Biology subjects

Begerow, D.

Publications and source records attributed to Begerow, D..

3 recordsLinked to original sources

bioRxiv2023

Comparative genomics of smut fungi suggest the ability of meiosis and mating in asexual species of the genus Pseudozyma (Ustilaginales)

BackgroundThe Ustilaginales comprise hundreds of plant-parasitic fungi with a characteristic life cycle that directly links sexual reproduction and parasitism: One of the two mating-type loci codes for a transcription factor that not only facilitates mating, but also initiates the infection process. However, several species within the Ustilaginales have no described parasitic stage and were historically assigned to the genus Pseudozyma. Molecular studies have shown that the group is polyphyletic, with members being scattered in various lineages of the Ustilag-inales. Together with recent findings of conserved fungal effectors in these non-parasitic species, this raises the question if parasitism has been lost recently and in multiple independent events or if there are hitherto undescribed parasitic stages of these fungi. ResultsIn this study, we sequenced genomes of five Pseudozyma species together with parasitic species from the Ustilaginales to compare their genomic capability to perform two central functions in sexual reproduction: mating and meiosis. While the loss of sexual capability is assumed in certain lineages and asexual species are common in Asco- and Basidiomycota, we were able to successfully annotate functional mating and meiosis genes that are conserved throughout the whole group. ConclusionOur data suggest that at least the key functions of a sexual lifestyle are maintained in the analyzed genomes, challenging the current understanding of the so-called asexual species with respect to their evolution and ecological role.

genomics↗

bioRxiv2021

Onset and stepwise extensions of recombination suppression are common in mating-type chromosomes of Microbotryum anther-smut fungi

Sex chromosomes and mating-type chromosomes can display large genomic regions without recombination. Recombination suppression often extended stepwise with time away from the sex- or mating-type-determining genes, generating evolutionary strata of differentiation between alternative sex or mating-type chromosomes. In anther-smut fungi of the Microbotryum genus, recombination suppression evolved repeatedly, linking the two mating-type loci and extended multiple times in regions distal to the mating-type genes. Here, we obtained high-quality genome assemblies of alternative mating types for four Microbotryum fungi. We found an additional event of independent chromosomal rearrangements bringing the two mating-type loci on the same chromosome followed by recombination suppression linking them. We also found, in a new clade analysed here, that recombination suppression between the two mating-type loci occurred in several steps, with first an ancestral recombination suppression between one of the mating-type locus and its centromere; later, completion of recombination suppression up to the second mating-type locus occurred independently in three species. The estimated dates of recombination suppression between the mating-type loci ranged from 0.15 to 3.58 million years ago. In total, this makes at least nine independent events of linkage between the mating-type loci across the Microbotryum genus. Several mating-type locus linkage events occurred through the same types of chromosomal rearrangements, where similar chromosome fissions at centromeres represent convergence in the genomic changes leading to the phenotypic convergence. These findings further highlight Microbotryum fungi as excellent models to study the evolution of recombination suppression.

evolutionary biology↗

bioRxiv2016

Adaptive anonymity: Crypsis as an evolutionary trait of floral yeasts?

Nectar-dwelling yeast and bacteria are common inhabitants of flowers and evidently involved in pollination. The limited number of floral plant-pollinator models studied to date reveal inconsistent conclusions on microbial effects, but coincide with respect to high microbial specificity: while bacteria reduce visitation frequencies of pollinators, nectar-borne specialist yeasts (in contrast to allochthonous or transient species) impose none or even a beneficial effect on flower visitation. However, these findings are in conflict with the strong impact of these predominantly fermenting organisms on the nectar environment. In order to cope with the ultimate dependency of nectar-dwellers on repeated transportation by foragers as a result of early floral senescence, the modifications of nectar associated with specialist growth have been interpreted as adaptations that suit foragers preferences. But, the development of foraging preferences to either axenic flowers or flowers colonized by specialist microorganisms would lead to a dead-end for nectar-dwellers, as the probability of inoculation into new suitable habitats would be reduced.\n\nBased on a critical survey of the available literature and an additional pollinator experiment where we find that the allochthonous species Cryptococcus victoriae negatively affects attraction and rewarding of floral visitors, while the specialist yeast Metschnikowia reukaufii does not, we propose the hypothesis that nectar-borne yeasts may have evolved to blend into their environment avoiding detection by pollinators, following the ecological concept of crypsis. Although, neither chemical nor olfactory crypsis has been reported for nectar-borne microorganisms, the attention to this mechanism in yeast dispersal needs to be directed in future studies.

ecology↗