Project description:The aim of the experiment was to study the gene expression changes occurring when cells of the diatom Skeletonema marinoi undergo sexual reproduction. In this species, sex can be induced by an environmental trigger, specifically a change in salinity of the cultivation media. In diatoms the unique mode of cell division with unequal inheritance of the rigid cell wall components determines a progressive cell size reduction as cells divide. Large cells above a given size threshold are not competent for sex, on the other hand small cells, under appropriate conditions, can undergo sexual reproduction. RNA-seq included three experimental conditions: a) large cells above the sexualization size threshold, grown at standard salinity (control condition: no sex, no salinity stress); b) large cells above the sexualization size threshold transferred to higher salinity (treatment 1: no sex, salinity stress); c) small cells below the sexualization size threshold transferred to higher salinity (treatment 2: sex, salinity stress).
Project description:In estuaries and coastal areas, salinity regimes vary with river discharge, seawater evaporation, morphology of the coastal waterways, and dynamics of marine water mixing. Therefore, microalgae have to respond to salinity variations at various time scales, from daily to annual cycling. They might also adapt to physical alteration that might induce loss of connectivity and enclosure of water bodies. Here we integrate physiological-based assays, morphological plasticity with functional genomics approach to examine the regulatory change that occur during the acclimation to salinity in an estuary diatom, Thalassiosira weissflogii. We found that this diatom respond to salinity (i.e. 21, 28 and 35 psu) with minute adjustments of its physiology (i.e., carbon and silicon metabolisms, pigments concentration and photosynthetic parameters). In contrast after short- (~ 5 generations) or long-term (~ 700 generations) culture at the different salinity we found a large transcriptome reprogramming. With most of the genes being down-regulated in long-term, and only a few genes in common between short and long term experiments.
Project description:Dehydrins (DHNs) are plant-specific proteins that accumulate during the abiotic stress that cause cellular dehydration, such as drought, salinity and freezing. How the dehydrin system in conifers reacts to more short-term drought stress is much less studied. Therefore, we studied the dynamics of dehydrin system in seedlings of Scots pine and Norway spruce both on mRNA and on protein levels under conditions of polyethylene glycole 6000 (PEG)-induced water deficit of different intensities.
Project description:Dehydrins (DHNs) are plant-specific proteins that accumulate during the abiotic stress that cause cellular dehydration, such as drought, salinity and freezing. How the dehydrin system in conifers reacts to more short-term drought stress is much less studied. Therefore, we studied the dynamics of dehydrin system in seedlings of Scots pine and Norway spruce both on mRNA and on protein levels under conditions of polyethylene glycole 6000 (PEG)-induced water deficit of different intensities.
Project description:Melatonin plays a potential role in multiple plant developmental processes and stress response. However, there are no reports regarding exogenous melatonin promoting rice seed germination under salinity and nor about the underlying molecular mechanisms at genome-wide. Here, we revealed that exogenous application of melatonin conferred roles in promoting rice seed germination under salinity. The putative molecular mechanisms of exogenous melatonin in promoting rice seed germination under high salinity were further investigated through metabolomic and transcriptomic analyses. The results state clearly that the phytohormone contents were reprogrammed, the activities of SOD, CAT, POD were enhanced, and the total antioxidant capacity was activated under salinity by exogenous melatonin. Additionally, melatonin-pre-treated seeds exhibited higher concentrations of glycosides than non-treated seeds under salinity. Furthermore, exogenous melatonin alleviated the accumulation of fatty acids induced by salinity. Genome-wide transcriptomic profiling identified 7160 transcripts that were differentially expressed in NaCl, MT100 and control. Pathway and GO term enrichment analysis revealed that genes involved in the response to oxidative stress, hormone metabolism, heme building, mitochondrion, tricarboxylic acid transformation were altered after melatonin pre-treatment under salinity. This study provides the first evidence of the protective roles of exogenous melatonin in increasing rice seed germination under salt stress, mainly via activation of antioxidants and modulation of metabolic homeostasis.
Project description:To identify known and novel miRNAs involved in the response and adaptation of sugar beet to short-term and long-term alkaline stress, miRNAs were identified by analysis of the deep sequencing of sRNA
Project description:<p>Microalgae are important primary producers and form the basis for the marine food web. As global climate changes, so do salinity levels that algae are exposed to. A metabolic response of algal cells partly alleviates the resulting osmotic stress. Some metabolites involved in the response are well studied, but the full metabolic implications of adaptation remain unclear. Improved analytical methodology provides an opportunity for additional insight. We can now follow responses to stress in major parts of the metabolome and derive comprehensive charts of the resulting metabolic re-wiring. In this study, we subjected three species of diatoms to high salinity conditions and compared their metabolome to controls in an untargeted manner. The three well-investigated species with sequenced genomes <em>Phaeodactylum tricornutum</em>, <em>Thalassiosira pseudonana</em> and <em>Skeletonema marinoi</em> were selected for our survey. The microalgae react to salinity stress with common adaptations in the metabolome by amino acid up-regulation, production of saccharides and inositols. But also species-specific dysregulation of metabolites is common. Several metabolites previously not connected with osmotic stress reactions are identified, including 4-hydroxyproline, pipecolinic acid, myo-inositol, threonic acid and acylcarnitines. This expands our knowledge about osmoadaptation and calls for further functional characterization of metabolites and pathways in algal stress physiology.</p>
Project description:Oilseed mustard, Brassica juncea, exhibits high levels of genetic variability for salinity tolerance. To obtain the global view of transcriptome and investigate the molecular basis of salinity tolerance in a salt-tolerant variety CS52 of B. juncea, we performed transcriptome sequencing of control and salt-stressed seedlings. De novo assembly of 184 million high-quality paired-end reads yielded 42,327 unique transcripts longer than 300 bp with RPKM ≥1. When compared with non-redundant proteins, we could annotate 67% unigenes obtained in our study. Based on the mapping to expressed sequence tags (ESTs), 52.6% unigenes are novel compared to EST data available for B. juncea and constituent genomes. Differential expression analysis revealed altered expression of 1469 unigenes in response to salinity stress. Of these, 587, mainly associated with ROS detoxification, sulfur assimilation and calcium signaling pathways, are up regulated. Notable of these is RSA1 (SHORT ROOT IN SALT MEDIUM 1) INTERACTING TRANSCRIPTION FACTOR 1 (RITF1) homolog up regulated by >100 folds in response to stress. RITF1, encoding a bHLH transcription factor, is a positive regulator of SOS1 and several key genes involved in scavenging of salt stress-induced reactive oxygen species (ROS). Further, we performed comparative expression profiling of key genes implicated in ion homeostasis and sequestration (SOS1, SOS2, SOS3, ENH1, NHX1), calcium sensing pathway (RITF1) and ROS detoxification in contrasting cultivars, B. juncea and B. nigra, for salinity tolerance. The results revealed higher transcript accumulation of most of these genes in B. juncea var. CS52 compared to salt-sensitive cultivar even under normal growth conditions. Together, these findings reveal key pathways and signaling components that contribute to salinity tolerance in B. juncea var. CS52. We report transcriptome sequencing of two-weeks-old seedlings of B. juncea var. CS52 under normal growth conditions (CTRL) and in response to salinity stress (SS) using Illumina paired-end sequencing