Project description:The rate, timing, and mode of species dispersal is recognized as a key driver of the structure and function of communities of macroorganisms, and may be one ecological process that determines the diversity of microbiomes. Many previous studies have quantified the modes and mechanisms of bacterial motility using monocultures of a few model bacterial species. But most microbes live in multispecies microbial communities, where direct interactions between microbes may inhibit or facilitate dispersal through a number of physical (e.g., hydrodynamic) and biological (e.g., chemotaxis) mechanisms, which remain largely unexplored. Using cheese rinds as a model microbiome, we demonstrate that physical networks created by filamentous fungi can impact the extent of small-scale bacterial dispersal and can shape the composition of microbiomes. From the cheese rind of Saint Nectaire, we serendipitously observed the bacterium Serratia proteamaculans actively spreads on networks formed by the fungus Mucor. By experimentally recreating these pairwise interactions in the lab, we show that Serratia spreads on actively growing and previously established fungal networks. The extent of symbiotic dispersal is dependent on the fungal network: diffuse and fast-growing Mucor networks provide the greatest dispersal facilitation of the Serratia species, while dense and slow-growing Penicillium networks provide limited dispersal facilitation. Fungal-mediated dispersal occurs in closely related Serratia species isolated from other environments, suggesting that this bacterial-fungal interaction is widespread in nature. Both RNA-seq and transposon mutagenesis point to specific molecular mechanisms that play key roles in this bacterial-fungal interaction, including chitin utilization and flagellin biosynthesis. By manipulating the presence and type of fungal networks in multispecies communities, we provide the first evidence that fungal networks shape the composition of bacterial communities, with Mucor networks shifting experimental bacterial communities to complete dominance by motile Proteobacteria. Collectively, our work demonstrates that these strong biophysical interactions between bacterial and fungi can have community-level consequences and may be operating in many other microbiomes.
Project description:To effectively monitor microbial populations in acidic environments and bioleaching systems, a comprehensive 50-mer-based oligonucleotide microarray was developed based on most of the known genes associated with the acidophiles. This array contained 1,072 probes in which there were 571 related to 16S rRNA and 501 related to functional genes. Acid mine drainage (AMD) presents numerous problems to the aquatic life and surrounding ecosystems. However, little is known about the geographic distribution, diversity, composition, structure and function of AMD microbial communities. In this study, we analyzed the geographic distribution of AMD microbial communities from twenty sites using restriction fragment length polymorphism (RFLP) analysis of 16S rRNA genes, and the results showed that AMD microbial communities were geographically distributed and had high variations among different sites. Then an AMD-specific microarray was used to further analyze nine AMD microbial communities, and showed that those nine AMD microbial communities had high variations measured by the number of detected genes, overlapping genes between samples, unique genes, and diversity indices. Statistical analyses indicated that the concentrations of Fe, S, Ca, Mg, Zn, Cu and pH had strong impacts on both phylogenetic and functional diversity, composition, and structure of AMD microbial communities. This study provides insights into our understanding of the geographic distribution, diversity, composition, structure and functional potential of AMD microbial communities and key environmental factors shaping them. This study investigated the geographic distribution of Acid Mine Drainages microbial communities using a 16S rRNA gene-based RFLP method and the diversity, composition and structure of AMD microbial communities phylogenetically and functionally using an AMD-specific microarray which contained 1,072 probes ( 571 related to 16S rRNA and 501 related to functional genes). The functional genes in the microarray were involved in carbon metabolism (158), nitrogen metabolism (72), sulfur metabolism (39), iron metabolism (68), DNA replication and repair (97), metal-resistance (27), membrane-relate gene (16), transposon (13) and IST sequence (11).
Project description:The increased susceptibility of ripe fruit to fungal pathogens poses a substantial threat to crop production and marketability. Here, we coupled transcriptomic analyses with mutant studies to uncover critical genes and processes governing ripening-associated susceptibility in tomato (Solanum lycopersicum) fruit. Using wild-type unripe and ripe fruit inoculated with three fungal pathogens—Botrytis cinerea, Fusarium acuminatum, and Rhizopus stolonifer—we identified common pathogen response genes reliant on chitinases, WRKY transcription factors, and reactive oxygen species detoxification. Interestingly, susceptible ripe fruit demonstrated a more extensive defense response than resistant unripe fruit, indicating that the magnitude and diversity of defense response does not significantly impact the interaction. To tease apart individual features of ripening that may be responsible for susceptibility, we utilized three tomato non-ripening mutants: Cnr, rin and nor. Fruit from these mutants displayed different patterns of susceptibility to fungal infection. Functional analysis of the genes altered during ripening in the susceptible genotypes revealed losses in the maintenance of cellular redox homeostasis. Moreover, jasmonic acid accumulation and signaling coincided with the activation of defenses in resistant fruit. Lastly, based on high gene expression in susceptible fruit, we identified and tested two candidate susceptibility factors, pectate lyase (PL) and polygalacturonase (PG2a). CRISPR-based knockouts of PL, but not PG2a, resulted in more than 50% decrease in the susceptibility of ripe fruit, demonstrating that PL is a major susceptibility factor. Ultimately, this study demonstrates that targeting specific genes that drive susceptibility is a viable strategy to improve resistance of tomato fruit against fungal pathogens.
2020-04-08 | GSE148217 | GEO
Project description:tomato root endophytic bacterial and fungal diversity
Project description:To effectively monitor microbial populations in acidic environments and bioleaching systems, a comprehensive 50-mer-based oligonucleotide microarray was developed based on most of the known genes associated with the acidophiles. This array contained 1,072 probes in which there were 571 related to 16S rRNA and 501 related to functional genes. Acid mine drainage (AMD) presents numerous problems to the aquatic life and surrounding ecosystems. However, little is known about the geographic distribution, diversity, composition, structure and function of AMD microbial communities. In this study, we analyzed the geographic distribution of AMD microbial communities from twenty sites using restriction fragment length polymorphism (RFLP) analysis of 16S rRNA genes, and the results showed that AMD microbial communities were geographically distributed and had high variations among different sites. Then an AMD-specific microarray was used to further analyze nine AMD microbial communities, and showed that those nine AMD microbial communities had high variations measured by the number of detected genes, overlapping genes between samples, unique genes, and diversity indices. Statistical analyses indicated that the concentrations of Fe, S, Ca, Mg, Zn, Cu and pH had strong impacts on both phylogenetic and functional diversity, composition, and structure of AMD microbial communities. This study provides insights into our understanding of the geographic distribution, diversity, composition, structure and functional potential of AMD microbial communities and key environmental factors shaping them.
Project description:The cell wall is among the first plant structures encountered by necrotrophic fungal pathogens, such as Botrytis cinerea. The composition of plant cell walls varies depending on the species, type of cell or tissue, and stage of development. Cell walls are important reservoirs of energy-rich sugars for pathogens, but also are barriers that impair colonization of host tissues. Growing fungal hyphae secrete enzymes that hydrolyze cell wall polysaccharides. Degradation of wall polysaccharides provides nutrients for the pathogen and improves the access of secreted Botrytis enzymes to all host cell wall targets and cytoplasmic constituents. Destruction of host cell walls results in tissue maceration, a hallmark of diseases caused by Botrytis. The Botrytis genome encodes 1,155 predicted carbohydrate-active enzyme (CAZy) genes; products of 275 are potentially secreted. Transcriptome sequencing identified Botrytis CAZy genes expressed during infections of lettuce leaves, ripe tomato fruit and grape berries. On all three hosts, Botrytis expresses a common group of 229 predicted CAZy genes including 28 pectin-modifying enzymes, 21 hemicellulose-modifying proteins, 18 enzymes targeting pectin and hemicellulose side-branches, and 16 enzymes that may degrade cellulose. Pectin polysaccharides are abundant in grape and tomato cell walls, but lettuce leaf walls are predominantly hemicelluloses and cellulose. These results suggest that Botrytis targets similar wall polysaccharide networks; e.g., pectins, on leaves and fruit, but also attacks unique host wall polysaccharide substrates The diversity of the Botrytis CAZy proteins may be partly responsible for its wide host range. 3 biological replicates consisting of groups of infected tomato fruits from different plants
Project description:Members of the tomato clade exhibit wide diversity in fruit coloration, growth habit, leaf morphology and mating preferences. However, the mechanisms governing inter-species diversity in fruit coloration are largely unknown. Therefore, a proteomic approach combined with carotenoid profiling and carotenogenic gene expression was used to decipher the diversity in carotenogenesis in green-fruited Solanum habrochaites, orange-fruited S. galapagense, and red-fruited S. pimpinellifolium with S. lycopersicum, cv. Ailsa Craig (tomato).