Ethylene is a gaseous phytohormone that delays flowering in Chrysanthemum morifolium Ramat. To date, however, there have been no systematic studies on genes involved in the ethylene response of this species, and the mechanism underlying ethylene-delayed flowering remains unclear. Herein, we applied RNA sequencing to characterize the ethylene response by comparing the transcriptomes of chrysanthemum cultivar ‘Jinba’ with or without ethephon treatment. Six unique RNA-seq libraries were generated. The identified differentially expressed genes (DEGs) primarily involved ethylene, auxin, and abscisic acid signaling genes; circadian clock genes; genes encoding functional proteins associated with floral transition, such as homologs of AP1/FRUITFUL-like 1 (AFL1), TERMINAL FLOWER 1 (TFL1), and so on; and genes encoding transcription factors, specifically of the MYB and bHLH families. Furthermore, quantitative RT-PCR was used to verify the DEGs identified by RNA-seq. Heterologous CmAFL1 overexpression in Arabidopsis thaliana resulted in early flowering. Our findings present a landscape of transcriptomes and reveal the candidate genes involved in the ethylene-mediated regulation of flowering time in chrysanthemum, providing useful data for further studies.

The Lycoris radiata (L’ Herit.) Herb. is a perennial bulbous plant characterized by its high ornamental and medicinal value, exhibiting a unique growth rhythm where the flower and leaf do not coexist and a period of summer dormancy. However, its metabolic response to various developmental stages remains unclear. To address this gap, we conducted a non-targeted metabolomic analysis spanning six developmental stages of L. radiata. The results showed that most differentially accumulated metabolites (DAMs) demonstrated enrichment predominantly in carbohydrate and amino acid metabolism pathways, with the former being more active during vegetative growth and the latter during reproductive stages. The proportion of DAMs categorized under “quaternary ammonium salts”, “tricarboxylic acids and derivatives”, “fatty acids and conjugates”, and “pyrimidine nucleotide sugars” was notably higher in comparisons between the flowering and dormancy stages than in other comparative groups. Furthermore, DAMs involved in the KEGG pathways of C5-branched dibasic acid metabolism and lysine biosynthesis were uniquely identified during the transition from Dormancy to Flowering. The proportion of DAMs associated with “linoleic acids and derivatives” and “pyridines and pyridine derivatives” was notably higher in the leafing out versus flowering comparison than in other comparative groups. Furthermore, the glycolysis/gluconeogenesis pathway was uniquely enriched by DAMs during this phase. This study provided an in-depth view of metabolite changes in L. radiata over its annual growth cycle, enriching our understanding of the regulatory mechanisms governing its development, dormancy, and flowering.

The transcription factor family RELATED to ABSCISIC ACID INSENSITIVE3 (ABI3)/VIVIPAROUS1(VP1) (RAV) is a plant-specific group of transcription factors that only contain a conserved B3 DNA binding domain or both their own B3 and APETALA2 (AP2) domains belonging to the B3 superfamily, which is vital for plant growth, development, and stress response. Although genome-wide characterization and analysis of the RAV family genes have been conducted in some species, they have not been systematically reported in chrysanthemums. Here, we found six RAV family genes in the diploid Chrysanthemum seticuspe genome. Based on domain similarity and homology comparison analyses, RAV genes in Chrysanthemum were categorized into two clades: Class-I and Class-II. Conserved motif analysis revealed that all CsRAV proteins contained the B3 repression domain. An analysis of cis-acting elements suggested that CsRAV family genes may play parts in light, hormonal, abiotic stress, growth, and developmental processes. Furthermore, quantitative RT-PCR analysis validated that all six CsRAV genes responded to ethylene treatment, whereas the genes in the Class-I clade responded most significantly to ethylene. In summary, the above results provided a conceptual basis for further investigation into the functions of CsRAV genes in C. seticuspe.

Chrysanthemum morifolium Ramat. is an important ornamental plant, holding dual economic value as a medicinal and edible plant. Jinsi Huangju is a popular healthy tea drink prepared from the large and elegant shaped flowers of C. morifolium. However, the suboptimal accumulation of bioactive flavonoids during conventional harvest (full bloom stage) limits its commercial potential. To elucidate the molecular mechanisms governing flavonoid biosynthesis in Jinsi Huangju flowers and identify key genetic regulators for metabolic engineering, we performed integrated metabolomic and transcriptomic analyses of flowers at distinct developmental stages using ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) and RNA-seq. Differential metabolites were screened, and candidate genes were validated via transient transformation assays. Among 2146 identified metabolites, flavonoids were the predominant differential compounds, with accumulation patterns being strongly stage dependent. Thirty-eight flavonoid biosynthetic genes and key transcription factors from the MYB, bHLH, and WD40 families exhibited dynamic expression. The CmMYB8a was confirmed as a positive regulator of flavonoid biosynthesis through transient overexpression. This study deciphers the stage-specific flavonoid accumulation in Jinsi Huangju and identifies CmMYB8a as a pivotal regulatory target. Our findings provide genetic resources for breeding high-flavonoid cultivars via molecular design.