ABSTRACT: Different wheat cultivars may be classified as either winter or spring varieties depending on whether they require exposure to an extended period of cold in order to become competent to flower. Using a growth regime that mimics the conditions that occur during a typical winter in Britain, we wished to survey the genes that are involved in phase transition as well as those involved in cold-acclimation. Keywords: Time course Overall design: We wished to study the profiles of expression of genes involved in both phase transition (vegetative to reproductive growth transition) and cold-acclimation. To that end we we exposed plants to a gradual, stepped decline in both temperature and light. We sampled plants at three time points (3 weeks post-germination, 5 weeks post germination and 9 weeks post germination). We took samples from two separate tissues (crown and leaf) to se whether responses were different. We used two biological reps for each time point and tissue. Control plants were exposed to a delined in day-length and light intensity, but not in temperature.
Project description:Different wheat cultivars may be classified as either winter or spring varieties depending on whether they require exposure to an extended period of cold in order to become competent to flower. Using a growth regime that mimics the conditions that occur during a typical winter in Britain, we wished to survey the genes that are involved in phase transition as well as those involved in cold-acclimation. Experiment Overall Design: We wished to study the profiles of expression of genes involved in both phase transition (vegetative to reproductive growth transition) and cold-acclimation. To that end we we exposed plants to a gradual, stepped decline in both temperature and light. We sampled plants at three time points (3 weeks post-germination, 5 weeks post germination and 9 weeks post germination). We took samples from two separate tissues (crown and leaf) to se whether responses were different. We used two biological reps for each time point and tissue. Control plants were exposed to a delined in day-length and light intensity, but not in temperature.
Project description:Frost tolerance is the main component of winter-hardiness. To express this trait, plants have to sense low temperature, and respond by activating the process of cold acclimation. The molecular mechanisms of this acclimation have not been fully understood in the agronomically important group of forage grasses, including Lolium-Festuca species. Herein, the introgression forms of L. multiflorum/F. arundinacea distinct with respect to their frost tolerance, were used as models for the comprehensive, proteomic and physiological, research to recognize the crucial components of cold acclimation in forage grasses. The obtained results stressed the importance of photosynthetic performance under acclimation to low temperature. The stable level of photochemical processes after three weeks of cold acclimation in the introgression form with a higher level of frost tolerance, combined simultaneously with the stable level of CO2 assimilation after that period, despite decreased stomatal conductance, indicated the capacity for that form to acclimate its photosynthetic apparatus to low temperature. This phenomenon was driven by the Calvin cycle efficiency, associated with revealed here accumulation profiles and activities of chloroplastic aldolase. The capacity to acclimate the photosynthetic machinery to cold could be one of the most crucial components of forage grass metabolism to improve frost tolerance.
Project description:Recently, intensive global climate change has become a major factor impacting plant survival during the winter. Freezing cold temperatures during the winter and abnormal temperature fluctuations during the winter and early spring are the most harmful ambient factors threatening tea plant winter survival and currently cause marked economic losses in tea production. In this study, by simulating natural climate change, we established cold acclimation (CA) and rapid cold stress (after CA) conditions to comprehensively investigate the transcriptome changes involved in CA and rapid cold stress. Electrolyte leakage (EL) rate and expression profile clustering analyses confirmed that the experimental design was valid. Comparative transcription analysis identified many differentially expressed genes (DEGs) involved in both processes. Time course and pathway enrichment analyses further revealed the physiological changes that occur during the initial period of CA and the cell wall changes that occur throughout the entire CA process; these changes play crucial roles in increasing freezing tolerance during this process. Compared with CA, different cold response mechanisms were rapidly activated under cold stress; however, the subsequent accumulation of reactive oxygen species, which affect multiple aspects, caused by freezing cold could be the harshest factor impairing tea leaves. Moreover, we investigated 60 DEGs shared by both processes and highlighted the importance of KCSs, HXXXD-type acyl-transferase family proteins, NAC080, SWEETs and ENOs in the responses to various cold conditions. These results greatly improve our knowledge of cold response mechanisms in tea plants and provide meaningful information for functional studies investigating cold tolerance-related genes. Overall design: Total of 8 biosamples including cold acclimation treatment and freezing cold treatment, triplication were applied. Therefore 24 microarray were used in this study.
Project description:To understand mRNA expression pattern during cold acclimation and deacclimation, transcriptional profiling of cold acclimation and deacclimation-treated plants were analyzed using Agilent-015059 Arabidopsis 3 Oligo Microarray 4x44K G2519F. Arabidopsis Col-0 were grown on MS plate for 2 weeks (16 hours light / 8 hours dark). Two week-old Arabidopsis samples (NA, non acclimation) were treated with cold (2 ºC) for 7 days (CA7d) under 12h/12h light/dark conditions. Deacclimation-treated samples (DA6h, DA12h, DA24h) were grown at normal growth temperature under long day conditions after cold treatment for 7 days. Then total RNA was prepared from the whole seedling and used for the microarray hybridization. Three replicative hybridization experiments for each array were carried out using the independent biological samples.
Project description:The crown is the critical region for survival of winter wheat exposed to low temperature stresses. When wheat is exposed to non-freezing low temperatures, they can increase their freezing tolerance (cold acclimation, ACC). Changes within the apoplast are thought to be crucial for acquisition of freezing tolerance. However, how individual tissues within the ccrown, namely the shoot apical meristem (SAM, responsible for new shoot growth) and vascular transition zone (VTZ, located at the base of the crown)enhance tolerance to freezing has not yet been characterized. In the present study, we conducted shotgun proteomic analysis of the apoplast fluid to investigate ACC-induced proteins in the SAM and VTZ.
Project description:During cold acclimation plants increase their freezing tolerance in response to low non-freezing temperatures. This is accompanied by many physiological, biochemical and molecular changes that have been extensively investigated. In addition, many cold acclimated plants become more freezing tolerant during exposure to mild, non-damaging sub-zero temperatures. There is hardly any information available about the molecular basis of this adaptation. However, Arabidopsis thaliana is among the species that acclimate to sub-zero temperatures. This makes it possible to use the molecular and genetic tools available in this species to identify components of sub-zero signal transduction and acclimation. Here, we have used microarrays and a qRT-PCR primer platform covering 1880 genes encoding transcription factors to monitor changes in gene expression in the accessions Columbia-0, Rschew and Tenela during the first three days of sub-zero acclimation at -3°C. The results indicate that gene expression during sub-zero acclimation follows a tighly controlled time-course. Especially AP2/EREBP and WRKY transcription factors may be important regulators of sub-zero acclimation, although the CBF signal transduction pathway seems to be less important during sub-zero than during cold acclimation. Globally, we estimate that approximately 5% of all Arabidopsis genes are regulated during sub-zero acclimation. Particularly photosynthesis-related genes were down-regulated and genes belonging to the functional classes of cell wall biosynthesis, hormone metabolism and RNA regulation of transcription were up-regulated. Collectively, these data provide the first global analysis of gene expression during sub-zero acclimation and allow the identification of candidate genes for forward and reverse genetic studies into the molecular mechanisms of sub-zero acclimation. We used whole genome microarrays to monitor changes in gene expression in the Arabidopsis thaliana accessions Columbia-0, Rschew and Tenela during three days of acclimation to sub-zero temperature at -3°C after cold acclimation Plants from Arabidopsis thaliana accessions Columbia-0, Rschew and Tenela were cold acclimated at 4°C for two weeks. Detached leaves were then sub-zero acclimated at -3°C for 8 h, 1 d or 3 d at -3°C. Leaves of cold acclimated plants and sub-zero acclimated leaves were collected for RNA extraction and hybridization on Affymetrix ATH1 microarrays in order to explore temporal transcriptome changes during sub-zero acclimation. For each sample total RNA was isolated from a pool of three leaves from three different plants. The experiment was performed in three idenpendent biological replicates.
Project description:Leafy spurge (Euphorbia esula) is an herbaceous perennial weed that produces vegetatively from an abundance of underground adventitious buds. The objectives of this study were to determine how mimicking natural seasonal conditions (photoperiod and temperature) under controlled environmental conditions affect dormancy and flowering competence; to determine molecular mechanisms associated with well-defined phases of seasonal dormancy transitions based on transcript profiles obtained by microarray analysis; and to link mechanisms regulating induction and release of endodormancy and flowering competence. Reduction in temperature (27 to 10°C) and photoperiod (16 to 8 h) over a three-month period induced a para- to endo-dormant transition in crown buds. An additional eleven weeks of prolonged cold (5-7°C) and short-photoperiod treatment resulted in accelerated shoot growth from crown buds, and 99% floral competence when plants were returned to growth promoting conditions. Exposure of paradormant plants to short-photoperiod and prolonged cold treatment alone had minimal affect growth potential or on flowering (~1%); whereas endodormant crown buds without prolonged cold treatment, had delayed shoot growth and approximately 2% flowering when returned to growth promoting conditions. Transcriptome analyses revealed that 373 and 260 genes were differentially expressed (p<0.005) during para- to endo-dormant and endo- to eco-dormant transitions, respectively. Transcripts from flower competent vs. non-flower competent crown buds identified 607 differentially expressed genes, and genes involved in cell cycle and DNA processing, oxidative stress, flower regulation, and proteolysis were over-represented. Further, sub-network analysis identified expression targets and binding partners associated with circadian clock, dehydration/cold signaling, phosphorylation cascades, and response to abscisic acid, ethylene, gibberellic acid, and jasmonic acid, suggesting these central regulators affect well-defined phases of dormancy. Potential genetic pathways associated with these dormancy transitions and flowering were used to develop a proposed conceptual model. Overall design: Leafy spurge is an herbaceous perennial weed that undergoes vegetative reproduction from an abundance of underground adventitious buds which exhibit phases of para-, endo-, and eco-dormancy (defined by Lang et al. 1987) during summer, fall, and winter, respectively (Anderson et al. 2005). In this study a population of leafy spurge plants were propagated through random cuttings from the genetically uniform biotype 1984-ND001. Paradormant crown buds from three-month old greenhouse plants were collected after one week of acclimation under growth chamber conditions. Induction of endodormancy in crown buds was accomplished by subjecting greenhouse grown and growth chamber acclimated plants to a ramp down (RD) treatment consisting of a reduction in temperature of 1.42°C week-1 (27°C → 10°C) and a decreasing photoperiod of 40 min week-1 (16h → 8h light) for 12 weeks as previously established by Foley et al. (2009). These conditions mimic the average seasonal environmental conditions experienced in Fargo, ND (46°54′ N, 96°48′ W) during the transition from para- to endo-dormancy (Anderson et al. 2005). To induce a transition of crown buds from endo- to eco-dormancy, plants subjected to the RD treatment were given prolonged cold treatment for 11 weeks at 5-7°C, under constant 8 h:16 h day:night cycle; light fluencies were approximately 250 μmol m-2 s-1. To compare the effects of the prolonged cold with or without RD treatment on dormancy status and flowering competence in crown buds, greenhouse-grown and growth chamber acclimated plants were subjected directly to an extended cold treatment for 11 weeks at 5-7°C, as previously described, without a RD treatment. For microarray hybridizations, labeled cDNAs were prepared from 30 µg of total RNA using the Alexa Fluor cDNA labeling kit (Invitrogen, Carlsbad, CA, USA) according to manufacturer's protocols. Labeled cDNAs were hybridized to a custom made 23K element microarray that contained 19,808 unigenes from a leafy spurge EST database (Anderson et al. 2007) and an additional 4,129 unigenes from a cassava EST database (Lokko et al. 2007). Comparison of gene expression between samples was accomplished using a rolling circle dye swap hybridization scheme (Churchill 2002) to provide every biological replicate with technical replicates. In our microarray analyses experiment, each of the four biological replicates included four technical replicates using two different dyes, resulting in a total of 16 technical replicates for each treatment. Microarray hybridization was visualized using a GenePix 4000B scanner and probe intensities and background were quantified using GenePix 6.0 software (Molecular Devices, Sunnyvale, California, USA). A quality control value of “1” was assigned to all probes that had intensity values greater than 2 times the standard deviation over average of the negative control and empty probe intensities (after deletion of 1% of the most intense negative/empty probe values). Hybridization intensities were log2 transformed, and arrays were centered and normalized against each other.
Project description:Jojoba (Simmondsia chinensis) is a new semi- arid, oil- producing industrial crop that has attracted much attention in recent years. Low temperature is one of the major environmental stress that impairs plant growth and development. To better understand the molecular mechanisms of cold stress adaptation and acclimation of jojoba plants, a quantitative proteomic analysis using iTRAQ technology was conducted to detect the effects of cold stress on protein expression profiles in jojoba seedlings. Our work provided useful infomation for understanding the cold stress response and cold acclimation in jojoba.
Project description:Gene expression was assyed in seedlings of isogenic barley lines differing in vernalization requirement. Seedlings were harvested after 5 days germination in darkness at 20 degrees. Seedlings were then subjected to 1 day at 4 degrees after 5 days germination in darkness at 20. Genotypes include the winter barley parent Dairokakku, and isogenic lines carrying a deletion of VRN2, active VRN1 allleles (VRN1-10, or VRN1-8) or an active allele of FT1/VRN3. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, Ben Trevaskis. The equivalent experiment is BB97 at PLEXdb.] Overall design: genetic line: +VRN1-10 - temperature: 20 C(3-replications); genetic line: +VRN1-10 - temperature: 4 C(3-replications); genetic line: -VRN2 - temperature: 20 C(3-replications); genetic line: -VRN2 - temperature: 4 C(3-replications); genetic line: +VRN1-8 - temperature: 20 C(3-replications); genetic line: +VRN1-8 - temperature: 4 C(3-replications); genetic line: +FT1/VRN3 - temperature: 20 C(3-replications); genetic line: +FT1/VRN3 - temperature: 4 C(3-replications); genetic line: Parent (winter type) - temperature: 20 C(3-replications); genetic line: Parent (winter type) - temperature: 4 C(3-replications)
Project description:Two azide mutagenized lines Freeze Resistance (FR, 75% survival) and Freeze Susceptible (FS, 30% survival) were compared with and without 4°C ± 1.5 cold acclimation of crown tissue to identify genes responsible for the difference in freeze resistance. Keywords: Wheat cold acclimation, stress response, cold, low temperature Overall design: Experiment design (8 hybridizations): Genotype: SD16029 (FR) or SD16169 (FS) Temperature: 25°C or 4°C