Project description:The PANarray design (GPL13324) contains the genes of eight P. aeruginosa genomes in non-redundant format, thus allowing identification of expression of non-PAO1 and other P. aeruginosa genes. For the series GSE28152, isogenic isolates were sequentially collected from two cystic fibrosis (CF) patients several years apart. The isolates had not been eradicated in the meantime and represent persister strains. One was an Australian Epidemic Strain-1 isolate and the other a non-epidemic strain. Strains were cultured in an artificial sputum medium (ASMDM) closely resembling CF sputum.
Project description:Balance between maternal and paternal genomes within the triploid endosperm is necessary for normal seed development. The majority of endosperm genes are expressed in a 2:1 maternal:paternal ratio, reflecting genomic DNA content. Here we find that the 2:1 transcriptional ratio is, unexpectedly, actively regulated. In A. thaliana and A. lyrata, endosperm 24 nt small RNAs are reduced in TEs and enriched in genes compared to the embryo. We find an inverse relationship between the parent-of-origin of sRNAs and mRNAs, with genes more likely to be associated with maternally than paternally biased sRNAs. Disruption of the Pol IV sRNA pathway causes a shift toward maternal allele mRNA expression for many genes. Furthermore, paternal inheritance of an RNA Pol IV mutation is sufficient to rescue seed abortion caused by excess paternal genome dosage. Thus, RNA Pol IV mediates transcriptional balance between maternally and paternally inherited genomes in endosperm.
Project description:Water deficiency and heat stress can severely limit crop production and quality. Stress imposed on the parents during reproduction could have transgenerational effects on their progeny. Seeds with different origins can vary significantly in germination time-course and early growth. Here, we investigated how water-deficit and heat stress on parental durum wheat plants affected seedling establishment of the subsequent generation. One stress-tolerant and one stress-sensitive Australian durum genotype were used. Seeds were collected from parents with or without exposure to stress during reproduction. Generally stress on the previous generation negatively affected seed germination and seedling vigour, but to a lesser extent in the tolerant variety. Small RNA sequencing utilising the new durum genome assembly has revealed significant differences in microRNA (miRNA) expression in the two genotypes. A bioinformatics approach was used to identify multiple miRNA targets which have critical molecular functions in stress adaptation and plant development and could therefore contribute to the phenotypic differences observed. Our data provides the first confirmation of the transgenerational effects of reproductive-stage stress on germination and seedling establishment in durum wheat. New insights gained on the epigenetic level indicate that durum miRNAs could be key factors in optimising seed vigour for superior breeding germplasm and/or varieties.
Project description:Seed development is sensitive to parental dosage, with excess maternal or paternal genomes creating reciprocal phenotypes. Paternal genomic excess results in extensive endosperm proliferation without cellularization and eventual seed abortion. We previously showed that loss of the RNA POL IV gene nrpd1 in tetraploid fathers represses seed abortion in paternal excess crosses. Here we show genetically that RNA-directed DNA methylation (RdDM) pathway activity in the paternal parent is sufficient to determine the viability of paternal excess seeds. The status of the RdDM pathway in paternal excess endosperm does not impact seed viability. Comparison of endosperm transcriptomes, DNA methylation, and small RNAs from balanced and paternal excess endosperm demonstrates that paternal excess seed abortion is unlikely to be dependent on either transposable element or imprinted gene mis-regulation. We suggest instead that loss of paternal RdDM modulates expression at a small subset of genes and desensitizes endosperm to paternal excess. Finally, using allele-specific transcription data, we present evidence of a transcriptional buffering system that up37 regulates maternal alleles and represses paternal alleles in response to excess paternal genomic dosage. These findings prompt reconsideration of models for dosage sensitivity in endosperm.
Project description:Rhizoctonia solani Kühn is a soilborne basidiomycetous fungus that causes significant damage to many economically important crops. R. solani isolates are classified into 13 Anastomosis Groups (AGs) with interspecific subgroups having distinctive morphology, pathogenicity and wide host range. However, the genetic factors that drive the unique fungal pathology are still not well characterized due to the limited number of available annotated genomes. Therefore, we performed genome sequencing, assembly, annotation and functional analysis of 13 R. solani isolates covering 7 AGs and selected subgroups (AG1-IA, AG1-IB, AG1-IC, AG2-2IIIB, AG3-PT, AG3-TB, AG4-HG-I, AG5, AG6, and AG8). Here, we report a pangenome comparative analysis of 13 R. solani isolates covering important groups to elucidate unique and common attributes associated with each isolate, including molecular factors potentially involved in determining AG-specific host preference. Finally, we present the largest repertoire of annotated R. solani genomes, compiled as a comprehensive and user-friendly database, viz. RsolaniDB. Since 7 genomes are reported for the first time, the database stands as a valuable platform for formulating new hypotheses by hosting annotated genomes, with tools for functional enrichment, orthologs and sequence analysis, currently not available with other accessible state-of-the-art platforms hosting Rhizoctonia genome sequences.