Nitrogen(N)is a key component in plants and their biological macromolecules,having a profound effect on developmental stages,such as germination,vegetative growth,and flowering.However,the mechanism of nitrogen-regula...Nitrogen(N)is a key component in plants and their biological macromolecules,having a profound effect on developmental stages,such as germination,vegetative growth,and flowering.However,the mechanism of nitrogen-regulated flowering time remains unclear.In this study,CmNLP7 was isolated from the chrysanthemum cultivar‘Jinba'and was characterized.CmNLP7 is a transcription factor localized in the nucleus but has no transcriptional activity.Tissue expression pattern analysis showed that CmNLP7 was mainly transcribed in leaves and roots.Knocking down CmNLP7 through the artificial-miRNA method in chrysanthemum resulted in early flowering under optimal nitrogen(ON)and low nitrogen(LN)conditions;whereas overexpression lines showed delayed flowering under LN conditions.Transcriptome sequencing analysis showed that the nitrate transporters NRT2.5,NPF3.1,and NPF4.6;SBP-like genes SPL7 and SPL12,and flowering integration factor FT were significantly up-regulated in the knockdown lines.Based on the KEGG pathway enrichment analysis,the differentially transcribed genes were enriched in phenylpropanoid biosynthesis and starch and sucrose metabolism pathways,which indicated their alleged function in nitrogen-regulated flowering and development in chrysanthemum.Furthermore CmPP6 as a homolog of the Arabidopsis phosphatase PP6,was verified as an interacting protein of CmNLP7 by yeast two-hybrid,BiFC,pull-down and Biacore in vitro and in vivo,and the knockdown line of CmPP6(amiR-CmPP6)flowered earlier compared to that of the wild-type chrysanthemum‘Jinba'.Collectively,these results demonstrated that CmPP6 interacts with CmNLP7 to regulate chrysanthemum flowering,and CmNLP7 could regulate flowering time in response to nitrogen,which lays a foundation for the regulation of flowering and molecular breeding of chrysanthemum through changes in nutrient signaling.展开更多
Nitrogen(N)is a limiting factor that determines the yield and quality of chrysanthemum.Genetic variation in N use efficiency(NUE)has been reported among chrysanthemum genotypes.We performed a transcriptome analysis of...Nitrogen(N)is a limiting factor that determines the yield and quality of chrysanthemum.Genetic variation in N use efficiency(NUE)has been reported among chrysanthemum genotypes.We performed a transcriptome analysis of two chrysanthemum genotypes,'Nannonglihuang'(LH,N-efficient genotype)and'Nannongxuefeng"(XF,N-inefficient genotype),under low N(0.4 mmol L^(-1)N)and normal N(8 mmol L^(-1)N)treatments for 15 d and an N recovery treatment for 12 h(low N treatment for 15 d and then normal N treatment for 12 h)to understand the genetic factors impacting NUE in chrysanthemum.The two genotypes exhibited contrasting responses to the different N treatments.The N-efficient genotype LH had significant superiority in agronomic traits,N accumulation and glutamine synthase activity under both normal N and low N treatments.Low N treatment promoted root growth in LH,but inhibited root growth in XF.Transcriptome analysis revealed that the low N treatment increased the expression of some N metabolism genes,genes related to auxin and abscisic acid signal transduction in the roots of both genotypes,as well as genes related to gibberellin signal transduction in roots of LH.The N recovery treatment just increased the expression of genes related to cytokinin signal transduction in roots of LH.The expression levels of the NRT2.1,AMT1.1,and Gln1 genes related to gibberellin and cytokinin signal transduction were higher in roots of LH than in XF under different N treatments,suggesting that the genes related to N metabolism and hormone(auxin,abscisic acid,gibberellin,and cytokinin)signal transduction in roots of LH are more sensitive to different N treatments than those of XF.Co-expression network analysis(WGCNA)also identified hub genes like bZIP43,bHLH93,NPF6.3,IBR10,MYB62,PP2C,PP2C06 and NLP7,which may be the key regulators of N-mediated responses in chrysanthemum and play crucial roles in enhancing NUE and resistance to low N stress in the N-efficient chrysanthemum genotype.These results revealed the key factors involved in regulating NUE in chrysanthemum at the genetic level,which provides new insights into the complex mechanism of efficient nitrogen utilization in chrysanthemum,and can be useful for the improvement and breeding of high NUE chrysanthemum genotypes.展开更多
Chrysanthemum is rich in active compounds such as flavonoids and phenolic acids,and its dried head flowers are commonly used for tea and medicinal purposes.However,the genetic determinism underlying chrysanthemum acti...Chrysanthemum is rich in active compounds such as flavonoids and phenolic acids,and its dried head flowers are commonly used for tea and medicinal purposes.However,the genetic determinism underlying chrysanthemum active compounds remains elusive.In this study,we evaluated a panel of 137 chrysanthemum accessions for total flavonoids,chlorogenic acid,luteolin,and isochlorogenic acid A across two consecutive years.The four active compounds exhibited considerable variation,with a coefficient of variation ranging from 44.96%to 76.30%.Significant differences were observed in genotype and environments,and the broad-sense heritability was estimated at 0.5e0.63 for all examined traits.Significant pair-wise correlation was found between the four active compounds.Several accessions showing the highest active compounds were figured out for breeding use by integrating the membership function and hierarchical cluster analysis methods.Based on the 327042 high-quality SNPs,a genome-wide association study(GWAS)captured 59 significant SNPs for the four active compounds,of which 24 elite alleles exhibited pyramiding effects.A total of 18 potential candidate genes were mined,among which evm.model.scaffold_1149.273(QUA1)has one linkage disequilibrium(LD)block corresponding to Hap4 with the highest luteolin content.The findings are beneficial to understanding the genetic basis of the active compounds and provide parental materials and valuable markers for the genetic improvement of active compounds in chrysanthemums.展开更多
Chrysanthemum(Chrysanthemum morifolium Ramat.)is a leading flower with applied value worldwide.Developing new chrysanthemum cultivars with novel characteristics such as new flower colors and shapes,plant architectures...Chrysanthemum(Chrysanthemum morifolium Ramat.)is a leading flower with applied value worldwide.Developing new chrysanthemum cultivars with novel characteristics such as new flower colors and shapes,plant architectures,flowering times,postharvest quality,and biotic and abiotic stress tolerance in a time-and cost-efficient manner is the ultimate goal for breeders.Various breeding strategies have been employed to improve the aforementioned traits,ranging from conventional techniques,including crossbreeding and mutation breeding,to a series of molecular breeding methods,including transgenic technology,genome editing,and marker-assisted selection(MAS).In addition,the recent extensive advances in high-throughput technologies,especially genomics,transcriptomics,proteomics,metabolomics,and microbiomics,which are collectively referred to as omics platforms,have led to the collection of substantial amounts of data.Integration of these omics data with phenotypic information will enable the identification of genes/pathways responsible for important traits.Several attempts have been made to use emerging molecular and omics methods with the aim of accelerating the breeding of chrysanthemum.However,applying the findings of such studies to practical chrysanthemum breeding remains a considerable challenge,primarily due to the high heterozygosity and polyploidy of the species.This review summarizes the recent achievements in conventional and modern molecular breeding methods and emerging omics technologies and discusses their future applications for improving the agronomic and horticultural characteristics of chrysanthemum.展开更多
Flavones are among the major colorless pigments synthesized through branches of the flavonoid pathway in plants.However,due to the absence of a gene encoding flavone synthase(FNS)in the model plant Arabidopsis thalian...Flavones are among the major colorless pigments synthesized through branches of the flavonoid pathway in plants.However,due to the absence of a gene encoding flavone synthase(FNS)in the model plant Arabidopsis thaliana species,the regulatory mechanism of FNS-catalyzed flavone biosynthesis has rarely been studied in plants.Here,it was found that flavones play a predominant role in the elimination of excess reactive oxygen species(ROS)at high temperatures in colorless plant organs.A novel atypical subgroup 7(SG7)R2R3-MYB transcription factor,CmMYB012,was found to be induced in response to prolonged high temperatures and to inhibit flavone biosynthesis by directly regulating CmFNS.Moreover,CmMYB012 was also found to inhibit anthocyanin biosynthesis by suppressing the expression of CmCHS,CmDFR,CmANS,and CmUFGT.CmMYB012 overexpression exerted a negative in fluence on plant fitness and pink flower color formation,while CmMYB012 suppression had the opposite effect in response to high temperatures.Our findings provide new insights into the mechanisms by which high temperatures regulate the metabolism of flavones and anthocyanins to affect plant fitness and flower color formation.展开更多
White rust caused by Puccinia horiana is a destructive disease of chrysanthemum plants.To better understand the resistance mechanisms of composite species to this disease,the leaf cuticular traits,antioxidant and defe...White rust caused by Puccinia horiana is a destructive disease of chrysanthemum plants.To better understand the resistance mechanisms of composite species to this disease,the leaf cuticular traits,antioxidant and defensive enzymes activities of immune(Chrysanthemum makinoi var.wakasaense)and highly susceptible(Ajania shiwogiku var.kinokuniense)species were compared.Trichome density of two species was markedly different,negatively associated with plant resistance to P.horiana.Total wax load in C.makinoi var.wakasaense was two times more than that in A.shiwogiku var.kinokuniense.The wax composition in immune one was abundant in esters and primary alcohols.Superoxide dismutase(SOD,EC 1.15.1.1),peroxidase(POD,EC 1.11.1.7),polyphenoloxidase(PPO,EC 1.14.18.1 or EC 1.10.3.2)and phenylalanine ammonia lyase(PAL,EC 4.3.1.5)activitieswere investigated.In C.makinoi var.wakasaense,the activity of SOD and POD increased rapidly after inoculation,whichmight be non-host induced reactive oxygen species(ROS)activated antioxidant enzymes,however SOD and POD remained a low and steady level in the highly susceptible one after inoculation.Quick increase in PPO activities after inoculation was observed in both species,however it remained higher in C.makinoi var.wakasaense at the late period of inoculation.PAL in C.makinoi var.wakasaense was induced after pathogen inoculation,but not in A.shiwogiku var.kinokuniense,suggesting that these two enzymes might contribute to the resistance to P.horiana.展开更多
Chrysanthemums are sensitive to waterlogging stress,and the development of screening methods for tolerant germplasms or genes and the breeding of tolerant new varieties are of great importance in chrysanthemum breedin...Chrysanthemums are sensitive to waterlogging stress,and the development of screening methods for tolerant germplasms or genes and the breeding of tolerant new varieties are of great importance in chrysanthemum breeding.To understand the genetic basis of waterlogging tolerance(WT)in chrysanthemums,we performed a genome-wide association study(GWAS)using 92,811 single nucleotide polymorphisms(SNPs)in a panel of 88 chrysanthemum accessions,including 64 spray cut and 24 disbud chrysanthemums.The results showed that the average MFVW(membership function value of waterlogging)of the disbud type(0.65)was significantly higher than that of the spray type(0.55)at P<0.05,and the MFVW of the Asian accessions(0.65)was significantly higher than that of the European accessions(0.48)at P<0.01.The GWAS performed using the general linear model(GLM)and mixed linear model(MLM)identified 137 and 14 SNP loci related to WT,respectively,and 11 associations were commonly predicted.By calculating the phenotypic effect values for 11 common SNP loci,six highly favorable SNP alleles that explained 12.85—21.85%of the phenotypic variations were identified.Furthermore,the dosage-pyramiding effects of the favorable alleles and the significant linear correlations between the numbers of highly favorable alleles and phenotypic values were identified(r2=0.45;P<0.01).A major SNP locus(Marker6619-75)was converted into a derived cleaved amplified polymorphic sequence(dCAPS)marker that cosegregated with WT with an average efficiency of 78.9%.Finally,four putative candidate genes in the WT were identified via quantitative real-time PCR(qRT-PCR).The results presented in this study provide insights for further research on WT mechanisms and the application of molecular marker-assisted selection(MAS)in chrysanthemum WT breeding programs.展开更多
MYB transcription factors are widely involved in the development of and physiological processes in plants.Here,we isolated the chrysanthemum R2R3-MYB family transcription factor CmMYB15,a homologous gene of AtMYB15.It...MYB transcription factors are widely involved in the development of and physiological processes in plants.Here,we isolated the chrysanthemum R2R3-MYB family transcription factor CmMYB15,a homologous gene of AtMYB15.It was demonstrated that CmMYB15 expression was induced by aphids and that CmMYB15 could bind to AC elements,which usually exist in the promoter of lignin biosynthesis genes.Overexpression of CmMYB15 in chrysanthemum enhanced the resistance of aphids.Additionally,the content of lignin and the expression of several lignin biosynthesis genes increased.In summary,the results indicate that CmMYB15 regulates lignin biosynthesis genes that enhance the resistance of chrysanthemum to aphids.展开更多
As the junction of floral development pathways,the FLOWERING LOCUS T(FT)protein called‘florigen’plays an important role in the process of plant flowering through signal integration.We isolated four transcripts encod...As the junction of floral development pathways,the FLOWERING LOCUS T(FT)protein called‘florigen’plays an important role in the process of plant flowering through signal integration.We isolated four transcripts encoding different isoforms of a FT orthologous gene CmFTL1,from Chrysanthemum morifolium cultivar‘Jimba’.Sequence alignments suggested that the four transcripts are related to the intron 1.Expression analysis showed that four alternative splicing(AS)forms of CmFTL1 varied depending on the developmental stage of the flower.The functional complement experiment using an Arabidopsis mutant ft-10 revealed that the archetypal and AS forms of CmFTL1 had the function of complementing late flower phenotype in different levels.In addition,transgenic confirmation at transcript level showed CmFTL1 and CmFTL1ast coexist in the same tissue type at the same developmental stage,indicating a post-transcriptional modification of CmFTL1 in Arabidopsis.Moreover,ectopic expression of different AS forms in chrysanthemum resulted in the development of multiple altered phenotypes,varying degrees of early flowering.We found that an alternative splicing form(CmFTL1-astE134)without the exon 2 lacked the ability causing the earlier flower phenotype.The evidence in this study indicates that complex alternative processing of CmFTL1 transcripts in C.morifolium may be associated with flowering regulation and hold some potential for biotechnical engineering to create early-flowering phenotypes in ornamental cultivars.展开更多
The chrysanthemum genome harbors three FT-like genes:CmFTL1 and CmFTL3 are thought to act as regulators of floral induction under long-day(LD)and short-day(SD)conditions,respectively,whereas the function of CmFTL2 is ...The chrysanthemum genome harbors three FT-like genes:CmFTL1 and CmFTL3 are thought to act as regulators of floral induction under long-day(LD)and short-day(SD)conditions,respectively,whereas the function of CmFTL2 is currently unclear.The objective of the present research was to explore the function of CmFTL2 in the determination of flowering time of the photo-insensitive chrysanthemum cultivar‘Floral Yuuka’,both in response to variation in the photoperiod and to the exogenous provision of sucrose.Spraying leaves of‘Floral Yuuka’plants with 50 mM sucrose accelerated flowering and increased the level of CmFTL2 transcription in the leaf more strongly than either CmFTL1 or FTL3 under both long and SD conditions.Transcription profiling indicated that all three CmFTL genes were upregulated during floral induction.The relationship of the CmFTL2 sequence with that of other members of the PEBP family suggested that its product contributes to the florigen rather than to the anti-florigen complex.The heterologous expression of CmFTL2 in the Arabidopsis thaliana ft-10 mutant rescued the mutant phenotype,showing that CmFTL2 could compensate for the absence of FT.These results suggest that CmFTL2 acts as a regulator of floral transition and responds to both the photoperiod and sucrose.展开更多
Chrysanthemum(Chrysanthemum morifolium)is one of the four major cut-flower plants worldwide and possesses both high ornamental value and cultural connotation.As most chrysanthemum varieties flower in autumn,it is cost...Chrysanthemum(Chrysanthemum morifolium)is one of the four major cut-flower plants worldwide and possesses both high ornamental value and cultural connotation.As most chrysanthemum varieties flower in autumn,it is costly to achieve annual production.JAZ genes in the TIFY family are core components of the jasmonic acid(JA)signaling pathway;in addition to playing a pivotal role in plant responses to defense,they are also widely implicated in regulating plant development processes.Here,we characterized the TIFY family gene CmJAZ1-like from the chrysanthemum cultivar‘Jinba’.CmJAZ1-like localizes in the nucleus and has no transcriptional activity in yeast.Tissue expression pattern analysis indicated that CmJAZ1-like was most active in the root and shoot apex.Overexpressing CmJAZ1-like with Jas domain deletion in chrysanthemum resulted in late flowering.RNA-Seq analysis of the overexpression lines revealed some differentially expressed genes(DEGs)involved in flowering,such as the homologs of the flowering integrators FT and SOC1,an FUL homolog involved in flower meristem identity,AP2 domain-containing transcription factors,MADS box genes,and autonomous pathway-related genes.Based on KEGG pathway enrichment analysis,the differentially transcribed genes were enriched in carbohydrate metabolic and fatty acid-related pathways,which are notable for their role in flowering in plants.This study preliminarily verified the function of CmJAZ1-like in chrysanthemum flowering,and the results can be used in molecular breeding programs aimed at flowering time regulation of chrysanthemum.展开更多
Chrysanthemum(Chrysanthemum morifolium)black spot disease(CBS)poses a major threat to Chrysanthemum cultivation owing to suitable climate conditions and current lack of resistant cultivars for greenhouse cultivation.I...Chrysanthemum(Chrysanthemum morifolium)black spot disease(CBS)poses a major threat to Chrysanthemum cultivation owing to suitable climate conditions and current lack of resistant cultivars for greenhouse cultivation.In this study,we identified a number of genes that respond to Alternaria alternata infection in resistant and susceptible Chrysanthemum cultivars.Based on RNA sequencing technology and a weighted gene coexpression network analysis(WGCNA),we constructed a model to elucidate the response of Chrysanthemum leaves to A.alternata infection at different stages and compared the mapped response of the resistant cultivar‘Jinba’to that of the susceptible cultivar‘Zaoyihong’.In the early stage of infection,when lesions had not yet formed,abscisic acid(ABA),salicylic acid(SA)and EDS1-mediated resistance played important roles in the Chrysanthemum defense system.With the formation of necrotic lesions,ethylene(ET)metabolism and the Ca^(2+)signal transduction pathway strongly responded to A.alternata infection.During the late stage,when necrotic lesions continued to expand,members of the multidrug and toxic compound extrusion(MATE)gene family were highly expressed,and their products may be involved in defense against A.alternata invasion by exporting toxins produced by the pathogen,which plays important roles in the pathogenicity of A.alternata.Furthermore,the function of hub genes was verified by qPCR and transgenic assays.The identification of hub genes at different stages,the comparison of hub genes between the two cultivars and the highly expressed genes in the resistant cultivar‘Jinba’provide a theoretical basis for breeding cultivars resistant to CBS.展开更多
The switch from vegetative growth to reproductive growth is a key event in the development of a plant.Here,the product of the chrysanthemum gene CmMYB2,an R2R3 MYB transcription factor that is localized in the nucleus...The switch from vegetative growth to reproductive growth is a key event in the development of a plant.Here,the product of the chrysanthemum gene CmMYB2,an R2R3 MYB transcription factor that is localized in the nucleus,was shown to be a component of the switching mechanism.Plants engineered to overexpress CmMYB2 flowered earlier than did wild-type plants,while those in which CmMYB2 was suppressed flowered later.In both the overexpression and RNAi knockdown plants,a number of genes encoding proteins involved in gibberellin synthesis or signaling,as well as in the response to photoperiod,were transcribed at a level that differed from that in the wild type.Both yeast two-hybrid and bimolecular fluorescence complementation assays revealed that CmMYB2 interacts with CmBBX24,a zinc-finger transcription factor known to regulate flowering by its influence on gibberellin synthesis.展开更多
The CmBBX8-CmFTL1 regulatory module is a key determinant in the transition from vegetative growth to reproductive development in summer-flowering chrysanthemum.However,the detailed regulatory mechanism of CmBBX8-media...The CmBBX8-CmFTL1 regulatory module is a key determinant in the transition from vegetative growth to reproductive development in summer-flowering chrysanthemum.However,the detailed regulatory mechanism of CmBBX8-mediated flowering remains elusive.In this study,we revealed that RADICAL-INDUCED CELL DEATH 1(CmRCD1)physically associated with CmBBX8 through bimolecular fluorescence complementation(BiFC),pulldown and Coimmunoprecipitation(CoIP)assays.Furthermore,the RCD1-SRO1-TAF4(RST)domain of CmRCD1 and the B-box of CmBBX8 mediated their interaction.In addition,Luciferase(LUC)assays and electrophoretic mobility shift assay(EMSAs)showed that CmRCD1 repressed the transcriptional activity of CmBBX8 and interfered with its binding to the CmFTL1 promoter,thereby leading to delayed flowering in the summer chrysanthemum‘Yuuka’.These results provide insight into the molecular framework of CmRCD1-CmBBX8-mediated flowering in chrysanthemum.展开更多
Chrysanthemum(Chrysanthemum morifolium)is an ideal model species for studying petal morphogenesis because of the diversity in the flower form across varieties;however,the molecular mechanisms underlying petal developm...Chrysanthemum(Chrysanthemum morifolium)is an ideal model species for studying petal morphogenesis because of the diversity in the flower form across varieties;however,the molecular mechanisms underlying petal development are poorly understood.Here,we show that the brassinosteroid transcription factor BRI1-EMS-SUPPRESSOR 1(CmBES1)in chrysanthemum(C.morifolium cv.Jinba)is important for organ boundary formation because it represses organ boundary identity genes.Chrysanthemum plants overexpressing CmBES1 displayed increased fusion of the outermost ray florets due to the loss of differentiation of the two dorsal petals,which developed simultaneously with the ventral petals.RNA-seq analysis of the overexpression lines revealed potential genes and pathways involved in petal development,such as CUP-SHAPED COTYLEDON(CUC2),CYCLOIDEA 4(CYC4),genes encoding MADS-box transcription factors and homeodomain-leucine zippers(HD-Zips)and auxin pathway-related genes.This study characterizes the role of CmBES1 in ray floret development by its modulation of flower development and boundary identity genes in chrysanthemum.展开更多
Chrysanthemum is frequently attacked by aphids,which greatly hinders the growth and ornamental value of this plant species.WRKY transcription factors play an important role in the response to biotic stresses such as p...Chrysanthemum is frequently attacked by aphids,which greatly hinders the growth and ornamental value of this plant species.WRKY transcription factors play an important role in the response to biotic stresses such as pathogen and insect stresses.Here,chrysanthemum CmWRKY53 was cloned,and its expression was induced by aphid infestation.To verify the role of CmWRKY53 in resistance to aphids,CmWRKY53 transgenic chrysanthemum was generated.CmWRKY53 was found to mediate the susceptibility of chrysanthemum to aphids.The expression levels of secondary metabolite biosynthesis genes,such as peroxidase-and polyphenol oxidase-encoding genes,decreased in CmWRKY53-overexpressing(CmWRKY53-Oe)plants but dramatically increased in chimeric dominant repressor(CmWRKY53-SRDX)plants,suggesting that CmWRKY53 contributes to the susceptibility of chrysanthemum to aphids,possibly due to its role in the regulation of secondary metabolites.展开更多
Allopolyploid formation involves two major events:interspecific hybridization and polyploidization.A number of species in the Asteraceae family are polyploids because of frequent hybridization.The effects of hybridiza...Allopolyploid formation involves two major events:interspecific hybridization and polyploidization.A number of species in the Asteraceae family are polyploids because of frequent hybridization.The effects of hybridization on genomics and transcriptomics in Chrysanthemum nankingense×Tanacetum vulgare hybrids have been reported.In this study,we obtained allopolyploids by applying a colchicine treatment to a synthesized C.nankingense×T.vulgare hybrid.Sequence-related amplified polymorphism(SRAP),methylation-sensitive amplification polymorphism(MSAP),and high-throughput RNA sequencing(RNA-Seq)technologies were used to investigate the genomic,epigenetic,and transcriptomic alterations in both the hybrid and allopolyploids.The genomic alterations in the hybrid and allopolyploids mainly involved the loss of parental fragments and the gain of novel fragments.The DNA methylation level of the hybrid was reduced by hybridization but was restored somewhat after polyploidization.There were more significant differences in gene expression between the hybrid/allopolyploid and the paternal parent than between the hybrid/allopolyploid and the maternal parent.Most differentially expressed genes(DEGs)showed down-regulation in the hybrid/allopolyploid relative to the parents.Among the non-additive genes,transgressive patterns appeared to be dominant,especially repression patterns.Maternal expression dominance was observed specifically for down-regulated genes.Many methylase and methyltransferase genes showed differential expression between the hybrid and parents and between the allopolyploid and parents.Our data indicate that hybridization may be a major factor affecting genomic and transcriptomic changes in newly formed allopolyploids.The formation of allopolyploids may not simply be the sum of hybridization and polyploidization changes but also may be influenced by the interaction between these processes.展开更多
Basic helix-loop-helix(bHLH)transcription factor gene family in plants controls various growth and development aspects;however,the actual roles of these genes in flowering plants are not well known.In this study,a nov...Basic helix-loop-helix(bHLH)transcription factor gene family in plants controls various growth and development aspects;however,the actual roles of these genes in flowering plants are not well known.In this study,a novel bHLH protein CmbHLH110 was found to interact with CmERF110 by in vitro and in vivo experiments,a chrysanthemum ERF110 homolog that acts as a positive flowering regulator.In addition,CmbHLH110 was also found to regulate the flowering of chrysanthemums,overexpression of CmbHLH110 causes chrysanthemums to flower earlier,and suppressed CmbHLH110 leads to delayed flowering.Furthermore,the loss-of-function Arabidopsis mutant of its homologue PERICYCLE FACTOR TYPE-A 5(PFA5)had a noticeable late flowering phenotype,and CmbHLH110 completely complemented the late flowering phenotype of the pfa5 mutant,whereas heterologous overexpression of CmbHLH110 in Arabidopsis Col-0 caused early flowering.Transcriptome sequencing revealed significant differential expression of flowering-related and circadian clock-related genes in transgenic chrysanthemum.Therefore,we concluded that CmbHLH110,as a novel flowering regulator,could interact with CmERF110 to regulate flowering in chrysanthemum.展开更多
Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in ...Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in the Hengduan Mountains,Yunnan Province.We took advantage of a special geographic region where the southernmost species of Ajania and the highest altitude population of Chrysanthemum indicum coexist to investigate their evolutionary origins.Diversity analysis of 9 populations of 5 species that came from 3 genera was carried out based on morphological traits and SRAP markers.Furthermore,topographical and ecological analyses and surveys of the vegetation communities in the plots were carried out for correlation analysis,and past data were used to reconstruct the ancient topography and vegetation to estimate the migration path and divergence time.We found that Chrysanthemum and Ajania were closely related based on the smooth transition states among marginal female florets and their common pollination system.The genetic relationship between Phaeostigma and Chrysanthemum was relatively distant,and Ajania was between them.Low light intensity and relatively humid habitats may be driving the elongation and evolution of marginal female florets.We found that Chrysanthemum and related genera were largely restricted to stony topographies at an altitude of~3000 m.a.s.l.and in specialized alpine coniferous(Pinus)and broadleaved(Quercus)mixed forest marginal communities.These stony topographies have become ecological islands of refuge for these species in the current interglacial period.The Hengduan Mountains play a key role in the evolution,divergence,and survival of Chrysanthemum and its allies.展开更多
基金supported by grants from the National Natural Science Foundation of China(Grant No.31930100)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Nitrogen(N)is a key component in plants and their biological macromolecules,having a profound effect on developmental stages,such as germination,vegetative growth,and flowering.However,the mechanism of nitrogen-regulated flowering time remains unclear.In this study,CmNLP7 was isolated from the chrysanthemum cultivar‘Jinba'and was characterized.CmNLP7 is a transcription factor localized in the nucleus but has no transcriptional activity.Tissue expression pattern analysis showed that CmNLP7 was mainly transcribed in leaves and roots.Knocking down CmNLP7 through the artificial-miRNA method in chrysanthemum resulted in early flowering under optimal nitrogen(ON)and low nitrogen(LN)conditions;whereas overexpression lines showed delayed flowering under LN conditions.Transcriptome sequencing analysis showed that the nitrate transporters NRT2.5,NPF3.1,and NPF4.6;SBP-like genes SPL7 and SPL12,and flowering integration factor FT were significantly up-regulated in the knockdown lines.Based on the KEGG pathway enrichment analysis,the differentially transcribed genes were enriched in phenylpropanoid biosynthesis and starch and sucrose metabolism pathways,which indicated their alleged function in nitrogen-regulated flowering and development in chrysanthemum.Furthermore CmPP6 as a homolog of the Arabidopsis phosphatase PP6,was verified as an interacting protein of CmNLP7 by yeast two-hybrid,BiFC,pull-down and Biacore in vitro and in vivo,and the knockdown line of CmPP6(amiR-CmPP6)flowered earlier compared to that of the wild-type chrysanthemum‘Jinba'.Collectively,these results demonstrated that CmPP6 interacts with CmNLP7 to regulate chrysanthemum flowering,and CmNLP7 could regulate flowering time in response to nitrogen,which lays a foundation for the regulation of flowering and molecular breeding of chrysanthemum through changes in nutrient signaling.
基金supported by the National Key R&D Programof China(2020YFD1000400)the National Natural Science Foundation of China(32072603)+1 种基金the Jiangsu Agriculture Science and Technology Innovation Fund,China(CX(21)2004)the JBGS Project of Seed Industry Revitalization in Jiangsu Province,China(JBGS[2021]020).
文摘Nitrogen(N)is a limiting factor that determines the yield and quality of chrysanthemum.Genetic variation in N use efficiency(NUE)has been reported among chrysanthemum genotypes.We performed a transcriptome analysis of two chrysanthemum genotypes,'Nannonglihuang'(LH,N-efficient genotype)and'Nannongxuefeng"(XF,N-inefficient genotype),under low N(0.4 mmol L^(-1)N)and normal N(8 mmol L^(-1)N)treatments for 15 d and an N recovery treatment for 12 h(low N treatment for 15 d and then normal N treatment for 12 h)to understand the genetic factors impacting NUE in chrysanthemum.The two genotypes exhibited contrasting responses to the different N treatments.The N-efficient genotype LH had significant superiority in agronomic traits,N accumulation and glutamine synthase activity under both normal N and low N treatments.Low N treatment promoted root growth in LH,but inhibited root growth in XF.Transcriptome analysis revealed that the low N treatment increased the expression of some N metabolism genes,genes related to auxin and abscisic acid signal transduction in the roots of both genotypes,as well as genes related to gibberellin signal transduction in roots of LH.The N recovery treatment just increased the expression of genes related to cytokinin signal transduction in roots of LH.The expression levels of the NRT2.1,AMT1.1,and Gln1 genes related to gibberellin and cytokinin signal transduction were higher in roots of LH than in XF under different N treatments,suggesting that the genes related to N metabolism and hormone(auxin,abscisic acid,gibberellin,and cytokinin)signal transduction in roots of LH are more sensitive to different N treatments than those of XF.Co-expression network analysis(WGCNA)also identified hub genes like bZIP43,bHLH93,NPF6.3,IBR10,MYB62,PP2C,PP2C06 and NLP7,which may be the key regulators of N-mediated responses in chrysanthemum and play crucial roles in enhancing NUE and resistance to low N stress in the N-efficient chrysanthemum genotype.These results revealed the key factors involved in regulating NUE in chrysanthemum at the genetic level,which provides new insights into the complex mechanism of efficient nitrogen utilization in chrysanthemum,and can be useful for the improvement and breeding of high NUE chrysanthemum genotypes.
基金supported by the National Key Research and Development Program of China(2022YFD1200504)the National Natural Science Foundation of China(32171857)+2 种基金China Agriculture Research System(CARS-23-A18)The“JBGS”Project of Seed Industry Revitalization in Jiangsu Province(JBGS[2021]094)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Chrysanthemum is rich in active compounds such as flavonoids and phenolic acids,and its dried head flowers are commonly used for tea and medicinal purposes.However,the genetic determinism underlying chrysanthemum active compounds remains elusive.In this study,we evaluated a panel of 137 chrysanthemum accessions for total flavonoids,chlorogenic acid,luteolin,and isochlorogenic acid A across two consecutive years.The four active compounds exhibited considerable variation,with a coefficient of variation ranging from 44.96%to 76.30%.Significant differences were observed in genotype and environments,and the broad-sense heritability was estimated at 0.5e0.63 for all examined traits.Significant pair-wise correlation was found between the four active compounds.Several accessions showing the highest active compounds were figured out for breeding use by integrating the membership function and hierarchical cluster analysis methods.Based on the 327042 high-quality SNPs,a genome-wide association study(GWAS)captured 59 significant SNPs for the four active compounds,of which 24 elite alleles exhibited pyramiding effects.A total of 18 potential candidate genes were mined,among which evm.model.scaffold_1149.273(QUA1)has one linkage disequilibrium(LD)block corresponding to Hap4 with the highest luteolin content.The findings are beneficial to understanding the genetic basis of the active compounds and provide parental materials and valuable markers for the genetic improvement of active compounds in chrysanthemums.
基金supported by the National Natural Science Foundation of China(31700620,31701959)the Modern Agricultural Industry Technology System of Jiangsu Province(JATS[2018]278)+2 种基金the National Science Fund for Distinguished Young Scholars(31425022)the Fundamental Research Funds for the Central Universities(KJQN201812,KJQN201815)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Chrysanthemum(Chrysanthemum morifolium Ramat.)is a leading flower with applied value worldwide.Developing new chrysanthemum cultivars with novel characteristics such as new flower colors and shapes,plant architectures,flowering times,postharvest quality,and biotic and abiotic stress tolerance in a time-and cost-efficient manner is the ultimate goal for breeders.Various breeding strategies have been employed to improve the aforementioned traits,ranging from conventional techniques,including crossbreeding and mutation breeding,to a series of molecular breeding methods,including transgenic technology,genome editing,and marker-assisted selection(MAS).In addition,the recent extensive advances in high-throughput technologies,especially genomics,transcriptomics,proteomics,metabolomics,and microbiomics,which are collectively referred to as omics platforms,have led to the collection of substantial amounts of data.Integration of these omics data with phenotypic information will enable the identification of genes/pathways responsible for important traits.Several attempts have been made to use emerging molecular and omics methods with the aim of accelerating the breeding of chrysanthemum.However,applying the findings of such studies to practical chrysanthemum breeding remains a considerable challenge,primarily due to the high heterozygosity and polyploidy of the species.This review summarizes the recent achievements in conventional and modern molecular breeding methods and emerging omics technologies and discusses their future applications for improving the agronomic and horticultural characteristics of chrysanthemum.
基金This work was fi nan cially supp or ted grants from the Nati onal Nat ural Scie nce Foundation of China(31902053)China Postdoctoral Science Foundation(2018M642273)+2 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(2019K169)The Fundamental Research Funds for the Central Universities(KYQN202031)The National Key Research and Development Program of China(2020YFD1000400).
文摘Flavones are among the major colorless pigments synthesized through branches of the flavonoid pathway in plants.However,due to the absence of a gene encoding flavone synthase(FNS)in the model plant Arabidopsis thaliana species,the regulatory mechanism of FNS-catalyzed flavone biosynthesis has rarely been studied in plants.Here,it was found that flavones play a predominant role in the elimination of excess reactive oxygen species(ROS)at high temperatures in colorless plant organs.A novel atypical subgroup 7(SG7)R2R3-MYB transcription factor,CmMYB012,was found to be induced in response to prolonged high temperatures and to inhibit flavone biosynthesis by directly regulating CmFNS.Moreover,CmMYB012 was also found to inhibit anthocyanin biosynthesis by suppressing the expression of CmCHS,CmDFR,CmANS,and CmUFGT.CmMYB012 overexpression exerted a negative in fluence on plant fitness and pink flower color formation,while CmMYB012 suppression had the opposite effect in response to high temperatures.Our findings provide new insights into the mechanisms by which high temperatures regulate the metabolism of flavones and anthocyanins to affect plant fitness and flower color formation.
基金supported by Jiangsu Agriculture Science and Technology Innovation Fund[Grant No.CX(18)2020]the National Natural Science Foundation of China(Grant Nos.31672192 and 31700620)+1 种基金the National Key Research and Development Program of China(Grant No.2018YFD1000402)the Fundamental Research Funds for the Central Universities(Grant No.KJQN201812).
文摘White rust caused by Puccinia horiana is a destructive disease of chrysanthemum plants.To better understand the resistance mechanisms of composite species to this disease,the leaf cuticular traits,antioxidant and defensive enzymes activities of immune(Chrysanthemum makinoi var.wakasaense)and highly susceptible(Ajania shiwogiku var.kinokuniense)species were compared.Trichome density of two species was markedly different,negatively associated with plant resistance to P.horiana.Total wax load in C.makinoi var.wakasaense was two times more than that in A.shiwogiku var.kinokuniense.The wax composition in immune one was abundant in esters and primary alcohols.Superoxide dismutase(SOD,EC 1.15.1.1),peroxidase(POD,EC 1.11.1.7),polyphenoloxidase(PPO,EC 1.14.18.1 or EC 1.10.3.2)and phenylalanine ammonia lyase(PAL,EC 4.3.1.5)activitieswere investigated.In C.makinoi var.wakasaense,the activity of SOD and POD increased rapidly after inoculation,whichmight be non-host induced reactive oxygen species(ROS)activated antioxidant enzymes,however SOD and POD remained a low and steady level in the highly susceptible one after inoculation.Quick increase in PPO activities after inoculation was observed in both species,however it remained higher in C.makinoi var.wakasaense at the late period of inoculation.PAL in C.makinoi var.wakasaense was induced after pathogen inoculation,but not in A.shiwogiku var.kinokuniense,suggesting that these two enzymes might contribute to the resistance to P.horiana.
基金supported by the National Natural Science Foundation of China(31730081)the National Science Fund for Distinguished Young Scholars(31425022)+2 种基金the National Natural Science Foundation of China(31572152)the National Science Fund of Jiangsu Province(BK20151429)the Fundamental Research Funds for the Central Universities(KYRC201601).
文摘Chrysanthemums are sensitive to waterlogging stress,and the development of screening methods for tolerant germplasms or genes and the breeding of tolerant new varieties are of great importance in chrysanthemum breeding.To understand the genetic basis of waterlogging tolerance(WT)in chrysanthemums,we performed a genome-wide association study(GWAS)using 92,811 single nucleotide polymorphisms(SNPs)in a panel of 88 chrysanthemum accessions,including 64 spray cut and 24 disbud chrysanthemums.The results showed that the average MFVW(membership function value of waterlogging)of the disbud type(0.65)was significantly higher than that of the spray type(0.55)at P<0.05,and the MFVW of the Asian accessions(0.65)was significantly higher than that of the European accessions(0.48)at P<0.01.The GWAS performed using the general linear model(GLM)and mixed linear model(MLM)identified 137 and 14 SNP loci related to WT,respectively,and 11 associations were commonly predicted.By calculating the phenotypic effect values for 11 common SNP loci,six highly favorable SNP alleles that explained 12.85—21.85%of the phenotypic variations were identified.Furthermore,the dosage-pyramiding effects of the favorable alleles and the significant linear correlations between the numbers of highly favorable alleles and phenotypic values were identified(r2=0.45;P<0.01).A major SNP locus(Marker6619-75)was converted into a derived cleaved amplified polymorphic sequence(dCAPS)marker that cosegregated with WT with an average efficiency of 78.9%.Finally,four putative candidate genes in the WT were identified via quantitative real-time PCR(qRT-PCR).The results presented in this study provide insights for further research on WT mechanisms and the application of molecular marker-assisted selection(MAS)in chrysanthemum WT breeding programs.
基金supported by the National Natural Science Foundation of China(Grant No.31672192)the Program for Key Research and Development,Jiangsu,China(Grant No.BE2017318)+1 种基金the National Key Research and Development Program of China(2018YFD1000402)the Fundamental Research Funds for the Central Universities(KJQN201812).
文摘MYB transcription factors are widely involved in the development of and physiological processes in plants.Here,we isolated the chrysanthemum R2R3-MYB family transcription factor CmMYB15,a homologous gene of AtMYB15.It was demonstrated that CmMYB15 expression was induced by aphids and that CmMYB15 could bind to AC elements,which usually exist in the promoter of lignin biosynthesis genes.Overexpression of CmMYB15 in chrysanthemum enhanced the resistance of aphids.Additionally,the content of lignin and the expression of several lignin biosynthesis genes increased.In summary,the results indicate that CmMYB15 regulates lignin biosynthesis genes that enhance the resistance of chrysanthemum to aphids.
基金This work was supported by funds from the National Natural Science Foundation of China(31372100)‘Programs of Innovation and Entrepreneurship Talents’of Jiangsu Province,the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘As the junction of floral development pathways,the FLOWERING LOCUS T(FT)protein called‘florigen’plays an important role in the process of plant flowering through signal integration.We isolated four transcripts encoding different isoforms of a FT orthologous gene CmFTL1,from Chrysanthemum morifolium cultivar‘Jimba’.Sequence alignments suggested that the four transcripts are related to the intron 1.Expression analysis showed that four alternative splicing(AS)forms of CmFTL1 varied depending on the developmental stage of the flower.The functional complement experiment using an Arabidopsis mutant ft-10 revealed that the archetypal and AS forms of CmFTL1 had the function of complementing late flower phenotype in different levels.In addition,transgenic confirmation at transcript level showed CmFTL1 and CmFTL1ast coexist in the same tissue type at the same developmental stage,indicating a post-transcriptional modification of CmFTL1 in Arabidopsis.Moreover,ectopic expression of different AS forms in chrysanthemum resulted in the development of multiple altered phenotypes,varying degrees of early flowering.We found that an alternative splicing form(CmFTL1-astE134)without the exon 2 lacked the ability causing the earlier flower phenotype.The evidence in this study indicates that complex alternative processing of CmFTL1 transcripts in C.morifolium may be associated with flowering regulation and hold some potential for biotechnical engineering to create early-flowering phenotypes in ornamental cultivars.
基金This work was supported by funding from the National Natural Science Foundation of China(31372100)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsby‘Programs of Innovation and Entrepreneurship Talents’of Jiangsu Province.
文摘The chrysanthemum genome harbors three FT-like genes:CmFTL1 and CmFTL3 are thought to act as regulators of floral induction under long-day(LD)and short-day(SD)conditions,respectively,whereas the function of CmFTL2 is currently unclear.The objective of the present research was to explore the function of CmFTL2 in the determination of flowering time of the photo-insensitive chrysanthemum cultivar‘Floral Yuuka’,both in response to variation in the photoperiod and to the exogenous provision of sucrose.Spraying leaves of‘Floral Yuuka’plants with 50 mM sucrose accelerated flowering and increased the level of CmFTL2 transcription in the leaf more strongly than either CmFTL1 or FTL3 under both long and SD conditions.Transcription profiling indicated that all three CmFTL genes were upregulated during floral induction.The relationship of the CmFTL2 sequence with that of other members of the PEBP family suggested that its product contributes to the florigen rather than to the anti-florigen complex.The heterologous expression of CmFTL2 in the Arabidopsis thaliana ft-10 mutant rescued the mutant phenotype,showing that CmFTL2 could compensate for the absence of FT.These results suggest that CmFTL2 acts as a regulator of floral transition and responds to both the photoperiod and sucrose.
基金the National Key Research and Development Program of China(2018YFD1000400)the National Natural Science Foundation of China(31930100,31701959)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Chrysanthemum(Chrysanthemum morifolium)is one of the four major cut-flower plants worldwide and possesses both high ornamental value and cultural connotation.As most chrysanthemum varieties flower in autumn,it is costly to achieve annual production.JAZ genes in the TIFY family are core components of the jasmonic acid(JA)signaling pathway;in addition to playing a pivotal role in plant responses to defense,they are also widely implicated in regulating plant development processes.Here,we characterized the TIFY family gene CmJAZ1-like from the chrysanthemum cultivar‘Jinba’.CmJAZ1-like localizes in the nucleus and has no transcriptional activity in yeast.Tissue expression pattern analysis indicated that CmJAZ1-like was most active in the root and shoot apex.Overexpressing CmJAZ1-like with Jas domain deletion in chrysanthemum resulted in late flowering.RNA-Seq analysis of the overexpression lines revealed some differentially expressed genes(DEGs)involved in flowering,such as the homologs of the flowering integrators FT and SOC1,an FUL homolog involved in flower meristem identity,AP2 domain-containing transcription factors,MADS box genes,and autonomous pathway-related genes.Based on KEGG pathway enrichment analysis,the differentially transcribed genes were enriched in carbohydrate metabolic and fatty acid-related pathways,which are notable for their role in flowering in plants.This study preliminarily verified the function of CmJAZ1-like in chrysanthemum flowering,and the results can be used in molecular breeding programs aimed at flowering time regulation of chrysanthemum.
基金supported by the National Natural Science Foundation of China(31700620)the Natural Science Fund of Jiangsu Province(BK20170722)the Fundamental Research Funds for the Central Universities(KJQN201812).
文摘Chrysanthemum(Chrysanthemum morifolium)black spot disease(CBS)poses a major threat to Chrysanthemum cultivation owing to suitable climate conditions and current lack of resistant cultivars for greenhouse cultivation.In this study,we identified a number of genes that respond to Alternaria alternata infection in resistant and susceptible Chrysanthemum cultivars.Based on RNA sequencing technology and a weighted gene coexpression network analysis(WGCNA),we constructed a model to elucidate the response of Chrysanthemum leaves to A.alternata infection at different stages and compared the mapped response of the resistant cultivar‘Jinba’to that of the susceptible cultivar‘Zaoyihong’.In the early stage of infection,when lesions had not yet formed,abscisic acid(ABA),salicylic acid(SA)and EDS1-mediated resistance played important roles in the Chrysanthemum defense system.With the formation of necrotic lesions,ethylene(ET)metabolism and the Ca^(2+)signal transduction pathway strongly responded to A.alternata infection.During the late stage,when necrotic lesions continued to expand,members of the multidrug and toxic compound extrusion(MATE)gene family were highly expressed,and their products may be involved in defense against A.alternata invasion by exporting toxins produced by the pathogen,which plays important roles in the pathogenicity of A.alternata.Furthermore,the function of hub genes was verified by qPCR and transgenic assays.The identification of hub genes at different stages,the comparison of hub genes between the two cultivars and the highly expressed genes in the resistant cultivar‘Jinba’provide a theoretical basis for breeding cultivars resistant to CBS.
基金supported by the National Natural Science Foundation of China(31572159)the Jiangsu Modern Agricultural Industry Technology System Construction Project(JATS[2018]278)+1 种基金the Fundamental Research Funds for Central Universities(KJQN201815,KYZ201832)the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Jiangsu Planned Projects for Postdoctoral Research Funds.
文摘The switch from vegetative growth to reproductive growth is a key event in the development of a plant.Here,the product of the chrysanthemum gene CmMYB2,an R2R3 MYB transcription factor that is localized in the nucleus,was shown to be a component of the switching mechanism.Plants engineered to overexpress CmMYB2 flowered earlier than did wild-type plants,while those in which CmMYB2 was suppressed flowered later.In both the overexpression and RNAi knockdown plants,a number of genes encoding proteins involved in gibberellin synthesis or signaling,as well as in the response to photoperiod,were transcribed at a level that differed from that in the wild type.Both yeast two-hybrid and bimolecular fluorescence complementation assays revealed that CmMYB2 interacts with CmBBX24,a zinc-finger transcription factor known to regulate flowering by its influence on gibberellin synthesis.
基金the National Natural Science Foundation of China(31930100,31872146)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The CmBBX8-CmFTL1 regulatory module is a key determinant in the transition from vegetative growth to reproductive development in summer-flowering chrysanthemum.However,the detailed regulatory mechanism of CmBBX8-mediated flowering remains elusive.In this study,we revealed that RADICAL-INDUCED CELL DEATH 1(CmRCD1)physically associated with CmBBX8 through bimolecular fluorescence complementation(BiFC),pulldown and Coimmunoprecipitation(CoIP)assays.Furthermore,the RCD1-SRO1-TAF4(RST)domain of CmRCD1 and the B-box of CmBBX8 mediated their interaction.In addition,Luciferase(LUC)assays and electrophoretic mobility shift assay(EMSAs)showed that CmRCD1 repressed the transcriptional activity of CmBBX8 and interfered with its binding to the CmFTL1 promoter,thereby leading to delayed flowering in the summer chrysanthemum‘Yuuka’.These results provide insight into the molecular framework of CmRCD1-CmBBX8-mediated flowering in chrysanthemum.
基金supported by the National Natural Science Foundation of China(31930100)the National Natural Science Foundation of China(31701959)+1 种基金the Natural Science Fund of Jiangsu Province(BK20170717)the Fundamental Research Funds for the Central Universities(KJQN201815).
文摘Chrysanthemum(Chrysanthemum morifolium)is an ideal model species for studying petal morphogenesis because of the diversity in the flower form across varieties;however,the molecular mechanisms underlying petal development are poorly understood.Here,we show that the brassinosteroid transcription factor BRI1-EMS-SUPPRESSOR 1(CmBES1)in chrysanthemum(C.morifolium cv.Jinba)is important for organ boundary formation because it represses organ boundary identity genes.Chrysanthemum plants overexpressing CmBES1 displayed increased fusion of the outermost ray florets due to the loss of differentiation of the two dorsal petals,which developed simultaneously with the ventral petals.RNA-seq analysis of the overexpression lines revealed potential genes and pathways involved in petal development,such as CUP-SHAPED COTYLEDON(CUC2),CYCLOIDEA 4(CYC4),genes encoding MADS-box transcription factors and homeodomain-leucine zippers(HD-Zips)and auxin pathway-related genes.This study characterizes the role of CmBES1 in ray floret development by its modulation of flower development and boundary identity genes in chrysanthemum.
基金supported by the National Natural Science Foundation of China(31672192)the Agricultural Science and Technology Innovation Fund Project of Jiangsu Province(CX(18)2020)+1 种基金the National Key Research and Development Project(2018YFD1000402)the Foundation of Key Laboratory of Landscaping(KF201801).
文摘Chrysanthemum is frequently attacked by aphids,which greatly hinders the growth and ornamental value of this plant species.WRKY transcription factors play an important role in the response to biotic stresses such as pathogen and insect stresses.Here,chrysanthemum CmWRKY53 was cloned,and its expression was induced by aphid infestation.To verify the role of CmWRKY53 in resistance to aphids,CmWRKY53 transgenic chrysanthemum was generated.CmWRKY53 was found to mediate the susceptibility of chrysanthemum to aphids.The expression levels of secondary metabolite biosynthesis genes,such as peroxidase-and polyphenol oxidase-encoding genes,decreased in CmWRKY53-overexpressing(CmWRKY53-Oe)plants but dramatically increased in chimeric dominant repressor(CmWRKY53-SRDX)plants,suggesting that CmWRKY53 contributes to the susceptibility of chrysanthemum to aphids,possibly due to its role in the regulation of secondary metabolites.
基金This work was financially supported by the“948”Project of the Ministry of Agriculture(2016-X18),the Jiangsu 333 talent project(BRA2017382)the Seed Industry Development Project of Shanghai[(2016)1–14]+1 种基金the Fund for Independent Innovation of Agricultural Sciences in Jiangsu Province[CX(16)1025]the Fundamental Research Funds for the Central Universities(KYZ201606,KYRC201601).
文摘Allopolyploid formation involves two major events:interspecific hybridization and polyploidization.A number of species in the Asteraceae family are polyploids because of frequent hybridization.The effects of hybridization on genomics and transcriptomics in Chrysanthemum nankingense×Tanacetum vulgare hybrids have been reported.In this study,we obtained allopolyploids by applying a colchicine treatment to a synthesized C.nankingense×T.vulgare hybrid.Sequence-related amplified polymorphism(SRAP),methylation-sensitive amplification polymorphism(MSAP),and high-throughput RNA sequencing(RNA-Seq)technologies were used to investigate the genomic,epigenetic,and transcriptomic alterations in both the hybrid and allopolyploids.The genomic alterations in the hybrid and allopolyploids mainly involved the loss of parental fragments and the gain of novel fragments.The DNA methylation level of the hybrid was reduced by hybridization but was restored somewhat after polyploidization.There were more significant differences in gene expression between the hybrid/allopolyploid and the paternal parent than between the hybrid/allopolyploid and the maternal parent.Most differentially expressed genes(DEGs)showed down-regulation in the hybrid/allopolyploid relative to the parents.Among the non-additive genes,transgressive patterns appeared to be dominant,especially repression patterns.Maternal expression dominance was observed specifically for down-regulated genes.Many methylase and methyltransferase genes showed differential expression between the hybrid and parents and between the allopolyploid and parents.Our data indicate that hybridization may be a major factor affecting genomic and transcriptomic changes in newly formed allopolyploids.The formation of allopolyploids may not simply be the sum of hybridization and polyploidization changes but also may be influenced by the interaction between these processes.
基金supported by the National Natural Science Foundation of China(Grant No.32072609)National Key Research and Development Program of China(Grant No.2018YFD1000400)+3 种基金National Natural Science Foundation of China(Grant No.32002075)the China Postdoctoral Science Foundation(Grant No.2019M661871)the Fundamental Research Funds for the Central Universities(Grant No.KJQN202126)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Basic helix-loop-helix(bHLH)transcription factor gene family in plants controls various growth and development aspects;however,the actual roles of these genes in flowering plants are not well known.In this study,a novel bHLH protein CmbHLH110 was found to interact with CmERF110 by in vitro and in vivo experiments,a chrysanthemum ERF110 homolog that acts as a positive flowering regulator.In addition,CmbHLH110 was also found to regulate the flowering of chrysanthemums,overexpression of CmbHLH110 causes chrysanthemums to flower earlier,and suppressed CmbHLH110 leads to delayed flowering.Furthermore,the loss-of-function Arabidopsis mutant of its homologue PERICYCLE FACTOR TYPE-A 5(PFA5)had a noticeable late flowering phenotype,and CmbHLH110 completely complemented the late flowering phenotype of the pfa5 mutant,whereas heterologous overexpression of CmbHLH110 in Arabidopsis Col-0 caused early flowering.Transcriptome sequencing revealed significant differential expression of flowering-related and circadian clock-related genes in transgenic chrysanthemum.Therefore,we concluded that CmbHLH110,as a novel flowering regulator,could interact with CmERF110 to regulate flowering in chrysanthemum.
基金funded by the National Key Research and Development Program of China(2019YFD1001501)the National Natural Science Foundation of China(31730081,31870306)+1 种基金the Youth Program of Science and Technology Department of Yunnan Province(2016FD070)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institution.
文摘Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in the Hengduan Mountains,Yunnan Province.We took advantage of a special geographic region where the southernmost species of Ajania and the highest altitude population of Chrysanthemum indicum coexist to investigate their evolutionary origins.Diversity analysis of 9 populations of 5 species that came from 3 genera was carried out based on morphological traits and SRAP markers.Furthermore,topographical and ecological analyses and surveys of the vegetation communities in the plots were carried out for correlation analysis,and past data were used to reconstruct the ancient topography and vegetation to estimate the migration path and divergence time.We found that Chrysanthemum and Ajania were closely related based on the smooth transition states among marginal female florets and their common pollination system.The genetic relationship between Phaeostigma and Chrysanthemum was relatively distant,and Ajania was between them.Low light intensity and relatively humid habitats may be driving the elongation and evolution of marginal female florets.We found that Chrysanthemum and related genera were largely restricted to stony topographies at an altitude of~3000 m.a.s.l.and in specialized alpine coniferous(Pinus)and broadleaved(Quercus)mixed forest marginal communities.These stony topographies have become ecological islands of refuge for these species in the current interglacial period.The Hengduan Mountains play a key role in the evolution,divergence,and survival of Chrysanthemum and its allies.
