Regulation Of Plant Metabolism Research Articles

A Molecular Pinball Machine of the Plasma Membrane Regulates Plant Growth-A New Paradigm.

Novel molecular pinball machines of the plasma membrane control cytosolic Ca2+ levels that regulate plant metabolism. The essential components involve: 1. an auxin-activated proton pump; 2. arabinogalactan glycoproteins (AGPs); 3. Ca2+ channels; 4. auxin-efflux “PIN” proteins. Typical pinball machines release pinballs that trigger various sound and visual effects. However, in plants, “proton pinballs” eject Ca2+ bound by paired glucuronic acid residues of numerous glycomodules in periplasmic AGP-Ca2+. Freed Ca2+ ions flow down the electrostatic gradient through open Ca2+ channels into the cytosol, thus activating numerous Ca2+-dependent activities. Clearly, cytosolic Ca2+ levels depend on the activity of the proton pump, the state of Ca2+ channels and the size of the periplasmic AGP-Ca2+ capacitor; proton pump activation is a major regulatory focal point tightly controlled by the supply of auxin. Auxin efflux carriers conveniently known as “PIN” proteins (null mutants are pin-shaped) pump auxin from cell to cell. Mechanosensitive Ca2+ channels and their activation by reactive oxygen species (ROS) are yet another factor regulating cytosolic Ca2+. Cell expansion also triggers proton pump/pinball activity by the mechanotransduction of wall stress via Hechtian adhesion, thus forming a Hechtian oscillator that underlies cycles of wall plasticity and oscillatory growth. Finally, the Ca2+ homeostasis of plants depends on cell surface external storage as a source of dynamic Ca2+, unlike the internal ER storage source of animals, where the added regulatory complexities ranging from vitamin D to parathormone contrast with the elegant simplicity of plant life. This paper summarizes a sixty-year Odyssey.

HBI transcription factor-mediated ROS homeostasis regulates nitrate signal transduction.

Nitrate is both an important nutrient and a critical signaling molecule that regulates plant metabolism, growth, and development. Although several components of the nitrate signaling pathway have been identified, the molecular mechanism of nitrate signaling remains unclear. Here, we showed that the growth-related transcription factors HOMOLOG OF BRASSINOSTEROID ENHANCED EXPRESSION2 INTERACTING WITH IBH1 (HBI1) and its three closest homologs (HBIs) positively regulate nitrate signaling in Arabidopsis thaliana. HBI1 is rapidly induced by nitrate through NLP6 and NLP7, which are master regulators of nitrate signaling. Mutations in HBIs result in the reduced effects of nitrate on plant growth and ∼22% nitrate-responsive genes no longer to be regulated by nitrate. HBIs increase the expression levels of a set of antioxidant genes to reduce the accumulation of reactive oxygen species (ROS) in plants. Nitrate treatment induces the nuclear localization of NLP7, whereas such promoting effects of nitrate are significantly impaired in the hbi-q and cat2 cat3 mutants, which accumulate high levels of H2O2. These results demonstrate that HBI-mediated ROS homeostasis regulates nitrate signal transduction through modulating the nucleocytoplasmic shuttling of NLP7. Overall, our findings reveal that nitrate treatment reduces the accumulation of H2O2, and H2O2 inhibits nitrate signaling, thereby forming a feedback regulatory loop to regulate plant growth and development.

Circadian Control of Metabolism by the Clock Component TOC1.

Photosynthesis in chloroplasts during the day and mitochondrial respiration during the night execute nearly opposing reactions that are coordinated with the internal cellular status and the external conditions. Here, we describe a mechanism by which the Arabidopsis clock component TIMING OF CAB EXPRESSION1 (TOC1) contributes to the diurnal regulation of metabolism. Proper expression of TOC1 is important for sustaining cellular energy and for the diel and circadian oscillations of sugars, amino acids and tricarboxylic acid (TCA) cycle intermediates. TOC1 binds to the promoter of the TCA-related gene FUMARASE 2 to repress its expression at night, which results in decreased fumarate accumulation in TOC1 over-expressing plants and increased in toc1-2 mutant. Genetic interaction studies confirmed that over-expression of FUMARASE 2 in TOC1 over-expressing plants alleviates the molecular and physiological energy-deprivation phenotypes of TOC1 over-expressing plants. Thus, we propose that the tandem TOC1-FUMARASE 2 is one of the mechanisms that contribute to the regulation of plant metabolism during the day and night.

Potassium modulates central carbon metabolism to participate in regulating CO2 transport and assimilation in Brassica napus leaves

Potassium (K) regulates plant metabolism and enhances plant’s ability to adapt to adversity. However, under different K deficiency stress, the net photosynthetic rate (An) was reduced, influenced by CO2 conductance or biochemical capacities. The interplay between metabolome and photosynthetic characteristics under K deficiency stress was analyzed to explore the mechanisms by which K regulates photosynthetic capacity. With increasing K deficiency stress, dominations limiting An varied from CO2 conductance to biochemical limitations. Multivariate analyses indicated that organic acids, amino acids and sedoheptulose-7-bisphosphate were significantly related to An, CO2 conductance and carboxylation rate. Under moderate K deficiency, organic acids were up-regulated. Acidification of subcellular compartments reduced sedoheptulose-1,7-bisphosphatase activity, inducing downregulation of sedoheptulose-7-bisphosphate and hindrance of ribulose bisphosphate regeneration. Moreover, increased CO2 shortage with increasing K deficiency induced a shift of increased citric acid to amino acid synthesis, causing excessive accumulation of amino acids. In addition, the reduced serine level indicated impaired photorespiration. These two changes triggered more serious reduction in photosynthetic capacity. The intimate, changes in photosynthetic capacities were tightly coupled with shifts in central C metabolism, which provides insights into the methods used to enhance An and plant’s adaptability to abiotic stresses, through the regulation of C metabolites using molecular technology.

Linking Plant Secondary Metabolites and Plant Microbiomes: A Review.

Plant secondary metabolites (PSMs) play many roles including defense against pathogens, pests, and herbivores; response to environmental stresses, and mediating organismal interactions. Similarly, plant microbiomes participate in many of the above-mentioned processes directly or indirectly by regulating plant metabolism. Studies have shown that plants can influence their microbiome by secreting various metabolites and, in turn, the microbiome may also impact the metabolome of the host plant. However, not much is known about the communications between the interacting partners to impact their phenotypic changes. In this article, we review the patterns and potential underlying mechanisms of interactions between PSMs and plant microbiomes. We describe the recent developments in analytical approaches and methods in this field. The applications of these new methods and approaches have increased our understanding of the relationships between PSMs and plant microbiomes. Though the current studies have primarily focused on model organisms, the methods and results obtained so far should help future studies of agriculturally important plants and facilitate the development of methods to manipulate PSMs–microbiome interactions with predictive outcomes for sustainable crop productions.

Thioredoxin-mediated regulation of (photo)respiration and central metabolism.

Thioredoxins (TRXs) are ubiquitous proteins engaged in the redox regulation of plant metabolism. Whilst the light-dependent TRX-mediated activation of Calvin-Benson cycle enzymes is well documented, the role of extraplastidial TRXs in the control of the mitochondrial (photo)respiratory metabolism has been revealed relatively recently. Mitochondrially located TRX o1 has been identified as a regulator of alternative oxidase, enzymes of, or associated with, the tricarboxylic acid (TCA) cycle, and the mitochondrial dihydrolipoamide dehydrogenase (mtLPD) involved in photorespiration, the TCA cycle, and the degradation of branched chain amino acids. TRXs are seemingly a major point of metabolic regulation responsible for activating photosynthesis and adjusting mitochondrial photorespiratory metabolism according to the prevailing cellular redox status. Furthermore, TRX-mediated (de)activation of TCA cycle enzymes contributes to explain the non-cyclic flux mode of operation of this cycle in illuminated leaves. Here we provide an overview on the decisive role of TRXs in the coordination of mitochondrial metabolism in the light and provide in silico evidence for other redox-regulated photorespiratory enzymes. We further discuss the consequences of mtLPD regulation beyond photorespiration and provide outstanding questions that should be addressed in future studies to improve our understanding of the role of TRXs in the regulation of central metabolism.

DgC3H1, a CCCH zinc finger protein gene, confers cold tolerance in transgenic chrysanthemum

Zinc finger proteins play a significant role in regulating plant metabolism and stress responses. Nevertheless, the role of CCCH-type zinc finger proteins in chrysanthemums remains unclear. In this study, DgC3H1 was isolated and cloned from chrysanthemum. The DgC3H1 predicted protein contained 282 amino acids and three CCCH zinc finger motifs (C-X5-14-C-X4-5-C-X3-H). Through subcellular localization, it was found that DgC3H1 is located in the nucleus and is a CCCH zinc finger transcription factor. DgC3H1 overexpression improved the low temperature resistance of chrysanthemum. The expression of endogenous C3H1 was downregulated under antisense inhibition, and the sensitivity of chrysanthemum to low temperature stress was increased. Under cold stress, the contents of proline and soluble sugar, and the activities of peroxidase and superoxide dismutase were enhanced in the DgC3H1 overexpression lines,and reduced in the antisense suppression lines. In addition, the low temperature stress response genes DgCOR413, DgDREBa, DgCSD1, and DgCSD2 were upregulated in the overexpression lines, and downregulated in the antisense suppression lines when compared to the wild type. These results indicate that DgC3H1 can improve the resistance of chrysanthemum to cold stress and can be selected as an excellent candidate gene for breeding cold-tolerant plants.

Peach PpSnRK1α interacts with bZIP11 and maintains trehalose balance in plants

The nonreducing disaccharide trehalose is widespread in nature. It plays a very important role in plant growth and development. In plants, trehalose is present in trace amounts. High concentration of trehalose disrupts energy balance and inhibits normal growth and development. Studies have shown that high levels of trehalose and trehalose-6-phosphate (T6P), the metabolic precursor of trehalose, inhibit sucrose non-fermenting-1-related protein kinase1 (SnRK1) activity, which affect plant growth and development. However, the role of SnRK1, the energy balance center, in the regulation of trehalose metabolism in plants is unknown. In this study, exogenous trehalose at higher concentrations inhibited the expression of SnRK1 genes, especially PpSnRK1α in peach (Prunus persica) seedlings. This change in gene expression was dependent on trehalose concentration. Furthermore, overexpression of peach PpSnRK1α in Arabidopsis thaliana significantly promoted trehalase activity, reduced T6P content, and suppressed the trehalose synthesis related genes (TPSs, TPPB) expression, promoted the trehalose metabolism of gene expression (TRE1), in addition the transgenic plants alleviated photosynthetic product distribution imbalance (aboveground and underground parts), and enhanced root growth. Yeast two-hybrid and bimolecular fluorescence assays revealed the interaction between PpSnRK1α and peach basic domain leucine zipper transcription factor 11 (PpbZIP11), a key transcription factor of trehalose metabolism, in the nucleus. To summarize, PpSnRK1α overexpression improved bZIP11 transcriptional activity and regulated trehalose metabolism to protect the plants against trehalose-induced damage. This study preliminarily explained the mechanism of SnRK1 regulating trehalose metabolism balance in plants, which laid a foundation for further understanding of energy metabolism and function of SnRK1 in plants.

The BpMYB4 Transcription Factor From Betula platyphylla Contributes Toward Abiotic Stress Resistance and Secondary Cell Wall Biosynthesis.

The MYB (v-myb avian myeloblastosis viral oncogene homolog) family is one of the largest transcription factor families in plants, and is widely involved in the regulation of plant metabolism. In this study, we show that a MYB4 transcription factor, BpMYB4, identified from birch (Betula platyphylla Suk.) and homologous to EgMYB1 from Eucalyptus robusta Smith and ZmMYB31 from Zea mays L. is involved in secondary cell wall synthesis. The expression level of BpMYB4 was higher in flowers relative to other tissues, and was induced by artificial bending and gravitational stimuli in developing xylem tissues. The expression of this gene was not enriched in the developing xylem during the active season, and showed higher transcript levels in xylem tissues around sprouting and near the dormant period. BpMYB4 also was induced express by abiotic stress. Functional analysis indicated that expression of BpMYB4 in transgenic Arabidopsis (Arabidopsis thaliana) plants could promote the growth of stems, and result in increased number of inflorescence stems and shoots. Anatomical observation of stem sections showed lower lignin deposition, and a chemical contents test also demonstrated increased cellulose and decreased lignin content in the transgenic plants. In addition, treatment with 100 mM NaCl and 200 mM mannitol resulted in the germination rate of the over-expressed lines being higher than that of the wild-type seeds. The proline content in transgenic plants was higher than that in WT, but MDA content was lower than that in WT. Further investigation in birch using transient transformation techniques indicated that overexpression of BpMYB4 could scavenge hydrogen peroxide and O2.– and reduce cell damage, compared with the wild-type plants. Therefore, we believe that BpMYB4 promotes stem development and cellulose biosynthesis as an inhibitor of lignin biosynthesis, and has a function in abiotic stress resistance.

Sugar-mediated regulation and the role of HXK1, SnRK1, TOR kinases in <i>Arabidopsis thaliana</i>

Sugars play an important role in plant metabolism. They are not only a source of energy, but also an integral part of the intracellular signalling network. Signals involving sugars regulate a variety of metabolic reactions, e.g. carbon and nitrogen metabolism, and produce plant response to biotic and abiotic stresses. This paper provides a brief review of modern publications about sugars acting as metabolites and signaling molecules. The well-known and recently discovered pathways for the transmission of sugar-mediated signals are described, along with their role in the regulation of plant metabolism and expression of nuclear genes. Hexokinase 1 (an enzyme for glucose synthesis), which was one of the first studied participants in the sugar-mediated signalling network, regulates the expression of many nuclear genes in response to changes in the glucose level. Hexokinase 1 should be considered as a broad-spectrum regulator due to its participation in the transmission of mitochondrial-nuclear signals and regulation of aging processes in plants, which functions lay beyond the regulation of metabolic reactions. Of particular interest is the participation of sugar-mediated signals in the switching of metabolic reactions in response to changes in carbohydrate concentrations. Sugar deficiency deactivates most energy-intensive processes, at the same time as stimulating photosynthesis or (in its absence) enhancing catabolic reactions due to activation of the SnRK1 kinase. Under sufficient sugar levels, the SnRK1 kinase is suppressed and the TOR kinase is activated, which stimulates anabolic reactions and growth. The role of competing SnRK1 and TOR kinases as the main regulators of such a process is considered, along with the function of signals mediated by trehalose-6-phosphate highly similar to the TOR signalling pathway. All these regulatory mechanisms enable plants to adapt to environmental changes and maintain homeostasis. It is possible that additional information will be obtained in the nearest future on the interaction of energy and stress-dependent signals in plants through the antagonism of TOR and SnRK1.

Metabolic engineering in plants: Its application, future prospects with reference to metabolomics

Plants are a natural leading exporter of metabolites, which generates a plethora of varied metabolites through a network of interconnected biosynthetic pathways and found to play a variety of functions in plant growth, development and have proved to be essential for mankind as well. In recent catastrophic COVID pandemic plant metabolites have been reported to serve as potent anti-SARS-CoV-2. In this review article, we provided an overview of an alternative approach that may be used to improve the biogenesis and for raising the production of beneficiary plant metabolites in plant system especially those of pharmaceutical and nutraceutical importance. Metabolic engineering is such an example with a lot of potential for developing plant metabolite and to regulate plant metabolism by over expressing or repressing single or multiple structural genes or transcriptional factors. Present review article also discusses the integrated approach of metabolic engineering with metabolomics for tracking metabolite levels as well as studying the dynamic behaviour of plant cell metabolism and nutritional control. Gradually getting acquainted more with plant metabolism, metabolic pathways and their regulation, we shall witness amplified growth and efficacy in these fields. © 2021 MEDIC SCIENTIFIC. All Rights Reserved.

NtMYB12a acts downstream of sucrose to inhibit fatty acid accumulation by targeting lipoxygenase and SFAR genes in tobacco.

MYB12 promotes flavonol biosynthesis in plants by targeting several early biosynthesis genes (EBGs) of this pathway. The transcriptions of these EBGs are also induced by sucrose signal. However, whether MYB12 is activated by sucrose signal and what the other roles MYB12 has in regulating plant metabolism are poorly understood. In this study, two NtMYB12 genes were cloned from Nicotiana tabacum. Both NtMYB12a and NtMYB12b are involved in regulating flavonoids biosynthesis in tobacco. NtMYB12a is further shown to inhibit the accumulation of fatty acid (FA) in tobacco leaves and seeds. Post-translational activation and chromatin immunoprecipitation assays demonstrate that NtMYB12a directly promotes the transcriptions of NtLOX6, NtLOX5, NtSFAR4 and NtGDSL2, which encode lipoxygenase (LOX) or SFAR enzymes catalyzing the degradation of FA. NtLOX6 and NtLOX5 are shown to prevent the accumulation of FA in the mature seeds and significantly reduced the percentage of polyunsaturated fatty acids (PUFAs) in tobacco. Sucrose stimulates the transcription of NtMYB12a, and loss function of NtMYB12a partially suppresses the decrease of FA content in tobacco seedlings caused by sucrose treatment. The regulation of sucrose on the expression of NtLOX6 and NtGDSL2 genes is mediated by NtMYB12a, whereas those of NtLOX5 and NtSFAR4 genes are independent of sucrose.

Recent Advances in Genetic Regulation of Chlorophyll Metabolism in Plants

Recent Advances in Genetic Regulation of Chlorophyll Metabolism in Plants

Regulation of ROS Metabolism in Plants under Environmental Stress: A Review of Recent Experimental Evidence.

Various environmental stresses singly or in combination generate excess amounts of reactive oxygen species (ROS), leading to oxidative stress and impaired redox homeostasis. Generation of ROS is the obvious outcome of abiotic stresses and is gaining importance not only for their ubiquitous generation and subsequent damaging effects in plants but also for their diversified roles in signaling cascade, affecting other biomolecules, hormones concerning growth, development, or regulation of stress tolerance. Therefore, a good balance between ROS generation and the antioxidant defense system protects photosynthetic machinery, maintains membrane integrity, and prevents damage to nucleic acids and proteins. Notably, the antioxidant defense system not only scavenges ROS but also regulates the ROS titer for signaling. A glut of studies have been executed over the last few decades to discover the pattern of ROS generation and ROS scavenging. Reports suggested a sharp threshold level of ROS for being beneficial or toxic, depending on the plant species, their growth stages, types of abiotic stresses, stress intensity, and duration. Approaches towards enhancing the antioxidant defense in plants is one of the vital areas of research for plant biologists. Therefore, in this review, we accumulated and discussed the physicochemical basis of ROS production, cellular compartment-specific ROS generation pathways, and their possible distressing effects. Moreover, the function of the antioxidant defense system for detoxification and homeostasis of ROS for maximizing defense is also discussed in light of the latest research endeavors and experimental evidence.

Integrative Metabolomic and Transcriptomic Analyses Reveal Metabolic Changes and Its Molecular Basis in Rice Mutants of the Strigolactone Pathway.

Plants have evolved many metabolites to meet the demands of growth and adaptation. Although strigolactones (SLs) play vital roles in controlling plant architecture, their function in regulating plant metabolism remains elusive. Here we report the integrative metabolomic and transcriptomic analyses of two rice SL mutants, d10 (a biosynthesis mutant) and d14 (a perception mutant). Both mutants displayed a series of metabolic and transcriptional alterations, especially in the lipid, flavonoid, and terpenoid pathways. Levels of several diterpenoid phytoalexins were substantially increased in d10 and d14, together with the induction of terpenoid gene cluster and the corresponding upstream transcription factor WRKY45, an established determinant of plant immunity. The fact that WRKY45 is a target of IPA1, which acted as a downstream transcription factor of SL signaling, suggests that SLs contribute to plant defense through WRKY45 and phytoalexins. Moreover, our data indicated that SLs may modulate rice metabolism through a vast number of clustered or tandemly duplicated genes. Our work revealed a central role of SLs in rice metabolism. Meanwhile, integrative analysis of the metabolome and transcriptome also suggested that SLs may contribute to metabolite-associated growth and defense.

Functional Analysis of Phosphate Transporter OsPHT4 Family Members in Rice

The transport of phosphate between cytoplasm and subcellular compartments is critical for plant metabolic regulation. We conducted bioinformatic analysis, heterologous expression in yeast, gene expression pattern and subcellular localization analysis to characterize the possible functions of OsPHT4 gene family in rice. Together with the PHT4 genes from higher plants, OsPHT4s can be classified into six distinct groups. OsPHT4;1–OsPHT4;4 are targeted to chloroplasts, and OsPHT4;6-1 and OsPHT4;6-2 are located to Golgi apparatus. OsPHT4 proteins can mediate inorganic phosphate (Pi) transport in yeast. In addition, dynamic transcriptional changes determined by qRT-PCR revealed different expression profiles of OsPHT4 genes in response to phosphate starvation, salicylic acid, abscisic acid and salt stress treatments. These results suggested that OsPHT4 proteins are involved in Pi distribution between the cytoplasm and chloroplast or Golgi apparatus and also involved in stress responses.

Physiological Mechanism Involved in the Response to Four Lettuce Varieties to a Pre-transplant Root Restriction and a 6, benzyl aminopurine (BAP) Spray

Vegetable yield is positively related to the environment and negatively affected by the pot root restriction during both the nursery and post-transplant stages. Root restriction is a physical stress imposed on the root system when plants are grown in small containers, which leads to a pronounced decrease in root and shoot growth at both the transplant and pot stages. Based on the assumption that the plant responses are mainly associated with a negative hormonal signaling from roots, some researchers have proposed that these abiotic stresses may be overridden by using a pre-transplant spray with benzyl amino purine (BAP), a synthetic cytokinin able to regulate plant metabolism. Although the physiological mechanisms induced by BAP have been described, the implementation of commercial applications of BAP for vegetables is still a pending issue. The aim of this work was to analyze growth changes in four lettuce genotypes in the presence of different root restrictions degree by the use of different plug cell volumes but sprayed with a single BAP spray under the hypothesis that it would play a role as abiotic stress alleviators. Our results showed that the higher biomass accumulation in lettuce plants non root-limited and BAP-sprayed ones are supported by higher photosynthetic rates, by higher leaf number initiation and expansion and by photo assimilate partition to shoots. Understanding the plant responses to this hormonal manipulation and the physiological mechanism involved will allow adjusting the agronomic advice for different vegetables and reaching commercial yields to each of them.

Role of Strigolactones: Signalling and Crosstalk with Other Phytohormones.

Plant hormones play important roles in controlling how plants grow and develop. While metabolism provides the energy needed for plant survival, hormones regulate the pace of plant growth. Strigolactones (SLs) were recently defined as new phytohormones that regulate plant metabolism and, in turn, plant growth and development. This group of phytohormones is derived from carotenoids and has been implicated in a wide range of physiological functions including regulation of plant architecture (inhibition of bud outgrowth and shoot branching), photomorphogenesis, seed germination, nodulation, and physiological reactions to abiotic factors. SLs also induce hyphal branching in germinating spores of arbuscular mycorrhizal fungi (AMF), a process that is important for initiating the connection between host plant roots and AMF. This review outlines the physiological roles of SLs and discusses the significance of interactions between SLs and other phytohormones to plant metabolic responses.

Enantioselective effects of imazethapyr residues on Arabidopsis thaliana metabolic profile and phyllosphere microbial communities

Imazethapyr (IM) is a widely used acetolactate synthase-inhibiting chiral herbicide. It has long-term residuals that may be absorbed by the human body through the edible parts of plants, such as vegetable leaves or fruits. Here, we selected a model plant, Arabidopsis thaliana, to determine the effects of R-IM and S-IM on its leaf structure, photosynthetic efficiency, and metabolites, as well as the structures of microorganisms in the phyllosphere, after 7 days of exposure. Our results indicated enantiomeric differences in plant growth between R-IM and S-IM; 133 µg/kg R-IM showed heavier inhibition of photosynthetic efficiency and greater changes to subcellular structure than S-IM. R-IM and S-IM also had different effects on metabolism and leaf microorganisms. S-IM mainly increased lipid compounds and decreased amino acids, while R-IM increased sugar accumulation. The relative abundance of Moraxellaceae human pathogenic bacteria was increased by R-IM treatment, indicating that R-IM treatment may increase leaf surface pathogenic bacteria. Our research provides a new perspective for evaluating the harmfulness of pesticide residues in soil, phyllosphere microbiome changes via the regulation of plant metabolism, and induced pathogenic bacterial accumulation risks.

Protein Phosphorylation Dynamics Under Carbon/Nitrogen-Nutrient Stress and Identification of a Cell Death-Related Receptor-Like Kinase in Arabidopsis.

Nutrient availability, in particular the availability of sugar [carbon (C)] and nitrogen (N), is important for the regulation of plant metabolism and development. In addition to independent utilization of C and N nutrients, plants sense and respond to the balance of C and N nutrients (C/N-nutrient) available to them. High C/low N-nutrient stress has been shown to arrest early post-germinative growth while promoting progression to senescence in Arabidopsis. Although several signaling components of the C/N-nutrient response have been identified, the inclusive molecular basis of plant C/N-nutrient response remains unclear. This proteome analysis evaluated phosphorylation dynamics in response to high C/low N-nutrient stress. Phosphoproteomics under conditions of C/N-nutrient stress showed a global change in the phosphorylation status of proteins, including plasma membrane H+-ATPase, carbon and nitrogen metabolic enzymes and signaling proteins such as protein kinases and transcription factors. Further analyses suggested that SNF1-related protein kinase 1 (SnRK1) is involved in primary C/N-nutrient signal mediation via the transcriptional regulation of C/N-regulatory kinases. We also identified a leucine-rich repeat receptor-like kinase with extracellular malectin-like domain, named as LMK1, which was shown to possess cell death induction activity in plant leaves. These results provide important insight into the C/N-nutrient signaling pathways connecting nutrition stress to various cellular and physiological processes in plants.