Project description:Soil salinity is a major production constrain for agricultural crops, especially in Oryza sativa (rice). Analyzing physiological effect and molecular mechanism under salt stress is key for developing stress-tolerant plants. Roots system has a major role in coping with the osmotic change impacted by salinity and few salt-stress-related transcriptome studies in rice have been previously reported. However, transcriptome data sets using rice roots grown in soil condition are more relevant for further applications, but have not yet been available. The present work analyzed rice root and shoot physiological characteristics in response to salt stress using 250 mM NaCl for different timepoints. Subsequently, we identified that 5 day treatment is critical timepoint for stress response in the specific experimental design. We then generated RNA-Seq-based transcriptome data set with rice roots treated with 250 mM NaCl for 5 days along with untreated controls in soil condition using rice japonica cultivar Chilbo. We identified 447 upregulated genes under salt stress with more than fourfold changes (p value < 0.05, FDR < 0.05) and used qRT-PCR for six genes to confirm their salt-dependent induction patterns. GO-enrichment analysis indicated that carbohydrate and amino-acid metabolic process are significantly affected by the salt stress. MapMan overview analysis indicated that secondary metabolite-related genes are induced under salt stress. Metabolites profiling analysis confirmed that phenolics and flavonoids accumulate in root under salt stress. We further constructed a functional network consisting of regulatory genes based on predicted protein–protein interactions, suggesting useful regulatory molecular network for future applications.
Project description:Dongxiang wild rice (Oryza rufipogon Griff.) is the progenitor of cultivated rice (Oryza sativa L.) and is well known for its superior level of tolerance against cold, drought and diseases. To date, however, little is known about the salt-tolerant character of Dongxiang wild rice. To elucidate the molecular genetic mechanisms of salt-stress tolerance in Dongxiang wild rice, the Illumina HiSeq 2000 platform was used to analyze the transcriptome profiles of the leaves and roots at the seedling stage under salt stress compared with those under normal conditions. The analysis results for the sequencing data showed that 6,867 transcripts were differentially expressed in the leaves (2,216 up-regulated and 4,651 down-regulated) and 4,988 transcripts in the roots (3,105 up-regulated and 1,883 down-regulated). Among these differentially expressed genes, the detection of many transcription factor genes demonstrated that multiple regulatory pathways were involved in salt stress tolerance. In addition, the differentially expressed genes were compared with the previous RNA-Seq analysis of salt-stress responses in cultivated rice Nipponbare, indicating the possible specific molecular mechanisms of salt-stress responses for Dongxiang wild rice. A large number of the salt-inducible genes identified in this study were co-localized onto fine-mapped salt-tolerance-related quantitative trait loci, providing candidates for gene cloning and elucidation of molecular mechanisms responsible for salt-stress tolerance in rice.
Project description:Rice seedlings at 3-leaf stage were used for expression analysis in control and salt stressed (incloudling salt treatment for 3, 24hrs and recovery from salt stress for 24hrs) samples. Samples of shoots and roots from biological replicates of both genotypes were generated and the expression profiles were determined using Phalanx Rice OneArray@ v1.
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: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:Salt-water Rice has stronger resistance than common rice under high salt environment. We aim to find anti-salt genes by comparing the gene expression, which can provide target genes for further function research
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:Background: Rice is a staple crop for over half of the global population, but soil salinization poses a significant threat to its production. As a type of polyamine, spermidine (Spd) has been shown to reduce stress-induced damage in plants, but its specific role and mechanism in protecting rice roots under salt stress require further investigation. Results: This study suggested spermidine (Spd) mitigates salt stress on rice root growth by enhancing antioxidant enzyme activity and reducing peroxide levels. Transcriptomic analysis showed that salt stress caused 333 genes to be upregulated and 1,765 to be downregulated. However, adding Spd during salt treatment significantly altered this pattern: 2,298 genes were upregulated and 844 were downregulated, which indicated Spd reverses some transcriptional changes caused by salt stress. KEGG pathway analysis suggested that Spd influenced key signaling pathways, including MAPK signaling, plant hormone signal transduction, and phenylalanine metabolism. Additionally, the bZIP transcription factor OsbZIP73 was upregulated after Spd treatment, which is confirmed by Western blot. Further insights into the interaction between OsbZIP73 and Spd were gained through fluorescence polarization experiments, showing that Spd enhances protein OsbZIP73's affinity for RNA. Functional enrichment analyses revealed that OsPYL1, OsSPARK1, and various SAUR family genes involved in Spd-affected pathways. The presence of G/A/C-box elements in these genes suggests they are potential targets for OsbZIP73. Conclusions: Our findings suggest a strategy of using spermidine as a chemical alleviator for salt stress and provide insights into the regulatory function of OsbZIP73 in mitigating salt stress in rice roots.
Project description:Roots make the first contact with the soil environment and are the first responders of stress. These root behaviors are quantifiable and adaptive. The response of rice varieties in mechanical and salinity stress was measured in a novel experimental setup that mimics the soil environment. We analyzed the response of roots by means of SAC (Stress Adaptation Coefficient) in 28 rice varieties that include high-yield salt tolerant varieties as well as geographically isolated native rice varieties. cDNA microarray of IR64 root-tip shows about 6000 common transcripts to be differentially regulated among the two stresses and common pathways were identified. Overall, our study indicates that there is an important commonality in the molecular basis of salt and mechanical stress and presents an easy-to-perform early establishment stress screen for rice varieties.
Project description:Dongxiang wild rice (Oryza rufipogon Griff.) is the progenitor of cultivated rice (Oryza sativa L.) and is well known for its superior level of tolerance against cold, drought and diseases. To date, however, little is known about the salt-tolerant character of Dongxiang wild rice. To elucidate the molecular genetic mechanisms of salt-stress tolerance in Dongxiang wild rice, the Illumina HiSeq 2000 platform was used to analyze the transcriptome profiles of the leaves and roots at the seedling stage under salt stress compared with those under normal conditions. The analysis results for the sequencing data showed that 6,867 transcripts were differentially expressed in the leaves (2,216 up-regulated and 4,651 down-regulated) and 4,988 transcripts in the roots (3,105 up-regulated and 1,883 down-regulated). Among these differentially expressed genes, the detection of many transcription factor genes demonstrated that multiple regulatory pathways were involved in salt stress tolerance. In addition, the differentially expressed genes were compared with the previous RNA-Seq analysis of salt-stress responses in cultivated rice Nipponbare, indicating the possible specific molecular mechanisms of salt-stress responses for Dongxiang wild rice. A large number of the salt-inducible genes identified in this study were co-localized onto fine-mapped salt-tolerance-related quantitative trait loci, providing candidates for gene cloning and elucidation of molecular mechanisms responsible for salt-stress tolerance in rice. Leaf and root mRNA profiles of Dongxiang wild rice at the seedling stage with or without salt stress were generated by deep sequencing, on Illumina Hiseq 2000 platform.