More than 40 million people worldwide are thought to be affected by Alzheimer's disease(AD).Of these,estimated less than10% develop symptoms usually well before the age of 65,due to familial(hereditary) AD predisp...More than 40 million people worldwide are thought to be affected by Alzheimer's disease(AD).Of these,estimated less than10% develop symptoms usually well before the age of 65,due to familial(hereditary) AD predisposition(Sierksma et al.,2020).AD is a multifactorial disorder,which includes a multitude of progressive degenerations in the brain parenchyma,but also in the vascular and hemostatic system.展开更多
Begomoviruses cause significant losses to a wide range of crops worldwide,and a great progress has been made in characterizing some noncanonical proteins encoded by begomoviruses.In the present study,a novel viral pro...Begomoviruses cause significant losses to a wide range of crops worldwide,and a great progress has been made in characterizing some noncanonical proteins encoded by begomoviruses.In the present study,a novel viral protein,C6,was detected in Nicotiana benthamiana plants infected with tomato leaf curl China virus(ToLCCNV).Sequence analyses revealed that the C6 ORF is on the complementary strand of approximately 36%reported begomovirus sequences with conserved amino acid sequence.ToLCCNV C6 specifically localizes to mitochondria.Analysis of deletion mutants showed that C6 possesses an internal mitochondrial targeting signal.Overall,these data uncover a novel begomovirus-encoded protein targeting distinct plant cell organelles.展开更多
Inositol pyrophosphates(PP-InsPs)are important signaling molecules that regulate diverse cellular processes in eukaryotes,including energy homeostasis,phosphate(Pi)signaling,and phytohormone perception.Yet,in plants,t...Inositol pyrophosphates(PP-InsPs)are important signaling molecules that regulate diverse cellular processes in eukaryotes,including energy homeostasis,phosphate(Pi)signaling,and phytohormone perception.Yet,in plants,the enzymes responsible for their turnover remain largely unknown.Using a non-hydrolysable PP-InsP analog in a pull-down approach,we identified a family of Arabidopsis NUDIX-type hydrolases(NUDTs)that group into two closely related subclades.Through in vitro assays,heterologous expression systems,and higher order gene-edited mutants,we explored the substrate specificities and physiological roles of these hydrolases.Using a combination of strong anion exchange high-performance liquid chromatography(SAX-HPLC),polyacrylamide gel electrophoresis(PAGE),and capillary electrophoresis electrospray ionization mass spectrometry(CE-ESI-MS),we found that their PP-InsP pyrophosphatase activity is enantiomer selective and Mg^(2+)dependent.Specifically,SubcladeⅠNUDTs preferentially hydrolyze 4-InsP_(7),while SubcladeⅡNUDTs target 3-InsP_(7),with minor activity against other PP-InsPs,including5-InsP_(7).In higher order mutants of SubcladeⅡNUDTs,we observed defects in both Piand iron homeostasis,accompanied by increased levels of 1/3-InsP_(7)and 5-InsP_(7),with a markedly larger increase in 1/3-InsP_(7).Ectopic expression of NUDTs from both subclades induced local Pi starvation responses(PSRs),while RNA-seq analysis comparing wild-type(WT)and SubcladeⅡnudt12/13/16 loss-of-function plants indicates additional PSR-independent roles,potentially involving 1/3-InsP_(7) in the regulation of plant defense.Consistently,nudt12/13/16 mutants displayed enhanced resistance to Pseudomonas syringae infection,indicating a role in bacterial pathogen susceptibility.Expanding beyond SubcladeⅡNUDTs,we demonstrated susceptibility of the 3PP-position of PP-InsPs to enzymatic activities unrelated to NUDTs,and found that such activities are conserved across plants and humans.Additionally,we observed that NUDT effectors from pathogenic ascomycete fungi exhibit a substrate specificity similar to SubcladeⅠNUDTs.Collectively,our findings reveal new roles for NUDTs in PP-InsP signaling,plant nutrient and immune responses,and highlight a cross-kingdom conservation of PP-InsP-metabolizing enzymes.展开更多
The chemical modifications of DNA and proteins are powerful mechanisms for regulating molecular and biological functions,influencing a wide array of signaling pathways in eukaryotes.Recent advance-ments in epitranscri...The chemical modifications of DNA and proteins are powerful mechanisms for regulating molecular and biological functions,influencing a wide array of signaling pathways in eukaryotes.Recent advance-ments in epitranscriptomics have shown that RNA modifications play crucial roles in diverse biological processes.Since their discovery in the 1970s,scientists have sought to decipher,identify,and elucidate the functions of these modifications across biological systems.Over the past decade,mounting evi-dence has demonstrated the importance of RNA modification pathways in plants,prompting significant efforts to decipher their physiological relevance.With the advent of high-resolution mapping tech-niques for RNA modifications and the gradual uncovering of their biological roles,our understanding of this additional layer of regulation is beginning to take shape.In this review,we summarize recent findings on the major RNA modifications identified in plants,with an emphasis on N^(6)-methyladenosine(m^(6)A),the most extensively studied modification.We discuss the functional signifi-cance of the effector components involved in m^(6)A modification and its diverse roles in plant biotic in-teractions,including plant–virus,plant–bacterium,plant–fungus,and plant–insect relationships.Furthermore,we highlight new technological developments driving research progress in this field and outline key challenges that remain to be addressed.展开更多
Plant viruses cause symptoms with devastating consequences for agriculture.However,the molecular mechanisms underlying symptom development in viral infections remain largely unexplored.Here,we show that tomato yellow ...Plant viruses cause symptoms with devastating consequences for agriculture.However,the molecular mechanisms underlying symptom development in viral infections remain largely unexplored.Here,we show that tomato yellow leaf curl virus(TYLCV)interferes with host developmental programs through a host-mimicking domain present in the viral C4 protein.This domain mediates the interaction between C4 and a family of RCC1-like domain-containing(RLD)proteins,previously shown to be required for proper plant development and environmental responses.C4 outcompetes an endogenous interactor of RLDs,hijacking RLD proteins to the plasma membrane and disrupting their function in orchestrating endomembrane trafficking and polar auxin transport.Strikingly,macroscopic symptoms do not affect viral accumulation in the plant but serve as attractants for the insect vector,presumably promoting pathogen spread in an ecological context.Our work sheds light on the molecular underpinnings and biological relevance of symptom development triggered by TYLCV in tomato.Since most plant viruses are insect-transmitted,the principles described here might have broad applicability to crop-virus interactions.展开更多
The coordination of floral developmental stages with the environment is important for reproductive success and optimization of crop yields.The timing of different developmental stages contributes to final yield potent...The coordination of floral developmental stages with the environment is important for reproductive success and optimization of crop yields.The timing of different developmental stages contributes to final yield potential,with optimal adaptation enabling development to proceed without being impacted by seasonal weather events,including frosts or end-of-season drought.Here,we characterize the role of FLOWERING LOCUS T 3(FT3)in hexaploid bread wheat(Triticum aestivum)during the early stages of floral development.By assaying the genetic diversity of landraces and modern wheat varieties,we identified a distribution of alleles for FT3 that indicated selection in modern varieties.We generated transgenic overexpression lines and found that FT3 is as powerful a florigen as FT1,which suggested that FT3 is under tight regulation.To investigate this possibility,we measured FT3 expression under variable environmental conditions and identified a role for both temperature and photoperiod in FT3 regulation.Gene expression analysis showed that FT3 transcription is partly coordinated by a temperature-sensitive pathway consisting of a TEOSINTE BRANCHED 1–CYCLOIDEA–PROLIFERATING CELL FACTOR(TCP)transcription factor and a warm-temperature-responsive microRNA.We show that this regulation is important for the timing of floral development under short days combined with lower ambient temperatures and that there has been strong selection on FT3 during cultivation.Deploying this understanding to enable targeted combinations of alleles involved in adaptation will further our ability to develop climate-change-robust cultivars.展开更多
The vast majority of known viruses belong to the positive-sense single-stranded RNA(+ss RNA)class.Tobamoviruses are among the most destructive plant viruses and threaten global food security.It is generally accepted t...The vast majority of known viruses belong to the positive-sense single-stranded RNA(+ss RNA)class.Tobamoviruses are among the most destructive plant viruses and threaten global food security.It is generally accepted that+ss RNA viruses including tobamoviruses encode proteins solely on their positive strand(+RNA).Here,we identified additional open-reading frames(ORFs)in the negative strand of tobamoviruses,named reverse ORFs(r ORFs).Using cucumber green mottle mosaic virus(CGMMV)as a model,we detected the corresponding peptides of r ORFs by mass spectrometry analysis and confirmed the translation of r ORFs by ribosome profiling.Furthermore,we demonstrated that these r ORFs may be translated from an internal ribosome entry site.Mutation of r ORF1 and r ORF2 significantly reduced the virulence of CGMMV,whereas ectopic expression of r ORF1 and r ORF2 could rescue the pathogenicity of the mutants.While the r ORF2 protein localizes at the cell membrane and in the nucleolus,r ORF1 colocalizes with peroxisomes,where it interacts with the viral 126-k D replication protein.Additionally,we screened peroxisomal r ORF1-interacting proteins using artificial intelligence tools and found that PEX3 mediated r ORF1 targeting to peroxisomes.This study reveals that the tobamoviral proteome is larger than previously thought,and sheds light on peroxisomes as novel virulence targets important for virus infectivity.展开更多
In order to assess the functional roles of heat stress-induced class B-heat shock factors in Arabidopsis, we investigated T-DNA knockout mutants of AtHsfB1 and AtHsfB2b. Micorarray analysis of double knockout hsfB1/hs...In order to assess the functional roles of heat stress-induced class B-heat shock factors in Arabidopsis, we investigated T-DNA knockout mutants of AtHsfB1 and AtHsfB2b. Micorarray analysis of double knockout hsfB1/hsfB2b plants revealed as strong an up-regulation of the basal mRNA-levels of the defensin genes Pdfl.2a/b in mutant plants. The Pdfexpression was further enhanced by jasmonic acid treatment or infection with the necrotrophic fungus Alternaria brassicicola. The single mutant hsfB2b and the double mutant hsfB 1/B2b were significantly improved in disease resistance after A. brassicicola infection. There was no indication for a direct interaction of Hsf with the promoter of Pdf1.2, which is devoid of perfect HSE consensus Hsf-binding sequences. However, changes in the formation of late HsfA2-dependent HSE binding were detected in hsfB1/B2b plants. This suggests that HsfB1/B2b may interact with class A-Hsf in regulating the shut-off of the heat shock response. The identification of Pdfgenes as targets of Hsf-dependent negative regulation is the first evidence for an interconnection of Hsf in the regulation of biotic and abiotic responses.展开更多
As the first and rate-limiting enzyme of proline degradation, PROLINE DEHYDROGENASE1 （PDH1） is tightly regulated during plant stress responses, including induction under hypoosmolarity and repression under water def...As the first and rate-limiting enzyme of proline degradation, PROLINE DEHYDROGENASE1 （PDH1） is tightly regulated during plant stress responses, including induction under hypoosmolarity and repression under water deficit. The plant receptor histidine kinases AHKs, elements of the two-component system （TCS） in Arabidopsis thaliana, are pro- posed to function in water stress responses by regulating different stress-responsive genes. However, little information is available concerning AHK phosphorelay-mediated downstream signaling. Here we show that the Arabidopsis type-B response regulator 18 （ARR18） functions as a positive osmotic stress response regulator in Arabidopsis seeds and affects the activity of the PDH1 promoter, known to be controlled by C-group bZlP transcription factors. Moreover, direct physical interaction of ARR18 with bZIP63 was identified and shown to be dependent on phosphorylation of the conserved aspar- tate residue in the ARR18 receiver domain. We further show that bZlP63 itself functions as a negative regulator of seed germination upon osmotic stress. Using reporter gene assays in protoplasts, we demonstrated that ARR18 interaction negatively interferes with the transcriptional activity of bZIP63 on the PDH1 promoter. Our findings provide new insight into the function of ARR18 and bZIP63 as antagonistic regulators of gene expression in Arabidopsis.展开更多
Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxi...Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASEI （CuAO1）, of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuaol-2. PA-induced and ABA-induced NO production investigated bY fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H2O2 increases, cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.展开更多
High-temperature stress, like any abiotic stress, impairs the physiology and development of plants, including the stages of seed setting and ripening. We used the Affymetrix 22K Barley1 GeneChip microarray to investig...High-temperature stress, like any abiotic stress, impairs the physiology and development of plants, including the stages of seed setting and ripening. We used the Affymetrix 22K Barley1 GeneChip microarray to investigate the response of developing barley （Hordeum vulgare） seeds, termed caryopses, after 0.5, 3, and 6 h of heat stress exposure; 958 induced and 1122 repressed genes exhibited spatial and temporal expression patterns that provide a detailed insight into the caryopses＇ early heat stress responses. Down-regulation of genes related to storage compound biosynthesis and cell growth provides evidence for a rapid impairment of the caryopsis＇ development. Increased levels of sugars and amino acids were indicative for both production of compatible solutes and feedback-induced accumulation of substrates for storage compound biosynthesis. Metadata analysis identified embryo and endosperm as primary locations of heat stress responses, indicating a strong impact of short-term heat stress on central developmental functions of the caryopsis. A comparison with heat stress responses in Arabidopsis shoots and drought stress responses in barley caryopses identified both conserved and presumably heat- and caryopsis-specific stress-responsive genes. Summarized, our data provide an important basis for further investigation of gene functions in order to aid an improved heat tolerance and reduced losses of yield in barley as a model for cereal crops.展开更多
In order to analyze the signaling function of hydrogen peroxide （H202） production in senescence in more detail, we manipulated intracellular H202 levels in Arabidopsis thaliala （L.） Heynh by using the hydrogen- pe...In order to analyze the signaling function of hydrogen peroxide （H202） production in senescence in more detail, we manipulated intracellular H202 levels in Arabidopsis thaliala （L.） Heynh by using the hydrogen- peroxide-sensitive part of the Escherichia coil transcription regulator OxyR, which was directed to the cytoplasm as well as into the peroxisomes. H202 levels were lowered and senescence was delayed in both transgenic lines, but OxyR was found to be more effective in the cytoplasm. To transfer this knowledge to crop plants, we analyzed oilseed rape plants Brassica napus L. cv. Mozart for H20~ and its scavenging enzymes catalase （CAT） and ascorbate peroxidase （APX） during leaf and plant development. H202 levels were found to increase during bolting and flowering time, but no increase could be observed in the very late stages of senescence. With increasing H202 levels, CAT and APX activities declined, so it is likely that similar mechanisms are used in oilseed rape and Arabidopsis to control H202 levels. Under elevated CO2 conditions, oilseed rape senescence was accelerated and coincided with an earlier increase in H202 levels, indicating that H202 may be one of the signals to inducing senescence in a broader range of Brassicaceae.展开更多
Seed size critically affects grain yield of crops and hence represents a key breeding target.The develop-ment of embryo-nourishing endosperm is a key driver of seed expansion.We here report unexpected dual roles of th...Seed size critically affects grain yield of crops and hence represents a key breeding target.The develop-ment of embryo-nourishing endosperm is a key driver of seed expansion.We here report unexpected dual roles of the transcription factor EIN3 in regulating seed size.These EIN3 functions have remained largely undiscovered because they oppose each other.Capitalizing on the analysis of multiple ethylene biosynthesis mutants,we demonstrate that EIN3 represses endosperm and seed development in a pathway regulated by ethylene.We,in addition,provide evidence that EIN3-mediated synergid nucleus disintegration promotes endosperm expansion.Interestingly,synergid nucleus disintegration is not affected in various ethylene biosynthesis mutants,suggesting that this promoting function of EIN3 is inde-pendent of ethylene.Whereas the growth-inhibitory ethylene-dependent EIN3 action appears to be encoded by sporophytic tissue,the growth-promoting role of EIN3 is induced by fertilization,revealing a generation conflict that converges toward the key signaling component EIN3.展开更多
Spectro-microscopy, a combination of fluorescence microscopy with spatially resolved spectroscopic techni- ques, provides new and exciting tools for functional cell biology in living organisms. This review focuses on ...Spectro-microscopy, a combination of fluorescence microscopy with spatially resolved spectroscopic techni- ques, provides new and exciting tools for functional cell biology in living organisms. This review focuses on recent devel- opments in spectro-microscopic applications for the investigation of living plant cells in their native tissue context. The application of spectro-microscopic methods led to the recent discovery of a fast signal response pathway for the brassi- nosteroide receptor BRI1 in the plasma membrane of living plant cells. Moreover, the competence of different plant cell types to respond to environmental or endogenous stimuli was determined in vivo by correlation analysis of different optical and spectroscopic readouts such as fluorescence lifetime （FLT）. Furthermore, a new spectro-microscopic technique, fluorescence intensity decay shape analysis microscopy （FIDSAM）, has been developed. FIDSAM is capable of imaging low- expressed fluorophore-tagged proteins at high spatial resolution and precludes the misinterpretation of autofluorescence artifacts. In addition, FIDSAM provides a very effective and sensitive tool on the basis of F6rster resonance energy transfer （FRET） for the qualitative and quantitative determination of protein-protein interaction. Finally, we report on the quan- titative analysis of the photosystem I and II （PSI/PSII） ratio in the chloroplasts of living Arabidopsis plants at room tem- perature, using high-resolution, spatially resolved fluorescence spectroscopy. With this technique, it was not only possible to measure PSI/PSII ratios, but also to demonstrate the differential competence of wild-type and carbohydrate-deficient plants to adapt the PSI/PSII ratio to different light conditions. In summary, the information content of standard microscopic images is extended by several dimensions by the use of spectro-microscopic approaches. Therefore, novel cell physiolog- ical and molecular topics can be addressed and valuable insights into molecular and subcellular processes can be obtained in living plants.展开更多
Brassinosteroids(BR) are involved in the control of several developmental processes ranging from root elongation to senescence and adaptation to environmental cues. Thus, BR perception and signaling have to be precise...Brassinosteroids(BR) are involved in the control of several developmental processes ranging from root elongation to senescence and adaptation to environmental cues. Thus, BR perception and signaling have to be precisely regulated. One regulator is BRI1-associated kinase 1(BAK1)-interacting receptor-like kinase 3(BIR3). In the absence of BR, BIR3 forms complexes with BR insensitive 1(BRI1) and BAK1.However, the biophysical and energetic requirements for complex formation in the absence of the ligand have yet to be determined. Using computational modeling, we simulated the potential complexes between the cytoplasmic domains of BAK1, BRI1 and BIR3. Our calculations and experimental data confirm the interaction of BIR3 Rewith BAK1 and BRI1, with the BAK1 BIR3 interaction clearly favored. Furthermore, we demonstrate that BIR3 and BRI1 share the same interaction site with BAK1. This suggests a competition between BIR3 and BRI1 for binding to BAK1, which results in preferential binding of BIR3 to BAK1 in the absence of the ligand thereby preventing the active participation of BAK1 in BR signaling. Our model also suggests that BAK1 and BRI1 can interact even while BAK1 is in complex with BIR3 at an additional binding site of BAK1 that does not allow active BR signaling.展开更多
Protein-protein interactions and the formation of protein complexes play a central role in the regulation of virtually all aspects of life.The identification and characterization of interactions between proteins is th...Protein-protein interactions and the formation of protein complexes play a central role in the regulation of virtually all aspects of life.The identification and characterization of interactions between proteins is the basis of our understanding of protein function and the biological processes they enable.展开更多
The polar, sub-cellular localization of PIN auxin efflux carriers determines the direction of intercellular auxin flow, thus defining the spatial aspect of auxin signalling. Dynamic, transcytosis-like relocalizations ...The polar, sub-cellular localization of PIN auxin efflux carriers determines the direction of intercellular auxin flow, thus defining the spatial aspect of auxin signalling. Dynamic, transcytosis-like relocalizations of PIN proteins occur in response to external and internal signals, integrating these signals into changes in auxin distribution. Here, we examine the cellular and molecular mechanisms of polar PIN delivery and transcytosis. The mechanisms of the ARF-GEF-dependent polar targeting and transcytosis are well conserved and show little variations among diverse Arabidopsis ecotypes consistent with their fundamental importance in regulating plant development. At the cellular level, we refine previous findings on the role of the actin cytoskeleton in apical and basal PIN targeting, and identify a previously unknown role for microtubules, specifically in basal targeting. PIN protein delivery to different sides of the cell is mediated by ARFdependent trafficking with a previously unknown complex level of distinct ARF-GEF vesicle trafficking regulators. Our data suggest that alternative recruitment of PIN proteins by these distinct pathways can account for cell type- and cargo-specific aspects of polar targeting, as well as for polarity changes in response to different signals. The resulting dynamic PIN positioning to different sides of cells defines a three-dimensional pattern of auxin fluxes within plant tissues.展开更多
DE-ETIOLATED 1(DET1)and CONSTITUTIVE PHOTOMORPHOGENESIS 1(COP1)are two essential repressors of Arabidopsis photomorphogenesis.These proteins can associate with CULLIN4 to form independent CRL4-based E3 ubiquitin ligas...DE-ETIOLATED 1(DET1)and CONSTITUTIVE PHOTOMORPHOGENESIS 1(COP1)are two essential repressors of Arabidopsis photomorphogenesis.These proteins can associate with CULLIN4 to form independent CRL4-based E3 ubiquitin ligases that mediate the degradation of several photomorphogenic transcription factors,including ELONGATED HYPOCOTYL 5(HY5),thereby controlling multiple gene-regulatory networks.Despite extensive biochemical and genetic analyses of their multi-subunit complexes,the functional links between DET1 and COP1 have long remained elusive.Here,we report that DET1 associates with COP1 in vivo,enhances COP1-HY5 interaction,and promotes COP1 destabilization in a process that dampens HY5 protein abundance.By regulating its accumulation,DET1 avoids HY5 association with hundreds of second-site genomic loci,which are also frequently targeted by the skotomorphogenic transcription factor PHYTOCHROME-INTERACTING FACTOR 3.Accordingly,ectopic HY5 chromatin enrichment favors local gene repression and can trigger fusca-like phenotypes.This study therefore shows that DET1-mediated regulation of COP1 stability tunes down the HY5 cistrome,avoiding hyper-photomorphogenic responses that might compromise plant viability.展开更多
Plants show an unparalleled regenerative capacity,allowing them to survive severe stress conditions,such as injury,herbivory attack,and harsh weather conditions.This potential not only replenishes tissues and restores...Plants show an unparalleled regenerative capacity,allowing them to survive severe stress conditions,such as injury,herbivory attack,and harsh weather conditions.This potential not only replenishes tissues and restores damaged organs but can also give rise to whole plant bodies.Despite the intertwined nature of development and regeneration,common upstream cues and signaling mechanisms are largely unknown.Here,we demonstrate that in addition to being activators of regeneration,ETHYLENE RESPONSE FACTOR 114(ERF114)and ERF115 govern developmental growth in the absence of wounding or injury.Increased ERF114 and ERF115 activity enhances auxin sensitivity,which is correlated with enhanced xylem maturation and lateral root formation,whereas their knockout results in a decrease in lateral roots.Moreover,we provide evidence that mechanical cues contribute to ERF114 and ERF115 expression in correlation with BZR1-mediated brassinosteroid signaling under both regenerative and developmental conditions.Antagonistically,cell wall integrity surveillance via mechanosensory FERONIA signaling suppresses their expression under both conditions.Taken together,our data suggest a molecular framework in which cell wall signals and mechanical strains regulate organ development and regenerative responses via ERF114-and ERF115-mediated auxin signaling.展开更多
Positive-sense single-stranded RNA(+ssRNA)viruses,the most abundant viruses of eukaryotes in nature,require the synthesis of negative-sense RNA(-RNA)using their genomic(positive-sense)RNA(+RNA)as a template for replic...Positive-sense single-stranded RNA(+ssRNA)viruses,the most abundant viruses of eukaryotes in nature,require the synthesis of negative-sense RNA(-RNA)using their genomic(positive-sense)RNA(+RNA)as a template for replication.Based on current evidence,viral proteins are translated via viral+RNAs,whereas-RNA is considered to be a viral replication intermediate without coding capacity.Here,we report that plant and animal+ssRNA viruses contain small open reading frames(ORFs)in their-RNA(reverse ORFs[rORFs]).Using turnip mosaic virus(TuMV)as a model for plant+ssRNA viruses,we demonstrate that small proteins encoded by rORFs display specific subcellularlocalizations,and confirm the presence of rORF2 in infected cells through mass spectrometry analysis.The protein encoded by TuMV rORF2 forms punctuate granules that are localized in the perinuclear region and co-localized with viral replication complexes.The rORF2 protein can directly interact with the viral RNA-dependent RNA polymerase,and mutation of rORF2 completely abolishes virus infection,whereas ectopic expression of rORF2 rescues the mutant virus.Furthermore,we show that several rORFs in the-RNA of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)have the ability to suppress type l interferon production and facilitate the infection of ve-sicular stomatitis virus.In addition,we provide evidence that TuMV might utilize internal ribosome entry sites to translate these small rORFs.Taken together,these findings indicate that the-RNA of+ssRNA vi-ruses can also have the coding capacity and that small proteins encoded therein play critical roles in viral infection,revealing a viral proteome larger than previously thought.展开更多
文摘More than 40 million people worldwide are thought to be affected by Alzheimer's disease(AD).Of these,estimated less than10% develop symptoms usually well before the age of 65,due to familial(hereditary) AD predisposition(Sierksma et al.,2020).AD is a multifactorial disorder,which includes a multitude of progressive degenerations in the brain parenchyma,but also in the vascular and hemostatic system.
基金supported by the National Natural Science Foundation of China(31720103914 and 32001866).
文摘Begomoviruses cause significant losses to a wide range of crops worldwide,and a great progress has been made in characterizing some noncanonical proteins encoded by begomoviruses.In the present study,a novel viral protein,C6,was detected in Nicotiana benthamiana plants infected with tomato leaf curl China virus(ToLCCNV).Sequence analyses revealed that the C6 ORF is on the complementary strand of approximately 36%reported begomovirus sequences with conserved amino acid sequence.ToLCCNV C6 specifically localizes to mitochondria.Analysis of deletion mutants showed that C6 possesses an internal mitochondrial targeting signal.Overall,these data uncover a novel begomovirus-encoded protein targeting distinct plant cell organelles.
基金funded by grants from the Deutsche Forschungsgemeinschaft(SCHA 1274/4-1,SCHA 1274/5-1,and under Germany's Excellence Strategy,EXC2070–390732324,Pheno Rob to G.S.,JE 572/4-1 and under Germany's Excellence Strategy,CIBSS–EXC-2189–Project ID 390939984 to H.J.J.,LA 1338/18-1 to T.L.,and TRR356/I(491090170),TP-B08 and Project No.451218338 to M.K.R.-L.)by the Marie Sklodowska-Curie Action(Grant Agreement ID 101108767)to S.W.by the Department of Biotechnology,Government of India(Grant No.BT/PR45561/AGIII/103/1386/2023)to S.B.Open Access funding enabled and organized by Projekt DEAL
文摘Inositol pyrophosphates(PP-InsPs)are important signaling molecules that regulate diverse cellular processes in eukaryotes,including energy homeostasis,phosphate(Pi)signaling,and phytohormone perception.Yet,in plants,the enzymes responsible for their turnover remain largely unknown.Using a non-hydrolysable PP-InsP analog in a pull-down approach,we identified a family of Arabidopsis NUDIX-type hydrolases(NUDTs)that group into two closely related subclades.Through in vitro assays,heterologous expression systems,and higher order gene-edited mutants,we explored the substrate specificities and physiological roles of these hydrolases.Using a combination of strong anion exchange high-performance liquid chromatography(SAX-HPLC),polyacrylamide gel electrophoresis(PAGE),and capillary electrophoresis electrospray ionization mass spectrometry(CE-ESI-MS),we found that their PP-InsP pyrophosphatase activity is enantiomer selective and Mg^(2+)dependent.Specifically,SubcladeⅠNUDTs preferentially hydrolyze 4-InsP_(7),while SubcladeⅡNUDTs target 3-InsP_(7),with minor activity against other PP-InsPs,including5-InsP_(7).In higher order mutants of SubcladeⅡNUDTs,we observed defects in both Piand iron homeostasis,accompanied by increased levels of 1/3-InsP_(7)and 5-InsP_(7),with a markedly larger increase in 1/3-InsP_(7).Ectopic expression of NUDTs from both subclades induced local Pi starvation responses(PSRs),while RNA-seq analysis comparing wild-type(WT)and SubcladeⅡnudt12/13/16 loss-of-function plants indicates additional PSR-independent roles,potentially involving 1/3-InsP_(7) in the regulation of plant defense.Consistently,nudt12/13/16 mutants displayed enhanced resistance to Pseudomonas syringae infection,indicating a role in bacterial pathogen susceptibility.Expanding beyond SubcladeⅡNUDTs,we demonstrated susceptibility of the 3PP-position of PP-InsPs to enzymatic activities unrelated to NUDTs,and found that such activities are conserved across plants and humans.Additionally,we observed that NUDT effectors from pathogenic ascomycete fungi exhibit a substrate specificity similar to SubcladeⅠNUDTs.Collectively,our findings reveal new roles for NUDTs in PP-InsP signaling,plant nutrient and immune responses,and highlight a cross-kingdom conservation of PP-InsP-metabolizing enzymes.
基金funded by the National Natural Science Foundation of China(32320103010)the National Key Research and Development Program of China(2021YFD1400400)to F.L.+1 种基金the National Natural Science Foundation of China(32302318)to L.G.the National Natural Science Foundation of China(32001868)to H.S.
文摘The chemical modifications of DNA and proteins are powerful mechanisms for regulating molecular and biological functions,influencing a wide array of signaling pathways in eukaryotes.Recent advance-ments in epitranscriptomics have shown that RNA modifications play crucial roles in diverse biological processes.Since their discovery in the 1970s,scientists have sought to decipher,identify,and elucidate the functions of these modifications across biological systems.Over the past decade,mounting evi-dence has demonstrated the importance of RNA modification pathways in plants,prompting significant efforts to decipher their physiological relevance.With the advent of high-resolution mapping tech-niques for RNA modifications and the gradual uncovering of their biological roles,our understanding of this additional layer of regulation is beginning to take shape.In this review,we summarize recent findings on the major RNA modifications identified in plants,with an emphasis on N^(6)-methyladenosine(m^(6)A),the most extensively studied modification.We discuss the functional signifi-cance of the effector components involved in m^(6)A modification and its diverse roles in plant biotic in-teractions,including plant–virus,plant–bacterium,plant–fungus,and plant–insect relationships.Furthermore,we highlight new technological developments driving research progress in this field and outline key challenges that remain to be addressed.
基金funded by the Excellence Strategy of the German Federal and State Governments,the ERC-COG GemOmics(101044142)the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)(project numbers TRR 356/1,B04 and SBF 1101/3,C08)+3 种基金a Royal Society Newton Advance Grant(NA140481-NAF\R2\180857)Metabolite analytics were funded by the DFG(Projektnummer 442641014)the recipient of a Marie Skłodowska-Curie Grant from the European Union’s Horizon 2020 Research and Innovation Program(grant 896910-GeminiDECODER)a President’s International Fellowship Initiative(PIFI)from the Chinese Academy of Science(CAS)(grant 2020PB0082).
文摘Plant viruses cause symptoms with devastating consequences for agriculture.However,the molecular mechanisms underlying symptom development in viral infections remain largely unexplored.Here,we show that tomato yellow leaf curl virus(TYLCV)interferes with host developmental programs through a host-mimicking domain present in the viral C4 protein.This domain mediates the interaction between C4 and a family of RCC1-like domain-containing(RLD)proteins,previously shown to be required for proper plant development and environmental responses.C4 outcompetes an endogenous interactor of RLDs,hijacking RLD proteins to the plasma membrane and disrupting their function in orchestrating endomembrane trafficking and polar auxin transport.Strikingly,macroscopic symptoms do not affect viral accumulation in the plant but serve as attractants for the insect vector,presumably promoting pathogen spread in an ecological context.Our work sheds light on the molecular underpinnings and biological relevance of symptom development triggered by TYLCV in tomato.Since most plant viruses are insect-transmitted,the principles described here might have broad applicability to crop-virus interactions.
基金supported through funding to L.D.via a UKRI FLF MR/S031677/1,Rank Prize Funds New Lecturer Award,and start-up funds from the University of LeedsA Molecules to Landscapes grant from BBSRC supported H.T.S.G.+2 种基金supported by BBSRC ISP“BBSRC Strategic Programme in Designing Future Wheat(DFW)”(BB/P016855/1)supported by BBSRC ISP“BBSRC Institute Strategic Programme:Delivering Sustainable Wheat(DSW)”(BB/X011003/1)supported by the the National Key Research and Development Program of China(2023YFF1000100 and 2023YFA0914600).
文摘The coordination of floral developmental stages with the environment is important for reproductive success and optimization of crop yields.The timing of different developmental stages contributes to final yield potential,with optimal adaptation enabling development to proceed without being impacted by seasonal weather events,including frosts or end-of-season drought.Here,we characterize the role of FLOWERING LOCUS T 3(FT3)in hexaploid bread wheat(Triticum aestivum)during the early stages of floral development.By assaying the genetic diversity of landraces and modern wheat varieties,we identified a distribution of alleles for FT3 that indicated selection in modern varieties.We generated transgenic overexpression lines and found that FT3 is as powerful a florigen as FT1,which suggested that FT3 is under tight regulation.To investigate this possibility,we measured FT3 expression under variable environmental conditions and identified a role for both temperature and photoperiod in FT3 regulation.Gene expression analysis showed that FT3 transcription is partly coordinated by a temperature-sensitive pathway consisting of a TEOSINTE BRANCHED 1–CYCLOIDEA–PROLIFERATING CELL FACTOR(TCP)transcription factor and a warm-temperature-responsive microRNA.We show that this regulation is important for the timing of floral development under short days combined with lower ambient temperatures and that there has been strong selection on FT3 during cultivation.Deploying this understanding to enable targeted combinations of alleles involved in adaptation will further our ability to develop climate-change-robust cultivars.
基金supported by the National Natural Science Foundation of China(32320103010,32172385)China Postdoctoral Science Foundation(BX20220345)Yunnan Provincial Science and Technology Project(202202AE090022)。
文摘The vast majority of known viruses belong to the positive-sense single-stranded RNA(+ss RNA)class.Tobamoviruses are among the most destructive plant viruses and threaten global food security.It is generally accepted that+ss RNA viruses including tobamoviruses encode proteins solely on their positive strand(+RNA).Here,we identified additional open-reading frames(ORFs)in the negative strand of tobamoviruses,named reverse ORFs(r ORFs).Using cucumber green mottle mosaic virus(CGMMV)as a model,we detected the corresponding peptides of r ORFs by mass spectrometry analysis and confirmed the translation of r ORFs by ribosome profiling.Furthermore,we demonstrated that these r ORFs may be translated from an internal ribosome entry site.Mutation of r ORF1 and r ORF2 significantly reduced the virulence of CGMMV,whereas ectopic expression of r ORF1 and r ORF2 could rescue the pathogenicity of the mutants.While the r ORF2 protein localizes at the cell membrane and in the nucleolus,r ORF1 colocalizes with peroxisomes,where it interacts with the viral 126-k D replication protein.Additionally,we screened peroxisomal r ORF1-interacting proteins using artificial intelligence tools and found that PEX3 mediated r ORF1 targeting to peroxisomes.This study reveals that the tobamoviral proteome is larger than previously thought,and sheds light on peroxisomes as novel virulence targets important for virus infectivity.
文摘In order to assess the functional roles of heat stress-induced class B-heat shock factors in Arabidopsis, we investigated T-DNA knockout mutants of AtHsfB1 and AtHsfB2b. Micorarray analysis of double knockout hsfB1/hsfB2b plants revealed as strong an up-regulation of the basal mRNA-levels of the defensin genes Pdfl.2a/b in mutant plants. The Pdfexpression was further enhanced by jasmonic acid treatment or infection with the necrotrophic fungus Alternaria brassicicola. The single mutant hsfB2b and the double mutant hsfB 1/B2b were significantly improved in disease resistance after A. brassicicola infection. There was no indication for a direct interaction of Hsf with the promoter of Pdf1.2, which is devoid of perfect HSE consensus Hsf-binding sequences. However, changes in the formation of late HsfA2-dependent HSE binding were detected in hsfB1/B2b plants. This suggests that HsfB1/B2b may interact with class A-Hsf in regulating the shut-off of the heat shock response. The identification of Pdfgenes as targets of Hsf-dependent negative regulation is the first evidence for an interconnection of Hsf in the regulation of biotic and abiotic responses.
文摘As the first and rate-limiting enzyme of proline degradation, PROLINE DEHYDROGENASE1 （PDH1） is tightly regulated during plant stress responses, including induction under hypoosmolarity and repression under water deficit. The plant receptor histidine kinases AHKs, elements of the two-component system （TCS） in Arabidopsis thaliana, are pro- posed to function in water stress responses by regulating different stress-responsive genes. However, little information is available concerning AHK phosphorelay-mediated downstream signaling. Here we show that the Arabidopsis type-B response regulator 18 （ARR18） functions as a positive osmotic stress response regulator in Arabidopsis seeds and affects the activity of the PDH1 promoter, known to be controlled by C-group bZlP transcription factors. Moreover, direct physical interaction of ARR18 with bZIP63 was identified and shown to be dependent on phosphorylation of the conserved aspar- tate residue in the ARR18 receiver domain. We further show that bZlP63 itself functions as a negative regulator of seed germination upon osmotic stress. Using reporter gene assays in protoplasts, we demonstrated that ARR18 interaction negatively interferes with the transcriptional activity of bZIP63 on the PDH1 promoter. Our findings provide new insight into the function of ARR18 and bZIP63 as antagonistic regulators of gene expression in Arabidopsis.
文摘Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASEI （CuAO1）, of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuaol-2. PA-induced and ABA-induced NO production investigated bY fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H2O2 increases, cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.
文摘High-temperature stress, like any abiotic stress, impairs the physiology and development of plants, including the stages of seed setting and ripening. We used the Affymetrix 22K Barley1 GeneChip microarray to investigate the response of developing barley （Hordeum vulgare） seeds, termed caryopses, after 0.5, 3, and 6 h of heat stress exposure; 958 induced and 1122 repressed genes exhibited spatial and temporal expression patterns that provide a detailed insight into the caryopses＇ early heat stress responses. Down-regulation of genes related to storage compound biosynthesis and cell growth provides evidence for a rapid impairment of the caryopsis＇ development. Increased levels of sugars and amino acids were indicative for both production of compatible solutes and feedback-induced accumulation of substrates for storage compound biosynthesis. Metadata analysis identified embryo and endosperm as primary locations of heat stress responses, indicating a strong impact of short-term heat stress on central developmental functions of the caryopsis. A comparison with heat stress responses in Arabidopsis shoots and drought stress responses in barley caryopses identified both conserved and presumably heat- and caryopsis-specific stress-responsive genes. Summarized, our data provide an important basis for further investigation of gene functions in order to aid an improved heat tolerance and reduced losses of yield in barley as a model for cereal crops.
文摘In order to analyze the signaling function of hydrogen peroxide （H202） production in senescence in more detail, we manipulated intracellular H202 levels in Arabidopsis thaliala （L.） Heynh by using the hydrogen- peroxide-sensitive part of the Escherichia coil transcription regulator OxyR, which was directed to the cytoplasm as well as into the peroxisomes. H202 levels were lowered and senescence was delayed in both transgenic lines, but OxyR was found to be more effective in the cytoplasm. To transfer this knowledge to crop plants, we analyzed oilseed rape plants Brassica napus L. cv. Mozart for H20~ and its scavenging enzymes catalase （CAT） and ascorbate peroxidase （APX） during leaf and plant development. H202 levels were found to increase during bolting and flowering time, but no increase could be observed in the very late stages of senescence. With increasing H202 levels, CAT and APX activities declined, so it is likely that similar mechanisms are used in oilseed rape and Arabidopsis to control H202 levels. Under elevated CO2 conditions, oilseed rape senescence was accelerated and coincided with an earlier increase in H202 levels, indicating that H202 may be one of the signals to inducing senescence in a broader range of Brassicaceae.
基金support from tho Europoan Rosearch Council to R.G.(ERC Consolidator Grant"bi-BL OCK"ID 646644,ERC Proof of Concept Grant"TnVolve"ID 957547).
文摘Seed size critically affects grain yield of crops and hence represents a key breeding target.The develop-ment of embryo-nourishing endosperm is a key driver of seed expansion.We here report unexpected dual roles of the transcription factor EIN3 in regulating seed size.These EIN3 functions have remained largely undiscovered because they oppose each other.Capitalizing on the analysis of multiple ethylene biosynthesis mutants,we demonstrate that EIN3 represses endosperm and seed development in a pathway regulated by ethylene.We,in addition,provide evidence that EIN3-mediated synergid nucleus disintegration promotes endosperm expansion.Interestingly,synergid nucleus disintegration is not affected in various ethylene biosynthesis mutants,suggesting that this promoting function of EIN3 is inde-pendent of ethylene.Whereas the growth-inhibitory ethylene-dependent EIN3 action appears to be encoded by sporophytic tissue,the growth-promoting role of EIN3 is induced by fertilization,revealing a generation conflict that converges toward the key signaling component EIN3.
文摘Spectro-microscopy, a combination of fluorescence microscopy with spatially resolved spectroscopic techni- ques, provides new and exciting tools for functional cell biology in living organisms. This review focuses on recent devel- opments in spectro-microscopic applications for the investigation of living plant cells in their native tissue context. The application of spectro-microscopic methods led to the recent discovery of a fast signal response pathway for the brassi- nosteroide receptor BRI1 in the plasma membrane of living plant cells. Moreover, the competence of different plant cell types to respond to environmental or endogenous stimuli was determined in vivo by correlation analysis of different optical and spectroscopic readouts such as fluorescence lifetime （FLT）. Furthermore, a new spectro-microscopic technique, fluorescence intensity decay shape analysis microscopy （FIDSAM）, has been developed. FIDSAM is capable of imaging low- expressed fluorophore-tagged proteins at high spatial resolution and precludes the misinterpretation of autofluorescence artifacts. In addition, FIDSAM provides a very effective and sensitive tool on the basis of F6rster resonance energy transfer （FRET） for the qualitative and quantitative determination of protein-protein interaction. Finally, we report on the quan- titative analysis of the photosystem I and II （PSI/PSII） ratio in the chloroplasts of living Arabidopsis plants at room tem- perature, using high-resolution, spatially resolved fluorescence spectroscopy. With this technique, it was not only possible to measure PSI/PSII ratios, but also to demonstrate the differential competence of wild-type and carbohydrate-deficient plants to adapt the PSI/PSII ratio to different light conditions. In summary, the information content of standard microscopic images is extended by several dimensions by the use of spectro-microscopic approaches. Therefore, novel cell physiolog- ical and molecular topics can be addressed and valuable insights into molecular and subcellular processes can be obtained in living plants.
基金the CRC 1101“Molecular Encoding of Specificity in Plant Processes”of the German Research Foundationthe Klaus Tschira Foundation for funding+1 种基金the Schmeil Foundation(Heidelberg)the Heidelberg Graduate School of Mathematical and Computational Methods for the Sciences(HGS Math Comp)for support。
文摘Brassinosteroids(BR) are involved in the control of several developmental processes ranging from root elongation to senescence and adaptation to environmental cues. Thus, BR perception and signaling have to be precisely regulated. One regulator is BRI1-associated kinase 1(BAK1)-interacting receptor-like kinase 3(BIR3). In the absence of BR, BIR3 forms complexes with BR insensitive 1(BRI1) and BAK1.However, the biophysical and energetic requirements for complex formation in the absence of the ligand have yet to be determined. Using computational modeling, we simulated the potential complexes between the cytoplasmic domains of BAK1, BRI1 and BIR3. Our calculations and experimental data confirm the interaction of BIR3 Rewith BAK1 and BRI1, with the BAK1 BIR3 interaction clearly favored. Furthermore, we demonstrate that BIR3 and BRI1 share the same interaction site with BAK1. This suggests a competition between BIR3 and BRI1 for binding to BAK1, which results in preferential binding of BIR3 to BAK1 in the absence of the ligand thereby preventing the active participation of BAK1 in BR signaling. Our model also suggests that BAK1 and BRI1 can interact even while BAK1 is in complex with BIR3 at an additional binding site of BAK1 that does not allow active BR signaling.
基金partially funded by the Excellence Strategy of the German Federal and State Governments,the ERC-COG Gem Omics(101044142)the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)(Project Numbers LO 2314/1-1 and SBF 1101/3,C08)。
文摘Protein-protein interactions and the formation of protein complexes play a central role in the regulation of virtually all aspects of life.The identification and characterization of interactions between proteins is the basis of our understanding of protein function and the biological processes they enable.
文摘The polar, sub-cellular localization of PIN auxin efflux carriers determines the direction of intercellular auxin flow, thus defining the spatial aspect of auxin signalling. Dynamic, transcytosis-like relocalizations of PIN proteins occur in response to external and internal signals, integrating these signals into changes in auxin distribution. Here, we examine the cellular and molecular mechanisms of polar PIN delivery and transcytosis. The mechanisms of the ARF-GEF-dependent polar targeting and transcytosis are well conserved and show little variations among diverse Arabidopsis ecotypes consistent with their fundamental importance in regulating plant development. At the cellular level, we refine previous findings on the role of the actin cytoskeleton in apical and basal PIN targeting, and identify a previously unknown role for microtubules, specifically in basal targeting. PIN protein delivery to different sides of the cell is mediated by ARFdependent trafficking with a previously unknown complex level of distinct ARF-GEF vesicle trafficking regulators. Our data suggest that alternative recruitment of PIN proteins by these distinct pathways can account for cell type- and cargo-specific aspects of polar targeting, as well as for polarity changes in response to different signals. The resulting dynamic PIN positioning to different sides of cells defines a three-dimensional pattern of auxin fluxes within plant tissues.
基金supported by a Ramon y Cajal(RYC-2014-16308)grant funded by the Ministerio de Economfa y Competitividad to S.F.Work by S.F.in F.B.’s lab was supported by the COST Action CA16212 INDEPTH(European Union)funded by the Agencia Estatal de Investigacion/Fondo Europeo de Desarollo Regional/European Union(BIO2016-80551-R and PID2019-105495GB-I00).+2 种基金supported by CNRS EPIPLANT Action(France)and funded by Agence Nationale de la Recherche grants ANR-10-LABX-54,ANR-18-CE13-0004-01,ANR-17-CE12-0026-02(France)by Velux Stiftung(Switzerland).B.G.G.is funded by President's International Fellowship Initiative postdoctoral fellowship(no.2020PB0082)the Chinese Academy of Sciences,and is the recipient of a Talent-Introduction grant(Chinese Postdoctoral International Exchange Program).
文摘DE-ETIOLATED 1(DET1)and CONSTITUTIVE PHOTOMORPHOGENESIS 1(COP1)are two essential repressors of Arabidopsis photomorphogenesis.These proteins can associate with CULLIN4 to form independent CRL4-based E3 ubiquitin ligases that mediate the degradation of several photomorphogenic transcription factors,including ELONGATED HYPOCOTYL 5(HY5),thereby controlling multiple gene-regulatory networks.Despite extensive biochemical and genetic analyses of their multi-subunit complexes,the functional links between DET1 and COP1 have long remained elusive.Here,we report that DET1 associates with COP1 in vivo,enhances COP1-HY5 interaction,and promotes COP1 destabilization in a process that dampens HY5 protein abundance.By regulating its accumulation,DET1 avoids HY5 association with hundreds of second-site genomic loci,which are also frequently targeted by the skotomorphogenic transcription factor PHYTOCHROME-INTERACTING FACTOR 3.Accordingly,ectopic HY5 chromatin enrichment favors local gene repression and can trigger fusca-like phenotypes.This study therefore shows that DET1-mediated regulation of COP1 stability tunes down the HY5 cistrome,avoiding hyper-photomorphogenic responses that might compromise plant viability.
基金grants G007218N and G010820N and a pre-doctoral fllowship(to FL.)from the Research Foundation-Flanders.A.Z.S.M.and C.W.M.were supported by a Wallenberg Academy Fllowship(2016-0274)a Vetenskapsradet grant(2017-05122).
文摘Plants show an unparalleled regenerative capacity,allowing them to survive severe stress conditions,such as injury,herbivory attack,and harsh weather conditions.This potential not only replenishes tissues and restores damaged organs but can also give rise to whole plant bodies.Despite the intertwined nature of development and regeneration,common upstream cues and signaling mechanisms are largely unknown.Here,we demonstrate that in addition to being activators of regeneration,ETHYLENE RESPONSE FACTOR 114(ERF114)and ERF115 govern developmental growth in the absence of wounding or injury.Increased ERF114 and ERF115 activity enhances auxin sensitivity,which is correlated with enhanced xylem maturation and lateral root formation,whereas their knockout results in a decrease in lateral roots.Moreover,we provide evidence that mechanical cues contribute to ERF114 and ERF115 expression in correlation with BZR1-mediated brassinosteroid signaling under both regenerative and developmental conditions.Antagonistically,cell wall integrity surveillance via mechanosensory FERONIA signaling suppresses their expression under both conditions.Taken together,our data suggest a molecular framework in which cell wall signals and mechanical strains regulate organ development and regenerative responses via ERF114-and ERF115-mediated auxin signaling.
基金funded by the National Key Research and Development Program of China(2021YFD1400400)to F.L.the National Natural Science Foundation of China(31930089 and 31972244)to X.Z.and F.L.+2 种基金a startup grant for High-level Talents of Fujian Medical University(XRCZX2019019)the Natural Science Foundation of Fujan Province,China(2020J01604)to Q.S.Work in the R.L.-D.lab is partially funded by the ERC-COG grant GemOmics(101044142)to R.L.-D.
文摘Positive-sense single-stranded RNA(+ssRNA)viruses,the most abundant viruses of eukaryotes in nature,require the synthesis of negative-sense RNA(-RNA)using their genomic(positive-sense)RNA(+RNA)as a template for replication.Based on current evidence,viral proteins are translated via viral+RNAs,whereas-RNA is considered to be a viral replication intermediate without coding capacity.Here,we report that plant and animal+ssRNA viruses contain small open reading frames(ORFs)in their-RNA(reverse ORFs[rORFs]).Using turnip mosaic virus(TuMV)as a model for plant+ssRNA viruses,we demonstrate that small proteins encoded by rORFs display specific subcellularlocalizations,and confirm the presence of rORF2 in infected cells through mass spectrometry analysis.The protein encoded by TuMV rORF2 forms punctuate granules that are localized in the perinuclear region and co-localized with viral replication complexes.The rORF2 protein can directly interact with the viral RNA-dependent RNA polymerase,and mutation of rORF2 completely abolishes virus infection,whereas ectopic expression of rORF2 rescues the mutant virus.Furthermore,we show that several rORFs in the-RNA of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)have the ability to suppress type l interferon production and facilitate the infection of ve-sicular stomatitis virus.In addition,we provide evidence that TuMV might utilize internal ribosome entry sites to translate these small rORFs.Taken together,these findings indicate that the-RNA of+ssRNA vi-ruses can also have the coding capacity and that small proteins encoded therein play critical roles in viral infection,revealing a viral proteome larger than previously thought.
