Project description:Nutrient availability, in particular that of carbon (C) and nitrogen (N), is one of the most important factors for the regulation of plant metabolism and development. In addition to independent utilization, the ratio of C to N metabolites in the cell is also important for the regulation of plant growth including. Plants sense and respond to the balance of carbon (C) and nitrogen (N) nutrients (C/N-nutrient) available to them, a process called the C/N-nutrient response. We previously demonstrated that disrupted high C/low N stress condition promotes the senescence progression in Arabidopsis plants. However, the molecular basis of C/N-nutrient responsive senescence regulation remains unclear. In this study, we carried out proteome analysis of phosphorylation dynamics in response to high C/low N nutrient stress.
Project description:Nitrogen (N) is a key nutrient that is often the limiting factor in plant growth. However, the molecular mechanisms underlying transcriptional regulation of N-starvation-responses remain largely unknown. AtNIGT1s are putative regulators of nitrogen-starvation responsive transcriptome in arabidopsis. We aimed to identify AtNIGT1s target genes by microarray experments.
Project description:To gain an insight into molecular mechanisms underlying plant-microbe interactions gene expression changes in rice plants in response to a plant growth promoting rhizobacteria such as the Pseudomonas putida, root transcriptome analysis through microarray technology was performed from rice roots in response to P. putida RF3. Species of Pseudomonas are well known as biocontrol agents hence defense response and genes related to root exudation of phytochemicals were analysed in detail. For treatment of rice plants with P. putida, aseptically germinated rice seedlings from half strength MS medium were transferred to flasks containing Hoaglands’ nutrient solution, treated with P. putida and incubated for 48 hours in growth chamber in an orbital shaker. Gene expression changes in rice roots were then analyzed by microarray experiment. Untreated roots served as control. Data analysis revealed defense responsive genes to be upregulated with greater fold changes. In addition to defense response genes, few genes involved in secondary metabolism were also upregulated significantly. Validation of microarray data was performed using real time PCR for defense responsive genes (OsPBZ, OsPR101a, OsCHIA, etc). Detailed analysis of the differentially expressed genes reveal the role of P. putida RF3 in inducing systemic resistance in plants thereby immunizing the rice plants against future attacks by pests/pathogens. Our study enhances the current understanding on gene expression changes occurring during plant-microbe associations and thus demonstrates the potential of P. putida RF3 as a biocontrol agent.
Project description:Plants and rhizosphere microbes rely closely on each other, with plants supplying carbon to bacteria in root exudates, and bacteria mobilizing soil-bound phosphate for plant nutrition. When the phosphate supply becomes limiting for plant growth, the composition of root exudation changes, affecting rhizosphere microbial communities and microbially-mediated nutrient fluxes. To evaluate how plant phosphate deprivation affects rhizosphere bacteria, Lolium perenne seedlings were root-inoculated with Pseudomonas aeruginosa 7NR, and grown in axenic microcosms under different phosphate regimes (330 uM vs 3-6 uM phosphate). The effect of biological nutrient limitation was examined by DNA microarray studies of rhizobacterial gene expression.
Project description:Roots are fundamental organs for plant development and response to their environment: they anchor the plant to its growth substrate, uptake nutrients and water vital to plant growth, and can sense and respond to a variety of biotic and abiotic stresses. The architecture of root systems and their growth are known to be strongly affected by the environmental conditions found in the soil. However, the acquisition of cell identities at the root meristem is still mainly viewed as ontogenetically driven, where a small number of stem cells generate all the cell types through stereotyped divisions followed by differentiation, along a simple developmental trajectory. The extent to which environmental cues precisely shape and affect these developmental trajectories remains an open question. We used single-cell RNA-seq, combined with spatial mapping, to deeply explore the trajectories of cell states at the tip of Arabidopsis roots, known to contain multiple developing lineages. Surprisingly, we found that most lineage trajectories exhibit a stereotyped bifid topology with two developmental trajectories rather than one. The formation of one of the trajectories is driven by a strong and specific activation of genes involved in the responses to various environmental stimuli, that affects only of a subset of the cells in multiple cell types simultaneously, revealing another layer of patterning of cell identities in the root that is independent of cell ontogeny. We demonstrate the robustness of this environmentally-responsive transcriptional state by showing that it is present in a mutant where cell type identities are greatly perturbed, as well as in different Arabidopsis ecotypes. We also show that the root can adapt the proportion of cells that acquire this particular state in response to environmental signals such as nutrient availability. The discovery of this transcriptional signature further highlights the adaptive potential of plant development.
Project description:Under crowded, nutrient-limiting conditions, growth in the marine chordate O. dioica arrests until favorable conditions return. We profiled translation genome-wide using ribosome profiling in O. dioica during growth arrest and growth arrest recovery. We found that initial recovery is independent of nutrient-responsive, trans-spliced genes, suggesting that animal density is the primary trigger for the resumption of development in this species.
Project description:In this study, we first assess the role of the GAL regulon in enabling efficient galactose utilization for cell growth by decoupling its regulatory responses from sugar catabolism. We provide evidence that regulon-controlled galactose assimilation is more efficient than constitutive expression of the catabolic genes in supporting fast growth rates to higher cell densities. Next, we assessed whether a regulon could enable more complete and efficient utilization of a nutrient that is non-native to this yeast – xylose. We first adapt the GAL regulon to respond to xylose through directed evolution of Gal3p, enabling coupling of nutrient stimulus with sensing, computation, and regulatory actuation. Next, by using a rational, model-guided approach, we test two different positive feedback signal transduction loop designs for the regulon and demonstrate their individual merits and weaknesses. We also show that implementation of a GAL-type xylose-responsive regulon can regulate multiple genes across the yeast genome and enable more homogeneous population-wide gene expression. By integrating a minimal set of heterologous catabolic genes into the synthetic regulon we demonstrate high cellular growth rates and high final cell densities on xylose as well as better growth in non-inducing carbon sources. Finally, we compare the genome-wide expression profiles of strains grown with regulon assistance and conventionally engineered strains to identify mechanistic reasons that account for the different phenotypes observed. We posit that this study strongly supports the need to re-evaluate how nutrient assimilation systems are currently implemented and introduces a new and unexplored paradigm of adapting a native regulon for efficient non-native sugar assimilation.
Project description:The objective of this study was to identify nutrient-responsive small RNAs in different tissues and in phloem sap of rape plants. miRNA microarrays containing all currently known plant miRNAs (Sanger miRBase versions 10.0, 10.1 and 11.0), and a set of unknown small RNAs cloned earlier from Brassica phloem sap (Bn_PsRNA) were used. The phloem, leaf and root response to nutrient deficiency were analyzed by removing either sulfate, copper or iron from the growth medium. The small RNA profile from phloem and inflorescence stems of plants grown under full nutrition conditions was also analyzed and compared. The study demonstrates that the phloem sap sRNA profile is distinct from that of the inflorescence stems, leaves and roots. Furthermore, we could identify phloem-enriched small RNAs and showed that some of them specifically accumulate in the phloem in response to nutrient deprivation.