RESUMO
Excessive soil salinity not only hampers plant growth and development but can also lead to plant death. Previously, we found that heat-shock factor A4 (CmHSFA4) enhances the tolerance of chrysanthemum (Chrysanthemum morifolium) to salt. However, the underlying molecular mechanism remains unclear. In this study, we identified a candidate MYB transcription factor, CmMYB121, which responded to salt stress. We observed that the CmMYB121 transcription is suppressed by CmHSFA4. Moreover, overexpression of CmMYB121 exacerbated chrysanthemum sensitivity to salt stress. CmHSFA4 directly bound to the promoter of CmMYB121 at the heat-shock element. Protein-protein interaction assays identified an interaction between CmHSFA4 and CmMYBS3, a transcriptional repressor, and recruited the corepressor TOPLESS (CmTPL) to inhibit CmMYB121 transcription by impairing the H3 and H4 histone acetylation levels of CmMYB121. Our study demonstrated that a CmHSFA4-CmMYBS3-CmTPL complex modulates CmMYB121 expression, consequently regulating the tolerance of chrysanthemum to salt. The findings shed light on the responses of plants to salt stress.
Assuntos
Chrysanthemum , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Tolerância ao Sal , Fatores de Transcrição , Chrysanthemum/genética , Chrysanthemum/fisiologia , Chrysanthemum/efeitos dos fármacos , Chrysanthemum/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Tolerância ao Sal/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Estresse Salino/genéticaRESUMO
Artemisia is a large genus encompassing about 400 diverse species, many of which have considerable medicinal and ecological value. However, complex morphological information and variation in ploidy level and nuclear DNA content have presented challenges for evolution studies of this genus. Consequently, taxonomic inconsistencies within the genus persist, hindering the utilization of such large plant resources. Researchers have utilized satellite DNAs to aid in chromosome identification, species classification, and evolutionary studies due to their significant sequence and copy number variation between species and close relatives. In the present study, the RepeatExplorer2 pipeline was utilized to identify 10 satellite DNAs from three species (Artemisia annua, Artemisia vulgaris, Artemisia viridisquama), and fluorescence in situ hybridization confirmed their distribution on chromosomes in 24 species, including 19 Artemisia species with 5 outgroup species from Ajania and Chrysanthemum. Signals of satellite DNAs exhibited substantial differences between species. We obtained one genus-specific satellite from the sequences. Additionally, molecular cytogenetic maps were constructed for Artemisia vulgaris, Artemisia leucophylla, and Artemisia viridisquama. One species (Artemisia verbenacea) showed a FISH distribution pattern suggestive of an allotriploid origin. Heteromorphic FISH signals between homologous chromosomes in Artemisia plants were observed at a high level. Additionally, the relative relationships between species were discussed by comparing ideograms. The results of the present study provide new insights into the accurate identification and taxonomy of the Artemisia genus using molecular cytological methods.
Assuntos
Artemisia , Artemisia/genética , Hibridização in Situ Fluorescente , Filogenia , DNA Satélite/genética , Variações do Número de Cópias de DNARESUMO
Horticultural plants contribute immensely to the quality of human's life. The rapid development of omics studies on horticultural plants has resulted in large volumes of valuable growth- and development-related data. Genes that are essential for growth and development are highly conserved in evolution. Cross-species data mining reduces the impact of species heterogeneity and has been extensively used for conserved gene identification. Owing to the lack of a comprehensive database for cross-species data mining using multi-omics data from all horticultural plant species, the current resources in this field are far from satisfactory. Here, we introduce GERDH (https://dphdatabase.com), a database platform for cross-species data mining among horticultural plants, based on 12 961 uniformly processed publicly available omics libraries from more than 150 horticultural plant accessions, including fruits, vegetables and ornamental plants. Important and conserved genes that are essential for a specific biological process can be obtained by cross-species analysis module with interactive web-based data analysis and visualization. Moreover, GERDH is equipped with seven online analysis tools, including gene expression, in-species analysis, epigenetic regulation, gene co-expression, enrichment/pathway and phylogenetic analysis. By interactive cross-species analysis, we identified key genes contributing to postharvest storage. By gene expression analysis, we explored new functions of CmEIN3 in flower development, which was validated by transgenic chrysanthemum analysis. We believe that GERDH will be a useful resource for key gene identification and will allow for omics big data to be more available and accessible to horticultural plant community members.
Assuntos
Epigênese Genética , Multiômica , Humanos , Filogenia , Produtos Agrícolas/genética , Bases de Dados Genéticas , Mineração de DadosRESUMO
TEMPRANILLO1 (TEM1) is a transcription factor belonging to related to ABI3 and VP1 family, which is also known as ethylene response DNA-binding factor 1 and functions as a repressor of flowering in Arabidopsis. Here, a putative homolog of AtTEM1 was isolated and characterized from chrysanthemum, designated as CmTEM1. Exogenous application of ethephon leads to an upregulation in the expression of CmTEM1. Knockdown of CmTEM1 promotes floral initiation, while overexpression of CmTEM1 retards floral transition. Further phenotypic observations suggested that CmTEM1 involves in the ethylene-mediated inhibition of flowering. Transcriptomic analysis established that expression of the flowering integrator CmAFL1, a member of the APETALA1/FRUITFULL subfamily, was downregulated significantly in CmTEM1-overexpressing transgenic plants compared with wild-type plants but was verified to be upregulated in amiR-CmTEM1 lines by quantitative RT-PCR. In addition, CmTEM1 is capable of binding to the promoter of the CmAFL1 gene to inhibit its transcription. Moreover, the genetic evidence supported the notion that CmTEM1 partially inhibits floral transition by targeting CmAFL1. In conclusion, these findings demonstrate that CmTEM1 acts as a regulator of ethylene-mediated delayed flowering in chrysanthemum, partly through its interaction with CmAFL1.
Assuntos
Chrysanthemum , Proteínas de Plantas , Fatores de Transcrição , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Chrysanthemum/fisiologia , Etilenos/metabolismo , Flores/fisiologia , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Plantas/metabolismoRESUMO
BACKGROUND: Heterosis breeding is one of the most important breeding methods for chrysanthemum. To date, the genetic mechanisms of heterosis for waterlogging tolerance in chrysanthemum are still unclear. This study aims to analyze the expression profiles and potential heterosis-related genes of two hybrid lines and their parents with extreme differences in waterlogging tolerance under control and waterlogging stress conditions by RNA-seq. RESULTS: A population of 140 F1 progeny derived from Chrysanthemum indicum (Nanchang) (waterlogging-tolerant) and Chrysanthemum indicum (Nanjing) (waterlogging-sensitive) was used to characterize the extent of genetic variation in terms of seven waterlogging tolerance-related traits across two years. Lines 98 and 95, respectively displaying positive and negative overdominance heterosis for the waterlogging tolerance traits together with their parents under control and waterlogging stress conditions, were used for RNA-seq. In consequence, the maximal number of differentially expressed genes (DEGs) occurred in line 98. Gene ontology (GO) enrichment analysis revealed multiple stress-related biological processes for the common up-regulated genes. Line 98 had a significant increase in non-additive genes under waterlogging stress, with transgressive up-regulation and paternal-expression dominant patterns being the major gene expression profiles. Further, GO analysis identified 55 and 95 transgressive up-regulation genes that overlapped with the up-regulated genes shared by two parents in terms of responses to stress and stimulus, respectively. 6,640 genes in total displaying maternal-expression dominance patterns were observed in line 95. In addition, 16 key candidate genes, including SAP12, DOX1, and ERF017 which might be of significant importance for the formation of waterlogging tolerance heterosis in line 98, were highlighted. CONCLUSION: The current study provides a comprehensive overview of the root transcriptomes among F1 hybrids and their parents under waterlogging stress. These findings lay the foundation for further studies on molecular mechanisms underlying chrysanthemum heterosis on waterlogging tolerance.
Assuntos
Chrysanthemum , Transcriptoma , Vigor Híbrido/genética , Chrysanthemum/genética , Melhoramento Vegetal , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de PlantasRESUMO
BACKGROUND: The growth and ornamental value of chrysanthemums are frequently hindered by aphid attacks. The ethylene-responsive factor (ERF) gene family is pivotal in responding to biotic stress, including insect stress. However, to date, little is known regarding the involvement of ERF transcription factors (TFs) in the response of chrysanthemum to aphids. RESULTS: In the present study, CmHRE2-like from chrysanthemum (Chrysanthemum morifolium), a transcription activator that localizes mainly to the nucleus, was cloned. Expression is induced by aphid infestation. Overexpression of CmHRE2-like in chrysanthemum mediated its susceptibility to aphids, whereas CmHRE2-like-SRDX dominant repressor transgenic plants enhanced the resistance of chrysanthemum to aphids, suggesting that CmHRE2-like contributes to the susceptibility of chrysanthemum to aphids. The flavonoids in CmHRE2-like-overexpression plants were decreased by 29% and 28% in two different lines, whereas they were increased by 42% and 29% in CmHRE2-like-SRDX dominant repressor transgenic plants. The expression of Chrysanthemum-chalcone-synthase gene(CmCHS), chalcone isomerase gene (CmCHI), and flavonoid 3'-hydroxylase gene(CmF3'H) was downregulated in CmHRE2-like overexpression plants and upregulated in CmHRE2-like-SRDX dominant repressor transgenic plants, suggesting that CmHRE2-like regulates the resistance of chrysanthemum to aphids partially through the regulation of flavonoid biosynthesis. CONCLUSION: CmHRE2-like was a key gene regulating the vulnerability of chrysanthemum to aphids. This study offers fresh perspectives on the molecular mechanisms of chrysanthemum-aphid interactions and may bear practical significance for developing new strategies to manage aphid infestation in chrysanthemums.
Assuntos
Afídeos , Chrysanthemum , Animais , Chrysanthemum/genética , Chrysanthemum/metabolismo , Afídeos/fisiologia , Flavonoides/metabolismo , Plantas Geneticamente Modificadas/genética , Regulação da Expressão Gênica de PlantasRESUMO
Plant flowering time is induced by environmental and endogenous signals perceived by the plant. The MCM1-AGAMOUSDEFICIENS-Serum Response Factor-box (MADS-box) protein SHORT VEGETATIVE PHASE (SVP) is a pivotal repressor that negatively regulates the floral transition during the vegetative phase; however, the transcriptional regulatory mechanism remains poorly understood. Here, we report that CmSVP, a chrysanthemum (Chrysanthemum morifolium Ramat.) homolog of SVP, can repress the expression of a key flowering gene, a chrysanthemum FLOWERING LOCUS T-like gene (CmFTL3), by binding its promoter CArG element to delay flowering in the ambient temperature pathway in chrysanthemum. Protein-protein interaction assays identified an interaction between CmSVP and CmTPL1-2, a chrysanthemum homologue of TOPLESS (TPL) that plays critical roles as transcriptional corepressor in many aspects of plant life. Genetic analyses revealed the CmSVP-CmTPL1-2 transcriptional complex is a prerequisite for CmSVP to act as a floral repressor. Furthermore, overexpression of CmSVP rescued the phenotype of the svp-31 mutant in Arabidopsis (Arabidopsis thaliana), overexpression of AtSVP or CmSVP in the Arabidopsis dominant-negative mutation tpl-1 led to ineffective late flowering, and AtSVP interacted with AtTPL, confirming the conserved function of SVP in chrysanthemum and Arabidopsis. We have validated a conserved machinery wherein SVP partially relies on TPL to inhibit flowering via a thermosensory pathway.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Chrysanthemum , Arabidopsis/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas Correpressoras/genética , Chrysanthemum/genética , Chrysanthemum/metabolismo , Flores/fisiologia , Regulação da Expressão Gênica de PlantasRESUMO
Floral transition, the switch from vegetative to reproductive growth, is extremely important for the growth and development of flowering plants. In the summer chrysanthemum, CmBBX8, a member of the subgroup II B-box (BBX) family, positively regulates the transition by physically interacting with CmERF3 to inhibit CmFTL1 expression. In this study, we show that CmBBX5, a B-box subgroup I member comprising two B-boxes and a CCT domain, interacts with CmBBX8. This interaction suppresses the recruitment of CmBBX8 to the CmFTL1 locus without affecting its transcriptional activation activity. CmBBX5 overexpression led to delayed flowering under both LD (long-day) and SD (short-day) conditions, while lines expressing the chimeric repressor gene-silencing (CmBBX5-SRDX) exhibited the opposite phenotype. Subsequent genetic evidence indicated that in regulating flowering, CmBBX5 is partially dependent on CmBBX8. Moreover, during the vegetative growth period, levels of CmBBX5 expression were found to exceed those of CmBBX8. Collectively, our findings indicate that both CmERF3 and CmBBX5 interact with CmBBX8 to dampen the regulation of CmFTL1 via distinct mechanisms, which contribute to preventing the premature flowering of summer chrysanthemum.
Assuntos
Chrysanthemum , Flores , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Chrysanthemum/genética , Chrysanthemum/crescimento & desenvolvimento , Chrysanthemum/metabolismo , Chrysanthemum/fisiologia , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Flores/crescimento & desenvolvimento , Flores/genética , Flores/metabolismo , Plantas Geneticamente Modificadas , Reprodução , FotoperíodoRESUMO
Ethylene-responsive factors (ERF) play an important role in plant responses to waterlogging stress. However, the function and mechanism of action of ERFVIII in response to waterlogging stress remain poorly understood. In this study, we found that expression of the ERF VIIIa gene CmERF4 in chrysanthemum was induced by waterlogging stress. CmERF4 localized to the nucleus when expressed in tobacco leaves. Yeast two-hybrid and luciferase assays showed that CmERF4 is a transcriptional inhibitor. CmERF4 overexpression in chrysanthemum reduced plant waterlogging tolerance, whereas overexpression of the chimeric activator CmERF4-VP64 reversed its transcriptional activity, promoting higher waterlogging tolerance than that observed in wild-type plants, indicating that CmERF4 negatively regulates waterlogging tolerance. Transcriptome profiling showed that energy metabolism and reactive oxygen species (ROS) pathway-associated genes were differentially expressed between CmERF4-VP64 and wild-type plants. RT-qPCR analysis of selected energy metabolism and reactive oxygen species-related genes showed that the gene expression patterns were consistent with the expression levels obtained from RNA-seq analysis. Overall, we identified new functions of CmERF4 in negatively regulating chrysanthemum waterlogging tolerance by modulating energy metabolism and ROS pathway genes.
Assuntos
Chrysanthemum , Espécies Reativas de Oxigênio/metabolismo , Chrysanthemum/genética , Chrysanthemum/metabolismo , Regulação da Expressão Gênica de Plantas , Etilenos/metabolismo , Estresse Fisiológico/genéticaRESUMO
Trichomes, specialized hair-like structures in the epidermal cells of the aboveground parts of plants, protect plants from pests and pathogens and produce valuable metabolites. Chrysanthemum morifolium, used in tea products, has ornamental and medicinal value. However, it is susceptible to Alternaria alternata fungal infection, posing a threat to its production and use, resulting in substantial economic losses. Increasing the density of glandular trichomes enhances disease resistance and improves the production of medicinal metabolites in chrysanthemums. Jasmonate (JA), promotes the formation of glandular trichomes in various plants. However, it remains unclear whether glandular trichome in chrysanthemums are regulated by JA. Grafting, a technique to improve plant resistance to biotic stresses, has been insufficiently explored in its impact on glandular trichomes, terpenoids, and disease resistance. In this study, we demonstrated that grafting with Artemisia vulgaris rootstocks improves the resistance of chrysanthemum scions to A. alternata. Heterografted chrysanthemums exhibited higher trichome density and terpenoid content compared to self-grafted counterparts. Transcriptome analysis highlighted the significant role of CmJAZ1-like in disease resistance in heterografted chrysanthemums. Overexpressing CmJAZ1-like lines exhibited sensitivity to A. alternate, characterized by reduced glandular trichome density and limited terpenoids. Conversely, silencing lines exhibited resistance to A. alternata showcasing increased glandular trichome density and abundant terpenoids. Higher JA content was confirmed in heterografted chrysanthemum scions compared to self-grafted ones. Furthermore, we established that JA promotes the development of glandular trichomes and the synthesis of terpenoids while inducing the degradation of CmJAZ1-like proteins in chrysanthemums. These findings suggest that higher JA increases trichome density and terpenoid content, enhancing resistance to A. alternata by regulating CmJAZ1-like in heterografted chrysanthemums.
RESUMO
Chrysanthemum morifolium is cultivated worldwide and has high ornamental, tea, and medicinal value. With the increasing area of chrysanthemum cultivation and years of continuous cropping, Fusarium wilt disease frequently occurs in various production areas, seriously affecting the quality and yield and causing huge economic losses. However, the molecular response mechanism of Fusarium wilt infection remains unclear, which limits the molecular breeding process for disease resistance in chrysanthemums. In the present study, we analyzed the molecular response mechanisms of 'Huangju,' one of the tea chrysanthemum cultivars severely infested with Fusarium wilt in the field at the early, middle, and late phases of F. oxysporum infestation. 'Huangju' responded to the infestation mainly through galactose metabolism, plant-pathogen interaction, auxin, abscisic acid, and ethylene signalling in the early phase; galactose metabolism, plant-pathogen interaction, auxin, salicylic acid signal, and certain transcription factors (e.g., CmWRKY48) in the middle phase; and galactose metabolism in the late phase. Notably, the galactose metabolism was important in the early, middle, and late phases of 'Huangju' response to F. oxysporum. Meanwhile, the phytohormone auxin was involved in the early and middle responses. Furthermore, silencing of CmWRKY48 in 'Huangju' resulted in resistance to F. oxysporum. Our results revealed a new molecular pattern for chrysanthemum in response to Fusarium wilt in the early, middle, and late phases, providing a foundation for the molecular breeding of chrysanthemum for disease resistance.
Assuntos
Chrysanthemum , Fusarium , Doenças das Plantas , Reguladores de Crescimento de Plantas , Fusarium/patogenicidade , Fusarium/fisiologia , Chrysanthemum/microbiologia , Chrysanthemum/genética , Chrysanthemum/metabolismo , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Reguladores de Crescimento de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Resistência à Doença/genética , Ácido Abscísico/metabolismo , Interações Hospedeiro-Patógeno , Galactose/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genéticaRESUMO
KEY MESSAGE: The dynamic genetic architecture of flowering time in chrysanthemum was elucidated by GWAS. Thirty-six known genes and 14 candidate genes were identified around the stable QTNs and QEIs, among which ERF-1 was highlighted. Flowering time (FT) adaptation is one of the major breeding goals in chrysanthemum, a multipurpose ornamental plant. In order to reveal the dynamic genetic architecture of FT in chrysanthemum, phenotype investigation of ten FT-related traits was conducted on 169 entries in 2 environments. The broad-sense heritability of five non-conditional FT traits, i.e., budding (FBD), visible coloring (VC), early opening (EO), full-bloom (OF) and decay period (DP), ranged from 56.93 to 84.26%, which were higher than that of the five derived conditional FT traits (38.51-75.13%). The phenotypic variation coefficients of OF_EO and DP_OF were relatively large ranging from 30.59 to 36.17%. Based on 375,865 SNPs, the compressed variance component mixed linear model 3VmrMLM was applied for a multi-locus genome-wide association study (GWAS). As a result, 313 quantitative trait nucleotides (QTNs) were identified for the non-conditional FT traits in single-environment analysis, while 119 QTNs and 67 QTN-by-environment interactions (QEIs) were identified in multi-environment analysis. As for the conditional traits, 343 QTNs were detected in single-environment analysis, and 119 QTNs and 83 QEIs were identified in multi- environment analysis. Among the genes around stable QTNs and QEIs, 36 were orthologs of known FT genes in Arabidopsis and other plants; 14 candidates were mined by combining the transcriptomics data and functional annotation, including ERF-1, ACA10, and FOP1. Furthermore, the haplotype analysis of ERF-1 revealed six elite accessions with extreme FBD. Our findings contribute to the understanding of dynamic genetic architecture of FT and provide valuable resources for future chrysanthemum molecular breeding programs.
Assuntos
Arabidopsis , Chrysanthemum , Estudo de Associação Genômica Ampla , Melhoramento Vegetal , Reprodução , Chrysanthemum/genéticaRESUMO
KEY MESSAGE: CmMYB308 was identified as a key regulator in chrysanthemum flower color variation from purple to pink by conducting transcriptome and metabolome analysis. CmMYB308 can inhibit anthocyanin biosynthesis by suppressing the expression of CmPAL, CmC4H, and Cm4CL. Flower color variation is a widespread natural occurrence that plays a significant role in floral breeding. We discovered a variation in the flower of the chrysanthemum cultivar 'Dante Purple' (abbreviated as 'DP'), where the flower color shifted from purple to pink. We successfully propagated these pink flowers through tissue culture and designated them as DPM. By conducting transcriptome and metabolome analysis, we identified a reduction in the expression of critical genes involved in anthocyanin biosynthesis-CmPAL, CmC4H, and Cm4CL-in the DPM. This downregulation led to an accumulation of phenylalanine and cinnamic acid within the general phenylpropanoid pathway (GPP), which prevented their conversion into cyanidin and cyanidin 3-glucoside. As a result, the flowers turned pink. Additional transformation and biochemical experiments confirmed that the upregulation of CmMYB308 gene expression in the DPM directly suppressed CmPAL-1 and CmC4H genes, which indirectly affected Cm4CL-3 expression and ultimately inhibited anthocyanin biosynthesis in the DPM. This study offers a preliminary insight into the molecular mechanism underlying chrysanthemum flower color mutation, paving the way for genetic improvements in chrysanthemum flower color breeding.
Assuntos
Antocianinas , Chrysanthemum , Flores , Regulação da Expressão Gênica de Plantas , Pigmentação , Proteínas de Plantas , Chrysanthemum/genética , Chrysanthemum/metabolismo , Flores/genética , Flores/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Antocianinas/metabolismo , Pigmentação/genética , Transcriptoma/genética , Metabolômica/métodos , Metaboloma/genética , Perfilação da Expressão Gênica , Cor , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
BACKGROUND: Anthocyanin is a class of important secondary metabolites that determines colorful petals in chrysanthemum, a famous cut flower. 'Arctic Queen' is a white chrysanthemum cultivar that does not accumulate anthocyanin during the flowering stage. During the post-flowering stage, the petals of 'Arctic Queen' accumulate anthocyanin and turn red. However, the molecular mechanism underlying this flower color change remains unclear. RESULTS: In this study, by using transcriptome analysis, we identified CmNAC25 as a candidate gene promoting anthocyanin accumulation in the post-flowering stage of 'Arctic Queen'. CmNAC25 is directly bound to the promoter of CmMYB6, a core member of the MBW protein complex that promotes anthocyanin biosynthesis in chrysanthemum, to activate its expression. CmNAC25 also directly activates the promoter of CmDFR, which encodes the key enzyme in anthocyanin biosynthesis. CmNAC25 was highly expressed during the post-flowering stage, while the expression level of CmMYB#7, a known R3 MYB transcription factor interfering with the formation of the CmMYB6-CmbHLH2 complex, significantly decreased. Genetic transformation of both chrysanthemum and Nicotiana tabacum verified that CmNAC25 was a positive regulator of anthocyanin biosynthesis. Another two cultivars that turned red during the post-flowering stages also demonstrated a similar mechanism. CONCLUSIONS: Altogether, our data revealed that CmNAC25 positively regulates anthocyanin biosynthesis in chrysanthemum petals during the post-flowering stages by directly activating CmMYB6 and CmDFR. Our results thus revealed a crucial role of CmNAC25 in regulating flower color change during petal senescence and provided a target gene for molecular design breeding of flower color in chrysanthemum.
Assuntos
Antocianinas , Chrysanthemum , Antocianinas/análise , Antocianinas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Chrysanthemum/genética , Chrysanthemum/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Flores/genética , Regulação da Expressão Gênica de PlantasRESUMO
Petals are the second floral whorl of angiosperms, exhibiting astonishing diversity in their size between and within species. This variation is essential for protecting their inner reproductive organs and attracting pollinators for fertilization. However, currently, the genetic and developmental control of petal size remains unexplored. Chrysanthemum (Chrysanthemum morifolium) belongs to the Asteraceae family, the largest group of angiosperms, and the extraordinary diversity of petal size in chrysanthemums makes it an ideal model for exploring the regulation mechanism of petal size. Here, we reveal that overexpression of a JAZ repressor CmJAZ1-like exhibits decreased petal size compared to that of the wild-type as a result of repressed cell expansion. Through further in-depth exploration, we confirm an interaction pair between CmJAZ1-like and the bHLH transcription factor CmBPE2. The inhibition of CmBPE2 expression negatively regulates petal size by downregulating the expression of genes involved in cell expansion. Furthermore, CmJAZ1-like significantly reduced the activation ability of CmBPE2 on its target gene CmEXPA7 by directly interacting with it, thus participating in the regulation of petal size development in chrysanthemum. Our results will provide insights into the molecular mechanisms of petal size regulation in flowering plants.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos , Chrysanthemum , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Flores , Chrysanthemum/genética , Chrysanthemum/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
BACKGROUND: Black spot disease caused by the necrotrophic fungus Alternaria spp. is one of the most devastating diseases affecting Chrysanthemum morifolium. There is currently no effective way to prevent chrysanthemum black spot. RESULTS: We revealed that pre-treatment of chrysanthemum leaves with the methy jasmonate (MeJA) significantly reduces their susceptibility to Alternaria alternata. To understand how MeJA treatment induces resistance, we monitored the dynamics of metabolites and the transcriptome in leaves after MeJA treatment following A. alternata infection. JA signaling affected the resistance of plants to pathogens through cell wall modification, Ca2+ regulation, reactive oxygen species (ROS) regulation, mitogen-activated protein kinase cascade and hormonal signaling processes, and the accumulation of anti-fungal and anti-oxidant metabolites. Furthermore, the expression of genes associated with these functions was verified by reverse transcription quantitative PCR and transgenic assays. CONCLUSION: Our findings indicate that MeJA pre-treatment could be a potential orchestrator of a broad-spectrum defense response that may help establish an ecologically friendly pest control strategy and offer a promising way of priming plants to induce defense responses against A. alternata.
Assuntos
Alternaria , Chrysanthemum , Antioxidantes , Chrysanthemum/genéticaRESUMO
BACKGROUND: Chrysanthemum Fusarium wilt is a common fungal disease caused by Fusarium oxysporum, which causes continuous cropping obstacles and huge losses to the chrysanthemum industry. The defense mechanism of chrysanthemum against F. oxysporum remains unclear, especially during the early stages of the disease. Therefore, in the present study, we analyzed chrysanthemum 'Jinba' samples inoculated with F. oxysporum at 0, 3, and 72 h using RNA-seq. RESULTS: The results revealed that 7985 differentially expressed genes (DEGs) were co-expressed at 3 and 72 h after F. oxysporum infection. We analyzed the identified DEGs using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology. The DEGs were primarily enriched in "Plant pathogen interaction", "MAPK signaling pathway", "Starch and sucrose metabolism", and "Biosynthesis of secondary metabolites". Genes related to the synthesis of secondary metabolites were upregulated in chrysanthemum early during the inoculation period. Furthermore, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase enzymes were consistently produced to accumulate large amounts of phenolic compounds to resist F. oxysporum infection. Additionally, genes related to the proline metabolic pathway were upregulated, and proline levels accumulated within 72 h, regulating osmotic balance in chrysanthemum. Notably, the soluble sugar content in chrysanthemum decreased early during the inoculation period; we speculate that this is a self-protective mechanism of chrysanthemums for inhibiting fungal reproduction by reducing the sugar content in vivo. In the meantime, we screened for transcription factors that respond to F. oxysporum at an early stage and analyzed the relationship between WRKY and DEGs in the "Plant-pathogen interaction" pathway. We screened a key WRKY as a research target for subsequent experiments. CONCLUSION: This study revealed the relevant physiological responses and gene expression changes in chrysanthemum in response to F. oxysporum infection, and provided a relevant candidate gene pool for subsequent studies on chrysanthemum Fusarium wilt.
Assuntos
Chrysanthemum , Fusarium , Catecol Oxidase , AçúcaresRESUMO
MAIN CONCLUSION: Multi-locus GWAS detected several known and candidate genes responsible for flowering time in chrysanthemum. The associations could greatly increase the predictive ability of genome selection that accelerates the possible application of GS in chrysanthemum breeding. Timely flowering is critical for successful reproduction and determines the economic value for ornamental plants. To investigate the genetic architecture of flowering time in chrysanthemum, a multi-locus genome-wide association study (GWAS) was performed using a collection of 200 accessions and 330,710 single-nucleotide polymorphisms (SNPs) via 3VmrMLM method. Five flowering time traits including budding (FBD), visible colouring (VC), early opening (EO), full-bloom (OF) and senescing (SF) stages, plus five derived conditional traits were recorded in two environments. Extensive phenotypic variations were observed for these flowering time traits with coefficients of variation ranging from 6.42 to 38.27%, and their broad-sense heritability ranged from 71.47 to 96.78%. GWAS revealed 88 stable quantitative trait nucleotides (QTNs) and 93 QTN-by-environment interactions (QEIs) associated with flowering time traits, accounting for 0.50-8.01% and 0.30-10.42% of the phenotypic variation, respectively. Amongst the genes around these stable QTNs and QEIs, 21 and 10 were homologous to known flowering genes in Arabidopsis; 20 and 11 candidate genes were mined by combining the functional annotation and transcriptomics data, respectively, such as MYB55, FRIGIDA-like, WRKY75 and ANT. Furthermore, genomic selection (GS) was assessed using three models and seven unique marker datasets. We found the prediction accuracy (PA) using significant SNPs identified by GWAS under SVM model exhibited the best performance with PA ranging from 0.90 to 0.95. Our findings provide new insights into the dynamic genetic architecture of flowering time and the identified significant SNPs and candidate genes will accelerate the future molecular improvement of chrysanthemum.
Assuntos
Chrysanthemum , Estudo de Associação Genômica Ampla , Mapeamento Cromossômico , Locos de Características Quantitativas/genética , Chrysanthemum/genética , Melhoramento Vegetal , Genômica , Reprodução , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Waterlogging stress affects plant growth by limiting root respiration and reducing yield and economic value. Therefore, identifying genes involved in regulating waterlogging stress is vital. This study reports the ethylene-responsive VII transcription factor (CmRAP2.3) in the chrysanthemum. Subcellular localization and transactivation assay analyses revealed that CmRAP2.3 was localized in the nucleus and possessed transactivation activity. Overexpression of CmRAP2.3 in chrysanthemum was found to enhance waterlogging tolerance by decreasing reactive oxygen species (ROS) levels. Furthermore, we found that the transcription factor CmERF5 binds to GCC-like motifs in the CmRAP2.3 promoter region and activates CmRAP2.3 expression. Additionally, CmERF5 overexpression maintained a low ROS level and improved chrysanthemum waterlogging tolerance. Taken together, this study shows a molecular mechanism by which CmERF5 transcriptionally activates CmRAP2.3 to reduce waterlogging stress via the ROS pathway in the chrysanthemum.
Assuntos
Chrysanthemum , Espécies Reativas de Oxigênio/metabolismo , Chrysanthemum/genética , Chrysanthemum/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
Lignin is a major component of plant cell walls and a conserved basic defense mechanism in higher plants deposited in response to aphid infection. However, the molecular mechanisms of lignin biosynthesis in response to aphid infection and the effect of lignin on aphid feeding behavior remain unclear. We report that 4-Coumarate:coenzyme A ligase 2 (Cm4CL2), a gene encoding a key enzyme in the lignin biosynthesis pathway, is induced by aphid feeding, resulting in lignin deposition and reduced aphid attack. Upstream regulator analysis showed that the expression of Cm4CL2 in response to aphid feeding was directly upregulated by CmMYB15-like, an SG2-type R2R3-MYB transcription factor. CmMYB15-like binds directly to the AC cis-element in the promoter region of Cm4CL2. Genetic validation demonstrated that CmMYB15-like was induced by aphid infection and contributed to lignin deposition and cell wall thickening, which consequently enhanced aphid resistance in a Cm4CL2-dependent manner. This study is the first to show that the CmMYB15-like-Cm4CL2 module regulates lignin biosynthesis in response to aphid feeding.