Comparative transcriptome analysis identifies key regulators of nitrogen use efficiency in chrysanthemum

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.

The CmCYC2 factors regulated the different biosynthesis and distribution of phenolic compounds in the capitulum of Chrysanthemum morifolium‘Hangju’

Chrysanthemum morifolium Ramat.is an important industrial crop with a high medicinal value,whose capitulum consists of ray and disc florets containing numerous bioactive components,such as flavonoids and phenolic acids.However,the distribution and accumulations of the bioactive metabolites in florets of Chrysanthemum morifolium were unclear.Herein,the ray and disc florets of Chrysanthemum morifolium were separated for comparing the bioactive metabolites.The contents of phenolic compounds and antioxidant activities were significantly different between the two florets.The metabolomic analysis identified 203 and 241 differential metabolites between ray and disc florets at two flowering stages.The derivatives of quercetin,isorhamnetin,tricin,and caffeoylquinic acid were enriched in the disc florets,while apigenin,kaempferol,acacetin,and their glycosides mainly accumulated in the ray florets.Besides,the results of transcriptome and qRT-PCR suggested that the F3H,F3'H,and FLS genes highly expressed in disc florets,while the FNS gene was well expressed in ray florets,which explained the different distribution of phenolic compounds between ray and disc florets.Furthermore,the expression of CmCYC2 genes was found to be significantly related to the distribution of flavones by correlation analysis.It was proved by the luciferase reporter assay that CmCYC2a and CmCYC2d factors could bind and activate the CmFNS promoter to regulate the flavones biosynthesis in ray florets.These results revealed the significant difference of metabolite contents and gene expression profile between ray and disc floret in Chrysanthemum morifolium and demonstrated that the quality of Chrysanthemum morifolium‘Hangju'was closely relevant to its flower morphology.

CmbHLH110,a novel bHLH transcription factor,accelerates flowering in chrysanthemum

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.

Flavonoid extracts from chrysanthemum with appropriate anthocyanins turn blue when exposed to iron ions

Although some species that accumulate only cyanidin(Cy)in nature can produce blue flowers through iron ions,there has been no evidence of blue chrysanthemums being generated in this manner.This study revealed that flavonoid extracts from the ray florets of the chrysanthemum cultivar‘Wandai Fengguang’turned blue when exposed to Fe^(3+).Samples that could turn blue were labeled as CB(Cy-determined blue flowers),while samples that did not turn blue were labeled as CN(Cy-determined non-blue flowers).After a series of experiments,a stable screening system was established using flavonoid extracts containing NaAc buffer at pH 5.5 and a total anthocyanin concentration(TAC)of 30 μmol·L^(-1),and the addition of Fe^(3+)from 0 to 0.25 μmol·L^(-1)allowed for the selection of five CB samples from 39 chrysanthemum cultivars.All five CB samples exhibited flower color phenotypes that belonged to Cluster-I with redness(a*)values ranging from 29.03 to 45.99,yellowness(b*)values from-11.31 to 3.77,and brightness(L*)values from 29.07 to 45.99.Additionally,the ratio of TAC to total luteolin concentration(TLC)was found to be a critical factor for distinguishing between CB and CN samples.To realize the desired blue hue in the flavonoid extracts with the participation of Fe^(3+),a TAC to TLC ratio of 2.25 and above is required.Moreover,the protoplasts and ray florets of CB samples that turned blue with the involvement of Fe^(2+)showed great potential for cultivating blue chrysanthemums through ferric-anthocyanin chelate.Overall,this study reveals that blue flowers can be cultivated through the increase in the iron ion concentration,combined with the accumulation of Cy.

CmMYB3-like negatively regulates anthocyanin biosynthesis and flower color formation during the post-flowering stage in Chrysanthemum morifolium

Color fading caused by a decrease in anthocyanin accumulation during the post-flowering stage significantly affects postharvest quality of chrysanthemum.However,the underlying mechanism by which anthocyanin accumulation decreases during the post-flowering stage still unclear,which greatly restricts design of molecular breeding in chrysanthemum.Here,a chrysanthemum SG7 R2R3 MYB transcription factor(TF),CmMYB3-like,was identified to have a function in regulating anthocyanin biosynthesis during the post-flowering stage.Quantitative real time PCR(qRT-PCR)assays showed that the expression of CmMYB3-like was gradually downregulated when anthocyanin content increased during the flowering stage and was significantly upregulated during the post-flowering stage.Genetic transformation of chrysanthemum and dual-luciferase assays in N.benthamiana leaves showed that CmMYB3-like suppressed anthocyanin accumulation by inhibiting the transcription of CmCHS and CmANS directly and that of CmF3H indirectly.However,overexpression or suppression of CmMYB3-like did not affect the biosynthesis of flavones or flavonols.Genetic transformation of chrysanthemum revealed that the overexpression of CmMYB3-like inhibited anthocyanin accumulation,but its suppression prevented the decrease in anthocyanin accumulation during the post-flowering stage.Our results revealed a crucial role of CmMYB3-like in regulating the color of petals during the post-flowering stage and provided a target gene for molecular design breeding to improve the postharvest quality of chrysanthemum.

Transcriptomic Analysis Reveals the Formation Mechanism of Anthocyanins Light-Independent Synthesis in Chrysanthemum

Chrysanthemum×morifolium is a horticultural crop which plays a vital role in theflower industry with signifi-cant economic value and has a cultivation history of over three thousand years in China.The accumulation of anthocyanins is always affected by light.Here,we revealed that anthocyanin accumulation is highly dependent on light in‘2021135’genotype chrysanthemum,while it is light-independent in‘2001402’genotype chrysanthe-mum.However,no literature has been reported regarding the non-photosensitive chrysanthemum in anthocya-nins light-independent synthesis pathways.Through the phenotype analysis of 44 F1 generations,we found that light-independence is a dominant trait which can be stable inherited by progeny.The transcriptome of the rayflorets of‘2021135’and‘2001402’under light and bagging treatment were sequenced and analyzed.Based on weighted gene co-expression network analysis(WGCNA),K-means analysis,and Real-Time Quantitative Poly-merase Chain Reaction(RT-qPCR)analysis,16 genes were highly correlated with the anthocyanin content.The anthocyanin content of rayflorets treated with different light-quality conditions indicated that blue light signifi-cantly affected anthocyanin accumulations.Through Yeast one-hybrid analysis,CmBIC1.1 and CmBIC1.2 can directly regulate the anthocyanin structural gene CmCHS2.In our study,we revealed the important characteristics of light-independent anthocyanin synthesis in chrysanthemums and screened regulatory factors in light-depen-dent and light-independent anthocyanin synthesis pathways.The results laid the groundwork for subsequent ana-lysis of the molecular mechanism involved in the light-independent synthesis of anthocyanins in chrysanthemums.

FLOWERING LOCUS T(FT)in Photosensitive Type Chrysanthemum Accelerates Flowering in Arabidopsis

FLOWERING LOCUS T(FT)is an important factor for integrating flowering signals through the photoperiod pathway,which significantly promotes flowering.Most chrysanthemum varieties are short-day plants,sensitive to the photoperiod,which limits their ornamental and annual production supply.In this study,we aim to analyze the nutrients and flowering-related genes of chrysanthemums with different photoperiod types and to clone and verify the function of the flowering-related gene CmFT.We found that the formation of floral buds requires the accumulation of starch while consuming soluble sugars and the expression patterns of flowering-related genes GIGANTEA(GI),CONSTANS(CO),and FT in C.morifolium‘Zilian’and C.morifolium‘Zihongtuogui’had a certain synchronization during floral buds differentiation according to our quantitative validation,and the expression levels of CmGI,CmCO and CmFT in C.morifolium‘Zihongtuogui’were higher than those in C.morifolium.‘Zilian’in the later stage of differentiation.CmFT was cloned from photosensitive chrysanthemums-C.morifolium‘Zihongtuogui’and polypeptide alignment and phylogenetic analysis showed that CmFT was clustered in FT-like subfamily.In further functional verification,we obtained two Arabidopsis transgenic lines.Our results showed that CmFT transgenic ft mutant lines can significantly accelerate flowering in Arabidopsis.Thus,we can initially confirm that CmFT plays an important role in promoting flowering,which may be the key reason for the photosensitivity of C.morifolium‘Zihongtuogui’.Overall,the results of this study are of great importance in revealing the flowering mechanism of different photoperiod types of chrysanthemums.

Pharmacological effects of volatile oil from chrysanthemum and its associated mechanisms:a review

Volatile oil(VO)is the main chemical component of common plants in Chrysanthemum genus,and it possesses several beneficial pharmacological properties,including bacteriostatic,antioxidant,anti-tumor,anti-inflammatory,antipyretic,analgesic,antiosteoporotic,antihypertensive,sedative,and hypnotic effects.To date,research on the effective components of Chrysanthemum extract has mainly focused on flavonoids,whereas limited data are available on the chemical constituents and underlying mechanisms of action of the VO components.In this review,the pharmacological activities and mechanisms of VO are comprehensively reviewed with the aim of providing a foundation for further development for medicinal,aromatherapy,and diet therapy applications.

Effect of Different Arbuscular Mycorrhizal Fungi Strains on Mineral Nutrition and Antioxidant Enzymes of Chrysanthemum morifolium

[Objective] The purpose was to study the effects of different arbuscular mycorrhizal fungi strains（AMF）on the mineral nutrition and antioxidant enzymes of Chrysanthemum morifolium.[Method] The pot experiment was conducted in the greenhouse,C.morifolium ＇Jinba＇ was inoculated with five kinds of AMF,N,P,K,malondial dehyde（MDA）content,as well as the superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） activity in roots,leaves and petals of C.morifolium were measured at seedling and flowering stages.[Result] The G.i,G.e and G.m treatments could promote mineral nutrient absorption,increase N,P,K content in roots,leaves and petals of C.morifolium compared with the control without inoculation.The G.d、G.e and G.m treatments could significantly reduce MDA content in roots and petals,thus alleviating membrane permeability and lipid peroxidation.The G.i treatments could also improve the SOD,POD and CAT activities of C.morifolium,thereby increasing the capability of scavenging oxygen free radicals.[Conclusion] According to the comprehensive analysis,G.i was screened out as the best strain to improve mineral nutrition and antioxidant enzyme activities of C.morifolium.

Antioxidase Activities of Tetraploid Lines and Diploid Control Line of Chrysanthemum cinerariifolium

Objective The SOD, POD and APX enzyme activities of tetraploid lines and diploid control line of Chrysanthemum cinerariifolium in test-tube and field were determined in order to provide a reference for the selective breeding of high resistance good tetraploid varieties of C. cinerariifolium. Method The SOD, POD and APX activities of each sample were determined. Every material should have 3 replicates which been determined and calculated mean value to analyze. Result The various kinds of antioxidase activities in protective enzyme system of tetraploid lines were increased generally in comparison with that of diploid control line. And there is certain relativity between the samples in field and in test-tube of these lines. Conclusion The antioxidase activities of each line in test-tube could be considered as reference index to screen high resistance good tetraploid varieties of C. cinerariifolium.

Effect of Sound Stimulation on the Lipid Physical States and Metabolism of Plasma Membrane from Chrysanthemum Callus

Plasma membrane vesicles of chrysanthemum ( Dendranthema morifolium (Ramat.) Tzvel.) callus was purified by sucrose gradient centrifugation to investigate the influence of sound stimulation on the lipid physical states and metabolism of plasma membrane. The results showed that sound stimulation decreased the content of phosphodiesters and the fluorescent intensity of DPH, but increased the light scattering value of the membrane, the fluorescent intensity of MC540 and the content of phosphomonoesters, indicating that the vesicles got looser, the charge density and hydrophobicity of membrane surface decreased under sound stimulation of some strength and frequency. However, the membrane fluidity increased under the condition. Meanwhile, the anabolism of membrane lipid increased and the catabolism decreased. It can be seen that the physical state and metabolism of membrane lipid is sensitive to sound stimulation.

Research on Pollen Grains of Tetraploid Lines and Diploid Control Line of Chrysanthemum cinerariifolium (Trev.) Vis.

[Objective] The aim was to study characters of pollen grains of tetraploid lines and diploid control line of Chrysanthemum cinerariifolium (Trev.) Vis.,morphological characters,fertility of pollen grain and germination percentage of seeds. [Method] Pollen grains were prepared by sulphuric acid-acetyl oxide decomposition method. The lengths of polar axis and equatorial axis of pollen grains were determined with general optical microscope. The morphology of pollen grains was observed with SEM (scanning electron microscope) and the typical visual fields of 2 500× (or 2 000×),7 000× were taken pictures. [Result] Comparing with the diploid control line,the pollen grains of five tetraploid lines which were tested were different from the diploid line in morphology,sculpture,etc.. 4 of the 5 tested samples were significant larger than the diploid line in size and one was similar to the diploid line. [Conclusion] This research provided references for breeding tetraploid improved varieties of Chrysanthemum cinerariifolium (Trev.) Vis. with good fertility and high germination percentage.

Cloning and Analysis of the cDNA Sequence of XTH Gene from Chrysanthemum morifolium Petal

[Objective] This study aimed to investigate the structural character of xy- Ioglucan endotransglycosylase/hydrolase （XTH） gene in ethylene-insensitive feverfew. [Method] The total RNA was extracted from Chrysanthemum rnorifolium petal using Trizol reagent, and the cDNA fragment of XTH gene was cloned by RT-PCR and T/A cloning. [Result] The sequencing result showed that the cloned cDNA sequence was 911 bp. It was predicted to encode a polypeptide of 293 amino acids and had seven active sites of XTH family, and then named as CmXTH （gene accession number HM752243）. In addition, The BLAST analysis showed that the deduced amino acid sequence of CmXTH showed high homology with other 19 chosen plant XTHs. Among of these, CmXTH shared closer genetic relationship with Gerbera jamesonii, Solanum lycopersicum, whereas had relatively distant relationship with Populus euparatica, Fragaria ananassa, Actinidia deliciosa, etc. [Conclusion] The cloned fragment was certainly the cDNA of XTH gene, which was associated with the petal growth and senescence in Chrysanthemum morifolium.

Optimization on Identification Standards and Artificial Inoculation Methods In Vitro on Resistance to Chrysanthemum White Rust

[Objective] This research aimed at exploring an effective way for inoculation and identification of chrysanthemum white rust under controlled conditions. [Method] By combining the observation methods with the naked eye and under optical microscope, we had established the identification standards for chrysanthemum white rust with six classifications and optimized artificial inoculation methods in vitro. [Result] The results showed that bottled cuttings identification method and petri dished leaves identification method both can be used for identification in vitro of chrysanthemum white rust, bottled cuttings identification method had shown better effects than petri dished leaves identification method, and was supposed to be best artificial inoculation and identification method in vitro. [Conclusion] This research had provided a scientific method for safe and effective researches on chrysanthemum white rust, in order to control the occurrence and diffusion of this quarantine disease.

Optimization of Extraction Process of Polyphenols from Chrysanthemum morifolium and the Development of Chrysanthemum Rice Wine

[Objectives]This study was conducted to provide a theoretical basis for the extraction and comprehensive utilization of functional active components of Chrysanthemum morifolium polyphenols.[Methods]With C.morifolium as a raw material,polyphenols were extracted by water extraction.The extraction process of polyphenols were optimized by single factor tests on solid-liquid ratio,extracting time and times.Old rice wine selected as the base wine was added with C.morifolium polyphenol extract,honey,citric acid and other auxiliary materials to prepare a kind of chrysanthemum old rice wine.Through sensory analysis combined with fuzzy mathematics comprehensive evaluation method,the optimal formula of chrysanthemum old rice wine was determined,and the corresponding physicochemical indicators of the obtained chrysanthemum old rice wine were tested.[Results]The optimal soaking process for C.morifolium was as follows:extraction time of 20 min,a solid-liquid ratio of C.morifolium to warm water at 1:40,extraction times of 3 times.The physical and chemical indicators of the chrysanthemum wine obtained from the above optimal formula were as follows:sugar content 5%,ethanol content 11%,and pH value 4.04.The chrysanthemum old rice wine obtained was clear and transparent,and the fragrance of chrysanthemum was coordinated with the mellow aroma of rice wine.The taste was refreshing and suitable for the vast majority of people to drink.[Conclusions]The new type of chrysanthemum old rice wine combines the polyphenolic active substances in C.morifolium with the low ethanol content of old rice wine,which not only improves the utilization rate of C.morifolium,but also strengthens the health function of old rice wine products,improves the quality of old rice wine,and promotes the healthy and rapid development of the old rice wine industry.

The Narrative Technique of Odour of Chrysanthemums

Odour of Chrysanthemums is one of the short stories by D. H. Lawrence. The fiction shows how humanity was ruined by bourgeois industrial civilization through the death of a miner. In embedding themes, the narrative technique of Odour of Chrysanthemums is worth our attention. This paper is intended to make an analysis of point of view, focalization and symbol in the light of narrative theory.

The Dynamic Changes in Cold Tolerance of Ground-cover Chrysanthemum Growing in the Open Field during the Overwintering

The ground-cover chrysanthemum （Dendranthemaxgrandiflorum Kitamura） ＇Zixunzhang＇ was used as the experimental material in this study. The physiological and biochemical indexes of leaves, emergent rhizomes and roots from ＇Zixunzhang＇ growing in the open field during the autumn and winter in Beijing area were deter- mined. These indexes showed that root activities decreased slowly with the drop in temperature. The relative water contents of leaves and emergent rhizomes, and the water content of roots decreased. The activities of SOD, CAT and POD from leaves and emergent rhizomes were affected significantly by low temperature, but their change trends were different, which suggested that these 3 enzymes might play an interacted role in the formation of the cold tolerance of ＇Zixunzhang＇ mum, while the changes of the three enzyme activities in roots were little when the tem- perature dropped. With the significant increasing of the content of soluble sugar from leaves, the contents of soluble protein and proline declined overall; and the contents of osmotic regulation substances of emergent rhizomes and roots increased at first and then decreased. The correlation analysis indicated that the cold toler- ance of ground-cover mum ＇Zixunzhang＇ was related closely to relative water con- tents, SOD enzyme activity, soluble protein, soluble sugar and root activity. The morphological observation of leaves, emergent rhizomes and roots also showed that the survival of the ground-cover mum mainly depended on the cold tolerance of roots during the overwintering.

Chrysanthemum extract alleviates acetaminophen-induced liver injury by inhibiting oxidative stress via AMPK pathway in rats

OBJECTIVE Acetaminophen(APAP),also known as paracetamol,is a commonly used antipyretic,anal⁃gesic and anti-inflammatory drug.However,during the use of APAP for more than half a century,people have not only used APAP to fight diseases but have also suffered the adverse effects brought about by APAP for more than half a cen⁃tury.The most serious adverse reaction to APAP is hepatotoxicity caused by overdose or long-term use.In Chinese tra⁃ditional medicine,chrysanthemums have the functions of dispelling wind,dissipating heat,clearing the liver and improv⁃ing eyesight.Although the chrysanthemum variety named Bianliang ziyu from Kaifeng is not a medicinal variety,it has good value for medicine and food.The aim of this study was to investigate the protective effect of Bianliang Ziyu extract(BZE)on APAP-damaged rats and the potential molecular mechanism.METHODS Male Sprague-Dawley rats(200-220 g)were intragastrically administered BZE(110,220 and 440 mg·kg^-1)for 8 d.On the ninth day,APAP(800 mg·kg^-1)was administered intragastrically to the rats 0.5 h after BZE administration to induced drug-induced liver injury.The serum and liver samples were collected after 24 h.The levels of alanine aminotransferase(ALT),aspartic aminotransferase(AST),reactive oxygen species(ROS),malondialdehyde(MDA),superoxide dismutase(SOD)and glutathione(GSH)in serum and liver tissue of rats were detected by kit method.HE staining was used to observe the histopathological changes in the liver of rat.The effects of BZE on the expression of the oxidative stress related proteins and the mitochondrial biosyn⁃thesis related proteins were detected by Western blot.RESULTS The results showed that BZE significantly reduced the levels of ALT,AST,MDA and ROS and increased the levels of GSH and SOD caused by APAP.Moreover,BZE increased phosphorylation of AMP-activated protein kinase(AMPK)and glycogen synthase kinase 3β(GSK3β),promoted the nuclear translocation of nuclear factor-erythroid 2-related factor 2(Nrf2).BZE also upregulated the expression of mitochondrial biosynthesis related proteins such as peroxisome proliferator-activated receptorγ(PPAR-γ),peroxisome proliferator-activated receptorγcoactivator-1α(PGC-1α),mitochondrial transcription factor(TFAM)and nuclear respira⁃tory factor 1(NRF1).CONCLUSION BZE alleviates APAP-induced liver injury in rats by inhibiting oxidative stress via GSK3β-Nrf2 signaling and the mitochondrial biosynthesis pathway mediated by AMPK.

Chrysanthemum weyrichii基因组测定及rDNA定位

以Chrysanthemum weyrichii为试材,采用流式细胞术估算其基因组大小,同时利用染色体计数法统计了C.weyrichii的染色体条数并对其rDNA染色体定位进行了研究。结果表明:C.weyrichii基因组大小为10.02Gb,染色条数为2n=8x=72,5S rDNA杂交信号有4对位点,位于染色体的亚中部;45S rDNA杂交信号有8对位点,位于染色体的末端。该研究结果为该物种基因组分析以及菊属植物染色体进化研究提供了依据。

Current achievements and future prospects in the genetic breeding of chrysanthemum:a review

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.