Project description:Pi availability is a significant limiting factor for plant growth in both natural and agricultural systems. To cope with such limiting conditions, plants have adapted developmental and biochemical strategies to enhance Pi acquisition and to avoid starvation. A myriad of genes that are involved in the regulation and display of these strategies have been identified. However, the possible epigenetic components regulating the phosphate starvation responses have not been thoroughly investigated. DNA methylation is a major epigenetic mark involved in diverse biological processes and it may play a critical role in Pi starvation stress adaptation, also changes in DNA methylation can lead to a unique gene expression pattern in response to specific developmental and environmental conditions. Here in we demonstrate that non-CpG DNA methylation is required for proper expression of a number of Pi-limitation responsive genes in Arabidopsis thaliana and results in altered morphologic and physiologic phosphate starvation responses.Our data suggest that DNA methylation is involved in the modulation of Pi starvation responses via the transcriptional regulation of a set of phosphate-starvation responsive genes. Analysis of 8 different treatments, 2 different Organs (Root and Shoot), 2 different Phosphate treatments (High Pi, Low Pi), 2 different Times (Short Term, Long Term), 2 biological replicates for treatment
Project description:The effects of phosphate starvation in Arabidopsis thaliana (L.) plants were compared in plants grown in liquid MS medium transferred in low or high Pi and in plants grown vertically in petri dishes during 10 days. In the transfer experiments, 2 treatments were analysed for evaluating the short-(3, 6 and 12 h pooled) and medium-(1 and 2 d pooled) term effects of Pi deficiency on the gene expression. Since some Arabidopsis genes are regulated by diurnal rhythm and circadian clocks, plantlets were harvested separately at the beginning and at the end of the photoperiod and pooled. In the long term experiment, leaves and roots were sampled separately after 10 days. Triplicates were analysed for each experiment.
Project description:A comprehensive time-course experiment of Pi-starved plants was undertaken, spanning medium (3 and 7 days), and long-term (21 days up to 52 days) Pi deprivation (âPi), as well as both short term (1 and 3 days) and long-term (31 days) recovery. The 52 days time point consisting of 21 days starvation +31 days recovery enabled investigation of the effects of long term resupply on Pi starved plants, and coincided with the emergence of the first panicles and grains. Pre-germinated rice seedlings were grown for 14 days in Pi sufficient conditions (0.32 mM Pi) before being transferred to either Pi sufficient (0.32 mM Pi) or Pi deficient (0 mM Pi) media for 21 days. After 21 days of Pi deficient treatment, half of the plants were either maintained under Pi deficient conditions or re-supplied with Pi (0.32 mM) for 1, 3 or 31 days. To confirm the effectiveness of the Pi starvation and resupply treatments, physiological and molecular analyses were performed.
Project description:A mutant previously isolated from a screen of EMS-mutagenized Arabidopsis lines, per1, showed normal root hair development under control conditions but displayed an inhibited root hair elongation phenotype upon Pi deficiency. Additionally, the per1 mutant exhibited a pleiotropic phenotype under control conditions, resembling Pi-deficient plants in several aspects. Under Pi deficiency, the accumulation of Pi and iron was increased in the mutant when compared to the wild-type. Inhibition of root hair elongation upon growth on low Pi media was reverted by treatment with the Pi analog phosphite, suggesting that the mutant phenotype is not the result of a defect in Pi sensing. Reciprocal grafting experiments revealed that the mutant rootstock is sufficient to cause the phenotype. Transcriptional profiling of per1 and wild-type plants subjected to short-term Pi starvation revealed genes that may be important for the signaling of Pi deficiency. We conclude that UBP14 function is crucial for adapting root development to the prevailing local availability of phosphate. Experiment Overall Design: Col-0 and per1 mutant plants were grown under control conditions or subjected to phosphate starvation for 10 h
Project description:To better understand the complex mechanisms regulating Pi homeostasis in rice (Oryza sativa L. cv. Nipponbare), a time course experiment was performed, where pre-germinated seedlings were grown hydroponically for two weeks on Pi-sufficient medium (0.32 mM Pi), before transferring half of the plants to Pi-deficient solution (0 mM Pi) for 21 days (d). After three weeks of Pi-starvation treatment, half of these plants where then re-supplied with Pi sufficient media for up to 24 hours (h). In total, nine time points were selected in order to cover short and long term responses to Pi starvation as well as the effects of Pi re-supply on Pi starved plants.
Project description:A mutant previously isolated from a screen of EMS-mutagenized Arabidopsis lines, per1, showed normal root hair development under control conditions but displayed an inhibited root hair elongation phenotype upon Pi deficiency. Additionally, the per1 mutant exhibited a pleiotropic phenotype under control conditions, resembling Pi-deficient plants in several aspects. Under Pi deficiency, the accumulation of Pi and iron was increased in the mutant when compared to the wild-type. Inhibition of root hair elongation upon growth on low Pi media was reverted by treatment with the Pi analog phosphite, suggesting that the mutant phenotype is not the result of a defect in Pi sensing. Reciprocal grafting experiments revealed that the mutant rootstock is sufficient to cause the phenotype. Transcriptional profiling of per1 and wild-type plants subjected to short-term Pi starvation revealed genes that may be important for the signaling of Pi deficiency. We conclude that UBP14 function is crucial for adapting root development to the prevailing local availability of phosphate.
Project description:Coordinated distribution of Pi between roots and shoots is an important process that plants use to maintain Pi homeostasis. SHR (SHORT-ROOT) is well-characterized for its function in root radial patterning1-3. Here, we demonstrate a new role of SHR in controlling phosphate (Pi) allocation from roots to shoots by regulating PHOSPHATE1 (PHO1) in the root differentiation zone. We recovered a weak mutant allele of SHR in Arabidopsis which accumulates much less Pi in the shoot and shows constitutive Pi starvation response (PSR) under Pi-sufficient condition. Besides, Pi starvation suppresses SHR protein accumulation and releases its inhibition on the HD-ZIP Ⅲ transcription factor PHB. PHB accumulates and directly binds the promoter of PHO2 to upregulate its transcription, resulting in PHO1 degradation in the xylem-pole pericycle cells. Our findings reveal a previously unrecognized mechanism of how plants repress Pi translocation from roots to shoots in response to Pi starvation.
Project description:We conducted a genome-wide transcriptomic analysis in soybean leaves treated with a short-term (24 h) Pi-deficiency using RNA sequencing (RNA-seq) technology. Two biological replicates of RNA-seq were included for both Pi-sufficient leaves (PSL) and Pi-deficient leaves (PDL), and therefore a total of four libraries were constructed. Using a 2-fold change and a P-value ≤0.05 as the cut-off for selecting the differentially expressed transcripts, we globally identified short-term Pi-stress responsive genes. Some DEGs potentially involved in Pi sensing, signaling, and homeostasis were up-regulated by Pi deprivation, including five SPX-containing genes. Some DEGs possibly associated with water and nutrient uptake, hormonal and calcium signaling, protein phosphorylation and dephosphorylation, and cell wall modification were affected at the early stage of Pi deprivation. At least thirty-one transcription factor genes belonging to 10 diverse families were found to be responsive to Pi starvation.
Project description:We performed a transcriptomic analysis of Pi-starvation and recovery after resupplying Pi in Arabidopsis thaliana (Columbia-0) wild type plants and double mutant spx1,spx2. Results show that SPX1 is a Pi-dependent inhibitor of the transcription factor PHR1, a central regulatory protein in the control of transcriptional responses to Pi starvation.
Project description:This study evaluates whether different pre-treatments (+Pi, -Pi and +Phi) influences the phosphate starvation transcriptional response triggered by a bacterial synthetic community in Arabidopsis seedlings.