Project description:Purpose: Zinc deficiency (ZnD) and iron deficiency (FeD), excess Zn (ZnE) and cadmium exposure (CdE) are major environmental problems for crop cultivation. Methods: Applying Tag-Seq technology to leaves of Brassica rapa grown under FeD, ZnD, ZnE or CdE conditions, with normal conditions as a control, we examined global gene expression changes and compared the expression patterns of multiple paralogs. Results: We identified 812, 543, 331 and 447 differentially expressed genes under FeD, ZnD, ZnE and CdE conditions, respectively, in B. rapa leaves.Further analysis revealed that genes associated with Zn, Fe and Cd responses tended to be over-retained in the B. rapa genome. Most of these multiple-copy genes showed the same direction of expression change under stress conditions. Conclusion: We conclude that the duplicated genes involved in trace element responses in B. rapa are functionally redundant, making the regulatory network more complex in B. rapa than in Arabidopsis thaliana. In total, there were 15 Digital gene expression libraries, one for each of the three replicates under the four trace metal element treatments and normal nutrient supply conditions as a control.
Project description:The metabolic response of maize source leaves to low nitrogen supply was analyzed in maize seedlings by parallel measurements of transcriptome and metabolome profiling. Inbred lines A188 and B73 were cultivated under controlled growth chamber conditions and supplied with either sufficient (15mM) or limiting (0.15mM) nitrate supply. Leaf lamina material was harvested at day 20 and day 30 after germination with the fifth and sixth leaf representing the main source leaf respectively. Four replicates were collecetd from individual plants for each combination of genotype, growth stage and nitrogen treatment. The leaf material was frozen, homogenised and aliquoted for transcriptome and metabolome analysis. The molecular data was further supplemented by phenotypic characterisation of the maize seedlings under investigation. Limited availability of nitrogen caused strong shifts in the metabolite profile of leaves. The transcriptome was less affected by the nitrogen stress but showed strong genotype and age dependent patterns. Nitrogen starvation initiated the selective down-regulation of processes involved in nitrate reduction and amino acid assimilation; ammonium assimilation related transcripts on the other hand were not influenced. Carbon assimilation related transcripts were characterized by high transcriptional coordination and general down-regulation under low nitrogen conditions. Nitrogen deprivation caused a slight accumulation of starch, but also directed increased amounts of carbohydrates into the cell wall and secondary metabolites. The decrease in N availability also resulted in accumulation of phosphate and by strong down-regulation of genes usually involved in phosphate starvation response, underlining the great importance of phosphate homeostasis control under stress conditions. Maize inbred lines A188 and B73 were cultivated in pots containing nutrient poor peat soil under the controlled conditions of a growth chamber. The plants were fertilized with modified Hoagland solutions containing either 15mM (high N) or 0.15mM nitrate (low N). Source leaf lamina were harvested at day 20 and day 30 after start of germination for parallel analysis of transcriptome and metabolome profiles. The molecular data is further supplemented by phenotypic characterization of the maize seedlings under investigation.
Project description:Plant cells contain different O-acetylserine(thiol)lyase (OASTL) enzymes involved in Cys biosynthesis and located in different subcellular compartments. These enzymes are made up of a complex variety of isoforms resulting in different subcellular Cys pools. To unravel the contribution of cytosolic Cys to plant metabolism, we characterized the knockout oas-a1.1 and osa-a1.2 mutants, deficient in the most abundant cytosolic OASTL isoform in Arabidposis thaliana. Total intracellular Cys and glutathione concentrations were reduced, and the glutathione redox state was shifted in favour of its oxidized form. Interestingly, the capability of the mutants to chelate heavy metals did not differ from that of the wild type, but the mutants have an enhanced sensitivity to Cd. With the aim of establishing the metabolic network most influenced by the cytosolic Cys pool, we used the ATH1 GeneChip for evaluation of differentially expressed genes in the oas-a1.1 mutant grown under non-stress conditions. The transcriptomic footprints of mutant plants had predicted functions associated with various physiological responses that are dependent on reactive oxygen species and suggested that the mutant was oxidatively stressed. To further elucidate the specific function(s) of the OAS-A1 isoform in the adaptation response to cadmium we extended the trasncriptome experiment to the wild type and oas-a1.1 mutant plants exposed to Cd. The comparison of transcriptomic profiles showed a higher proportion of genes with altered expression in the mutant than in the wild type, highlighting up-regulated genes identified as of the general oxidative stress response rather than metal-responsive genes. Wild type and oas-a1.1 mutant plants were grown hydroponically and, after a two-week acclimation period, the roots and shoots were harvested separately. Total RNA was then prepared and analyzed using the Affymetrix-Arabidopsis ATH1GeneChip array. Three biological replicates were performed for each sample. We made two different comparisons to classify the differently expressed genes in the mutant plant: oas-a1.1 roots versus wild-type roots and oas-a1.1 shoots versus wild-type shoots. Hydroponically-grown wild type and oas-a1.1 mutant plants were further treated with 50µM CdCl2 and 18h-treated-roots and 24h-treated-shoots were harvested. Total RNA was then prepared and analyzed using the Affymetrix-Arabidopsis ATH1GeneChip array. Three biological replicates were performed for each sample. Different comparisons were performed as follows: 18h Cd-treated wild type roots versus untreated wild type roots; 24h Cd-treated wild type shoots versus untreated wild type shoots; 18h Cd-treated oas-a1.1 roots versus untreated oas-a1.1 roots; 24h Cd-treated oas-a1.1 shoots versus untreated oas-a1.1 shoots; 18h Cd-treated oas-a1.1 roots versus 18h Cd-treated wild type roots; 24h Cd-treated oas-a1.1 shoots versus 24h Cd-treated wild type shoots
Project description:Although urea is the most used nitrogen fertilizer worldwide, little is known on the capacity of crop plants to use urea per se as a nitrogen source for development and growth. To date, the molecular and physiological bases of its transport have been investigated only in a limited number of species. In particular, up to date only one study reported the transcriptomic modulation induced by urea treatment in the model plant Arabidopsis (MM-CM-)rigout et al., 2008 doi: 10.1104/pp.108.119339). In maize, one of crops using huge amount of urea, only a physiological characterization of uptake and assimilation of the N-source has been conducted. General aim of the present work was the comprehension of the molecular basis of urea uptake and assimilation in maize plants, using a transcriptomic approach. In addition, the work focused on the possible interactions between the two main N-sources, conceivably occurring concomitantly in the soil, urea and nitrate. 5 dd-old maize plants were treated for 8 hours with nutrient solution containing nitrogen in form of urea; nitrate; urea and nitrate; or not exposed to any form of nitrogen. Three different biological replicates were used for each sample repeating the experiment three times. All samples were obtained pooling roots of six plants.
Project description:affy_nitrogen_medicago - affy_nitrogen_medicago - Experiment has been designed to characterize the molecular expression patterns associated to a contrasted modification of the nitrogen status of the whole plant. The systemic effects of nitrogen status modifications are investigated and compared on non nodulated plant supplied with NO3, NH4 or nodulated plants (Sinorhizobium meliloti 2011) supplied with air. The root systems were separated in two compartments of unequal sizes (split root system). Two treatments were applied on the larger compartment in order to modulate the nitrogen status of the plant: for the S treatment, roots are supplied with nutrient solution containing 10 mM NH4NO3,, whereas for the C treatment, roots are supplied with nitrogen free medium. In the case of N2 fixing plants, N limitation was obtained by replacing air by a mixture of Ar and O2 80 per cent and 20 per cent. The effects of these treatments were investigated on roots of the minor compartment supplied continuously with either NO3 1 mM, NH4 1 mM or air (N2) and on the shoots. We were also interested in the molecular expression patterns associated to the roots deprived of N.-The root system of non-nodulated (NO3- and NH4+) or nodulated (N2) plants is split into two unequal parts and each one is installed in a separate compartment. For the S treatement, the major root part is supplied with NH4NO3 10 mM whereas the minor part is supplied with either NO3- 1mM, NH4+ 1mM or N2. For the C treatement, the major root part is supplied with nitrogen-free nutrient solution whereas the minor part is supplied with either NO3- 1mM, NH4plus 1mM or N2. Each treatement is four days long. Samples of roots of six biological types (NO3S, NO3C, NH4S, NH4C, N2S and N2C) were collected. Two biological repeats per biological types have been analyzed. The effect of the S and C treatments were investigated for each N sources by comparing Affymetrix transcriptomes (NO3C vs NO3S, NH4C vs NH4S, N2C vs N2S). Experiment Overall Design: 26 arrays - medicago
Project description:To identify more targets in soybean, particularly specific targets of Cd-stress-responsive miRNAs, high-throughput degradome sequencing was used. In total, we obtained 8913111 raw reads from the library which was constructed from a mixture of four samples (HX3-CK, HX3-Cd-treatment, ZH24-CK and ZH24-Cd-treatment). After removing the reads without the CAGAG adaptor, 5430126 unique raw-reads were obtained. The unique sequences were aligned to the G. max genome database, and 6516276 reads were mapped to the genome. The mapped reads from the libraries represented 51481 annotated G. max genes. Identification of miRNA targerts in soybean roots
Project description:The responses to waterlogging stress of two wheat genotypes including one sensitive and one resistant were systematic investigated. The labeling-based quantitative proteomic analysis was conducted in parallel on these two genotypes in responding to waterlogging for 1-3 days, 951 and 320 differentially expressed proteins (DEP) were detected in the during treat, and 270 DEPs were shared. The results might help to reveal the regulatory mechanism of waterlogging stress tolerance in wheat.
Project description:We investigated chilling response of seedlings of three inbred maize lines: chilling tolerant S68911, chilling-sensitive S160 and moderate chilling-sensitive S50676. Kernels were germinated in wet sand in darkness at 25C. Seedlings were transferred to growth chamber (photoperiod 14/10h, temperature 24, light 250 umol quanta x m-2 x s-1), grown till the third-leaf stage and used in experiment. Chilling treatment started at the start of the dark period and lasted 38h (10h dark, 14h light,10h dark, 4h light). Growth conditions was as previously described but temperature was set to 14 (light/dark). At the same time control plants were grown as previously described. There were three biological replications of hybridization scheme.
Project description:The use of biofertilizers is becoming an economical and environmentally friendly alternative to promote sustainable agriculture. Biochar from microalgae can be applied to enhance the productivity of food crops through soil improvement, slow nutrient absorption and release, increased water uptake, and long-term mitigation of greenhouse gas sequestration. Therefore, the aim of this study was to evaluate the stimulatory effects of biochar produced from Spirulina platensis biomass on the development and seed production of rice plants. Biochar was produced by slow pyrolysis at 300°C, and characterization was performed through microscopy, chemical, and structural composition analyses. Molecular and physiological analyses were performed in rice plants submitted to different biochar concentrations (0.02, 0.1, and 0.5 mg mL-1) to assess growth and productivity parameters. Morphological and physicochemical characterization revealed a heterogeneous morphology and the presence of K and Mg minerals in the biochar composition. Chemical modification of compounds post-pyrolysis and a highly porous structure with micropores were observed. Rice plants submitted to 0.5 mg mL-1 of biochar presented a decrease in root length, followed by an increase in root dry weight. The same concentration influenced seed production, with an increase of 44% in the number of seeds per plant, 17% in the percentage of full seeds per plant, 12% in the weight of 1,000 full seeds, 53% in the seed weight per plant, and 12% in grain area. Differential proteomic analyses in shoots and roots of rice plants submitted to 0.5 mg mL-1 of biochar for 20 days revealed a fine-tuning of resource allocation towards seed production. These results suggest that biochar derived from Spirulina platensis biomass can stimulate rice seed production.
Project description:Cadmium (Cd)-contamination in soil has been becoming a major environmental problem in China. Ramie, a fiber crop, was frequently proposed to be used as the crop for phytoremediation of Cd-contaminated farmlands. However, high level Cd accumulation can cause a great inhibition of growth in ramie. To understand the potential mechanism for this phenomenon, the ramie genes involved in the Cd stress response were identified using Illumina pair-end sequencing in two Cd-stressed plants (CdS1 and CdS2) and two control plants (CO1 and CO2) in this study. Approximately 48.7, 51.6, 41.2, and 47.1 million clean sequencing reads generated from the libraries of CO1, CO2, CdS1, and CdS2, respectively, were De novo assembled to yield 56,932 non-redundant unigenes. A total of 26,686 (46.9%) genes were annotated for their function. Comparison of gene expression levels between CO and CdS ramie revealed 155 differentially expressed genes (DEGs). Sixteen DEGs was further confirmed their expression difference by real-time quantitative PCR (qRT-PCR). Among these 16 DEGs, 2 genes encoding GA2-oxidase which is a major enzyme for deactivating bioactive gibberellins (GAs) were found with a markedly up-regulated expression, which is possibly responsible for the growth inhibition of Cd-stressed ramie. Pathway enrichment analysis revealed that a pathway (Cutin, suberine and wax biosynthesis) was markedly enriched by DEGs. The discovery of these Cd stress-responsive genes and pathways will be helpful for further understanding the mechanism of Cd-stressed response and improving the ability of Cd stress tolerance in ramie. A total of four samples, two replicates of control plants (CO1 and CO2) and two replicates of cadmium-stressed plants (CdS1 and CdS2) were used for RNA-seq.