Project description:During their co-evolution, plants have learned to counteract bacterial infection by preparing yet uninfected tissues for an enhanced defence response, the so-called systemic acquired resistance or priming response. Primed leaves express a wide range of genes that enhance the defence response once an infection takes place. While hormone-driven defence signalling and generation of defensive metabolites has been well studied, less focus has been set on the reorganization of primary metabolism in systemic leaves. Since primary metabolism plays an essential role for fuelling and optimizing defences in terms of providing energy and chemical building blocks, we investigated medium-term primed changes in primary metabolism at RNA and metabolite levels in systemic leaves of Arabidopsis thaliana plants that were locally infected with Pseudomonas syringae. While known defence genes were still activated 3-4 days after infection, we also found several parts of primary metabolism to be significantly altered. Nitrogen (N)-metabolism and content of amino acids and other N-containing metabolites were significantly reduced, whereas the organic acids fumarate and malate were strongly increased. We suggest that reduction of N-metabolites in systemic, yet non-infected leaves primes defence against bacterial infection by reducing the nutritional value of systemic tissue. The increased organic acids serve as a quickly available metabolic resource of energy and carbon-building blocks for the production of defence metabolites during subsequent secondary infections.
Project description:N-glycosylation is an important post-translational modification of proteins in all eukaryotes and involved in a number of diseases in mammalian systems. However, little is known about the role of protein N-glycosylation in plant defense responses to pathogen invasion. In the present study, we first identified glycoproteins related to systemic acquired resistance (SAR) in an Arabidopsis thaliana model using glycoproteomics platform based on high-resolution mass spectrometry. In total, 427 glycosylate sites corresponding to 391 glycopeptides and 273 unique glycoproteins were identified. A total of 65 significantly changed glycoproteins with 80 N-glycosylation were detected in systemic leaves of SAR-induced plants, including numerous GDSL-like lipases, thioglucoside glucohydrolases, kinases and glycosidases. A variety of significantly changed glycoproteins were involved in stomatal movement, and stomata aperture measurements further confirmed that stomata movement were regulated in systemic leaves of SAR-induced plants, suggesting that these proteins may be functionally involved in systemic stomatal immunity through glycosylation or deglycosylation. Functional enrichment analysis reveals that the significantly changed glycoproteins were mainly involved in N-glycan biosynthesis and degradation, phenylpropanoid biosynthesis, cutin and wax biosynthesis, plant-pathogen interactions. Comparative analysis of glycoproteomics data with proteomics and transcriptomics data suggest that these significantly changed glycoproteins were mainly regulated by post-translational modification during SAR. This study provides substantial insight into the role of protein glycosylation in SAR.
Project description:Systemic acquired resistance (SAR) is a long-lasting broad-spectrum plant defense mechanism that is induced by mobile signals generated in the primarily infected leaves. Although multiple mobile SAR signals have been proposed, how these signals are perceived in the systemic leaves is unknown. Here, we show that extracellular nicotinamide adenine dinucleotide (phosphate) (eNAD(P)) accumulates in the systemic leaves and that both eNAD(P) and its receptor, the lectin receptor kinase (LecRK), LecRK-VI.2, are required in the systemic leaves for the establishment of SAR. Moreover, the mobile signal N-hydroxypipecolic acid (NHP) induces de novo NAD(P) leakage in the systemic leaves through the respiratory burst oxidase homolog RBOHF-produced reactive oxygen species (ROS). Importantly, NHP-induced systemic immunity depends on ROS, eNAD(P), and the eNAD(P) receptor complex LecRK-VI.2/ BAK1, indicating that NHP triggers SAR through the ROS-eNAD(P)-LecRK-VI.2/BAK1 signaling pathway. Our results uncovered a long-sought-after mechanism underlying the perception of mobile SAR signals in the systemic leaves
Project description:Arabidopsis thaliana plants were infested i) with sucking insect herbivores (the generalist aphid Myzus persicae and the specialist aphid Brevicoryne brassicae), ii) with chewing insect herbivores (generalist caterpillars of Spodoptera exigua and specialist caterpillars of Pieris rapae) or iii) were treated by wounding. For each treatment, rosette leaves were harvested at two time points (6h and 24h) after removal of insects. For chewing herbivores and wounding both local, i.e. immediately damaged leaves, and systemic, i.e. undamaged leaves from the same plant, were collected. Control plants were uninfested, but otherwise equally treated and harvested in parallel. We tested the hypothesis that Arabidopsis can recognize and respond differentially to insect species at the transcriptional level using a genome wide microarray. Transcriptional reprogramming was characterized using co-expression analysis in damaged and undamaged leaves at two times in response to mechanical wounding and four insect species. In all, 2778 (10.6%) of annotated genes on the array were differentially expressed in at least one treatment. Responses differed mainly between aphid and caterpillar and sampling times. Responses to aphids and caterpillars shared only 10% of up-regulated and 8% of down-regulated genes. Responses to two caterpillars shared 21% and 12% of up- and down-regulated genes, whereas responses to the two aphids shared only 7% and 4% of up-regulated and down-regulated genes. Overlap in genes expressed between 6h and 24h was 3-15%, and depended on the insect species. Responses in attacked and unattacked leaves differed at 6h but converged by 24h. Genes responding to the insects are also responsive to many stressors and included primary metabolism. Aphids down-regulated amino acid catabolism; caterpillars stimulated production of amino acids involved in glucosinolate synthesis. Co-expression analysis revealed 17 response networks. Transcription factors were a major portion of differentially expressed genes throughout and responsive genes shared most of the known or postulated binding sites.
Project description:The goal of this project is to compare the primary metabolite profile in different tissue types of the model plant Arabidopsis thaliana. Specifically, plants were grown hydroponically under the long-day (16hr light/day) condition at 21C. Tissue samples, including leaves, inflorescences, and roots were harvest 4 1/2 weeks post sowing. Untargeted primary metabolites profiling was carried out using GCTOF.
Project description:deOliveiraDalMolin2010 - Genome-scale
metabolic network of Arabidopsis thaliana (AraGEM)
This model is described in the article:
AraGEM, a genome-scale
reconstruction of the primary metabolic network in
Arabidopsis.
de Oliveira Dal'Molin CG, Quek LE,
Palfreyman RW, Brumbley SM, Nielsen LK.
Plant Physiol. 2010 Feb; 152(2):
579-589
Abstract:
Genome-scale metabolic network models have been successfully
used to describe metabolism in a variety of microbial organisms
as well as specific mammalian cell types and organelles. This
systems-based framework enables the exploration of global
phenotypic effects of gene knockouts, gene insertion, and
up-regulation of gene expression. We have developed a
genome-scale metabolic network model (AraGEM) covering primary
metabolism for a compartmentalized plant cell based on the
Arabidopsis (Arabidopsis thaliana) genome. AraGEM is a
comprehensive literature-based, genome-scale metabolic
reconstruction that accounts for the functions of 1,419 unique
open reading frames, 1,748 metabolites, 5,253 gene-enzyme
reaction-association entries, and 1,567 unique reactions
compartmentalized into the cytoplasm, mitochondrion, plastid,
peroxisome, and vacuole. The curation process identified 75
essential reactions with respective enzyme associations not
assigned to any particular gene in the Kyoto Encyclopedia of
Genes and Genomes or AraCyc. With the addition of these
reactions, AraGEM describes a functional primary metabolism of
Arabidopsis. The reconstructed network was transformed into an
in silico metabolic flux model of plant metabolism and
validated through the simulation of plant metabolic functions
inferred from the literature. Using efficient resource
utilization as the optimality criterion, AraGEM predicted the
classical photorespiratory cycle as well as known key
differences between redox metabolism in photosynthetic and
nonphotosynthetic plant cells. AraGEM is a viable framework for
in silico functional analysis and can be used to derive new,
nontrivial hypotheses for exploring plant metabolism.
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Project description:HPLC-MSMS rawdata for arabidopsis systemic leaves in WT(C) and npr1(n). Pst DC3000 was used as priming and treatment. The primed(P) and mock(M) leaves with control (0) and Pst infection (3). Every group has 3 biological replicates (1-3).
Project description:Plants have developed a complicated resistance system, and they exhibit various defense patterns in response to different attackers. However, the determine factors of plant defense patterns are still not clear. Here, we hypothesized that damage patterns of plant attackers play an important role in determining the plant defense patterns. To test this hypothesis, we selected leafminer, which has a special feeding pattern more similar to pathogen damage than chewing insects, as our model insect, and Arabidopsis thaliana as the response plants. The local and systemic responses of Arabidopsis thaliana to leafminer feeding were investigated using the Affymetrix ATH1 genome array. Damaged leaves of Arabidopsis thaliana for local damage analysis and the intact leaves on the same plant for systemic damage analysis were separately frozen by liquid nitrogen. Then, we used an Affymetrix ATH1 Arabidopsis microarray to study the expression changes pattern of Arabidopsis thaliana to pea leafminers damage, both locally (LI) and systemically (SI). We downloaded data from the web database and used hierarchical clustering to explore the relationships of Arabidopsis thaliana expression pattern to different kinds of attackers.
Project description:Magnesium (Mg) is essential for many biological processes in plant cells and its deficiency causes yield reduction in crop systems. Low Mg status reportedly impacts on photosynthesis, sucrose partitioning and biomass allocation. However, earlier responses to Mg deficiency are scarcely described. Generally, symptoms of nutrient deficiency appear in specific ages of leaves. Therefore, we hypothesised that transcriptional responses to Mg deficiency are different depending on the ages of leaves, and performed a global transcriptomic analysis in two types of leaves; source and sink leaves of the model plant species Arabidopsis thaliana to reveal the earlier responses to Mg deficiency. The global transcriptomic study revealed that short-term Mg deficiency triggers the expression of defence response genes in sink leaves. In roots, although short-term Mg deficiency enhanced the Mg2+ uptake from the environmnet, transcriptional levels of genes encoding putative Mg2+ transporters in roots were unchanged, suggesting non-transcriptional regulation of Mg2+ uptake in roots.