Transcriptomic dynamics provides an insight into the mechanism for silicon-mediated alleviation of salt stress in cucumber plants
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ABSTRACT: Salinity seriously reduces the yield and quality of crops. Silicon (Si) has been widely reported to have beneficial effects on plant growth and development under salt stress. However, the mechanism is still poorly understood. In an attempt to identify genes or gene networks that may be orchestrated to improve salt tolerance of cucumber plants, we profiled the RNA-seq transcriptomes of both control and salt-stressed cucumber leaves in the presence or absence of added Si. The comparative transcriptome analysis revealed that Si plays an important role in shaping the transcriptome of cucumber: the expression levels of >1,000 genes (differtially expressed genes, DEGs) were changed in response to Si treatment as compared with the control, and these genes were mainly involved in ion transport, hormone and signal transduction, biosynthesis and metabolic processes, stress and defense responses, and antioxidant activity. Under salt stress, many genes functionally associated with metabolic processes and responses to environmental stimuli were strongly up- or down-regulated in their expressions. Si treatment showed a tendency that induced the transcriptomic profile of salt-stressed cucumber back to that of the control with large majority of Na down-regulated DEGs and about half of Na up-regulated DEGs being adjusted back to CT levels. This study provides a novel insight into the mechanism for Si-mediated alleviation of salt stress in plants at the transcriptome level, and it suggests that Si may act as an elicitor to precondition cucumber plants and induce salt tolerance.
Project description:In a previous study, we found that H2S alleviates salinity stress in cucumber by maintaining the Na+/K+ balance and by regulating H2S metabolism and the oxidative stress response. However, little is known about the molecular mechanisms behind H2S-regulated salt-stress tolerance in cucumber. Here, an integrated transcriptomic and proteomic analysis based on RNA-seq and 2-DE was used to investigate the global mechanism underlying H2S-regulated salt-stress tolerance. In total, 11 761 differentially expressed genes (DEGs) and 61 differentially expressed proteins (DEPs) were identified. Analysis of the pathways associated with the DEGs showed that salt stress enriched expression of genes in primary and energy metabolism, such as photosynthesis, carbon metabolism and biosynthesis of amino acids. Application of H2S significantly decreased these DEGs but enriched DEGs related to plant-pathogen interaction, sulfur-containing metabolism, cell defense and signal transduction pathways. Notably, changes related to sulfur-containing metabolism and cell defense were also observed through proteome analysis, such as Cysteine synthase 1, Glutathione S-transferase U25-like, Protein disulfide-isomerase and Peroxidase 2. We present the first global analysis of the mechanism underlying H2S regulation of salt-stress tolerance in cucumber through tracking changes in the expression of specific proteins and genes.
Project description:Although previous studies have addressed the possible benefits of arbuscular mycorrhizal (AM) symbiosis for rice plants under salinity, the underlying molecular mechanisms are still unclear. Here, we showed that rice colonized with AM fungi had better growth performance and higher K+/Na+ ratio under salt stress. Differentially expressed genes (DEGs) responding to AM symbiosis especially under salt stress were obtained from RNA sequencing. AM-regulated DEGs in cell wall modification and peroxidases categories were mainly upregulated in shoots, suggesting AM symbiosis might assist in relaxing the cell wall and scavenging reactive oxygen species (ROS). AM symbiosis indeed improved ROS scavenging capacity in rice shoots under salt stress. In addition, genes involved in Calvin cycle and terpenoid synthesis were enhanced by AM symbiosis in shoots and roots under salt stress, respectively. AM-upregulated cation transporters and aquaporin in both shoots and roots were highlighted. Strikingly, “protein tyrosine kinase activity” subcategory was the most significantly over-represented GO term among all AM-upregulated and downregulated DEGs in both shoots and roots, highlighting the importance of kinase on AM-enhanced salinity tolerance. Overall, our results from the transcriptomic analyses indicate that AM symbiosis uses a multipronged approach to help plants achieve salt stress tolerance.
Project description:Rice (Oryza sativa) stands among the world's most important crop species and is salt-sensitive. The undue accumulation of sodium ions (Na+) in shoots has the strongest negative correlation with rice productivity under long-term salinity. The plasma membrane Na+/H+ exchanger protein SOS1 is the only Na+ efflux transporter that has to date been genetically characterized and only in dicot plants. Here, the importance of Na+ fluxes governed by the SOS system in the salt tolerance of rice was analyzed by a reverse-genetics approach. A sos1 loss-of-function mutant displayed exceptional salt sensitivity that correlated with excessive Na+ intake and impaired Na+ loading into the xylem. Thus, SOS1 controls net Na+ uptake by roots and the long-distance transport to shoots. The acute Na+ sensitivity of sos1 plants at low NaCl concentrations allowed the inspection of the transcriptional response to sodicity stress, without interference by the osmotic challenge intrinsic to high salinity treatments. The transcriptional response to salt of the sos1 mutant roots involved the preferential down-regulation of stress-related genes compared to the wild-type despite the greater intensity of the stress imposed to the mutant, which suggested impaired stress detection or inability to mount a comprehensive response to salinity.
Project description:The role and essentiality of silicon (Si) in plant biology has been debated for over 150 years in spite of numerous reports describing its beneficial properties. To obtain unique insights regarding the effect of Si on plants, we performed a complete transcriptome analysis of both control and powdery mildew-stressed Arabidopsis plants, with or without Si application, using a 44K microarray. Surprisingly, the expression of all but two genes was unaffected by Si in control plants, a result contradicting reports of possible direct effect of Si as a fertilizer. In contrast, inoculation of plants, treated or not with Si, altered the expression of a set of nearly 4,000 genes. Following functional categorization, many of the up-regulated genes were defense-related whereas a large proportion of down-regulated genes were involved in primary metabolism. Regulated defense genes included R genes, stress-related transcription factors, genes involved in signal transduction, the biosynthesis of stress hormones (SA, JA, ethylene), and the metabolism of reactive oxygen species. In inoculated plants treated with Si, the magnitude of down-regulation was attenuated by over 25%, an indication of stress alleviation. Our results demonstrate that Si treatment had no effect on the metabolism of unstressed plants suggesting a non essential role for the element, but that it has beneficial properties attributable to modulation of a more efficient response to pathogen stress. Keywords: compound effect, stress response
Project description:The aim of this study was to characterize the tissue tolerance mechanisms of rice under salt stress. Our preliminary experiment identified a japonica rice landrace Shuzenji-kokumai (SZK), which is considered to be tissue-tolerant because it can maintain better growth than salt-sensitive rice while having a high Na+ concentration in the shoots under salt stress. These mechanisms differ from those of most salt-tolerant rice varieties, which have low Na+ concentrations in the shoots. We compared the physiological and molecular characteristics of SZK with those of FL478, a salt-tolerant variety, and Kunishi, a salt-sensitive variety. Under salt stress conditions, SZK accumulated high levels of Na+ in roots, leaf sheaths, and leaf blades, which were almost as high as those in the salt-sensitive Kunishi. Simultaneously, SZK maintained better growth and physiological status, as determined by its higher dry weight, lower electrolyte leakage ratio, and lower malondialdehyde concentration. OsNHX1 and OsNHX2 were up-regulated in the leaf sheaths of SZK, suggesting that Na+ is compartmentalized in the vacuole to avoid Na+ toxicity. In contrast, FL478 showed up-regulation of OsHKT1;5 and OsSOS1 in the roots, which exclude Na+ from the shoots. RNA-seq analysis showed that 4623 and 1998 differentially expressed genes (DEGs) were detected in the leaf sheaths and leaf blades of SZK, respectively. Among them, the HSP (heat shock protein) gene expression was highly up-regulated only in SZK, indicating that SZK protects against the protein damage caused by Na+ toxicity. Our findings suggest that SZK has atypical survival mechanisms under salt-stress conditions. These mechanisms offer potential traits for improving salt tolerance in rice.
Project description:Cadmium (Cd)-contamination in soil has been becoming a major environmental problem in China. Ramie, a fiber crop, was frequently proposed to be used as the crop for phytoremediation of Cd-contaminated farmlands. However, high level Cd accumulation can cause a great inhibition of growth in ramie. To understand the potential mechanism for this phenomenon, the ramie genes involved in the Cd stress response were identified using Illumina pair-end sequencing in two Cd-stressed plants (CdS1 and CdS2) and two control plants (CO1 and CO2) in this study. Approximately 48.7, 51.6, 41.2, and 47.1 million clean sequencing reads generated from the libraries of CO1, CO2, CdS1, and CdS2, respectively, were De novo assembled to yield 56,932 non-redundant unigenes. A total of 26,686 (46.9%) genes were annotated for their function. Comparison of gene expression levels between CO and CdS ramie revealed 155 differentially expressed genes (DEGs). Sixteen DEGs was further confirmed their expression difference by real-time quantitative PCR (qRT-PCR). Among these 16 DEGs, 2 genes encoding GA2-oxidase which is a major enzyme for deactivating bioactive gibberellins (GAs) were found with a markedly up-regulated expression, which is possibly responsible for the growth inhibition of Cd-stressed ramie. Pathway enrichment analysis revealed that a pathway (Cutin, suberine and wax biosynthesis) was markedly enriched by DEGs. The discovery of these Cd stress-responsive genes and pathways will be helpful for further understanding the mechanism of Cd-stressed response and improving the ability of Cd stress tolerance in ramie. A total of four samples, two replicates of control plants (CO1 and CO2) and two replicates of cadmium-stressed plants (CdS1 and CdS2) were used for RNA-seq.
Project description:Purpose: The goals of this study are using RNA-seq to obtain cucumber and Botrytis cinerea transcriptome changes during infection Methods: mRNA profiles of anti-infection samples and interaction sample were generate by deep sequencing,using Illumina Hiseq 2500. The sequence reads that passed quality filters were analyzed at the transcript isoform level with two methods: BurrowsâWheeler Aligner (BWA) followed by ANOVA (ANOVA) and TopHat followed by Cufflinks. qRTâPCR validation was performed using SYBR Green assays Results: Using an optimized data analysis workflow,In total, 248,908,688 raw reads were generated; after removing low-quality reads and those containing adapter and poly-N, 238,341,648 clean reads remained to map the reference genome. There were 3,512 cucumber (differential expression genes) DEGs and 1,735 B. cinerea DEGs. GO enrichment and KEGG enrichment analysis were performed on these DEGs to study the interaction between cucumber and B. cinerea. To verify the reliability and accuracy of our transcriptome data, 5 cucumber DEGs and 5 B. cinerea DEGs were chosen for RT-PCR verification. Conclusions:To the best of our knowledge, this is the first analysis of large-scale transcriptome changes of cucumber during the infection of Botrytis cinerea. These results will increase our understanding of the molecular mechanisms of the cucumber defense Botrytis cinerea and may be used to protect plants against disasters caused by necrotrophic fungal pathogens. mRNA profiles of infection and anti-infection cucumber were generated by deep sequencing, using Illumina Hiseq 2500 .
Project description:Both barley (Hordeum vulgare) and rice (Oryza sativa) belong to Poaceae family, but differ greatly in salt tolerance. In order to understand molecular mechanisms in the difference of salt tolerance between the two species, the responses of transcriptomic profiles to salt stress were compared between rice (cultivar Nipponbare) and barley (accession XZ26) to reveal how alternative splicing (AS) coordinates with transcriptional regulation in adaptation to salt stress. Physiological study showed that XZ26 had higher salt tolerance than Nipponbare, as reflected by less growth inhibition, lower shoot Na+ concentration and higher K+/Na+ ratio when exposed to salt stress. Transcriptomic analysis showed that XZ26 had higher ROS scavenging ability, less degradation of protein kinases and enhanced anti-oxidation. Moreover, AS genes related to ion transporter genes and transcription factors could enhance and amplify K+/Na+ homeostasis and signal transduction cascades. We proposed that higher salt tolerance of barley accession XZ26 is attributed to its superior K+/Na+ homeostasis, tissue detoxication and less energy consumption. The present results provide insights at transcriptomic levels into reasons why barley has higher salt tolerance than rice.
Project description:Purpose: To characterize the functional implication of autophagy in the wheat response to stress, the key genes contributing in mediated salt tolerance of wheat seedlings through 3-MA were identified in normal or salt stress conditions in the presence or absence of added 3-MA by the transcriptome profiles. Methods: Four days after NaCl and 3-MA treatment, the roots and the third leaves were collected respectively with every 10 of them being mixed as one biological replicate for each treatment. Every treatment had four biological replicates. The wheat root and leaves mRNA profiles were generated by deep sequencing, in triplicate, using Illumina GAIIx. The sequence reads that passed quality filters were analyzed at the transcript isoform level with two methods: Burrows–Wheeler Aligner (BWA) followed by ANOVA (ANOVA) and TopHat followed by Cufflinks. qRT–PCR validation was performed using TaqMan and SYBR Green assays. Results: The RNA-Seq data had high quality and reliable results were obtained from the transcriptome assembly. A high correlation between biological replicates was observed for all treatments, which indicated that the four biological replicates were reliable in this study. Based on the principal component analysis (PCA), a clear separation between the NaCl-treated group and controls could be observed. The Q30 percentage (sequences with sequencing error rate lower than 0.1%) was over 94%, and the average GC content of the RNA-seq reads was 55.46%. After removing the adaptor and low-quality sequence, each library received 68310810-83844286 clean reads. These clean reads were mapped to the reference genome with match ratios in the range of 93.6%-95.9%, and 120744 genes predicted from the genome were found to be expressed (with FPKM > 0), including 25180 annotated genes in wheat genome. 3-MA treatment shifted the transcriptome a salt-stressed wheat seedling. The up-regulated DEGs and DEMs were increased, and the down-regulated DEGs and DEMs were decreased in 3-MA-added plants under NaCl stress condition. The study may help us understand the mechanism for 3-MA mediated salt tolerance and provide a theoretical basis for autophagy regulated salt response in wheat seedlings. Conclusions: 3-MA treatment shifted the transcriptome a salt-stressed wheat seedling. The up-regulated DEGs and DEMs were increased, and the down-regulated DEGs and DEMs were decreased in 3-MA-added plants under NaCl stress condition. The study may help us understand the mechanism for 3-MA mediated salt tolerance and provide a theoretical basis for autophagy regulated salt response in wheat seedlings.
Project description:Sesuvium portulacastrum (L.) is a halophyte, adapted to grow naturally under high-saline environments. Under control conditions, an inverse correlation was seen between Na and K accumulation, suggesting its facultative nature and ability to use Na-K interchangeably. No significant growth reduction was seen in seedlings upto 250 mM NaCl, except for youngest leaf-curling. Significantly higher accumulation of proline (4.3/1.8-folds), glycine betaine (1.4/1.4-folds) and selected amino-acids (1.4-4.2/1.4-2.3-folds) were seen in root/shoot of seedlings within 8 h stress duration. Inspite of having higher Na-accumulation, significantly lower number of differentially expressed genes (DEGs) were identified at 24 h than 8 h stress duration, indicating transcriptional restoration. As initial hours after NaCl stress are dominated by osmotic-component, 8h-specific DEGs, which are mainly transporters and transcription factors, reflect plant’s response towards NaCl-induced osmotic challenge. Most of the growth-related pathways including photosynthesis and ribosome-associated biogenesis gets suppressed, to support the activation of stress defence. Overexpression of SpRAB18 (an ABA-responsive dehydrin), one of the top-ranked DEGs, was found to impart salt-tolerance in soybean, indicating gene-function level conservation between halophyte and glycophyte. An open-access transcriptome database “SesuviumKB” (https:/ /cb.imsc.res.in/sesuviumkb) was developed to enable wide-scale gene function studies in S. portulacastrum, that could pave the way to engineer salt-tolerance in crops.