Global transcriptome profiling of poplar bark during stored N remobilization
ABSTRACT: Seasonal nitrogen (N) storage and reuse is important to the N-use efficiency of temperate deciduous trees. In poplar, bark storage proteins (BSPs) accumulate in protein storage vacuoles of the bark parenchyma and xylem ray cells in the fall. During spring growth, N from stored BSPs is remobilized and utilized by growing shoots. The goal of this study is to investigate global gene expression changes in the bark during BSP remobilization and shoot regrowth under long-day conditions. Long-day (LD) grown poplar (Populus trichocarpa, Nisqually-1) plants were transferred to short-day (SD) for 8 weeks at 20°C followed by an addition 12 weeks of SD at 10°C (day) and 4°C (night). Following this treatment plants were then moved to LD and 20°C for 3 weeks for regrowth. Bark samples were collected from plants released from dormancy just prior to transfer to LD and at weekly intervals for 3 weeks after exposure to LD at 20°C.
Project description:The role of bark storage proteins (BSPs) in seasonal N storage and cycling has been well documented. However, the regulatory mechanisms and pathways associated with this physiological process are poorly understood. The objective of this study is to investigate global patterns of gene expression associated with photoperiod regulated BSP accumulation and to identify candidate genes, pathways and regulatory factors governing N storage and cycling in poplar. In this study, differential expression of protease inhibitors, proteases, transcription factors, and other genes coincided with increased BSP gene expression, suggesting a complex regulatory network that might play an important role in BSP accumulation. Bark of Populus trichocarpa (Nisqually-1) was collected at weekly intervals for 6 weeks from plants treated with short-day (SD) photoperiods at 20°C as well as from long-day (LD) grown plants immediately before the SD treatment.
Project description:Previous research has shown that glutamine and sucrose treatment of excised poplar stems induces bark storage protein (BSP) gene expression. The objectivel of this research is to identify changes in gene expression associated with metabolic regulation of nitrogen storage and cycling and use this information to identify potential regulatory genes. Significant, differentially expressed genes were identified in excised poplar stems incubated in solutions of glutamine or glutamine+glucose compared to incubation with water alone Poplar shoots with approximately 10 nodes were excised from greenhouse stock plants that were grown in LD photoperiods. The basal leaves were removed to leave only the 5 apical leaves. The basal end of the 5-leaved shoots were preincubated by placing in water for 24 h in a growth chamber (20 ◦C, 16-light/8-h dark). After 24 h pre-incubation, the trimed stems were then transfered to 25 mM aqueous solutions of glutamine, glucose, or glutamine+glucose as well as a water control and incubated for either 48 or 72 h. After 48 h and 72 h of incubation in the respective solutions, bark tissue was collected from each treatement and immediately frozen in liquid nitrogen. For each treatment, 3 biological replicates were collected with 5 excised stems per biological replicate. Bark from 2 control with 3 biological replicates were also collected. Control 1 was collected immediately after excising from the stock plant and control 2 was collected after the 24 h preincubation period.
Project description:Nongken 58S is photoperiod-sensitive genic male sterile (PGMS) rice. Its pollens are fully sterile when it is treated with LD condition from glume primordium differentiation stage to pistil/stamen primordium forming stage, and its pollens are fertile when treated with SD condition during these stages. We used microarrays to detail the global programme of leaf gene expression under LD and SD condition for investigating the transcriptomes in the male sterility transition in PGMS rice to find out the genes related to this transition We compared the transcriptomes of Nongken 58S under shortday (SD) and longday (LD) at the glume primordium differentiation stage and pistil/stamen primordium forming stage, respectively. 12 samples were analyzed, and each treatment had biological triplicates. Supplementary files: SD vs LD during the glume primordium differentiation stage and the pistil/stamen primordium forming stage.
Project description:To explore daily rhythms of ocular gene expression in adult mice we performed the following experiments: i) Mice were entrained to a 12:12-hr light-dark (LD) cycle for 3 weeks. Then mice were transferred to constant darkness (DD) or remained in LD and eyes were collected at four-hour intervals over a three-day period; ii) Bmal1-/- mice and wild-type littermates were entrained to a 12:12-hr LD cycle for 3 weeks and eyes were collected at four-hour intervals over a one-day period in LD.
Project description:SVP is a key MADS-box transcription factor for Arabidopsis development since it acts both during vegetative and reproductive phases where it plays different roles probably by interacting with different partners to regulate specific sets of target genes. In fact, whereas SVP functions as a repressor of floral transition during the vegetative phase, it works as floral meristem gene during reproductive phase. We studied the behavior of SVP during two distinct developmental phases: the vegetative and reproductive phase. The aim of these studies is to identify subsets of genes that are directly bound by SVP by means of ChIP sequencing (Illumina Solexa Sequencing) approach during the two distinct phases of development. Arabidopsis thaliana seedlings and inflorescences were selected at successive stages of early development for chromatin extraction and subsequent immunoprecipitation using GFP antibody. The identification of genome wide binding sites of SVP using the ChIP-SEQ approach were performed in the vegetative phase using pSVP::SVP-GFP svp-41 and wild-type seedlings grown for 2 weeks in Short Day (SD) conditions (8 h light/16 h dark); for the reproductive phase we used wild-type and pSVP::SVP-GFP svp-41 inflorescences grown for 2 weeks in SD conditions and then moved in (LD) conditions (16 h light/16 h dark). The inflorescences were collected at 2 weeks after bolting.
Project description:To monitor gene expression changes pre floral transition and during early flower development col-0 and tps1-2 GVG::TPS1 (von Dijken, 2004) plants were grown under SD (8 hr light, 16 hr dark) for 21 days. Plants were then shifted to LD (16 hr light, 8 hr dark) conditions to induce flowering. RNA was isolated from micro-dissected apical tissue harvested 0 and 5 days after the shift to LD and double-stranded cDNA was synthesized. Biotinylated cRNA probes were prepared and hybridized to the Affymetrix ATH1 array in duplicate (biological replicates).
Project description:SVP is a key MADS-box transcription factor for Arabidopsis development since it acts both during vegetative and reproductive phases where it plays different roles probably by interacting with different partners to regulate specific sets of target genes. In fact, whereas SVP functions as a repressor of floral transition during the vegetative phase, it works as floral meristem gene during reproductive phase. We studied the behavior of SVP during two distinct developmental phases: the vegetative and reproductive phase. The aim of these studies is to identify subsets of genes that are regulated by SVP by means of Arabidopsis Tiling 1.0R Arrays (Affymetrix) during the two distinct phases of development. Arabidopsis thaliana seedlings and inflorescences were selected at successive stages of early development for RNA extraction and hybridization on Affymetrix microarrays. To evaluate the amount of SVP expression in the vegetative phase we used svp-41 single mutant and wild-type seedlings grown for 2 weeks in Short Day (SD) conditions (8 h light/16 h dark); for the reproductive phase we used wild-type and svp-41 agl24-2 ap1-12 triple mutant inflorescences grown for 2 weeks in SD conditions and then moved in (LD) conditions (16 h light/16 h dark). The inflorescences were collected at 2 weeks after bolting.
Project description:Softwood bark is an important by-product of forest industry. Currently, bark is under-utilized and mainly directed for energy production, although it can be extracted with hot water to obtain compounds for value-added use. In Norway spruce (Picea abies [L.] Karst.) bark, condensed tannins and stilbene glycosides are among the compounds that comprise majority of the antioxidative extractives. For developing feasible production chain for softwood bark extractives, knowledge on raw material quality is critical. This study examined the fate of spruce bark tannins and stilbenes during storage treatment with two seasonal replications (i.e., during winter and summer). In the experiment, mature logs were harvested and stored outside. During six-month-storage periods, samples were periodically collected for chemical analysis from both inner and outer bark layers. Additionally, bark extractives were analyzed for antioxidative activities by FRAP, ORAC, and H2O2 scavenging assays. According to the results, stilbenes rapidly degraded during storage, whereas tannins were more stable: only 5-7% of the original stilbene amount and ca. 30-50% of the original amount of condensed tannins were found after 24-week-storage. Summer conditions led to the faster modification of bark chemistry than winter conditions. Changes in antioxidative activity were less pronounced than those of analyzed chemical compounds, indicating that the derivatives of the compounds contribute to the antioxidative activity. The results of the assays showed that, on average, ca. 27% of the original antioxidative capacity remained 24 weeks after the onset of the storage treatment, while a large variation (2-95% of the original capacity remaining) was found between assays, seasons, and bark layers. Inner bark preserved its activities longer than outer bark, and intact bark attached to timber is expected to maintain its activities longer than a debarked one. Thus, to ensure prolonged quality, no debarking before storage is suggested: outer bark protects the inner bark, and debarking enhances the degradation.
Project description:In bacteria, the biosynthesis of cysteine is accomplished by two enzymes that are encoged by the cysK and cysM genes. CysM is also able to incorporate thiosulfate to produce S-sulfocysteine. In plant cells, the biosynthesis of cysteine occurs in the cytosol, mitochondria and chloroplasts. Chloroplasts contain two O-acetylserine(thiol)lyase homologs, which are encoded by the OAS-B and CS26 genes. An in vitro enzymatic analysis of the recombinant CS26 protein demonstrated that this isoform possesses S-sulfocysteine synthase activity and lacks O-acetylserine(thiol)lyase activity. In vivo functional analysis of this enzyme in knockout mutants demonstrated that mutation of cs26 suppressed the S-sulfocysteine synthase activity that was detected in wild type; furthermore, the mutants exhibited a growth phenotype, but penetrance depended on the light regime. The cs26 mutant plants also had reductions in chlorophyll content and photosynthetic activity (neither of which were observed in oas-b mutants), as well as elevated glutathione levels. However, cs26 leaves were not able to properly detoxify ROS, which accumulated to high levels under long-day growth conditions. The transcriptional profile of the cs26 mutant revealed that the mutation had a pleiotropic effect on many cellular and metabolic processes. Our finding reveals that S-sulfocysteine and the activity of S-sulfocysteine synthase play an important role in chloroplast function and are essential for light-dependent redox regulation within the chloroplast. Using the Affymetrix ATH1 GeneChips, we performed a comparative transcriptomic analysis on leaves of the cs26 and wild type plants under two different photoperiod conditions. Wild type and cs26 mutant plants were grown on soil under a long-day photoperiod (LD) or under a short-day photoperiod (SD). Total RNA was extracted from the leaves of 3-week-old plants grown under identical LD conditions, and from the leaves of 5-week-old plants grown under identical SD conditions. Three biological replicates were performed for each sample and hybridized to the chips. We made two different comparisons to classify the differently expressed genes in the mutant plant: cs26 leaves under LD versus wild-type leaves under LD and cs26 leaves under SD versus wild-type leaves under SD.