Arabidopsis mutants representing each of the four Mediator modules reveal unique functions in the transcriptional response to salt stress (original) (raw)
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Scientific Reports, 2020
Adverse environmental conditions are detrimental to plant growth and development. Acclimation to abiotic stress conditions involves activation of signaling pathways which often results in changes in gene expression via networks of transcription factors (TFs). Mediator is a highly conserved co-regulator complex and an essential component of the transcriptional machinery in eukaryotes. Some Mediator subunits have been implicated in stress-responsive signaling pathways; however, much remains unknown regarding the role of plant Mediator in abiotic stress responses. Here, we use RNA-seq to analyze the transcriptional response of Arabidopsis thaliana to heat, cold and salt stress conditions. We identify a set of common abiotic stress regulons and describe the sequential and combinatorial nature of TFs involved in their transcriptional regulation. Furthermore, we identify stress-specific roles for the Mediator subunits MED9, MED16, MED18 and CDK8, and putative TFs connecting them to differ...
BMC Plant Biology, 2011
Background Salt stress hinders the growth of plants and reduces crop production worldwide. However, different plant species might possess different adaptive mechanisms to mitigate salt stress. We conducted a detailed pathway analysis of transcriptional dynamics in the roots of Medicago truncatula seedlings under salt stress and selected a transcription factor gene, MtCBF4, for experimental validation. Results A microarray experiment was conducted using root samples collected 6, 24, and 48 h after application of 180 mM NaCl. Analysis of 11 statistically significant expression profiles revealed different behaviors between primary and secondary metabolism pathways in response to external stress. Secondary metabolism that helps to maintain osmotic balance was induced. One of the highly induced transcription factor genes was successfully cloned, and was named MtCBF4. Phylogenetic analysis revealed that MtCBF4, which belongs to the AP2-EREBP transcription factor family, is a novel member of the CBF transcription factor in M. truncatula. MtCBF4 is shown to be a nuclear-localized protein. Expression of MtCBF4 in M. truncatula was induced by most of the abiotic stresses, including salt, drought, cold, and abscisic acid, suggesting crosstalk between these abiotic stresses. Transgenic Arabidopsis over-expressing MtCBF4 enhanced tolerance to drought and salt stress, and activated expression of downstream genes that contain DRE elements. Over-expression of MtCBF4 in M. truncatula also enhanced salt tolerance and induced expression level of corresponding downstream genes. Conclusion Comprehensive transcriptomic analysis revealed complex mechanisms exist in plants in response to salt stress. The novel transcription factor gene MtCBF4 identified here played an important role in response to abiotic stresses, indicating that it might be a good candidate gene for genetic improvement to produce stress-tolerant plants.
Plant Molecular Responses to Salt Stress
2020
Plants are frequenly exposed to environmental changes. In fact, abiotic stresses are the most serious factors limiting the productivity of agricultural crops, with adverse effects on germination, plant vigor and crop quality and yield. In particular, salinity stress is a global problem widespread that affects over 800 million ha. In the Mediterranean area, seawater intrusion into freshwater aquifers highly contribute to soil salinisation, resulting in crops productivity decrease. Responses to abiotic stresses are complicated pathways involving the interaction of different signalling molecules to coordinate a specific metabolic pathways. The regulation of these responses involves transcriptional factors, which regulate gene expression by binding to specific DNA promoter sequences. Transcription factors involved in salt stress responses include DRE-related binding factors, leucine zipper DNA binding proteins, putative zinc finger proteins, myb proteins, bZIP/HD-ZIPs, and AP2/EREBP. Particularly, AP2/ERF domain proteins include the DREB or CBF proteins binding to dehydration response elements (DRE) or C-repeats. Transcription factors are powerful targets for genetic engineering in abiotic stress resistance in crops and many studies have been focused on this topic.
Transcriptomic and Physiological Variations of Three Arabidopsis Ecotypes in Response to Salt Stress
PLoS ONE, 2013
Salt stress is one of the major abiotic stresses in agriculture worldwide. Analysis of natural genetic variation in Arabidopsis is an effective approach to characterize candidate salt responsive genes. Differences in salt tolerance of three Arabidopsis ecotypes were compared in this study based on their responses to salt treatments at two developmental stages: seed germination and later growth. The Sha ecotype had higher germination rates, longer roots and less accumulation of superoxide radical and hydrogen peroxide than the Ler and Col ecotypes after short term salt treatment. With long term salt treatment, Sha exhibited higher survival rates and lower electrolyte leakage. Transcriptome analysis revealed that many genes involved in cell wall, photosynthesis, and redox were mainly down-regulated by salinity effects, while transposable element genes, microRNA and biotic stress related genes were significantly changed in comparisons of Sha vs. Ler and Sha vs. Col. Several pathways involved in tricarboxylic acid cycle, hormone metabolism and development, and the Gene Ontology terms involved in response to stress and defense response were enriched after salt treatment, and between Sha and other two ecotypes. Collectively, these results suggest that the Sha ecotype is preconditioned to withstand abiotic stress. Further studies about detailed gene function are needed. These comparative transcriptomic and analytical results also provide insight into the complexity of salt stress tolerance mechanisms.
Molecular plant responses to combined abiotic stresses put a spotlight on unknown and abundant genes
Journal of Experimental Botany
Environmental stresses such as drought, heat, and salinity limit plant development and agricultural productivity. While individual stresses have been studied extensively, much less is known about the molecular interaction of responses to multiple stresses. To address this problem, we investigated molecular responses of Arabidopsis to single, double, and triple combinations of salt, osmotic, and heat stresses. A metabolite profiling analysis indicated the production of specific compatible solutes depending on the nature of the stress applied. We found that in combination with other stresses, heat has a dominant effect on global gene expression and metabolite level patterns. Treatments that include heat stress lead to strongly reduced transcription of genes coding for abundant photosynthetic proteins and proteins regulating the cell life cycle, while genes involved in protein degradation are up-regulated. Under combined stress conditions, the plants shifted their metabolism to a survi...
International Journal of Molecular Sciences, 2020
Salt stress is one of the most serious threats in plants, reducing crop yield and production. The salt overly sensitive (SOS) pathway in plants is a salt-responsive pathway that acts as a janitor of the cell to sweep out Na+ ions. Transcription factors (TFs) are key regulators of expression and/or repression of genes. The basic leucine zipper (bZIP) TF is a large family of TFs regulating various cellular processes in plants. In the current study, we investigated the role of the Arabidopsis thaliana bZIP62 TF in the regulation of SOS signaling pathway by measuring the transcript accumulation of its key genes such as SOS1, 2, and 3, in both wild-type (WT) and atbzip62 knock-out (KO) mutants under salinity stress. We further observed the activation of enzymatic and non-enzymatic antioxidant systems in the wild-type, atbzip62, atcat2 (lacking catalase activity), and atnced3 (lacking 9-cis-epoxycarotenoid dioxygenase involved in the ABA pathway) KO mutants. Our findings revealed that atb...
A Krüppel-like transcription factor gene is involved in salt stress responses in Medicago spp
Plant and Soil, 2003
Legume plants are able to fix nitrogen in symbiotic association with rhizobia and, like many crops, are sensitive to high salt conditions. However, very few molecular markers can be associated to stress tolerance in legume crops. A Krüppel-like transcription factor, Mtzpt2-1, required for the formation of the nitrogen-fixing region, confers salt tolerance to yeast cells. Here, legume responses to salt stresses were studied using alfalfa and its close relative Medicago truncatula, a model legume species. Salt stress induces the Mszpt2-1 gene both in roots and root harbouring nodules. In addition, Sinorhizobium meliloti strains tolerating up to 700 mM NaCl, were used in nodulation assays to assess salt tolerance of the symbiotic response of M. truncatula. Few nodules, mainly in the upper part of the root, could be detected in plants treated with 200 m{M} NaCl, suggesting that nodule initiation was particularly sensitive to salt stress. We have also defined for M. truncatula the threshold of NaCl tolerance after which recovery of stressed plants is irreversible under laboratory conditions. After analysing several times of salt treatment (150 m{M} NaCl), M. truncatula 108R plants stressed for 7 days could not recover (less than 5%), whereas a 4-day treatment allowed at least 75% recovery. Transgenic M. truncatula plants expressing Mtzpt2-1 in antisense configuration are more sensitive to `recover' from salt stress than the wild type. These results identify Mtzpt2-1 as a molecular marker potentially linked to stress tolerance in M. truncatula and suggest its participation in a transcriptional program induced in these plants to cope with salt stress.
The genetic architecture of plant growth and development of cereal crops are greatly affected by abiotic stress conditions such as drought, salinity, and low temperature. Plants respond to these environmental challenges through a number of molecular and physiological mechanisms that alter the signal transduction pathways and expression of different genes. These stress inducible genes are altered in order to sustain under adverse climatic factors. Several regulatory of molecular and metabolic pathways that activate or repress the stress tolerance genes with the help of transcription factors and cis-acting elements in the stress-responsive promoters function for the plant adaptation to environmental stresses. Here, we summarize recent studies highlighting the role of stress signaling molecules and specific members of transcription factors and genes expression in the adaptive responses to abiotic stresses.
DNA
WRKY transcription factors play a pivotal role in regulating stress signaling pathways, including those associated with salt stress response. The present work characterized the effects of two WRKY genes from Vigna unguiculata, namely VuWRKY21 and VuWRKY87, on enhancing plant salinity tolerance. Under salt stress conditions, Arabidopsis lines expressing VuWRKY21 or VuWRKY87 showed elevated expression of genes participating in saline stress response pathways and reduced oxidative stress induced by reactive oxygen species (ROS). Among the salt-responsive genes in Arabidopsis, AtP5CS1, AtNHX1, AtRD29A, AtSOS3, AtSOS2, and AtSOS1 exhibited modulated expression levels after stress imposition. Furthermore, compared to wild-type plants, at most evaluated times, transgenic lines, on average, presented lower H2O2 content while displaying higher content of SOD (EC: 1.15.1.1) and CAT (EC: 1.11.1.6) at early stages of salt stress. These findings suggest that the expression of both VuWRKY genes i...