The main goal of the study was to identify a novel source of human multipotent cells, overcoming ethical issues involved in embryonic stem cell research and the limited availability of most adult stem cells. Amniotic ...The main goal of the study was to identify a novel source of human multipotent cells, overcoming ethical issues involved in embryonic stem cell research and the limited availability of most adult stem cells. Amniotic fluid cells （AFCs） are routinely obtained for prenatal diagnosis and can be expanded in vitro; nevertheless current knowledge about their origin and properties is limited. Twenty samples of AFCs were exposed in culture to adipogenic, osteogenic, neurogenic and myogenic media. Differentiation was evaluated using immunocytochemistry, RT-PCR and Western blotting. Before treatments, AFCs showed heterogeneous morphologies. They were negative for MyoD, Myf-5, MRF4, Myogenin and Desmin but positive for osteocalcin, PPARgamma2, GAP43, NSE, Nestin, MAP2, GFAP and beta tubulin III by RT-PCR. The cells expressed Oct-4, Rex-1 and Runx-1, which characterize the undifferentiated stem cell state. By immunocytochemistry they expressed neural-glial proteins, mesenchymal and epithelial markers. After culture, AFCs differentiated into adipocytes and osteoblasts when the predominant cellular component was fibroblastic. Early and late neuronal antigens were still present after 2 week culture in neural specific media even if no neuronal morphologies were detectable. Our results provide evidence that human amniotic fluid contains progenitor cells with multi-lineage potential showing stem and tissue-specific gene/protein presence for several lineages.展开更多
Leaf senescence,the last stage of leaf development,is a type of postmitotic senescence and is characterized by the functional transition from nutrient assimilation to nutrient remobilization which is essential for pla...Leaf senescence,the last stage of leaf development,is a type of postmitotic senescence and is characterized by the functional transition from nutrient assimilation to nutrient remobilization which is essential for plants’fitness.The initiation and progression of leaf senescence are regulated by a variety of internal and external factors such as age,phytohormones,and environmental stresses.Significant breakthroughs in dissecting the molecular mechanisms underpinning leaf senescence have benefited from the identification of senescence-altered mutants through forward genetic screening and functional assessment of hundreds of senescence-associated genes(SAGs)via reverse genetic research in model plant Arabidopsis thaliana as well as in crop plants.Leaf senescence involves highly complex genetic programs that are tightly tuned by multiple layers of regulation,including chromatin and transcription regulation,post-transcriptional,translational and post-translational regulation.Due to the significant impact of leaf senescence on photosynthesis,nutrient remobilization,stress responses,and productivity,much effort has been made in devising strategies based on known senescence regulatory mechanisms to manipulate the initiation and progression of leaf senescence,aiming for higher yield,better quality,or improved horticultural performance in crop plants.This review aims to provide an overview of leaf senescence and discuss recent advances in multi-dimensional regulation of leaf senescence from genetic and molecular network perspectives.We also put forward the key issues that need to be addressed,including the nature of leaf age,functional stay-green trait,coordination between different regulatory pathways,source-sink relationship and nutrient remobilization,as well as translational researches on leaf senescence.展开更多
Plants deploy versatile scaffold proteins to intricately modulate complex cell signaling.Among these,RACK1A(Receptors for Activated C Kinase 1A)stands out as a multifaceted scaffold protein functioning as a central in...Plants deploy versatile scaffold proteins to intricately modulate complex cell signaling.Among these,RACK1A(Receptors for Activated C Kinase 1A)stands out as a multifaceted scaffold protein functioning as a central integrative hub for diverse signaling pathways.However,the precise mechanisms by which RACK1A orchestrates signal transduction to optimize seedling development remain largely unclear.Here,we demonstrate that RACK1A facilitates hypocotyl elongation by functioning as a flexible platform that connects multiple key components of light signaling pathways.RACK1A interacts with PHYTOCHROME INTERACTING FACTOR(PIF)3,enhances PIF3 binding to the promoter of BBX11 and down-regulates its transcription.Furthermore,RACK1A associates with ELONGATED HYPOCOTYL 5(HY5)to repress HY5 biochemical activity toward target genes,ultimately contributing to hypocotyl elongation.In darkness,RACK1A is targeted by CONSTITUTIVELY PHOTOMORPHOGENIC(COP)1 upon phosphorylation and subjected to COP1-mediated degradation via the 26 S proteasome system.Our findings provide new insights into how plants utilize scaffold proteins to regulate hypocotyl elongation,ensuring proper skoto-and photo-morphogenic development.展开更多
ATP-binding cassette(ABC)transporters are integral membrane proteins that have evolved diverse func-tions fulfilled via the transport of various substrates.In Arabidopsis,the G subfamily of ABC proteins is particularl...ATP-binding cassette(ABC)transporters are integral membrane proteins that have evolved diverse func-tions fulfilled via the transport of various substrates.In Arabidopsis,the G subfamily of ABC proteins is particularly abundant and participates in multiple signaling pathways during plant development and stress responses.In this study,we revealed that two Arabidopsis ABCG transporters,ABCG16 and ABCG25,engage in ABA-mediated stress responses and early plant growth through endomembrane-specific dimerization-coupled transport of ABA and ABA-glucosyl ester(ABA-GE),respectively.We first revealed that ABCG16 contributes to osmotic stress tolerance via ABA signaling.More specifically,ABCG16 induces cellular ABA efflux in both yeast and plant cells.Using FRET analysis,we showed that ABCG16 forms oblig-atory homodimers for ABA export activity and that the plasma membrane-resident ABCG16 homodimers specifically respond to ABA,undergoing notable conformational changes.Furthermore,we demonstrated that ABCG16 heterodimerizes with ABCG25 at the endoplasmic reticulum(ER)membrane and facilitates the ER entry of ABA-GE in both Arabidopsis and tobacco cells.The specific responsiveness of the ABCG16-ABCG25 heterodimer to ABA-GE and the superior growth of their double mutant support an inhib-itory role of these twoABCGs in early seedling establishment via regulation of ABA-GE translocation across the ER membrane.Our endomembrane-specific analysis of the FRET signals derived from the homo-or heterodimerized ABcG complexes allowed us to link endomembrane-biased dimerization to the transloca-tion of distinct substrates by ABcG transporters,providing a prototypic framework for understanding the omnipotence of ABcG transporters in plant development and stress responses.展开更多
Plant natural products have been extensively exploited in food,medicine,flavor,cosmetic,renewable fuel,and other industrial sectors.Synthetic biology has recently emerged as a promising means for the cost-effective an...Plant natural products have been extensively exploited in food,medicine,flavor,cosmetic,renewable fuel,and other industrial sectors.Synthetic biology has recently emerged as a promising means for the cost-effective and sustainable production of natural products.Compared with engineering microbes for the production of plant natural products,the potential of plants as chassis for producing these compounds is underestimated,largely due to challenges encountered in engineering plants.Knowledge in plant engineering is instrumental for enabling the effective and efficient production of valuable phytochemicals in plants,and also paves the way for a more sustainable future agriculture.In this manuscript,we briefly recap the biosynthesis of plant natural products,focusing primarily on industrially important terpenoids,alkaloids,and phenylpropanoids.We further summarize the plant hosts and strategies that have been used to engineer the production of natural products.The challenges and opportunities of using plant synthetic biology to achieve rapid and scalable production of high-value plant natural products are also discussed.展开更多
Minichromosome Maintenance protein 10(MCM10)is essential for DNA replication initiation and DNA elongation in yeasts and animals.Although the functions of MCM10 in DNA replication and repair have been well documented,...Minichromosome Maintenance protein 10(MCM10)is essential for DNA replication initiation and DNA elongation in yeasts and animals.Although the functions of MCM10 in DNA replication and repair have been well documented,the detailed mechanisms for MCM10 in these processes are not well known.Here,we identified AtMCM10 gene through a forward genetic screening for releasing a silenced marker gene.Although plant MCM10 possesses a similar crystal structure as animal MCM10,AtMCM10 is not essential for plant growth or development in Arabidopsis.AtMCM10 can directly bind to histone H3-H4 and promotes nucleosome assembly in vitro.The nucleosome density is decreased in Atmcm10,and most of the nucleosome density decreased regions in Atmcm10 are also regulated by newly synthesized histone chaperone Chromatin Assembly Factor-1(CAF-1).Loss of both AtMCM10 and CAF-1 is embryo lethal,indicating that AtM CM10 and CAF-1 are indispensable for replication-coupled nucleosome assembly.AtMCM10 interacts with both new and parental histones.Atmcm10 mutants have lower H3.1abundance and reduced H3K27me1/3 levels with releasing some silenced transposons.We propose that AtM CM10 deposits new and parental histones during nucleosome assembly,maintaining proper epigenetic modifications and genome stability during DNA replication.展开更多
Both phytohormone signaling and epigenetic mechanisms have long been known to play crucial roles in plant development and plasticity in response to ambient stimuli.Indeed,diverse signaling pathways mediated by phytoho...Both phytohormone signaling and epigenetic mechanisms have long been known to play crucial roles in plant development and plasticity in response to ambient stimuli.Indeed,diverse signaling pathways mediated by phytohormones and epigenetic processes integrate multiple upstream signals to regulate various plant traits.Emerging evidence indicates that phytohormones and epigenetic processes interact at multiple levels.In this review,we summarize the current knowledge of the interplay between phytohormones and epigenetic processes from the perspective of phytohormone biology.We also review chemical regulators used in epigenetic studies and propose strategies for developing novel regulators using multidisciplinary approaches.展开更多
Delivery of proteins to the plasma membrane occurs via secretion,which requires tethering,docking,priming,and fusion of vesicles.In yeast and mammalian cells,an evolutionarily conserved RAB GTPase activation cascade f...Delivery of proteins to the plasma membrane occurs via secretion,which requires tethering,docking,priming,and fusion of vesicles.In yeast and mammalian cells,an evolutionarily conserved RAB GTPase activation cascade functions together with the exocyst and SNARE proteins to coordinate vesicle transport with fusion at the plasma membrane.However,it is unclear whether this is the case in plants.In this study,we show that the small GTPase RABA2a recruits and interacts with the VAMP721/722-SYP121-SNAP33 SNARE ternary complex for membrane fusion.Through immunoprecipitation coupled with mass spectrometry analysis followed by the validatation with a series of biochemical assays,we identified the SNARE proteins VAMP721 and SYP121 as the interactors and downstream effectors of RABA2a.Further expreiments showed that RABA2a interacts with all members of the SNARE complex in its GTP-bound form and modulates the assembly of the VAMP721/722-SYP121-SNAP33 SNARE ternary complex.Intriguingly,we did not observe the interaction of the exocyst subunits with either RABA2a or theSNARE proteins in several different experiments.Neither RABA2a inactivation affects the subcellular localization or assembly of the exocystnor the exocyst subunit mutant exo84b shows the disrupted RABA2a-SNARE association or SNARE assembly,suggesting that the RABA2a-SNARE-and exocyst-mediated secretory pathways are largely independent.Consistently,our live imaging experiments reveal that the two sets of proteins follow non-overlapping trafficking routes,and genetic and cell biologyanalyses indicate that the two pathways select different cargos.Finally,we demonstrate that the plant-specific RABA2a-SNARE pathway is essential for the maintenance of potassium homeostasis in Arabisopsis seedlings.Collectively,our findings imply that higher plants might have generated different endomembrane sorting pathways during evolution and may enable the highly conserved endomembrane proteins to participate in plant-specific trafficking mechanisms for adaptation to the changing 展开更多
Apical hook is a simple curved structure formed at the upper part of hypocotyls when dicot seeds germinate in darkness.The hook structure is transient but essential for seedlings’survival during soil emergence due to...Apical hook is a simple curved structure formed at the upper part of hypocotyls when dicot seeds germinate in darkness.The hook structure is transient but essential for seedlings’survival during soil emergence due to its efficient protection of the delicate shoot apex from mechanical injury.As a superb model system for studying plant differential growth,apical hook has fascinated botanists as early as the Darwin age,and significant advances have been achieved at both the morphological and molecular levels to understand how apical hook development is regulated.Here,we will mainly summarize the research progress at these two levels.We will also briefly compare the growth dynamics between apical hook and hypocotyl gravitropic bending at early seed germination phase,with the aim to deduce a certain consensus on their connections.Finally,we will outline the remaining questions and future research perspectives for apical hook development.展开更多
Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and int...Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and internal signals. However,the functions of plant scaffold proteins in response to senescence signals are not well understood. Here, we report that the scaffold protein RACK1A(RECEPTOR FOR ACTIVATED C KINASE1A) participates in leaf senescence mediated by ethylene signaling via the coordination of the EIN3-miR164-ORE1 transcriptional regulatory cascade. RACK1A is a novel positive regulator of ethylene-mediated leaf senescence. The rack1a mutant exhibits delayed leaf senescence, while transgenic lines overexpressing RACK1A display early leaf senescence. Moreover, RACK1A promotes EIN3(ETHYLENE INSENSITIVE 3) protein accumulation, and directly interacts with EIN3 to enhance its DNA-binding activity. Together, they then associate with the miR164 promoter to inhibit its transcription, leading to the release of the inhibition on downstream ORE1(ORESARA 1) transcription and the promotion of leaf senescence.This study reveals a mechanistic framework by which RACK1A promotes leaf senescence via the EIN3-miR164-ORE1 transcriptional cascade, and provides a paradigm for how scaffold proteins finely tune phytohormone signaling to control plant development.展开更多
Intron retention is the most common alternative splicing event in plants and plays a crucial role in the responses of plants to environmental signals.Despite a large number of RNA-seq libraries from different treatmen...Intron retention is the most common alternative splicing event in plants and plays a crucial role in the responses of plants to environmental signals.Despite a large number of RNA-seq libraries from different treatments and genetic mutants stored in public domains,a resource for querying the intron-splicing ratio of individual intron is still required.Here,we established the first-ever large-scale splicing efficiency database in any organism.Our database includes over 57,000 plant public RNA-seq libraries,comprising 25,283 from Arabidopsis,17,789 from maize,10,710 from rice,and 3,974 from soybean,and covers a total of 1.6 million introns in these four species.In addition,we manually curated and annotated all the mutant-and treatment-related libraries as well as their matched controls included in our library collection,and added graphics to display intron-splicing efficiency across various tissues,developmental stages,and stress-related conditions.The result is a large collection of 3,313treatment conditions and 3,594 genetic mutants for discovering differentially regulated splicing efficiency.Our online database can be accessed at https://plantintron.com/.展开更多
The development of a hook-like structure at the apical part of the soil-emerging organs has fascinated botanists for centuries,but how it is initiated remains unclear.Here,we demonstrate with highthroughput infrared i...The development of a hook-like structure at the apical part of the soil-emerging organs has fascinated botanists for centuries,but how it is initiated remains unclear.Here,we demonstrate with highthroughput infrared imaging and 2-D clinostat treatment that,when gravity-induced root bending is absent,apical hook formation still takes place.In such scenarios,hook formation begins with a de novo growth asymmetry at the apical part of a straightly elongating hypocotyl.Remarkably,suchde novo asymmetric growth,but not the following hook enlargement,precedes the establishment of a detectable auxin response asymmetry,and is largely independent of auxin biosynthesis,transport and signaling.Moreover,we found that functional cortical microtubule array is essential for the following enlargement of hook curvature.When microtubule array was disrupted by oryzalin,the polar localization of PIN proteins and the formation of an auxin maximum became impaired at the to-be-hook region.Taken together,we propose a more comprehensive model for apical hook initiation,in which the microtubuledependent polar localization of PINs may mediate the instruction of growth asymmetry that is either stochastically taking place,induced by gravitropic response,or both,to generate a significant auxin gradient that drives the full development of the apical hook.展开更多
Light signaling precisely controls photomorphogenic development in plants.PHYTOCHROME INTERACTING FACTOR 4 and 5(PIF4 and PIF5)play critical roles in the regulation of this developmental process.In this study,we repor...Light signaling precisely controls photomorphogenic development in plants.PHYTOCHROME INTERACTING FACTOR 4 and 5(PIF4 and PIF5)play critical roles in the regulation of this developmental process.In this study,we report CONSTITUTIVELY PHOTOMORPHOGENIC 1 SUPPRESSOR 6(CSU6)functions as a key regulator of light signaling.Loss of CSU6 function largely rescues the cop1-6 constitutively photomorphogenic phenotype.CSU6 promotes hypocotyl growth in the dark,but inhibits hypocotyl elongation in the light.CSU6 not only associates with the promoter regions of PIF4 and PIF5 to inhibit their expression in the morning,but also directly interacts with both PIF4 and PIF5 to repress their transcriptional activation activity.CSU6 negatively controls a group of PIF4-and PIF5-regulated gene expressions.Mutations in PIF4 and/or PIF5 are epistatic to the loss of CSU6,suggesting that CSU6 acts upstream of PIF4 and PIF5.Taken together,CSU6 promotes light-inhibited hypocotyl elongation by negatively regulating PIF4 and PIF5 transcription and biochemical activity.展开更多
phytochrome B(phyB)acts as the red light photoreceptor and negatively regulates the growth-promoting factor PHYTOCHROME INTERACTING 4(PIF4)through a direct physical interaction,which in turn changes the expression of ...phytochrome B(phyB)acts as the red light photoreceptor and negatively regulates the growth-promoting factor PHYTOCHROME INTERACTING 4(PIF4)through a direct physical interaction,which in turn changes the expression of a large number of genes.phyB-PIF4 module regulates a variety of biological and developmental processes in plants.In this study,we demonstrate that B-BOX PROTEIN 11(BBX11)physically interacts with both phyB and PIF4.BBX11 negatively regulates PIF4 accumulation as well as its biochemical activity,consequently leading to the repression of PIF4-controlled genes’expression and promotion of photomorphogenesis in the prolonged red light.This study reveals a regulatory mechanism that mediates red light signal transduction and sheds a light on phyB-PIF4 module in promoting red light-dependent photomorphognenesis.展开更多
In the last decade,RNA-sequencing(RNA-seq)has surpassed microarray to become the gold standard for gene expression profiling due to the continuous drop in sequencing cost and the latest development of easy-to-use libr...In the last decade,RNA-sequencing(RNA-seq)has surpassed microarray to become the gold standard for gene expression profiling due to the continuous drop in sequencing cost and the latest development of easy-to-use library construction kits.To date,the Arabidopsis community has collectively released more than 20000 RNA-seq libraries,with over 1300 libraries deposited just in the first quarter of 2019(Figure 1A).This vast resource is tremendously useful for all Arabidopsis researchers to study transcriptional regulation,tissue specificity,stress responses,and developmental dynamics of genes in which they are interested.展开更多
The transcription factor CONSTANS(CO)integrates day-length information to induce the expression of florigen FLOWERING LOCUS T(FT)in Arabidopsis.We recently reported that the C-terminal CCT domain of CO forms a complex...The transcription factor CONSTANS(CO)integrates day-length information to induce the expression of florigen FLOWERING LOCUS T(FT)in Arabidopsis.We recently reported that the C-terminal CCT domain of CO forms a complex with NUCLEAR FACTOR-YB/YC to recognize multiple cis-elements in the FT promoter,and the N-terminal tandem B-box domains form a homomultimeric assembly.However,the mechanism and biological function of CO multimerization remained unclear.Here,we report that CO takes on a head-to-tail oligomeric configuration via its B-boxes to mediate FT activation in long days.The crystal structure of B-boxesCOreveals a closely connected tandem B-box fold forming a continuous head-to-tail assembly through unique CDHH zinc fingers.Mutating the key residues involved in CO oligomerization resulted in a non-functional CO,as evidenced by the inability to rescue co mutants.By contrast,a transgene encoding a human p53-derived tetrameric peptide in place of the B-boxesCOrescued co mutant,emphasizing the essential role of BboxesCO-mediated oligomerization.Furthermore,we found that the four TGTG-bearing cis-elements in FT proximal promoter are required for FT activation in long days.Our results suggest that CO forms a multimer to bind to the four TGTG motifs in the FT promoter to mediate FT activation.展开更多
RNA-directed DNA methylation(Rd DM) is a plant-specific de novo DNA methylation pathway,which has extensive cross-talk with histone modifications. Here, we report that the maize RdDM regulator SAWADEE HOMEODOMAIN HOMO...RNA-directed DNA methylation(Rd DM) is a plant-specific de novo DNA methylation pathway,which has extensive cross-talk with histone modifications. Here, we report that the maize RdDM regulator SAWADEE HOMEODOMAIN HOMOLOG 2(SHH2) is an H3 K9 me1 reader. Our structural studies reveal that H3 K9 me1 recognition is achieved by recognition of the methyl group via a classic aromatic cage and hydrogen-bonding and salt-bridge interactions with the free protons of the mono-methyllysine. The di-and tri-methylation states disrupt the polar interactions, decreasing the binding affinity. Our study reveals a monomethyllysine recognition mechanism which potentially links RdDM to H3 K9 me1 in maize.展开更多
Leaf senescence,the final stage of leaf development,is influenced by numerous internal and environmental signals.So far,how biotic stresses such as pathogen infection regulate leaf senescence is unclear.Here,we found ...Leaf senescence,the final stage of leaf development,is influenced by numerous internal and environmental signals.So far,how biotic stresses such as pathogen infection regulate leaf senescence is unclear.Here,we found that the premature leaf senescence caused by a soil-borne vascular fungus Verticillium dahliae in Arabidopsis was impaired by the mutation of a protein elicitor from V.dahliae 1(PevD1).Constitutive or inducible overexpression of PevD1 accelerated Arabidopsis leaf senescence.A senescence-associated NAC transcription factor,ORE1,was targeted by PevD1.PevD1 interacted with and stabilized ORE1 protein by disrupting its interaction with the RING-type ubiquitin E3 ligase NLA.Mutation of ORE1 suppressed the premature senescence caused by overexpressing PevD1.Overexpression of ORE1 or PevD1 led to enhanced ethylene production,and ORE1 mediated PevD1-induced ethylene biosynthesis by directly binding to the ACS6 promoter.Loss-of-function of ACSs suppressed V.dahliae-induced leaf senescence in ORE1-overexpressing plants.Interestingly,PevD1 also interacted with Gossypium hirsutum ORE1(GhORE1),and virus-induced gene silencing of GhORE1 delayed V.dahliae-triggered leaf senescence in cotton,indicative of the existence of a conserved mechanism in plants.Altogether,our study demonstrates that V.dahliae induces leaf senescence by secreting the effector PevD1 to regulate the ORE1-ACS6 cascade,providing new insight into biotic stress-induced senescence in plants.展开更多
Drought is a critical environmental factor which constrains plant survival and growth.Genetic engineering provides a credible strategy to improve drought tolerance of plants.Here,we generated transgenic poplar lines e...Drought is a critical environmental factor which constrains plant survival and growth.Genetic engineering provides a credible strategy to improve drought tolerance of plants.Here,we generated transgenic poplar lines expressing the isopentenyl transferase gene(IPT)under the driver of Pt RD26 promoter(PtRD26 pro-IPT).Pt RD26 is a senescence and drought-inducible NAC transcription factor.Pt RD26 pro-IPT plants displayed multiple phenotypes,including improved growth and drought tolerance.Transcriptome analysis revealed that auxin biosynthesis pathway was activated in the PtRD26 pro-IPT plants,leading to an increase in auxin contents.Biochemical analysis revealed that ARABIDOPSIS RESPONSE REGULATOR10(PtARR10),one of the type-B ARR transcription factors in the cytokinin pathway,was induced in PtRD26 pro-IPT plants and directly regulated the transcripts of YUCCA4(Pt YUC4)and YUCCA5(PtYUC5),two enzymes in the auxin biosynthesis pathway.Overexpression of PtYUC4 enhanced drought tolerance,while simultaneous silencing of PtYUC4/5 evidently attenuated the drought tolerance of Pt RD26 pro-IPT plants.Intriguingly,Pt YUC4/5 displayed a conserved thioredoxin reductase activity that is required for drought tolerance by deterring reactive oxygen species accumulation.Our work reveals the molecular basis of cytokinin and auxin interactions in response to environmental stresses,and shed light on the improvement of drought tolerance without a growth penalty in trees by molecular breeding.展开更多
DNA methylation,a conserved epigenetic mark,is critical for tuning temporal and spatial gene expression.The Arabidopsis thaliana DNA glycosylase/lyase REPRESSOR OF SILENCING 1(ROS1)initiates active DNA demethylation a...DNA methylation,a conserved epigenetic mark,is critical for tuning temporal and spatial gene expression.The Arabidopsis thaliana DNA glycosylase/lyase REPRESSOR OF SILENCING 1(ROS1)initiates active DNA demethylation and is required to prevent DNA hypermethylation at thousands of genomic loci.However,how ROS1 is recruited to specific loci is not well understood.Here,we report the discovery of Arabidopsis AGENET Domain Containing Protein 3(AGDP3)as a cellular factor that is required to prevent gene silencing and DNA hypermethylation.AGDP3 binds to H3K9me2 marks in its target DNA via its AGD12 cassette.Analysis of the crystal structure of the AGD12 cassette of AGDP3 in complex with an H3K9me2 peptide revealed that dimethylated H3 K9 and unmodified H3 K4 are specifically anchored into two different surface pockets.A histidine residue located in the methyllysine binding aromatic cage provides AGDP3 with pH-dependent H3K9me2 binding capacity.Our results uncover a molecular mechanism for the regulation of DNA demethylation by the gene silencing mark H3K9me2.展开更多
文摘The main goal of the study was to identify a novel source of human multipotent cells, overcoming ethical issues involved in embryonic stem cell research and the limited availability of most adult stem cells. Amniotic fluid cells （AFCs） are routinely obtained for prenatal diagnosis and can be expanded in vitro; nevertheless current knowledge about their origin and properties is limited. Twenty samples of AFCs were exposed in culture to adipogenic, osteogenic, neurogenic and myogenic media. Differentiation was evaluated using immunocytochemistry, RT-PCR and Western blotting. Before treatments, AFCs showed heterogeneous morphologies. They were negative for MyoD, Myf-5, MRF4, Myogenin and Desmin but positive for osteocalcin, PPARgamma2, GAP43, NSE, Nestin, MAP2, GFAP and beta tubulin III by RT-PCR. The cells expressed Oct-4, Rex-1 and Runx-1, which characterize the undifferentiated stem cell state. By immunocytochemistry they expressed neural-glial proteins, mesenchymal and epithelial markers. After culture, AFCs differentiated into adipocytes and osteoblasts when the predominant cellular component was fibroblastic. Early and late neuronal antigens were still present after 2 week culture in neural specific media even if no neuronal morphologies were detectable. Our results provide evidence that human amniotic fluid contains progenitor cells with multi-lineage potential showing stem and tissue-specific gene/protein presence for several lineages.
基金This work was supported by the National Natural Science Foundation of China(31970196 to Z.L.,31570286 to H.G.,31670277 to K.Z.,31770318 to Y.M.)the National Key Research and Development Program of China(No.2019YFA0903904)+2 种基金Shenzhen Science and Technology Program(KQTD20190929173906742)to H.G.Science and Technology Commission of Shanghai Municipality(15JC1400800 to G.R.)the Agricultural Science and Technology Innovation Program of China,Chinese Academy of Agricultural Sciences(ASTIP-TRI02 to Y.G.).
文摘Leaf senescence,the last stage of leaf development,is a type of postmitotic senescence and is characterized by the functional transition from nutrient assimilation to nutrient remobilization which is essential for plants’fitness.The initiation and progression of leaf senescence are regulated by a variety of internal and external factors such as age,phytohormones,and environmental stresses.Significant breakthroughs in dissecting the molecular mechanisms underpinning leaf senescence have benefited from the identification of senescence-altered mutants through forward genetic screening and functional assessment of hundreds of senescence-associated genes(SAGs)via reverse genetic research in model plant Arabidopsis thaliana as well as in crop plants.Leaf senescence involves highly complex genetic programs that are tightly tuned by multiple layers of regulation,including chromatin and transcription regulation,post-transcriptional,translational and post-translational regulation.Due to the significant impact of leaf senescence on photosynthesis,nutrient remobilization,stress responses,and productivity,much effort has been made in devising strategies based on known senescence regulatory mechanisms to manipulate the initiation and progression of leaf senescence,aiming for higher yield,better quality,or improved horticultural performance in crop plants.This review aims to provide an overview of leaf senescence and discuss recent advances in multi-dimensional regulation of leaf senescence from genetic and molecular network perspectives.We also put forward the key issues that need to be addressed,including the nature of leaf age,functional stay-green trait,coordination between different regulatory pathways,source-sink relationship and nutrient remobilization,as well as translational researches on leaf senescence.
基金supported by grants from National Natural Science Foundation of China(32070292 to J.L.)Shenzhen Science and Technology Program(KQTD20190929173906742 to J.L.)+1 种基金The Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006 to J.L.)Scientific Research Funding for postdoctoral researchers staying at Shenzhen(K19227561,K21227504 to W.Z.).
文摘Plants deploy versatile scaffold proteins to intricately modulate complex cell signaling.Among these,RACK1A(Receptors for Activated C Kinase 1A)stands out as a multifaceted scaffold protein functioning as a central integrative hub for diverse signaling pathways.However,the precise mechanisms by which RACK1A orchestrates signal transduction to optimize seedling development remain largely unclear.Here,we demonstrate that RACK1A facilitates hypocotyl elongation by functioning as a flexible platform that connects multiple key components of light signaling pathways.RACK1A interacts with PHYTOCHROME INTERACTING FACTOR(PIF)3,enhances PIF3 binding to the promoter of BBX11 and down-regulates its transcription.Furthermore,RACK1A associates with ELONGATED HYPOCOTYL 5(HY5)to repress HY5 biochemical activity toward target genes,ultimately contributing to hypocotyl elongation.In darkness,RACK1A is targeted by CONSTITUTIVELY PHOTOMORPHOGENIC(COP)1 upon phosphorylation and subjected to COP1-mediated degradation via the 26 S proteasome system.Our findings provide new insights into how plants utilize scaffold proteins to regulate hypocotyl elongation,ensuring proper skoto-and photo-morphogenic development.
基金supported by the National Natural Science Foundation of China(grant 32070292)the Shenzhen Science and Technology Program (grant KQTD20190929173906742)+2 种基金the Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(grant 2019KSYS006)Shenzhen government for fundamental research(grant JCYJ20170817104523456)Scientific research funding for postdoctoral researchers staying at Shenzhen(grant K20227507).
文摘ATP-binding cassette(ABC)transporters are integral membrane proteins that have evolved diverse func-tions fulfilled via the transport of various substrates.In Arabidopsis,the G subfamily of ABC proteins is particularly abundant and participates in multiple signaling pathways during plant development and stress responses.In this study,we revealed that two Arabidopsis ABCG transporters,ABCG16 and ABCG25,engage in ABA-mediated stress responses and early plant growth through endomembrane-specific dimerization-coupled transport of ABA and ABA-glucosyl ester(ABA-GE),respectively.We first revealed that ABCG16 contributes to osmotic stress tolerance via ABA signaling.More specifically,ABCG16 induces cellular ABA efflux in both yeast and plant cells.Using FRET analysis,we showed that ABCG16 forms oblig-atory homodimers for ABA export activity and that the plasma membrane-resident ABCG16 homodimers specifically respond to ABA,undergoing notable conformational changes.Furthermore,we demonstrated that ABCG16 heterodimerizes with ABCG25 at the endoplasmic reticulum(ER)membrane and facilitates the ER entry of ABA-GE in both Arabidopsis and tobacco cells.The specific responsiveness of the ABCG16-ABCG25 heterodimer to ABA-GE and the superior growth of their double mutant support an inhib-itory role of these twoABCGs in early seedling establishment via regulation of ABA-GE translocation across the ER membrane.Our endomembrane-specific analysis of the FRET signals derived from the homo-or heterodimerized ABcG complexes allowed us to link endomembrane-biased dimerization to the transloca-tion of distinct substrates by ABcG transporters,providing a prototypic framework for understanding the omnipotence of ABcG transporters in plant development and stress responses.
基金supported by the National Natural Science Foundation of China(Grant No.32061143023)Shenzhen Municipal Startup Fund and the Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(Grant No.2019KSYS006)。
文摘Plant natural products have been extensively exploited in food,medicine,flavor,cosmetic,renewable fuel,and other industrial sectors.Synthetic biology has recently emerged as a promising means for the cost-effective and sustainable production of natural products.Compared with engineering microbes for the production of plant natural products,the potential of plants as chassis for producing these compounds is underestimated,largely due to challenges encountered in engineering plants.Knowledge in plant engineering is instrumental for enabling the effective and efficient production of valuable phytochemicals in plants,and also paves the way for a more sustainable future agriculture.In this manuscript,we briefly recap the biosynthesis of plant natural products,focusing primarily on industrially important terpenoids,alkaloids,and phenylpropanoids.We further summarize the plant hosts and strategies that have been used to engineer the production of natural products.The challenges and opportunities of using plant synthetic biology to achieve rapid and scalable production of high-value plant natural products are also discussed.
基金supported by National Natural Science Foundation of China (31921001)。
文摘Minichromosome Maintenance protein 10(MCM10)is essential for DNA replication initiation and DNA elongation in yeasts and animals.Although the functions of MCM10 in DNA replication and repair have been well documented,the detailed mechanisms for MCM10 in these processes are not well known.Here,we identified AtMCM10 gene through a forward genetic screening for releasing a silenced marker gene.Although plant MCM10 possesses a similar crystal structure as animal MCM10,AtMCM10 is not essential for plant growth or development in Arabidopsis.AtMCM10 can directly bind to histone H3-H4 and promotes nucleosome assembly in vitro.The nucleosome density is decreased in Atmcm10,and most of the nucleosome density decreased regions in Atmcm10 are also regulated by newly synthesized histone chaperone Chromatin Assembly Factor-1(CAF-1).Loss of both AtMCM10 and CAF-1 is embryo lethal,indicating that AtM CM10 and CAF-1 are indispensable for replication-coupled nucleosome assembly.AtMCM10 interacts with both new and parental histones.Atmcm10 mutants have lower H3.1abundance and reduced H3K27me1/3 levels with releasing some silenced transposons.We propose that AtM CM10 deposits new and parental histones during nucleosome assembly,maintaining proper epigenetic modifications and genome stability during DNA replication.
基金supported by the Stable Support Plan Program of Shenzhen Natural Science Fund Grant(20200925153345004)to JZthe National Natural Science Foundation of China(Grant No.21907049 to KJ and Grant No.3191154007091740203 to HG)+1 种基金the Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06S172)to KJ and JZthe Shenzhen Science and Technology Program(Grant No.KYTDPT20181011104005)to KJ and JZ。
文摘Both phytohormone signaling and epigenetic mechanisms have long been known to play crucial roles in plant development and plasticity in response to ambient stimuli.Indeed,diverse signaling pathways mediated by phytohormones and epigenetic processes integrate multiple upstream signals to regulate various plant traits.Emerging evidence indicates that phytohormones and epigenetic processes interact at multiple levels.In this review,we summarize the current knowledge of the interplay between phytohormones and epigenetic processes from the perspective of phytohormone biology.We also review chemical regulators used in epigenetic studies and propose strategies for developing novel regulators using multidisciplinary approaches.
基金This work was supported by the Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006)was also financially supported by grants from the Natural Science Foundation of China(31770306)+7 种基金the Natural Science Foundation of Guangdong Province(2020A1515010966)the Guangdong Innovation Research Team Fund(2016ZT06S172)the Shenzhen Sci-Tech Fund(KYTDPT20181011104005)Z.M.and Y.M.were supported financially by the Singapore Ministry of Education(MOE)Tier 1(RG32/20)and Tier 3(MOE2019-T3-1-012)X.Z.was supported financially by the National Science Foundation for Young Scientists of China(32000558)the China Postdoctoral Science Foundation(grant no.2019M660494)R.L.L.was supported financially by the Natural Science Foundation of China(31970182,31670182)the Fundamental Research Funds for the Central Universities(2019ZY29).
文摘Delivery of proteins to the plasma membrane occurs via secretion,which requires tethering,docking,priming,and fusion of vesicles.In yeast and mammalian cells,an evolutionarily conserved RAB GTPase activation cascade functions together with the exocyst and SNARE proteins to coordinate vesicle transport with fusion at the plasma membrane.However,it is unclear whether this is the case in plants.In this study,we show that the small GTPase RABA2a recruits and interacts with the VAMP721/722-SYP121-SNAP33 SNARE ternary complex for membrane fusion.Through immunoprecipitation coupled with mass spectrometry analysis followed by the validatation with a series of biochemical assays,we identified the SNARE proteins VAMP721 and SYP121 as the interactors and downstream effectors of RABA2a.Further expreiments showed that RABA2a interacts with all members of the SNARE complex in its GTP-bound form and modulates the assembly of the VAMP721/722-SYP121-SNAP33 SNARE ternary complex.Intriguingly,we did not observe the interaction of the exocyst subunits with either RABA2a or theSNARE proteins in several different experiments.Neither RABA2a inactivation affects the subcellular localization or assembly of the exocystnor the exocyst subunit mutant exo84b shows the disrupted RABA2a-SNARE association or SNARE assembly,suggesting that the RABA2a-SNARE-and exocyst-mediated secretory pathways are largely independent.Consistently,our live imaging experiments reveal that the two sets of proteins follow non-overlapping trafficking routes,and genetic and cell biologyanalyses indicate that the two pathways select different cargos.Finally,we demonstrate that the plant-specific RABA2a-SNARE pathway is essential for the maintenance of potassium homeostasis in Arabisopsis seedlings.Collectively,our findings imply that higher plants might have generated different endomembrane sorting pathways during evolution and may enable the highly conserved endomembrane proteins to participate in plant-specific trafficking mechanisms for adaptation to the changing
基金supported by National Natural Science Foundation of China(32230008 to H.G.)Shenzhen Science and Technology Program(KQTD20190929173906742 to H.G.)Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006 to H.G.)。
文摘Apical hook is a simple curved structure formed at the upper part of hypocotyls when dicot seeds germinate in darkness.The hook structure is transient but essential for seedlings’survival during soil emergence due to its efficient protection of the delicate shoot apex from mechanical injury.As a superb model system for studying plant differential growth,apical hook has fascinated botanists as early as the Darwin age,and significant advances have been achieved at both the morphological and molecular levels to understand how apical hook development is regulated.Here,we will mainly summarize the research progress at these two levels.We will also briefly compare the growth dynamics between apical hook and hypocotyl gravitropic bending at early seed germination phase,with the aim to deduce a certain consensus on their connections.Finally,we will outline the remaining questions and future research perspectives for apical hook development.
基金supported by grants from the National Natural Science Foundation of China (32070292 to J.L.)Shenzhen Science and Technology Program (KQTD2019 0929173906742 to J.L.)+1 种基金The Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes (2019KSYS006 to J.L.)Scientific Research Funding for postdoctoral researchers staying at Shenzhen (K19227561, K21227504 to W.Z.)。
文摘Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and internal signals. However,the functions of plant scaffold proteins in response to senescence signals are not well understood. Here, we report that the scaffold protein RACK1A(RECEPTOR FOR ACTIVATED C KINASE1A) participates in leaf senescence mediated by ethylene signaling via the coordination of the EIN3-miR164-ORE1 transcriptional regulatory cascade. RACK1A is a novel positive regulator of ethylene-mediated leaf senescence. The rack1a mutant exhibits delayed leaf senescence, while transgenic lines overexpressing RACK1A display early leaf senescence. Moreover, RACK1A promotes EIN3(ETHYLENE INSENSITIVE 3) protein accumulation, and directly interacts with EIN3 to enhance its DNA-binding activity. Together, they then associate with the miR164 promoter to inhibit its transcription, leading to the release of the inhibition on downstream ORE1(ORESARA 1) transcription and the promotion of leaf senescence.This study reveals a mechanistic framework by which RACK1A promotes leaf senescence via the EIN3-miR164-ORE1 transcriptional cascade, and provides a paradigm for how scaffold proteins finely tune phytohormone signaling to control plant development.
基金supported by the National Key R&D Program of China(2019YFA0903903)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2016ZT06S172)+4 种基金the Shenzhen Sci-Tech Fund(KYTDPT20181011104005)the Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006)the Stable Support Plan Program of Shenzhen Natural Science Fund(20200925153345004)supported by the National Natural Science Foundation of China(32100444)the Shenzhen Fundamental Research Program(JCYJ20210324105202007)。
文摘Intron retention is the most common alternative splicing event in plants and plays a crucial role in the responses of plants to environmental signals.Despite a large number of RNA-seq libraries from different treatments and genetic mutants stored in public domains,a resource for querying the intron-splicing ratio of individual intron is still required.Here,we established the first-ever large-scale splicing efficiency database in any organism.Our database includes over 57,000 plant public RNA-seq libraries,comprising 25,283 from Arabidopsis,17,789 from maize,10,710 from rice,and 3,974 from soybean,and covers a total of 1.6 million introns in these four species.In addition,we manually curated and annotated all the mutant-and treatment-related libraries as well as their matched controls included in our library collection,and added graphics to display intron-splicing efficiency across various tissues,developmental stages,and stress-related conditions.The result is a large collection of 3,313treatment conditions and 3,594 genetic mutants for discovering differentially regulated splicing efficiency.Our online database can be accessed at https://plantintron.com/.
基金funded by the Southern University of Science and Technology for scientific research start-ups(Grant No.Y01226124 to H.G.)National Natural Science Foundation of China(Grant No.31700239 to Y.W.)+1 种基金Shenzhen Science and Technology Innovation Program(Grant No.JCYJ20170817105503416 to W.L.)Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(SUSTech)(2019KSYS006 to H.G.)。
文摘The development of a hook-like structure at the apical part of the soil-emerging organs has fascinated botanists for centuries,but how it is initiated remains unclear.Here,we demonstrate with highthroughput infrared imaging and 2-D clinostat treatment that,when gravity-induced root bending is absent,apical hook formation still takes place.In such scenarios,hook formation begins with a de novo growth asymmetry at the apical part of a straightly elongating hypocotyl.Remarkably,suchde novo asymmetric growth,but not the following hook enlargement,precedes the establishment of a detectable auxin response asymmetry,and is largely independent of auxin biosynthesis,transport and signaling.Moreover,we found that functional cortical microtubule array is essential for the following enlargement of hook curvature.When microtubule array was disrupted by oryzalin,the polar localization of PIN proteins and the formation of an auxin maximum became impaired at the to-be-hook region.Taken together,we propose a more comprehensive model for apical hook initiation,in which the microtubuledependent polar localization of PINs may mediate the instruction of growth asymmetry that is either stochastically taking place,induced by gravitropic response,or both,to generate a significant auxin gradient that drives the full development of the apical hook.
基金supported by the National Natural Science Foundation of China(Grant Nos 32100199,31900210,and 31970258)the Peking-Tsinghua Center for Life Sciences(to X.W.D)+4 种基金the Southern University of Science and Technology(to X.W.D)the Jiangsu Natural Science Foundation for Distinguished Young Scholars(Grant No.BK20211525)the Jiangsu"Innovativeand Entrepreneurial Talent"program(to D.X.)the Nanjing Agricultural University(start-up funding to D.X.)the Jiangsu Collaborative Innovation Center for Modern Crop Production(to D.X.).
文摘Light signaling precisely controls photomorphogenic development in plants.PHYTOCHROME INTERACTING FACTOR 4 and 5(PIF4 and PIF5)play critical roles in the regulation of this developmental process.In this study,we report CONSTITUTIVELY PHOTOMORPHOGENIC 1 SUPPRESSOR 6(CSU6)functions as a key regulator of light signaling.Loss of CSU6 function largely rescues the cop1-6 constitutively photomorphogenic phenotype.CSU6 promotes hypocotyl growth in the dark,but inhibits hypocotyl elongation in the light.CSU6 not only associates with the promoter regions of PIF4 and PIF5 to inhibit their expression in the morning,but also directly interacts with both PIF4 and PIF5 to repress their transcriptional activation activity.CSU6 negatively controls a group of PIF4-and PIF5-regulated gene expressions.Mutations in PIF4 and/or PIF5 are epistatic to the loss of CSU6,suggesting that CSU6 acts upstream of PIF4 and PIF5.Taken together,CSU6 promotes light-inhibited hypocotyl elongation by negatively regulating PIF4 and PIF5 transcription and biochemical activity.
基金by a grant from the National Natural Science Foundation of China(31970258)by start-up funding from Nan-jing Agricultural University(to D.X.)+2 种基金by grants from Jiangsu‘‘In-novative and Entrepreneurial Talent’’program(to D.X.)Nanjing Science and Technology Innovation Program for Overseas Stu-dents(to D.X.)the Jiangsu Collaborative Innovation Center for Modern Crop Production.
文摘phytochrome B(phyB)acts as the red light photoreceptor and negatively regulates the growth-promoting factor PHYTOCHROME INTERACTING 4(PIF4)through a direct physical interaction,which in turn changes the expression of a large number of genes.phyB-PIF4 module regulates a variety of biological and developmental processes in plants.In this study,we demonstrate that B-BOX PROTEIN 11(BBX11)physically interacts with both phyB and PIF4.BBX11 negatively regulates PIF4 accumulation as well as its biochemical activity,consequently leading to the repression of PIF4-controlled genes’expression and promotion of photomorphogenesis in the prolonged red light.This study reveals a regulatory mechanism that mediates red light signal transduction and sheds a light on phyB-PIF4 module in promoting red light-dependent photomorphognenesis.
基金supported by National Natural Science Foundation of China(31871234)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2016ZT06S172)+1 种基金the Shenzhen Sci-Tech Fund(KYTDPT20181011104005)supported by the Center for Computational Science and Engineering at Southern University of Science and Technology.
文摘In the last decade,RNA-sequencing(RNA-seq)has surpassed microarray to become the gold standard for gene expression profiling due to the continuous drop in sequencing cost and the latest development of easy-to-use library construction kits.To date,the Arabidopsis community has collectively released more than 20000 RNA-seq libraries,with over 1300 libraries deposited just in the first quarter of 2019(Figure 1A).This vast resource is tremendously useful for all Arabidopsis researchers to study transcriptional regulation,tissue specificity,stress responses,and developmental dynamics of genes in which they are interested.
基金supported by the Shenzhen Science and Technology Program(JCYJ20200109110403829 and KQTD20190929173906742 to Jiamu Du)the National Natural Science Foundation of China(31721001 to Yuehui He)+1 种基金the National Key Research and Development Program of China(2017YFA0503803 to Yuehui He)the Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006 to Jiamu Du)。
文摘The transcription factor CONSTANS(CO)integrates day-length information to induce the expression of florigen FLOWERING LOCUS T(FT)in Arabidopsis.We recently reported that the C-terminal CCT domain of CO forms a complex with NUCLEAR FACTOR-YB/YC to recognize multiple cis-elements in the FT promoter,and the N-terminal tandem B-box domains form a homomultimeric assembly.However,the mechanism and biological function of CO multimerization remained unclear.Here,we report that CO takes on a head-to-tail oligomeric configuration via its B-boxes to mediate FT activation in long days.The crystal structure of B-boxesCOreveals a closely connected tandem B-box fold forming a continuous head-to-tail assembly through unique CDHH zinc fingers.Mutating the key residues involved in CO oligomerization resulted in a non-functional CO,as evidenced by the inability to rescue co mutants.By contrast,a transgene encoding a human p53-derived tetrameric peptide in place of the B-boxesCOrescued co mutant,emphasizing the essential role of BboxesCO-mediated oligomerization.Furthermore,we found that the four TGTG-bearing cis-elements in FT proximal promoter are required for FT activation in long days.Our results suggest that CO forms a multimer to bind to the four TGTG motifs in the FT promoter to mediate FT activation.
基金supported by National Natural Science Foundation of China(31770782)the Ministry of Science and Technology of China(2016YFA0503200)+1 种基金the Shenzhen Science and Technology Program(JCYJ20200109110403829 and KQTD20190929173906742)Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006)to J.D.
文摘RNA-directed DNA methylation(Rd DM) is a plant-specific de novo DNA methylation pathway,which has extensive cross-talk with histone modifications. Here, we report that the maize RdDM regulator SAWADEE HOMEODOMAIN HOMOLOG 2(SHH2) is an H3 K9 me1 reader. Our structural studies reveal that H3 K9 me1 recognition is achieved by recognition of the methyl group via a classic aromatic cage and hydrogen-bonding and salt-bridge interactions with the free protons of the mono-methyllysine. The di-and tri-methylation states disrupt the polar interactions, decreasing the binding affinity. Our study reveals a monomethyllysine recognition mechanism which potentially links RdDM to H3 K9 me1 in maize.
基金This work was supported by the National Natural Science Foundation of China(31970196 and 32011540381 to Z.L.,31900173 to H.W.,31770649 to X.X.)the National Key Research and Development Program of China(No.2019YFA0903904 to H.G.)+2 种基金Shenzhen Science and Technology Program(KQTD20190929173906742 to H.G.)China Postdoctoral Science Foundation(2019M650514 to Y.Z.and 2020M670544 to Y.G.,and 2019M650516 to H.W.)the startup funding for plant aging research from"Beijing Advanced Innovation Center for Tree Breeding by Molecular Design,Beijing Forestry University".
文摘Leaf senescence,the final stage of leaf development,is influenced by numerous internal and environmental signals.So far,how biotic stresses such as pathogen infection regulate leaf senescence is unclear.Here,we found that the premature leaf senescence caused by a soil-borne vascular fungus Verticillium dahliae in Arabidopsis was impaired by the mutation of a protein elicitor from V.dahliae 1(PevD1).Constitutive or inducible overexpression of PevD1 accelerated Arabidopsis leaf senescence.A senescence-associated NAC transcription factor,ORE1,was targeted by PevD1.PevD1 interacted with and stabilized ORE1 protein by disrupting its interaction with the RING-type ubiquitin E3 ligase NLA.Mutation of ORE1 suppressed the premature senescence caused by overexpressing PevD1.Overexpression of ORE1 or PevD1 led to enhanced ethylene production,and ORE1 mediated PevD1-induced ethylene biosynthesis by directly binding to the ACS6 promoter.Loss-of-function of ACSs suppressed V.dahliae-induced leaf senescence in ORE1-overexpressing plants.Interestingly,PevD1 also interacted with Gossypium hirsutum ORE1(GhORE1),and virus-induced gene silencing of GhORE1 delayed V.dahliae-triggered leaf senescence in cotton,indicative of the existence of a conserved mechanism in plants.Altogether,our study demonstrates that V.dahliae induces leaf senescence by secreting the effector PevD1 to regulate the ORE1-ACS6 cascade,providing new insight into biotic stress-induced senescence in plants.
基金supported by the National Natural Science Foundation of China(32170345,31970196 and 32011540381 to Z.L.,31900173 to H.-L.W.,31770649 to X.X.)Open Fund of State Key Laboratory of Tree Genetics and Breeding,Chinese Academy of Forestry(TGB2021007 to H.-L.W.)+1 种基金the National Key Research and Development Program of China(2019YFA0903904 to H.G.)startup funding for plant aging research(BJFU2021YJRC00600K)。
文摘Drought is a critical environmental factor which constrains plant survival and growth.Genetic engineering provides a credible strategy to improve drought tolerance of plants.Here,we generated transgenic poplar lines expressing the isopentenyl transferase gene(IPT)under the driver of Pt RD26 promoter(PtRD26 pro-IPT).Pt RD26 is a senescence and drought-inducible NAC transcription factor.Pt RD26 pro-IPT plants displayed multiple phenotypes,including improved growth and drought tolerance.Transcriptome analysis revealed that auxin biosynthesis pathway was activated in the PtRD26 pro-IPT plants,leading to an increase in auxin contents.Biochemical analysis revealed that ARABIDOPSIS RESPONSE REGULATOR10(PtARR10),one of the type-B ARR transcription factors in the cytokinin pathway,was induced in PtRD26 pro-IPT plants and directly regulated the transcripts of YUCCA4(Pt YUC4)and YUCCA5(PtYUC5),two enzymes in the auxin biosynthesis pathway.Overexpression of PtYUC4 enhanced drought tolerance,while simultaneous silencing of PtYUC4/5 evidently attenuated the drought tolerance of Pt RD26 pro-IPT plants.Intriguingly,Pt YUC4/5 displayed a conserved thioredoxin reductase activity that is required for drought tolerance by deterring reactive oxygen species accumulation.Our work reveals the molecular basis of cytokinin and auxin interactions in response to environmental stresses,and shed light on the improvement of drought tolerance without a growth penalty in trees by molecular breeding.
基金the Chinese Academy of Sciences and the National Natural Science Foundation of China(31970580)to M.L.the National Key R&D Program(2016YFA0503200)+1 种基金Shenzhen Science and Technology Program(JCYJ20200109110403829 and KQTD20190929173906742)Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes(2019KSYS006)to J.D.
文摘DNA methylation,a conserved epigenetic mark,is critical for tuning temporal and spatial gene expression.The Arabidopsis thaliana DNA glycosylase/lyase REPRESSOR OF SILENCING 1(ROS1)initiates active DNA demethylation and is required to prevent DNA hypermethylation at thousands of genomic loci.However,how ROS1 is recruited to specific loci is not well understood.Here,we report the discovery of Arabidopsis AGENET Domain Containing Protein 3(AGDP3)as a cellular factor that is required to prevent gene silencing and DNA hypermethylation.AGDP3 binds to H3K9me2 marks in its target DNA via its AGD12 cassette.Analysis of the crystal structure of the AGD12 cassette of AGDP3 in complex with an H3K9me2 peptide revealed that dimethylated H3 K9 and unmodified H3 K4 are specifically anchored into two different surface pockets.A histidine residue located in the methyllysine binding aromatic cage provides AGDP3 with pH-dependent H3K9me2 binding capacity.Our results uncover a molecular mechanism for the regulation of DNA demethylation by the gene silencing mark H3K9me2.
