Project description:The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve virulence potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we performed a multi-condition sRNA-seq analysis comparing expression of several RNAi double knockout mutants with the wild-type strain in conidia and mycelium grown for 24 or 48 hours.
Project description:The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve virulence potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we performed a multi-condition mRNA-seq analysis comparing expression of several RNAi double knockout mutants with the wild-type strain in conidia and mycelium grown for 24 or 48 hours. The analysis linked the A. fumigatus dicer-like enzymes and RNA-dependent RNA polymerases to regulation of conidial ribosome biogenesis. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.
Project description:The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve growth potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we first investigated the genetic variation in RNAi-associated genes in a large collection of environmental and clinical genomes, where we found that RNAi is evolutionarily conserved even in clinical strains. Using endogenously expressed inverted-repeat transgenes complementary to both a conditionally essential gene and a nonessential gene, we determined that a subset of the RNAi componentry is active in inverted-repeat transgene silencing in conidia and mycelium. A multi-condition mRNA-seq analysis linked the A. fumigatus dicer-like enzymes and RNA-dependent RNA polymerases to regulation of conidial ribosome biogenesis genes; however, surprisingly few endogenous small RNAs were identified in conidia that could explain this broad change. Although RNAi was not clearly linked to growth or stress response defects in the RNAi knockouts, serial passaging of RNAi knockout strains for six generations resulted in lineages with diminished spore production over time, indicating that loss of RNAi can exert a fitness cost on the fungus. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.
Project description:We generated single and double knockouts of AtNHX5 and AtNHX6 in order to invesigate possible functions in Arabidopsis. nhx5/nhx6 exhibited severe growth retardation related to cell size and proliferation, as well as endosomal trafficking perutrbations. The results implicate endosomal NHX antiporters in novel cellular functions. In order to investigate further the possible functions of AtNHX5 and AtNHX6, we compared the transcrptional profiles of single and double AtNHX5 and AtNHX6 knockouts. We looked for changes in gene expression might help us to elucidate the molecular events associated with the apparent requirement of AtNHX5 and AtNHX6 for normal growth and development.
Project description:RNAi is a conserved mechanism in eukaryotic organisms and has been the subject of recent attention pertaining to many animal and plant models. But research related to fungal systems is limited, especially in plant pathogenic models. The present study was undertaken to examine the involvement of RNAi components on the biogenesis of small RNAs and their impact on growth and pathogenicity of the plant pathogenic model organism Magnaporthe oryzae. Through genetic and genomic analyses, we demonstrate that an individual Dicer, an RdRP and an Argonaute are essential for the generation of sRNAs. Collectively, they are involved in biogenesis of sRNAs matching to coding regions, repeats and intergenic regions. The loss of a particular Argonaute made the fungus less virulent on barley leaves and was also essential for sRNA production. Furthermore, one specific RdRP that was not essential to sRNA generation nonetheless reduced fungal virulence. In total, ten deletion mutants were constructed in each of the putative sRNA-generating genes, as well as a double deletion mutant in the two Dicers, and comparison of sRNA and RNA-seq profiles of each mutant yielded new insights into the involvement of sRNAs in transcriptional regulation and intergenic regions in M. oryzae. Together, these data support that RNAi machinery in M. oryzae is not only involved in generation of sRNAs, but is involved in regulating various developmental processes including fungal growth and virulence.
Project description:We generated single and double knockouts of AtNHX5 and AtNHX6 in order to invesigate possible functions in Arabidopsis. nhx5/nhx6 exhibited severe growth retardation related to cell size and proliferation, as well as endosomal trafficking perutrbations. The results implicate endosomal NHX antiporters in novel cellular functions. In order to investigate further the possible functions of AtNHX5 and AtNHX6, we compared the transcrptional profiles of single and double AtNHX5 and AtNHX6 knockouts. We looked for changes in gene expression might help us to elucidate the molecular events associated with the apparent requirement of AtNHX5 and AtNHX6 for normal growth and development. Rosette leaves from 4 weeks old plants grown on soil under normal conditons and 8h L / 16 D were collected for RNA extraction and hybridization on Affymetrix microarray chips.
Project description:To explore the effect of stable RNAi on the small RNA (sRNA) population in wheat, we constructed a sRNA library from hexaploid wheat that expresses an RNAi construct under the 35S promoter that targets the endogenous NO APICAL MERISTEM (TaNAM) gene. The presence of this RNAi transgene causes a 40% reduction in expression of the target genes as measured by quantitative RT-PCR and significantly delays senescence and reduces remobilization of N, Fe, and Zn to the grain.
Project description:Here we show that the human fungal pathogen Mucor circinelloides develops spontaneous resistance to the antifungal drug FK506 via two distinct mechanisms. One involves Mendelian mutations that confer stable drug resistance and the other via an epigenetic RNA interference (RNAi)-mediated pathway that results in unstable drug resistance. The peptidyl-prolyl isomerase FKBP12 interacts with FK506 to form a complex that inhibits the protein phosphatase calcineurin. In M. circinelloides, inhibition of calcineurin by FK506 blocks the transition to hyphae and enforces yeast growth. Mutations in the fkbA gene encoding FKBP12 or the calcineurin cnbR or cnaA genes confer FK506 resistance, restoring hyphal growth in the presence of this drug. In parallel, RNAi is spontaneously triggered to silence the FKBP12 fkbA gene, giving rise to drug-resistant epimutants. FK506-resistant epimutants readily reverted to the drug-sensitive wild type (WT) phenotype when selection was released by growth without drug. High-throughput small RNA (sRNA) sequencing showed abundant sRNA antisense to fkbA only in the epimutants and not in the WT or revertant strains. Analysis of RNAi mutants revealed components required for the establishment of drug resistant epimutants as well as other factors that constrain or reverse the epimutation pathway. Silencing involves generation of a double stranded RNA trigger intermediate using the fkbA mature mRNA as template. These results uncover a novel epigenetic RNAi-based epimutation mechanism controlling phenotypic plasticity, with possible implications for antimicrobial drug resistance and RNAi regulatory mechanisms in fungi and other eukaryotes.
Project description:All non-essential protein kinases and phosphatases knockouts have been investigated by expression profiling. To investigate redundancy, double mutants are profiled that show a reduced growth according to synthetic genetic interaction data.