Project description:Arabidopsis thaliana is a well-established model system for the analysis of the basic physiological and metabolic pathways of plants. The presented model is a new semi-quantitative mathematical model of the metabolism of Arabidopsis thaliana. The Petri net formalism was used to express the complex reaction system in a mathematically unique manner. To verify the model for correctness and consistency concepts of network decomposition and network reduction such as transition invariants, common transition pairs, and invariant transition pairs were applied. Based on recent knowledge from literature, including the Calvin cycle, glycolysis and citric acid cycle, glyoxylate cycle, urea cycle, sucrose synthesis, and the starch metabolism, the core metabolism of Arabidopsis thaliana was formulated. Each reaction (transition) is experimentally proven. The complete Petri net model consists of 134 metabolites, represented by places, and 243 reactions, represented by transitions. Places and transitions are connected via 572 edges.
Project description:In this study we explain the physiological, biochemical and gene expression mechanisms adopted by ammonium nitrate-fed Arabidopsis thaliana plants growing under elevated [CO2], highlighting the importance of root-to-shoot interactions in these responses A transcriptomic analysis enabled the identification of photoassimilate allocation and remobilization as fundamental process used by the plants to maintain the outstanding photosynthetic performance. Moreover, based on the relationship between plant carbon status and hormone functioning, the transcriptomic analyses provided an explanation of why phenology accelerates in elevated [CO2] conditions.
Project description:In this study we explain the physiological, biochemical and gene expression mechanisms adopted by ammonium nitrate-fed Arabidopsis thaliana plants growing under elevated [CO2], highlighting the importance of root-to-shoot interactions in these responses A transcriptomic analysis enabled the identification of photoassimilate allocation and remobilization as fundamental process used by the plants to maintain the outstanding photosynthetic performance. Moreover, based on the relationship between plant carbon status and hormone functioning, the transcriptomic analyses provided an explanation of why phenology accelerates in elevated [CO2] conditions.
Project description:We explore where transcriptional regulation of ascorbate concentration lies in plants. Is it in biosynthesis, recycling, regulation or consumption? Arabidopsis thaliana plants were grown under controlled environment at four photon flux density levels (PFD). Rosettes from plants were harvested at the four PFD levels and over a diurnal cycle and after a step change in PFD and analysed for ascorbate concentration and transcript levels measured by RNAseq. Ascorbate concentrations and expression of genes in the L-galactose ascorbate biosynthesis, recycling, consumption pathways and regulation are presented to provide a full analysis of the control of ascorbate by environmentally modulated gene expression. Ascorbate concentration responded to PFD levels but not to time of day and showed only a small response to change of PFD after 2 days. Of the L-galactose pathway genes, only GDP galactose phosphorylase (GGP) showed a significant response in to different PFDs, time of day and to change in PFD. Other genes also showed limited responses. This study compares gene expression of a range of ascorbate related genes to changes in environment in a unified way and supports the concept that GGP is the key regulatory gene in ascorbate biosynthesis and that post transcriptional regulation is also important.
Project description:Phosphate is an essential macronutrient required for plant growth and development. However, it is present at suboptimal levels in many terrestrial ecosystems. To ameliorate this limitation, plants have evolved developmental and physiological mechanisms known as phosphate starvation responses (PSR). One of the main PSR in Arabidopsis thaliana is a deep restructuration of the root system architecture, which includes a reduction in primary root growth resulting in a shallower root system better adapted to explore the nutrient-rich topsoil. Intense research over the last years has shown that this developmental change is dependent on the accumulation and redistribution of iron (Fe) at the root tip, which in turn, participates in Fenton reactions and generates reactive oxygen species that affect meristem function and cell elongation. We have recently identified and characterized a cytochrome-containing protein in A. thaliana, named CRR, which is involved in the primary root growth response to phosphate starvation. Our results showed that CRR is an ascorbate-dependent ferric-reductase whose expression levels modulates iron distribution pattern in the root, affecting meristem function and cell elongation. Moreover, this activity also has shown to be critical for iron toxicity tolerance since CRR determines the transport rate of iron from root to shoot.
Project description:Phosphate is an essential macronutrient required for plant growth and development. However, it is present at suboptimal levels in many terrestrial ecosystems. To ameliorate this limitation, plants have evolved developmental and physiological mechanisms known as phosphate starvation responses (PSR). One of the main PSR in Arabidopsis thaliana is a deep restructuration of the root system architecture, which includes a reduction in primary root growth resulting in a shallower root system better adapted to explore the nutrient-rich topsoil. Intense research over the last years has shown that this developmental change is dependent on the accumulation and redistribution of iron (Fe) at the root tip, which in turn, participates in Fenton reactions and generates reactive oxygen species that affect meristem function and cell elongation. We have recently identified and characterized a cytochrome-containing protein in A. thaliana, named CRR, which is involved in the primary root growth response to phosphate starvation. Our results showed that CRR is an ascorbate-dependent ferric-reductase whose expression levels modulates iron distribution pattern in the root, affecting meristem function and cell elongation. Moreover, this activity also has shown to be critical for iron toxicity tolerance since CRR determines the transport rate of iron from root to shoot.