Project description:Purpose: Analyze changes in the transcriptome of Arabidopsis thaliana in response to chronic exposure to silver nitrate at 4 μg/mL concentration. Methods: mRNA was extracted from non-treated and silver nitrate-treated 14-day old Arabidopsis thaliana seedlings using the RNAeasy extraction kit (Qiagen). RNA-seq libraries (3 rep/treatment and 3 reps/control) constructed with the TruSeq Stranded mRNA Sample Preparation kit (Illumina) were paired-end sequenced (100-nt read length) on an Illumina Nova Seq6000 system. Reads were mapped to the A. thaliana TAIR10 reference genome sequence and transcript levels were analyzed using the softare CLC Genomics Workbench (version 20.0.4, Qiagen). Results: Chronic exposure of A. thaliana plants to silver nitrate caused a change in the abundance of transcripts: AT2G01520 and AT4G12550, but no measureable impact on the rest of the transcriptome. Conclusions: Exposure of A. thaliana to silver nitrate at 4 μg/mL has minor impact on the transcriptome.
Project description:To gain insight into the molecular mechanisms underlying the increased growth of Col-0:MtNPF1.7 CE plants compared to WT, leaves from plants grown for 21 days on defined media were subjected to transcript profiling using the Affymetrix Arabidopsis ATH1 microarray. We tested gene expression from plants grown at 0.1 mM nitrate and at 10 mM nitrate. The 0.1 mM nitrate concentration is below MtNPF1.7’s Km and at that nitrate concentration, large growth differences between Col-0:MtNPF1.7 CE and wild-type Col-0 plants were observed, while 10 mM nitrate is well above MtNPF1.7’s Km, where fewer differences in growth were seen. Three independent biological replicates were collected.
Project description:Plants take up nitrate in soils and utilize it both for nitrogen assimilation and as a signaling molecule. Thus, an essential role of nitrate in plants is triggering changes in gene expression patterns, including immediate induction of the expression of genes involved in nitrate transport and assimilation as well as several transcription factor genes and genes related with carbon metabolism and cytokinin biosynthesis and response. Recently we identified NIN-like proteins (NLPs) as transcription factors governing nitrate-inducible gene expression in Arabidopsis. Because of their similar DNA-binding property, nine NLP proteins may play redundant roles in controlling nitrate-regulated gene expression in Arabidopsis. The physiological roles of NLPs were therefore assessed by generating transgenic Arabidopsis plants expressing NLP6 fused to the transcriptional repression domain of SUPERMAN (SUPRD), which has an ability to convert transcriptional activators into transcriptional repressors. Our transcriptome analysis revealed that levels of nitrate-inducible expression of nitrate transporter genes (NRT1.1 and NRT2.1), nitrate reduction enzyme genes (NIA1, NIA2 and NIR1), the genes associated with ammonium assimilation (GLT1 for glutamine-2-oxoglutarate aminotransferase and ASN2 for asparagine synthetase), LBD37-39 transcription factor genes and genes encoding homologs of rice nitrate-inducible NIGT1 transcriptional repressor, were reduced in the NLP6-SUPRD lines. Furthermore, levels of nitrate-inducible expression of the genes associated with the oxidative pentose phosphate pathway (G6PD2 and G6PD3 for glucose-6-phosphate dehydrogenases, and 6-phosphogluconate dehydrogenase genes), cytokinin biosynthesis (IPT3) and signal transduction (A-type ARR genes), a gene encoding a Ser/Thr protein kinase associated with a calcineurin B–like calcium sensor (CIPK3) were also found to be largely decreased by reductions in NLP activity. Because induction folds by nitrate and reduction folds by decreases in the NLP activity were well proportional, the NLP activity appeared to be responsible for most of nitrate responsiveness of the genes whose expression occurs immediately after nitrate treatment.
Project description:Plants aquire nitrogen from the soil, most commonly in the form of either nitrate or ammonium. Unlike ammonium, nitrate must be reduced (with NADH and ferredoxin as electron donors) prior to assimilation. Thus, nitrate nutrition imposes a substantially greater energetic cost than ammonium nutrition. Our goal was to compare the transcriptomes of nitrate-supplied and ammonium-supplied plants, with a particular interest in characterizing the differences in redox metabolism elicited by different forms of inorganic nitrogen. We used microarrays to compare the short-term transcriptional response to either nitrogen supply or ammonium supply in Arabidopsis roots. Genes upregulated or downregulated by nitrate only, ammonium only, or both ammonium and nitrate were identified and analyzed.
Project description:Identification of the earliest transcriptional responses of adult Arabidopsis plant roots towards N-deprivation. Hydroponically grown Plants (35 days old) were 5 days adapted to nitrate or ammonium,respectively, as sole N-source to detect N-form specific transcripts. 24 Samples: 2 Pre-Treatments (5 Day adaptation to 3mM Ammonium/Nitrate) x 3 sampling time-points (0min, 15 min, 180 min) x 3 independent replications per time-point + 6 additional controls (2 x 15min, 1x 180min per Pre-Treatment)
Project description:Identification of the earliest transcriptional responses of adult Arabidopsis plant roots towards N-deprivation. Hydroponically grown Plants (35 days old) were 5 days adapted to nitrate or ammonium,respectively, as sole N-source to detect N-form specific transcripts.