Project description:ABSTRACT: Exposure to abiotic stresses triggers global changes in the expression of thousands of eukaryotic genes at the transcriptional 70 and post-transcriptional levels. Small RNA (smRNA) pathways and splicing both function as crucial mechanisms regulating stress-responsive gene expression. However, examples of smRNAs regulating gene expression remain largely limited to effects on mRNA stability, translation, and epigenetic regulation. Also, our understanding of the networks controlling plant gene expression in response to environmental changes, and examples of these regulatory pathways intersecting, remains limited. Here, to investigate the role of smRNAs in stress responses we examined smRNA transcriptomes of Brachypodium distachyon plants subjected to various abiotic stresses. We found that exposure to different abiotic stresses specifically induced a group 75 of novel, endogenous small interfering RNAs (stress-induced, UTR-derived siRNAs, or sutr-siRNAs) that originate from the 3M-bM-^@M-2 UTRs of a subset of coding genes. Our bioinformatics analyses predicted that sutr-siRNAs have potential regulatory functions and that over 90% of sutr-siRNAs target intronic regions of many mRNAs in trans. Importantly, a subgroup of these sutr- siRNAs target the important intron regulatory regions, such as branch point sequences, that could affect splicing. Our study indicates that in Brachypodium, sutr-siRNAs may affect splicing by masking or changing accessibility of specific cis-elements 80 through base-pairing interactions to mediate gene expression in response to stresses. We hypothesize that this mode of regulation of gene expression may also serve as a general mechanism for regulation of gene expression in plants and potentially in other eukaryotes. Analysis of smRNA populations in Brachypodium plants challenged by abiotic stresses: To profile the populations of smRNAs in the model monocot Brachypodium distachyon and examine their regulation in response to abiotic stresses, we conducted high-throughput sequencing of small RNAs from plants exposed to four different abiotic stress conditions, cold, heat (air), heat (water immersion), and salt, in the wild type Brachypodium cultivar Bd21. For our experiments we used information from the literature to select two time-points for stress durations, short and long, which differed for each stress: cold (6 and 24 hours), heat-air (1 and 3 hours), heat-water (1 and 3 hours), and salt (48 hours). We generated small RNA libraries for Illumina sequencing (GAII) from the leaves of Brachypodium plants subjected to stresses and selected smRNAs between 15 and 40 nt in length, which we mapped to the Brachypodium genome.

Project description:Considering global climate changes, incidences of combined drought and heat stress are likely to increase in the future and will considerably influence plant-pathogen interactions. Until now, little is known about plants exposed to simultaneously occurring abiotic and biotic stresses. To shed some light on molecular plant responses to multiple stress factors, a versatile multi-factorial test system, allowing simultaneous application of heat, drought and virus stress, was developed. Comparative analysis of single, double and triple stress responses by transcriptome and metabolome analysis revealed that gene expression under multi-factorial stress is not predictable from single stress treatments. Hierarchical cluster and principal component analysis identified heat as the major stress factor clearly separating heat-stressed from non-heat stressed plants. We identified 11 genes differentially regulated in all stress combinations as well as 23 genes specifically-regulated under triple stress. Furthermore, we showed that virus treated plants displayed enhanced expression of defense genes, which was abolished in plants additionally subjected to heat and drought stress. Triple stress also reduced expression of genes involved in the R-mediated disease response and increased the cytoplasmic protein response which was not seen under single stress conditions. These observations suggested that abiotic stress factors significantly altered TuMV-specific signaling networks which lead to a deactivation of defense responses and a higher susceptibility of plants. Collectively, our transcriptome and metabolome data provide a powerful resource to study plant responses during multi-factorial stress and allows identifying metabolic processes and functional networks involved in tripartite interactions of plants with their environment. Stress induced gene expression in Arabidopsis leaves was measured after exposure to single and combined abiotic and biotic stress. Plants were grown on soil for 21 days till virus infection. Eight days later controlled drought stress was applied. At the end of the treatments heat was applied for three days. Four biological replicates have been hybridized for each treatment. Furthermore, Arabidopsis plants were exposed to a single severe heat stress (37Â°C day/33Â°C night) to mimic the severity of the triple stress experiment.

Project description:Considering global climate changes, incidences of combined drought and heat stress are likely to increase in the future and will considerably influence plant-pathogen interactions. Until now, little is known about plants exposed to simultaneously occurring abiotic and biotic stresses. To shed some light on molecular plant responses to multiple stress factors, a versatile multi-factorial test system, allowing simultaneous application of heat, drought and virus stress, was developed. Comparative analysis of single, double and triple stress responses by transcriptome and metabolome analysis revealed that gene expression under multi-factorial stress is not predictable from single stress treatments. Hierarchical cluster and principal component analysis identified heat as the major stress factor clearly separating heat-stressed from non-heat stressed plants. We identified 11 genes differentially regulated in all stress combinations as well as 23 genes specifically-regulated under triple stress. Furthermore, we showed that virus treated plants displayed enhanced expression of defense genes, which was abolished in plants additionally subjected to heat and drought stress. Triple stress also reduced expression of genes involved in the R-mediated disease response and increased the cytoplasmic protein response which was not seen under single stress conditions. These observations suggested that abiotic stress factors significantly altered TuMV-specific signaling networks which lead to a deactivation of defense responses and a higher susceptibility of plants. Collectively, our transcriptome and metabolome data provide a powerful resource to study plant responses during multi-factorial stress and allows identifying metabolic processes and functional networks involved in tripartite interactions of plants with their environment. Stress induced gene expression in Arabidopsis leaves was measured after exposure to single and combined abiotic and biotic stress. Plants were grown on soil for 21 days till virus infection. Eight days later controlled drought stress was applied. At the end of the treatments heat was applied for three days. Four biological replicates have been hybridized for each treatment.

Project description:Considering global climate changes, incidences of combined drought and heat stress are likely to increase in the future and will considerably influence plant-pathogen interactions. Until now, little is known about plants exposed to simultaneously occurring abiotic and biotic stresses. To shed some light on molecular plant responses to multiple stress factors, a versatile multi-factorial test system, allowing simultaneous application of heat, drought and virus stress, was developed. Comparative analysis of single, double and triple stress responses by transcriptome and metabolome analysis revealed that gene expression under multi-factorial stress is not predictable from single stress treatments. Hierarchical cluster and principal component analysis identified heat as the major stress factor clearly separating heat-stressed from non-heat stressed plants. We identified 11 genes differentially regulated in all stress combinations as well as 23 genes specifically-regulated under triple stress. Furthermore, we showed that virus treated plants displayed enhanced expression of defense genes, which was abolished in plants additionally subjected to heat and drought stress. Triple stress also reduced expression of genes involved in the R-mediated disease response and increased the cytoplasmic protein response which was not seen under single stress conditions. These observations suggested that abiotic stress factors significantly altered TuMV-specific signaling networks which lead to a deactivation of defense responses and a higher susceptibility of plants. Collectively, our transcriptome and metabolome data provide a powerful resource to study plant responses during multi-factorial stress and allows identifying metabolic processes and functional networks involved in tripartite interactions of plants with their environment. Stress induced gene expression in Arabidopsis leaves was measured after exposure to single and combined abiotic and biotic stress. Plants were grown on soil for 21 days till virus infection. Eight days later controlled drought stress was applied. At the end of the treatments heat was applied for three days. In parallel, a homozougus T-DNA insertion line SALK_021115C (N672283), located in the Arabidopsis gene At5g45000 has been exposed to the same stress conditions. Four biological replicates have been hybridized for each treatment.

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Integrating microRNA and mRNA expression profiling in Symbiodinium, the dinoflagellate symbiont of reef-building corals (smRNA)

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