Project description:Copper (Cu) homeostasis has not been well-documented in filamentous fungi, especially extremophiles. Acidophilic fungus Acidomyces richmondensis MEY-1 has extremely high Cu tolerance among filamentous fungi, and the transcription factor ArAceA has been shown to be involved in this process. The ArAceA deletion mutant (ΔArAceA) exhibits specific growth defects at Cu concentrations of ≥ 10 mM. To gain genomic insight into the Cu tolerance mechanism and the role of ArAceA in Cu tolerance, we treated the ΔArAceA mutant and WT strains with or without 15 mM CuCl2 for 6 h. Transcriptional profiling analysis revealed that ΔArAceA mutant is transcriptionally more sensitive to Cu than the wild-type strain. Our findings provide insights into the molecular basis of Cu tolerance in acidophilic filamentous fungi.
Project description:Non-conventional yeasts represent a great genetic and phenotypic diversity with potential for industrial strain development in the bio-production of green chemicals. In recent years, mass genome sequencing of non-conventional yeasts has opened avenues to improved understanding of transcriptional networks and phenotypic plasticity and gene function, including the discovery of novel genes. Here, we investigated the gene expression changes at low-pH in three strains of the acidophilic yeast Maudiozyma bulderi (previously Kazachstania bulderi): CBS8638, CBS8639 and NRRL-Y27205. The comparison of the transcriptome of cells growing in a bioreactor at pH=5.5 vs pH= 2.5, primarily showed dysregulation of genes involved in cell wall integrity, with NRRL-Y27205, the least acidophilic strain, showing the largest transcriptional response when compared to the other two strains. We identified four uncharacterised genes, unique to M. bulderi ,and predicted function as transporters, upregulated at low pH. We also showed that M. bulderi cell wall and membrane lipid composition is not significantly affected by low pH unlike Saccharomyces cerevisiae. Overall, our data on transcriptional variability in M. bulderi highlights genes and cellular pathways involved in the acidophilic adaptation of this species and can aid further strain development.
Project description:Disease resistance is mediated by specific recognition of pathogen avriulence effectors (AVR) by nucleotide-binding leucine-rich repeat (NLR) receptors. The barley (Hordeum vulgare) mildew locus A (mla) resistance gene homolog 1 (RGH1) encoded NLRs (MLAs) confer isolate-specific resistance to the widespread mildew fungus Blumeria graminis forma specialis hordei (Bgh). In barley, MLA has been subject to extensive functional diversification, resulting in allelic resistance specificities, each recognizing a cognate Bgh AVRa. The by genetic association isolated AVRa1 and AVRa13 effectors belong to the candidate secreted effector protein (CSEP) gene family (Lu et al., 2016). To unravel the complex mechanisms underlying MLA functional diversification in barley and wheat, isolation of numerous Bgh AVRa genes and recognition of their gene products by MLA is necessary. Our here deployed higher resolution genetic association approach identified the Bgh avirulence gene candidate loci AVRa7, AVRa9, AVRa22 and AVRa10 by associating of transcript polymorphisms and AVRa phenotypes from a collection of 27 Bgh isolates. We collected 10 Bgh isolates from a local Bgh population in Cologne in addition to our previous collection of 17 Bgh isolates (Lu et al., 2016).
Project description:Disease resistance (R) genes encoding intracellular nucleotide-binding domain and Leucine-rich repeat proteins (NLRs) are key components of the plant innate immune system and typically detect the presence of isolate-specific avirulence (AVR) effectors from pathogens. NLRs define the fastest evolving gene family of flowering plants and are often arranged in gene clusters containing multiple paralogs, contributing to extensive copy number and allele-specific NLR variation within a host species. Barley mildew resistance gene locus A (MLA) represents one of only few R genes that have been subject to extreme functional diversification, resulting in allelic resistance specificities each recognizing a cognate but largely unidentified AVRA gene of the powdery mildew fungus, Blumeria graminis f sp hordei (Bgh). We performed RNA-sequencing of Bgh-infected barley leaves at two different time-points to obtain transcriptome data for 16 Bgh isolates, containing different AVRA genes. Subsequently, we analyzed the expression levels in the different isolates with a specific focus on previously described candidate secreted effectors (CSEPs) and additionally performed a transcriptome-wide association analysis including these 16 isolates and the previously published reference isolate DH14. These analyses identified AVRA1 and AVRA13, encoding two CSEPs that are recognized by MLA1 and MLA13 alleles, respectively. The avirulence function of both candidates could be verified by transient expression of the effector genes in barley leaves or protoplasts that was sufficient to trigger an MLA1 or MLA13 allele-specific cell death response. AVRA1 recognition by MLA1 is also retained in transgenic Arabidopsis lines.
Project description:In this study, we showed that three bacteria were able to inhibit the mycelial growth of the phytopathogenic fungus Thielaviopsis ethacetica, by the emission of microbial volatile organic compounds (mVOCs). Aiming to understand the molecular mechanisms of these interactions, we evaluated the transcriptomic response of T. ethacetica to the mVOCs produced by one of these bacterial isolates.
Project description:Acididesulfobacillus acetoxydans is an acidophilic sulfate reducer that can dissimilatory reduce nitrate to ammonia (DNRA). However, no known nitrite reductase is encoded. This study was performed to investigate how A. acetoxydans reduces nitrate to nitrite and elucidated a novel DNRA mechanism and potential nitrosative stress resistance mechanisms in acidophiles.