8 research outputs found
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Fungal community assembly in drought-stressed sorghum shows stochasticity, selection, and universal ecological dynamics.
Community assembly of crop-associated fungi is thought to be strongly influenced by deterministic selection exerted by the plant host, rather than stochastic processes. Here we use a simple, sorghum system with abundant sampling to show that stochastic forces (drift or stochastic dispersal) act on fungal community assembly in leaves and roots early in host development and when sorghum is drought stressed, conditions when mycobiomes are small. Unexpectedly, we find no signal for stochasticity when drought stress is relieved, likely due to renewed selection by the host. In our experimental system, the host compartment exerts the strongest effects on mycobiome assembly, followed by the timing of plant development and lastly by plant genotype. Using a dissimilarity-overlap approach, we find a universality in the forces of community assembly of the mycobiomes of the different sorghum compartments and in functional guilds of fungi
Mating types and Reproductive success
Reproductive success of 239 crosses (478 matings). Columns represent the 16 mat A strains, and rows represent the 15 mat a strains, with isolates numbers along the row and column headings of the matrix. Numbers within matrix cells indicate the reproductive success ratings (see below) of the two reciprocal matings of the cross between the corresponding isolates (mat a isolate as the perithecial parent/mat A isolate as the perithecial parent). The matrix cells have been shaded in proportion to the reproductive success of the best mating (see Figure 5B in the corresponding publication). Additional row and column headings indicate the lineage designation (see Figure 1). Isolates P581 and TX8127 are tester strains of N. discreta sensu stricto. Categories of reproductive success, corresponding to different stages in reproductive development, from the development of perithecia, to the formation of black ascospores were scored as follows: 0 & 1 if sterile, no perithecia produced; & barren perithecia, no ostiole developed; 2 if perithecia developed ostioles, but no spores; 3 & 4 if 50% black ascospores
Data from: Genomic sequencing reveals historical, demographic and selective factors associated with the diversification of the fire-associated fungus Neurospora discreta
Delineating microbial populations, discovering ecologically relevant phenotypes and identifying migrants, hybrids or admixed individuals have long proved notoriously difficult, thereby limiting our understanding of the evolutionary forces at play during the diversification of microbial species. However, recent advances in sequencing and computational methods have enabled an unbiased approach whereby incipient species and the genetic correlates of speciation can be identified by examining patterns of genomic variation within and between lineages. We present here a population genomic study of a phylogenetic species in the Neurospora discreta species complex, based on the resequencing of full genomes (~37 Mb) for 52 fungal isolates from nine sites in three continents. Population structure analyses revealed two distinct lineages in South–East Asia, and three lineages in North America/Europe with a broad longitudinal and latitudinal range and limited admixture between lineages. Genome scans for selective sweeps and comparisons of the genomic landscapes of diversity and recombination provided no support for a role of selection at linked sites on genomic heterogeneity in levels of divergence between lineages. However, demographic inference indicated that the observed genomic heterogeneity in divergence was generated by varying rates of gene flow between lineages following a period of isolation. Many putative cases of exchange of genetic material between phylogenetically divergent fungal lineages have been discovered, and our work highlights the quantitative importance of genetic exchanges between more closely related taxa to the evolution of fungal genomes. Our study also supports the role of allopatric isolation as a driver of diversification in saprobic microbes
Genomic Sequencing Reveals Demographic, Historical, and Selective Factors Associated with the Diversification of the Fire-Associated Fungus Neurospora discreta
International audienceBackground. Delineating microbial populations, discovering ecologically relevant phe¬notypes, and identifying migrants and admixed individuals has long proved notoriously difficult, thereby limiting our understanding the evolutionary forces at play during the diversification of microbial species. However, recent advances in sequencing and com¬putational methods have enabled an unbiased approach whereby incipient species and the genetic correlates of speciation can be identified by examining patterns of genomic variation within and between lineages. Results. We present here a population genomic study of a phylogenetic species in the Neurospora discreta species complex, based on the resequencing of full genomes (ca. 37Mb) for 52 fungal isolates from 9 sites in three continents. Population structure analy¬ses revealed two distinct lineages in Southeast Asia, three lineages in North America/ Europe with a broad longitudinal and latitudinal range, and limited admixture between lineages. Genome scans for selective sweeps and comparisons of the genomic land¬scapes of diversity and recombination provided no support for a role of linked selection on genomic heterogeneity in levels of divergence between lineages. However, demo¬graphic inference indicated that the observed genomic heterogeneity in divergence was generated by varying rates of gene flow between lineages following a period of isolation. Conclusion. Many putative gene transfer events between phylogenetically divergent fungal lineages have been discovered, and our work highlights the quantitative impor¬tance of genetic exchanges between more closely related taxa to the evolution of fungal genomes. Our study also supports the role of allopatric isolation as a driver of diversi¬fication in saprobic microbes
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Strong succession in arbuscular mycorrhizal fungal communities
Neighbor-joining tree constructed based on a matrix F84 distance computed using the full set of sequences
Neighbor-joining tree based on F84 distance (DNADIST, PHYLIP Package). Computations were performed on the full set of SNPs and this analysis was used to identify redundant (i.e. nearly identical, or clonal) genomic sequences
Co-occurrence networks reveal more complexity than community composition in resistance and resilience of microbial communities.
Plant response to drought stress involves fungi and bacteria that live on and in plants and in the rhizosphere, yet the stability of these myco- and micro-biomes remains poorly understood. We investigate the resistance and resilience of fungi and bacteria to drought in an agricultural system using both community composition and microbial associations. Here we show that tests of the fundamental hypotheses that fungi, as compared to bacteria, are (i) more resistant to drought stress but (ii) less resilient when rewetting relieves the stress, found robust support at the level of community composition. Results were more complex using all-correlations and co-occurrence networks. In general, drought disrupts microbial networks based on significant positive correlations among bacteria, among fungi, and between bacteria and fungi. Surprisingly, co-occurrence networks among functional guilds of rhizosphere fungi and leaf bacteria were strengthened by drought, and the same was seen for networks involving arbuscular mycorrhizal fungi in the rhizosphere. We also found support for the stress gradient hypothesis because drought increased the relative frequency of positive correlations