ABSTRACT
ELONGATED HYPOCOTOYL5 (HY5) and PHYTOCHROME INTERACTING FACTORs (PIFs) are two types of important light-related regulators of plant growth, however, their interplay remains elusive. Here, we report that the activated tomato (Solanum lycopersicum) HY5 (SlHY5) triggers the transcription of a Calcium-dependent Protein Kinase SlCPK27. SlCPK27 interacts with and phosphorylates SlPIF4 at Ser-252 and Ser-308 phosphosites to promote its degradation. SlPIF4 promotes hypocotyl elongation mainly by activating the transcription of SlDWF, a key gene in brassinosteroid (BR) biosynthesis. Such a SlHY5-SlCPK27-SlPIF4-BR cascade not only plays a crucial role in photomorphogenesis but also regulates thermomorphogenesis. Our results uncover a previously unidentified mechanism that integrates Ca2+ signaling with the light signaling pathways to regulate plant growth by modulating BR biosynthesis in response to changes in ambient light and temperature.
Subject(s)
Brassinosteroids , Gene Expression Regulation, Plant , Plant Proteins , Protein Kinases , Solanum lycopersicum , Solanum lycopersicum/metabolism , Solanum lycopersicum/growth & development , Solanum lycopersicum/genetics , Brassinosteroids/metabolism , Plant Proteins/metabolism , Plant Proteins/genetics , Protein Kinases/metabolism , Protein Kinases/genetics , Light , Phosphorylation , Hypocotyl/metabolism , Hypocotyl/growth & development , Temperature , MorphogenesisABSTRACT
This Special Issue was assembled to mark the 25th anniversary of the proposal of the d -mannose/ l -galactose (Smirnoff-Wheeler) ascorbate biosynthesis pathway in plants ( Wheeler et al., 1998 ). The issue aims to assess the current state of knowledge and to identify outstanding questions about ascorbate metabolism and functions in plants.
Subject(s)
Ascorbic Acid , Plants , Ascorbic Acid/metabolism , Plants/metabolismABSTRACT
Hypoxia occurs when oxygen levels fall below the levels required for mitochondria to support respiration. Regulated hypoxia is associated with quiescence, particularly in storage organs (seeds) and stem cell niches. In contrast, environmentally induced hypoxia poses significant challenges for metabolically active cells that are adapted to aerobic respiration. The perception of oxygen availability through cysteine oxidases, which function as oxygen-sensing enzymes in plants that control the N-degron pathway, and the regulation of hypoxia-responsive genes and processes is essential to survival. Functioning together with reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2) and reactive nitrogen species (RNS), such as nitric oxide (·NO), nitrogen dioxide (·NO2), S-nitrosothiols (SNOs), and peroxynitrite (ONOO-), hypoxia signaling pathways trigger anatomical adaptations such as formation of aerenchyma, mobilization of sugar reserves for anaerobic germination, formation of aerial adventitious roots, and the hyponastic response. NO and H2O2 participate in local and systemic signaling pathways that facilitate acclimation to changing energetic requirements, controlling glycolytic fermentation, the γ-aminobutyric acid (GABA) shunt, and amino acid synthesis. NO enhances antioxidant capacity and contributes to the recycling of redox equivalents in energy metabolism through the phytoglobin (Pgb)-NO cycle. Here, we summarize current knowledge of the central role of NO and redox regulation in adaptive responses that prevent hypoxia-induced death in challenging conditions such as flooding.
Subject(s)
Nitric Oxide , Oxidation-Reduction , Nitric Oxide/metabolism , Plants/metabolism , Energy Metabolism , Oxygen/metabolism , Signal TransductionABSTRACT
Quiescence is an essential property of meristematic cells, which restrains the cell cycle while retaining the capacity to divide. This crucial process not only facilitates life-long tissue homeostasis and regenerative capacity but also provides protection against adverse environmental conditions, enabling cells to conserve the proliferative potency while minimising DNA damage. As a survival attribute, quiescence is inherently regulated by the products of aerobic life, in particular reactive oxygen species (ROS) and the redox (reduction/ oxidation) mechanisms that plant have evolved to channel these into pervasive signals. Adaptive responses allow quiescent cells to compensate for reduced oxygen tension (hypoxia) in a reversible manner, while the regulated production of the superoxide anion (.O2-) facilitates cell division and the maintenance of stem cells. Here we discuss the role of ROS and redox reactions in the control of the quiescent state in plant meristems, and how this process is integrated with cellular energy and hormone biochemistry. We consider the pathways that sense and transmit redox signals with a focus on the central significance of redox regulation in the mitochondria and nucleus, which is a major regulator of quiescence in meristems. We discuss recent studies that suggest ROS are a critical component of the feedback loops that control stem cell identity and fate and suggest that the ROS/hypoxia interface is an important "outside/ in" positional cue for plant cells, particularly in meristems.
ABSTRACT
The interplay between reactive oxygen species (ROS) and the redox state of cells is deeply rooted in the biology of almost all organisms, regulating development, growth, and responses to the environment. Recent studies revealed that the ROS levels and redox state of one cell can be transmitted, as an information 'state' or 'currency', to other cells and spread by cell-to-cell communication within an entire community of cells or an organism. Here, we discuss the different pathways that mediate cell-to-cell signaling in plants, their hierarchy, and the different mechanisms that transmit ROS/redox signaling between different cells. We further hypothesize that ROS/redox signaling between different organisms could play a key role within the 'one world' principle, impacting human health and our future.
Subject(s)
Cell Communication , Plants , Reactive Oxygen Species , Signal Transduction , Reactive Oxygen Species/metabolism , Plants/metabolism , Oxidation-Reduction , Stress, Physiological , Plant Physiological PhenomenaABSTRACT
Enhancing carbohydrate export from source to sink tissues is considered to be a realistic approach for improving photosynthetic efficiency and crop yield. The rice sucrose transporters OsSUT1, OsSWEET11a and OsSWEET14 contribute to sucrose phloem loading and seed filling. Crucially, Xanthomonas oryzae pv. oryzae (Xoo) infection in rice enhances the expression of OsSWEET11a and OsSWEET14 genes, and causes leaf blight. Here we show that co-overexpression of OsSUT1, OsSWEET11a and OsSWEET14 in rice reduced sucrose synthesis and transport leading to lower growth and yield but reduced susceptibility to Xoo relative to controls. The immunity-related hypersensitive response (HR) was enhanced in the transformed lines as indicated by the increased expression of defence genes, higher salicylic acid content and presence of HR lesions on the leaves. The results suggest that the increased expression of OsSWEET11a and OsSWEET14 in rice is perceived as a pathogen (Xoo) attack that triggers HR and results in constitutive activation of plant defences that are related to the signalling pathways of pathogen starvation. These findings provide a mechanistic basis for the trade-off between plant growth and immunity because decreased susceptibility against Xoo compromised plant growth and yield.
Subject(s)
Gene Expression Regulation, Plant , Membrane Transport Proteins , Oryza , Plant Diseases , Plant Immunity , Plant Proteins , Plants, Genetically Modified , Salicylic Acid , Sucrose , Xanthomonas , Oryza/microbiology , Oryza/genetics , Oryza/immunology , Oryza/metabolism , Plant Proteins/metabolism , Plant Proteins/genetics , Xanthomonas/physiology , Plant Diseases/microbiology , Plant Diseases/immunology , Sucrose/metabolism , Membrane Transport Proteins/metabolism , Membrane Transport Proteins/genetics , Salicylic Acid/metabolism , Plant Leaves/metabolism , Plant Leaves/immunologyABSTRACT
The superoxide anion radical (O2·-) is a one-electron reduction product of molecular oxygen. Compared with other forms of reactive oxygen species (ROS), superoxide has limited reactivity. Nevertheless, superoxide reacts with nitric oxide, ascorbate, and the iron moieties of [Fe-S] cluster-containing proteins. Superoxide has largely been neglected as a signalling molecule in the plant literature in favour of the most stable ROS form, hydrogen peroxide. However, superoxide can accumulate in plant cells, particularly in meristems, where superoxide dismutase activity and ascorbate accumulation are limited (or absent), or when superoxide is generated within the lipid environment of membranes. Moreover, oxidation of the nucleus in response to environmental stresses is a widespread phenomenon. Superoxide is generated in many intracellular compartments including mitochondria, chloroplasts, and on the apoplastic/cell wall face of the plasma membrane. However, nuclear superoxide production and functions remain poorly documented in plants. Accumulating evidence suggests that the nuclear pools of antioxidants such as glutathione are discrete and separate from the cytosolic pools, allowing compartment-specific signalling in the nucleus. We consider the potential mechanisms of superoxide generation and targets in the nucleus, together with the importance of antioxidant processing in regulating superoxide signalling.
Subject(s)
Antioxidants , Cell Nucleus , Signal Transduction , Superoxides , Superoxides/metabolism , Antioxidants/metabolism , Cell Nucleus/metabolism , Plants/metabolismABSTRACT
Jasmonates (JAs), a class of lipid-derived stress hormones, play a crucial role across an array of plant physiological processes and stress responses. Although JA signaling is thought to rely predominantly on the degradation of specific JAZ proteins by SCFCOI1, it remains unclear whether other pathways are involved in the regulation of JAZ protein stability. Here, we report that PUB22, a plant U-box type E3 ubiquitin ligase, plays a critical role in the regulation of plant resistance against Helicoverpa armigera and other JA responses in tomato. Whereas COI1 physically interacts with JAZ1/2/5/7, PUB22 physically interacts with JAZ1/3/4/6. PUB22 ubiquitinates JAZ4 to promote its degradation via the 26S proteasome pathway. Importantly, we observed that pub22 mutants showreduced resistance to H. armigera, whereas jaz4 single mutants and jaz1 jaz3 jaz4 jaz6 quadruple mutants have enhanced resistance. The hypersensitivity of pub22 mutants to herbivores could be partially rescued by JAZ4 mutation. Moreover, we found that expression of PUB22 can be transcriptionally activated by MYC2, thus forming a positive feedback circuit in JA signaling. We noticed that the PUB22-JAZ4 module also regulates other JA responses, including defense against B. cinerea, inhibition of root elongation, and anthocyanin accumulation. Taken together, these results indicate that PUB22 plays a crucial role in plant growth and defense responses, together with COI1-regulated JA signaling, by targeting specific JAZs.
Subject(s)
Arabidopsis Proteins , Arabidopsis , Solanum lycopersicum , Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Repressor Proteins/metabolism , Solanum lycopersicum/genetics , Cyclopentanes/metabolism , Oxylipins/metabolism , Plants/metabolism , Gene Expression Regulation, Plant , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Ubiquitin-Protein Ligases/metabolismABSTRACT
Concepts regarding the operation of the ascorbate-glutathione cycle and the associated water/water cycle in the processing of metabolically generated hydrogen peroxide and other forms of reactive oxygen species (ROS) are well established in the literature. However, our knowledge of the functions of these cycles and their component enzymes continues to grow and evolve. Recent insights include participation in the intrinsic environmental and developmental signalling pathways that regulate plant growth, development, and defence. In addition to ROS processing, the enzymes of the two cycles not only support the functions of ascorbate and glutathione, they also have 'moonlighting' functions. They are subject to post-translational modifications and have an extensive interactome, particularly with other signalling proteins. In this assessment of current knowledge, we highlight the central position of the ascorbate-glutathione cycle in the network of cellular redox systems that underpin the energy-sensitive communication within the different cellular compartments and integrate plant signalling pathways.
Subject(s)
Ascorbic Acid , Glutathione , Plants , Ascorbic Acid/metabolism , Glutathione/metabolism , Plants/metabolism , Signal Transduction , Oxidation-Reduction , Reactive Oxygen Species/metabolismABSTRACT
Climate change threatens global food and nutritional security through negative effects on crop growth and agricultural productivity. Many countries have adopted ambitious climate change mitigation and adaptation targets that will exacerbate the problem, as they require significant changes in current agri-food systems. In this review, we provide a roadmap for improved crop production that encompasses the effective transfer of current knowledge into plant breeding and crop management strategies that will underpin sustainable agriculture intensification and climate resilience. We identify the main problem areas and highlight outstanding questions and potential solutions that can be applied to mitigate the impacts of climate change on crop growth and productivity. Although translation of scientific advances into crop production lags far behind current scientific knowledge and technology, we consider that a holistic approach, combining disciplines in collaborative efforts, can drive better connections between research, policy, and the needs of society.
Subject(s)
Climate Change , Crops, Agricultural , Plant Breeding , Agriculture , Crop ProductionABSTRACT
Plants are vital to human health and well-being, as well as helping to protect the environment against the negative impacts of climate change. They are an essential part of the 'One Health' strategy that seeks to balance and optimize the health of people, animals and the environment. Crucially, plants are central to nature-based solutions to climate mitigation, not least because soil carbon storage is an attractive strategy for mitigating greenhouse gas emissions and the associated climate change. Agriculture depends on genetically pure, high-quality seeds that are free from pests and pathogens and contain a required degree of genetic purity. This themed collection addresses key questions in the field encompassing the biochemical mechanisms that underlie plant responses and adaptations to a changing climate. This collection encompasses an analysis of the biochemistry and molecular mechanisms underpinning crop and forest resilience, together with considerations of plant adaptations to climate change-associated stresses, including drought, floods and heatwaves, and the increased threats posed by pathogens and pests.
Subject(s)
Climate Change , Seeds , Animals , Humans , SoilABSTRACT
The blackening of cut carrots causes substantial economic losses to the food industry. Blackening was not observed in carrots that had been stored underground for less than a year, but the susceptibility to blackening increased with the age of the carrots that were stored underground for longer periods. Samples of black, border, and orange tissues from processed carrot batons and slices, prepared under industry standard conditions, were analyzed to identify the molecular and metabolic mechanisms underpinning processing-induced blackening. The black tissues showed substantial molecular and metabolic rewiring and large changes in the cell wall structure, with a decreased abundance of xyloglucan, pectins (homogalacturonan, rhamnogalacturonan-I, galactan and arabinan), and higher levels of lignin and other phenolic compounds when compared to orange tissues. Metabolite profiling analysis showed that there was a major shift from primary to secondary metabolism in the black tissues, which were depleted in sugars, amino acids, and tricarboxylic acid (TCA) cycle intermediates but were rich in phenolic compounds. These findings suggest that processing triggers a release from quiescence. Transcripts encoding proteins associated with secondary metabolism were less abundant in the black tissues, but there were no increases in transcripts associated with oxidative stress responses, programmed cell death, or senescence. We conclude that restraining quiescence release alters cell wall metabolism and composition, particularly regarding pectin composition, in a manner that increases susceptibility to blackening upon processing.
Subject(s)
Daucus carota , Daucus carota/metabolism , Plant Cells , Lignin/metabolism , Cell Wall/chemistryABSTRACT
KEY MESSAGE: GmTSA and GmALS were screened out for salt stress in soybean and explore the poteintial amino acid secondary metabolism pathways. Soybean (Glycine max L.) is an oil and protein crop of global importance, and salinity has significant effects on soybean growth. Here, a population of soybean chromosome segment substitution lines was screened to identify highly salt-tolerant lines. In total, 24 quantitative trait loci (QTLs) on seven chromosomes were associated with salt tolerance, and CSSL_R71 was selected for further analysis. Although numerous genes were differentially expressed in CSSL_R71 in response to salt statically no differently, transcript levels of classical salt-response genes, including those of the salt overly sensitive pathway. Rather, salt tolerance in CSSL_R71 was associated with changes in amino acid and lipid metabolism. In particular, changes in p-coumaric acid, shikimic acid, and pyrrole-2-carboxylic acid levels accompanied salt tolerance in CSSL_R71. Eleven differentially expressed genes (DEGs) related to amino acid and secondary metabolism were identified as candidate genes on the substituted chromosome fragment. Six of these showed differences in coding sequence between the parental genotypes. Crucially, overexpression of GmTSA (Glyma.03G158400, tryptophan synthase) significantly enhanced salt tolerance in soybean hairy roots, whereas overexpression of GmALS (Glyma.13G241000, acetolactate synthase) decreased salt tolerance. Two KASP markers were developed for GmALS and used to genotype salt-tolerant and salt-sensitive lines in the CSSL population. Non-synonymous mutations were directly associated with salt tolerance. Taken together, these data provide evidence that changes in amino acid and secondary metabolism have the potential to confer salt tolerance in soybean.
Subject(s)
Amino Acids , Glycine max , Secondary Metabolism , Glycine max/genetics , Salt Tolerance/genetics , Salt StressABSTRACT
In addition to the challenge of meeting global demand for food production, there are increasing concerns about food safety and the need to protect consumer health from the negative effects of foodborne allergies. Certain bio-molecules (usually proteins) present in food can act as allergens that trigger unusual immunological reactions, with potentially life-threatening consequences. The relentless working lifestyles of the modern era often incorporate poor eating habits that include readymade prepackaged and processed foods, which contain additives such as peanuts, tree nuts, wheat, and soy-based products, rather than traditional home cooking. Of the predominant allergenic foods (soybean, wheat, fish, peanut, shellfish, tree nuts, eggs, and milk), peanuts (Arachis hypogaea) are the best characterized source of allergens, followed by tree nuts (Juglans regia, Prunus amygdalus, Corylus avellana, Carya illinoinensis, Anacardium occidentale, Pistacia vera, Bertholletia excels), wheat (Triticum aestivum), soybeans (Glycine max), and kidney beans (Phaseolus vulgaris). The prevalence of food allergies has risen significantly in recent years including chance of accidental exposure to such foods. In contrast, the standards of detection, diagnosis, and cure have not kept pace and unfortunately are often suboptimal. In this review, we mainly focus on the prevalence of allergies associated with peanut, tree nuts, wheat, soybean, and kidney bean, highlighting their physiological properties and functions as well as considering research directions for tailoring allergen gene expression. In particular, we discuss how recent advances in molecular breeding, genetic engineering, and genome editing can be used to develop potential low allergen food crops that protect consumer health.
Subject(s)
Food Hypersensitivity , Animals , Nuts , Arachis , Allergens , Glycine max , Crops, AgriculturalABSTRACT
Aims: Reactive oxygen species (ROS) are key regulators of plant growth, development, and stress tolerance. Stress-induced changes in ROS levels trigger multilevel signaling. However, the precise mechanisms by which ROS signals are translated into changes in gene expression remain poorly defined. Focusing on six key antioxidant enzymes, we performed a meta-analysis of transcriptome data available in public databases to analyze ROS-mediated control of nuclear gene expression. Results: An information-guided pipeline was developed, which identified 19 putative transcription factors (TFs), as components in a "common alarm signal cascade" pathway following perception of changes in ROS levels. Crucially, 30%-35% of the abiotic stress transcriptome signatures had binding sites for common alarm signal-transcription factors (CAS-TFs) in their promoter regions. Furthermore, Phloem Early Dof 2 (PEAR2), DNA binding with one finger 5.8 (DOF5.8), and Obf-Binding Protein 3 (OBP3) were identified as top-ranked TFs on the basis of a cumulative DAPseq (DNA-affinity purification sequencing) score on the promoters of selected genes regulating core pathways of salt, drought, heat, and cold stress tolerance. Innovation: This study identifies a set of CAS-TFs that may play a major role in shaping the transcriptome of abiotic stress-induced ROS signaling. Ranking analysis identified PEAR2, DOF5.8, and OBP3 as the top-ranked CAS-TFs that regulated known markers of abiotic stress tolerance. Conclusion: The current findings suggest a major role of ROS in the abiotic stress signaling and also identify a set of TFs that take part in the signaling. Taken together, these findings suggested that the common alarm signal cascade underpins broad-range tolerance against multistress conditions. The identification of associated ROS-responsive CAS-TFs may provide novel targets for crop improvement.
ABSTRACT
Hydrogen cyanamide (HC) has been widely used in horticulture to trigger bud burst following dormancy. Its use has been banned in some countries due to human health concerns, however the search for effective safe alternatives is delayed by lack of knowledge of the mechanism of HC action. Earlier studies demonstrate that HC stimulates the production of reactive oxygen species (ROS) and alters the rate of cell division. However, the relationships between HC effects on ROS, redox (reduction/oxidation) homeostasis and cell division are unknown. This study used Arabidopsis thaliana ((L.) Heynh.) seedlings expressing the redox reporter roGFP2 to measure the oxidation states of the nuclei and cytosol in response to HC treatment. The Cytrap dual cell cycle phase marker system and flow cytometry were used to study associated changes in cell proliferation. HC (1.5 mM) reversibly inhibited root growth during a 24 h treatment. Higher concentrations were not reversible. HC did not synchronise the cell cycle, in contrast to hydroxyurea. Rather, HC caused a gradual accumulation of cells in the G2/M phase and decline of G1/S phase cells, 16 to 24 h post-treatment. This was accompanied by increased oxidation of both the nuclei and cytosol. Taken together, these findings show that HC impairs proliferation of embryonic root meristem cells in a reversible manner through restriction of G2/M transition accompanied by increased cellular oxidation.
ABSTRACT
The WHIRLY (WHY) family of DNA/RNA binding proteins fulfil multiple but poorly characterised functions in plants. We analysed WHY protein functions in the Arabidopsis Atwhy1, Atwhy3, Atwhy1why3 single and double mutants and wild type controls. The Atwhy3 and Atwhy1why3 double mutants showed a significant delay in flowering, having more siliques per plant but with fewer seeds per silique than the wild type. While germination was similar in the unaged high-quality seeds of all lines, significant decreases in vigour and viability were observed in the aged mutant seeds compared with the wild type. Imbibition of unaged high-quality seeds was characterised by large increases in transcripts that encode proteins involved in oxygen sensing and responses to hypoxia. Seed aging resulted in a disruption of the imbibition-induced transcriptome profile such that transcripts encoding RNA metabolism and processing became the most abundant components of the imbibition signature. The imbibition-related profile of the Atwhy1why3 mutant seeds, was characterised by decreased expression of hypoxia-related and oxygen metabolism genes even in the absence of aging. Seed aging further decreased the abundance of hypoxia-related and oxygen metabolism transcripts relative to the wild type. These findings suggest that the WHY1 and WHY3 proteins regulate the imbibition-induced responses to oxygen availability and hypoxia. Loss of WHY1 and WHY3 functions decreases the ability of Arabidopsis seeds to resist the adverse effects of seed aging.