Project description:Recent studies have shown that several plant species require microbial associations for stress tolerance and survival. In this work, we show that the desert endophytic bacterium Enterobacter sp. SA187 enhances yield and biomass of alfalfa in field trials, revealing a high potential for improving desert agriculture. To understand the underlying molecular mechanisms, we studied SA187 interaction with Arabidopsis thaliana. SA187 colonized surface and inner tissues of Arabidopsis roots and shoots and conferred tolerance to salt and osmotic stresses. Transcriptome, genetic and pharmacological studies revealed that the ethylene signaling pathway plays a key role in mediating SA187-triggered abiotic stress tolerance to plants. While plant ethylene production is not required, our data suggest that SA187 induces abiotic stress tolerance by bacterial production of 2-keto-4-methylthiobutyric acid (KMBA), known be converted into ethylene in planta. These results reveal a part of the complex molecular communication process during beneficial plant-microbe interactions and unravel an important role of ethylene in protecting plants under abiotic stress conditions.
Project description:Drought is an inevitable stress almost all terrestrial plants face in their life cycles. Desert dwelling plants show extreme adaptations to drought but their genomes are largely unexplored compared to drought sensitive model plants generally studied to understand plant drought tolerance. Haloxylon ammodendron is a pioneer species extremely tolerant to drought and capable of colonizing desert sand dunes. Seedling establishment is the most critical development stage in the survival of H. ammodendron. H. ammodendron seedlings are able to withstand high light, and low temperature stresses characteristic of temperate desert environments in addition to drought. We have investigated the genome-wide transcript responses under induced drought stress during early seedling establishment to identify prevailing basal and induced gene clusters that likely contribute to survival and stress adapted growth in H. ammodendron. We find staggering support for drought response transcript accumulation together with other transcripts that may transform the cellular expression space into a preadapted state for salt, light, osmotic, and temperature stress tolerance. While transcript accumulation is excessive for genes associated with abiotic stress tolerance under an induced drought treatment, H. ammodendron seems to enhance biotic stress tolerance simultaneously by down-regulation of several genes that would be found at an up-regulated state during pathogen entry in susceptible plants. We detected enriched basal level transcript allocation that suggests preadaptation to abiotic stresses as well as pathogen defense in H. ammodendron when compared to other Amaranthaceae family transcriptomes under stress neutral conditions. Amaranthaceae is one of the most enriched plant families for extremophytes. We found transcripts that are generally maintained at low levels and some induced only under abiotic stress in Arabidopsis thaliana to be highly expressed under basal conditions in the Amaranthaceae transcriptomes including H. ammodendron. These could be novel candidates to expand or initiate discovery of new stress adaptive gene networks and mechanisms naturally selected in extremophytes that allow survival under environmental stresses.
Project description:This study evaluated the level of genetic variation among 543 wheat associations differing in K-deficiency tolerance at seedling and adult plant stages. Two of the 543 wheat associations, i.e. KN9204 and BN207, were identified as extreme K-deficiency tolerant and sensitive cultivars, respectively. We further conducted transcriptomic and metabolomics analyses using the roots of KN9204 and BN207 under normal or K-deficient conditions.Integrated analysis of gene expression and metabolite profiles revealed that dramatically more genes including those involved in ion homeostasis, cellular reactive oxygen species (ROS) homeostasis and glutamine synthetase pathways were induced in KN9204 as compared with BN207 under K-deficient conditions, which might indicate their unique roles in regulating plant K-starvation tolerance. These findings provided a better understanding of molecular responses of root adaptive strategies to K deprivation in wheat.
Project description:Food resource access can mediate establishment success in invasive species, and generalist herbivorous insects are thought to rely on mechanisms of transcriptional plasticity to respond to dietary variation. While asexually reproducing invasives typically have low genetic variation, the twofold reproductive capacity of asexual organisms is a marked advantage for colonization. We studied host-related transcriptional acclimation in parthenogenetic, invasive, and polyphagous weevils: Naupactus cervinus and N. leucoloma. We analyzed patterns of gene expression in three gene categories that can mediate weevil-host plant interactions through identification of suitable host plants, short-term acclimation to host plant defenses, and long-term adaptation to host plant defenses and their pathogens. This approach employed comparative transcriptomic methods to investigate differentially expressed host detection, detoxification, immune defense genes, and pathway-level gene set enrichment. Our results show that weevil gene expression responses can be host plant-specific, and that elements of that response can be . Some host plant groups, such as legumes, appear to be more taxing as they elicit a complex gene expression response which is both strong in intensity and specific in identity. However, the weevil response to taxing host plants shares many differentially expressed genes with other stressful situations, such as host plant cultivation conditions and transition to novel host, suggesting that there is an evolutionarily favorable shared gene expression regime for responding to different types of stressful situations. Modulating gene expression in the absence of other avenues for phenotypic adaptation may be an important mechanism of successful colonization for these introduced insects.
Project description:Endocycle is an alternative cell cycle during which the DNA is replicated in the absence of cytokinesis, resulting in cellular endopolyploidy. The endocycle is frequenctly observed in plant species that grow under extreme conditions. Thus, endopolyploidy has been postulated to be a mechanism facilitating adaptive growth. We used microarrays to assess endoploidy-dependant gene expression profiles in Arabidopsis thaliana root and to understand how subpopulations of cells with different endoploidy contributes to plant growth under different environmental conditions
Project description:This dataset contains raw files for metabolites collected from the soil and roots of four wetland plant species under non-sterile conditions, both in soil and hydroponically, during the day and night time periods.
Project description:Background: Roots are essential for plant growth and serve a variety of functions, such as anchoring the plant to the ground and absorbing water and nutrients. OsERF106MZ is a salinity-induced gene that is expressed in germinating seeds and the roots of rice seedlings. However, the roles of OsERF106MZ in root growth remain poorly understood. Results: Histochemical staining of GUS (β-glucuronidase) activity in transgenic rice seedlings harboring OsERF106MZp::GUS indicated that OsERF106MZ is mainly expressed in the exodermis, sclerenchyma layer, and vascular system of roots. Overexpression of OsERF106MZ in rice seedlings leads to an increase in the length of primary roots (PRs). The expression of the ABA (abscisic acid) biosynthetic gene, OsAO3, is downregulated in OsERF106MZ-overexpressing roots under normal conditions, while the expression of OsNPC3, an AtNPC4 homolog involved in ABA sensitivity, is reduced in OsERF106MZ-overexpressin roots under both normal and NaCl-treated conditions. Under normal conditions, OsERF106MZ-overexpressing roots have a significantly low level of ABA; moreover, exogenous application of 1.0 µM ABA can suppress the OsERF106MZ-mediated promotion of root growth. Meanwhile, OsERF106MZ-overexpressing roots display less sensitivity to the ABA-mediated inhibition of root growth, when they are treated with ABA at 5.0 µM under normal conditions or exposed to NaCl-treated conditions. Chromatin immunoprecipitation (ChIP)-qPCR and luciferase (LUC) reporter assays showed that OsERF106MZ can bind directly to the sequence containing the GCC-box in the promoter region of OsAO3 gene and repress its expression. Conclusion: OsERF106MZ may play a role in maintaining root growth for resource uptake when rice seeds are sprouted under salinity stress, which is arrived at by alleviating the ABA-mediated inhibition of root growth.
Project description:The shoots and roots of a plant respond differently to osmotic stress, as they have distinct functions and anatomical structures. Under conditions of high solute concentration, such as in saline soils or drought, water uptake by the roots is reduced, resulting in cellular dehydration. In this study, we performed transcriptional profiling of roots of Arabidopsis under osmotic stress conditions such as high salinity and drought using mRNA-Seq for the assessment of gene expression changes in roots of Arabidopsis. mRNA-Seq analysis showed that many differentially expressed genes showed differential expressions under both salt stress and drought stress conditions in roots and were distinct from aerial parts. We confirmed 68 transcription factor genes which is involved in osmotic stress signal transduction in roots and are connected tightly. Interestingly, well-known ABA-dependent and/or -independent osmotic stress-responsive genes were less increased in roots, indicating that osmotic stress response in roots might be regulated by stress pathways other than well-known pathways. We identified 26 osmotic stress-responsive genes, which have alternative splicing variant isoforms, showed distinct expression in roots under osmotic stress conditions from the mRNA-Seq analysis. Quantitative RT-PCR confirmed that alternative splicing variants, such as ANNAT4, MAGL6, TRM19, and CAD9, have differential expressions in roots under osmotic stress conditions, indicating that alternative splicing is an important regulatory mechanism in osmotic stress response in roots. Taken together, our study suggest that many transcription factor families are involved in osmotic stress response in roots and tightly connected each other. In addition, alternative splicing and function of alternative splicing variant isoforms are also important in osmotic stress response in roots. To understand the alternative splicing mechanism in roots, further study is necessary.