ABSTRACT: Dissecting physiological and transcriptional responses of nitric oxide to drought stress by increasing in vivo nitric oxide content in Arabidopsis
Project description:Nitric oxide (NO) is involved in all major environmental stresses. However, most of these understandings were mainly based on pharmacological study using NO modulator compounds. Recently, our studies together with others provided a new class of plant experimental system with specific in vivo NO release through constitutively overexpressing rat neuronal NO synthase (nNOS) in plants. In this study, we found that the nNOS transgenic Arabidopsis plants displayed lower level of H2O2 content, but higher levels of antioxidant enzyme activities and osmolytes under drought stress conditions. Transcriptomic analysis identified 490 and 20 genes that were differentially expressed in wild type (WT) and nNOS transgenic plants under control and drought stress conditions, respectively. Pathway analysis revealed that many genes involved in photosynthesis, cell, misc, co-factor and vitamin metabolism, major CHO metabolism, OPP and secondary metabolism were largely changed in nNOS vs. WT under control or drought stress conditions. Interestingly, CBF1/2 and 13 zinc finger family proteins, known as important family of transcription regulators in modulating several stress-responsive genes, were differentially expressed by nNOS transgenic effect. Additionally, some genes were commonly regulated by nNOS transgenic and abscisic acid (ABA) effects, indicating new insights to cross-talk between ABA and NO. Taken together, in vivo NO modulated antioxidant enzyme activities, osmolyte level, and the expression of genes involved in several pathways, thereby resulting in enhanced stress tolerance in nNOS transgenic plants. These observations might provide some insights to understand the physiological and molecular mechanisms of NO in response to drought stress in Arabidopsis. Two transgenic Arabidopsis lines (nNOS-2 and nNOS-25) with the nNOS gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter, as well as Col-0 (WT), were used in this research. RNA samples from two nNOS transgenic lines were pooled for cRNA labelling and chip hybridization.
Project description:Nitric oxide (NO) is involved in all major environmental stresses. However, most of these understandings were mainly based on pharmacological study using NO modulator compounds. Recently, our studies together with others provided a new class of plant experimental system with specific in vivo NO release through constitutively overexpressing rat neuronal NO synthase (nNOS) in plants. In this study, we found that the nNOS transgenic Arabidopsis plants displayed lower level of H2O2 content, but higher levels of antioxidant enzyme activities and osmolytes under drought stress conditions. Transcriptomic analysis identified 490 and 20 genes that were differentially expressed in wild type (WT) and nNOS transgenic plants under control and drought stress conditions, respectively. Pathway analysis revealed that many genes involved in photosynthesis, cell, misc, co-factor and vitamin metabolism, major CHO metabolism, OPP and secondary metabolism were largely changed in nNOS vs. WT under control or drought stress conditions. Interestingly, CBF1/2 and 13 zinc finger family proteins, known as important family of transcription regulators in modulating several stress-responsive genes, were differentially expressed by nNOS transgenic effect. Additionally, some genes were commonly regulated by nNOS transgenic and abscisic acid (ABA) effects, indicating new insights to cross-talk between ABA and NO. Taken together, in vivo NO modulated antioxidant enzyme activities, osmolyte level, and the expression of genes involved in several pathways, thereby resulting in enhanced stress tolerance in nNOS transgenic plants. These observations might provide some insights to understand the physiological and molecular mechanisms of NO in response to drought stress in Arabidopsis.
Project description:Water availability is the biggest single limitation on plant productivity worldwide. In Arabidopsis, adjustments to drought stress, involving changes in metabolism and gene expression drive increased drought tolerance and initiate diverse drought avoidance and escape responses. To address regulatory processes that integrate these complex responses we hypothesised that we needed to identify genes that govern early responses to drought. To this end, we produced a high-resolution time series transcriptomics dataset, coupled with detailed physiological and metabolic analyses of plants subjected to a slow transition from well-watered to the onset of drought conditions. 1825 differentially expressed genes (DEGs) were identified which showed no significant enrichment in gene ontology terms associated with dehydration responses and abscisic acid (ABA) regulation, confirming that the gene expression time series had targeted events prior to severe drought stress. Initial changes in gene expression coincided with a drop in carbon assimilation, not the later increase in foliar ABA content. Thus the early physiological and gene expression responses to drought were not driven by changes in leaf ABA content. In order to identify gene regulatory networks (GRNs) linked to early events, we used Bayesian network modelling of differentially expressed transcription factor (TF) genes. This approach identified AGAMOUS-LIKE 22 as key hub gene in a TF GRN. AGL22 is involved in the transition from vegetative state to flowering. Loss of AGL22 expression affected flowering time and drying rate providing a link between early changes in metabolism and the subsequent initiation of developmental responses to stress that govern plant productivity.
2016-02-29 | GSE65046 | GEO
Project description:Dissecting drought stress responses of closely related Brassicaceae
Project description:Sucrose synthase (SUS), a key enzyme of sugar metabolism, plays an important role in the regulation of carbon partitioning in plant, and affects important agronomic traits and abiotic responses to adversity. However, the function of ZmSUS1 in plant drought tolerance is still unknown. In this study, the expression patterns of ZmSUS1 in different tissues and under drought stress were analyzed in maize (Zea mays L.). It was found that ZmSUS1 was highly expressed during kernel development but also in leaves and roots of maize, and ZmSUS1 was induced by drought stress. Homozygous transgenic maize lines of ZmSUS1 overexpressing increased the content and activity of SUS under drought stress and exhibited higher relative water content, proline and abscisic acid content in leaves. Specifically, the net photosynthetic rate and the soluble sugar contents including sucrose、glucose、fructose、UDP-glucose and ADP-glucose in transgenic plants was significantly improved after drought stress. RNA-seq analysis showed that overexpressing of ZmSUS1 mainly affected the expression level of carbon metabolism-related genes, especially the expression level of sucrose metabolism-related genes including ZmSUS、ZmSPS and ZmINV were significantly up-regulated in transgenic maize. Overall, these results suggested that ZmSUS1 improved drought tolerance by regulating sucrose metabolism and increasing soluble sugar content, and endowing transgenic maize with higher relative water content and photosynthesis levels, which can be served as a new gene candidate for cultivating drought resistant maize varieties.
Project description:Cadmium treatment induces slow but long lasting nitric oxide production in plant tissues. This NO production can be suppressed using the commonly used Nitric Oxide Synthase inhibitor L-NAME. This inhibitor tends to partially alleviate Cd toxicity. This effect is correlated with a strong diminution of Cd content in roots of plants treated both with Cd and L-NAME compared to roots from plants treated with Cd only. The main goal of this study is the identification of transcriptionnal changes caused by Cd-induced nitric oxide, and that could potentially result in enhanced Cd root accumulation.
Project description:We describe the effects of restraint stress in presence or absence of an inhibitor of nitric oxide synthase on metastasis formation in lungs of in vivo syngeneic model of mouse breast cancer analysed by whole genome expression microarrays
Project description:Abscisic acid (ABA)-, stress-, and ripening-induced (ASR) proteins are involved in abiotic stress responses. However, the exact molecular mechanism underlying their function remains unclear. Notably, the direct targets of ASRs that confer drought stress tolerance have not yet been identified.In this study, we report that MaASR expression was induced by drought stress and MaASR overexpression in Arabidopsis strongly enhanced drought stress tolerance. Physiological analyses indicated that transgenic lines had higher survival rates, germination rates and proline content, and lower water loss rates (WLR) and malondialdehyde (MDA) content. MaASR-overexpressing lines also showed smaller leaves and reduced sensitivity to ABA. Further, microarray and chromatin immunoprecipitation-based sequencing (ChIP-seq) analysis revealed that MaASR participates in regulating photosynthesis, respiration, carbohydrate and phytohormone metabolism and signal transduction to confer plants with enhanced drought stress tolerance. Direct interactions of MaASR with promoters for the hexose transporter and Rho GTPase-activating protein (RhoGAP) genes were confirmed by electrophoresis mobility shift array (EMSA) analysis. Our results indicate that MaASR acts as a crucial regulator of photosynthesis, respiration, carbohydrate and phytohormone metabolism and signal transduction to mediate drought stress tolerance.
Project description:Our analysis provides a comprehensive picture of how P. trichocarpa responds to drought stress at physiological and transcriptome levels which may help to understand molecular mechanisms associated with drought response and could be useful for genetic engineering of woody plants. Drought stress treatment was performed dividing P. trichocarpa plants into the well-watered (WW) group (soil volumetric water content of 40â45 %) and the water-limited group (soil volumetric water content of 10â15 %). Two cDNA libraries constructed separately from the WW and WL groups were subjected to high-throughput Illumina sequencing.