheromones released by white cells induce opaque cells to form mating projections and thus facilitate both opposite- and same-sex mating of opaque cells. Deletion of genes encoding the pheromone precursor proteins and inactivation of the pheromone response signaling pathway (Ste2-MAPK-Cph1) impair the promoting role of white cells (MTLa) in sexual mating of opaque cells. White and opaque cells communicate via a paracrine pheromone signaling and thus create an environment conducive to sexual mating. This coordination behavior of the two different cell types may be a trade-off strategy between sexual and asexual lifestyles in C. albicans.
Project description:The human fungal pathogen Candida albicans can switch stochastically and heritably between a “white” phase and an “opaque” phase. Opaque cells are the mating-competent form of the species whereas white cells are essentially “sterile”. Here, we report that glucose depletion, a common nutrient stress, enables C. albicans white cells to undergo efficient sexual mating. The relative expression levels of pheromone-sensing and mating-associated genes (including STE2/3, MFA1, MFalpha1, FIG1, FUS1, and CEK1/2) were increased under glucose depletion conditions, while expression of mating repressors TEC1 and DIG1 was decreased. We show that Cph1 and Tec1, factors that act downstream of the pheromone MAPK pathway, play opposite roles in regulating white cell mating as TEC1 deletion or CPH1 overexpression promoted white cell mating. Moreover, inactivation of the Cph1 repressor Dig1 increased white cell mating ~4,000 fold in glucose-depleted medium relative to that in the presence of glucose. These findings reveal that the white-to-opaque epigenetic switch may not be a prerequisite for sexual mating in C. albicans in nature. Given parallels between C. albicans white cell mating to that of other yeast species, this mechanism of mating could represent a more ancient strategy of sexual reproduction in C. albicans.