Unveiling the aesthetic secrets: exploring connections between genetic makeup, chemical, and environmental factors for enhancing/improving the color and fragrance/aroma of Chimonanthus praecox.

Floral color and scent profiles vary across species, geographical locations, and developmental stages. The exclusive floral color and fragrance of Chimonanthus praecox is contributed by a range of endogenous chemicals that distinguish it from other flowers and present amazing ornamental value. This comprehensive review explores the intricate interplay of environmental factors, chemicals and genes shaping the flower color and fragrance of Chimonanthus praecox. Genetic and physiological factors control morpho-anatomical attributes as well as pigment synthesis, while environmental factors such as temperature, light intensity, and soil composition influence flower characteristics. Specific genes control pigment synthesis, and environmental factors such as temperature, light intensity, and soil composition influence flower characteristics. Physiological processes including plant hormone contribute to flower color and fragrance. Hormones, notably ethylene, exert a profound influence on varioustraits. Pigment investigations have spotlighted specific flavonoids, including kaempferol 3-O-rutinoside, quercetin, and rutin. Red tepals exhibit unique composition with cyanidin-3-O-rutinoside and cyanidin-3-O-glucoside being distinctive components. Elucidating the molecular basis of tepal color variation, particularly in red and yellow varieties, involves the identification of crucial regulatory genes. In conclusion, this review unravels the mysteries of Chimonanthus praecox, providing a holistic understanding of its flower color and fragrance for landscape applications. This comprehensive review uniquely explores the genetic intricacies, chemical and environmental influences that govern the mesmerizing flower color and fragrance of Chimonanthus praecox, providing valuable insights for its landscape applications. This review article is designed for a diverse audience, including plant geneticists, horticulturists, environmental scientists, urban planners, and students, offering understandings into the genetic intricacies, ecological significance, and practical applications of Chimonanthus praecox across various disciplines. Its appeal extends to professionals and enthusiasts interested in plant biology, conservation, and industries dependent on unique floral characteristics.

Genome-wide identification and analysis of the evolution and expression pattern of the SBP gene family in two Chimonanthus species.

BACKGROUND: Chimonanthus praecox and Chimonanthus salicifolius are closely related species that diverged approximately six million years ago. While both C. praecox and C. salicifolius could withstand brief periods of low temperatures of - 15 °C. Their flowering times are different, C. praecox blooms in early spring, whereas C. salicifolius blooms in autumn. The SBP-box (SQUAMOSA promoter-binding protein) is a plant-specific gene family that plays a crucial vital role in regulating plant flowering. Although extensively studied in various plants, the SBP gene family remains uncharacterized in Calycanthaceae. METHODS AND RESULTS: We conducted genome-wide identification of SBP genes in both C. praecox and C. salicifolius and comprehensively characterized the chromosomal localization, gene structure, conserved motifs, and domains of the identified SBP genes. In total, 15 and 18 SBP genes were identified in C. praecox and C. salicifolius, respectively. According to phylogenetic analysis, the SBP genes from Arabidopsis, C. praecox, and C. salicifolius were clustered into eight groups. Analysis of the gene structure and conserved protein motifs showed that SBP proteins of the same subfamily have similar motif structures. The expression patterns of SBP genes were analyzed using transcriptome data. The results revealed that more than half of the genes exhibited lower expression levels in leaves than in flowers, suggesting their potential involvement in the flower development process and may be linked to the winter and autumn flowering of C. praecox and C. salicifolius. CONCLUSION: Thirty-three SBPs were identified in C. praecox and C. salicifolius. The evolutionary characteristics and expression patterns were examined in this study. These results provide valuable information to elucidate the evolutionary relationships of the SBP family and help determine the functional characteristics of the SBP genes in subsequent studies.

Proteomics and metabolomics reveal the mechanism underlying differential antioxidant activity among the organs of two base plants of Shiliang tea (Chimonanthus salicifolius and Chimonanthus zhejiangensis).

The leaves and branches of Chimonanthus salicifolius and Chimonanthus zhejiangensis are the base ingredients of Shiliang tea. In this study, proteomics and metabolomics were performed to understand the molecular mechanisms underlying antioxidant activity (AA) in the leaves and branches of the two species. Stress and redox related proteins are differentially expressed among organs. The abundance of isoprenoid pathway-related proteins is higher in leaves while the abundance of phenylpropanoid and flavonoid pathway-related proteins is higher in branches in both species. Metabolomics revealed the flavonoid composition and demonstrated that procyanidins are more abundant in branches. Superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and AA are stronger in branches than leaves. Overall, branches might contribute to redox homeostasis through SOD/GSH-PX and flavonoids. Furthermore, the high level of AA of branches might be largely due to their increased accumulation of procyanidins.

Overexpression of CpWRKY75 from Chimonanthus praecox Promotes Flowering Time in Transgenic Arabidopsis.

WRKY transcription factors play critical roles in the physiological processes of plants. Although the roles of WRKYs have been characterized in some model plants, their roles in woody plants, especially wintersweet (Chimonanthus praecox), are largely unclear. In this study, a wintersweet WRKY gene named CpWRKY75 belonging to group IIc was isolated and its characteristics were identified. CpWRKY75 is a nucleus-localized protein, and exhibited no transcriptional activation activity in yeast. CpWRKY75 was highly expressed in flowers at different bloom stages. Ectopic expression of CpWRKY75 significantly promoted the flowering time of transgenic Arabidopsis (Arabidopsis thaliana), as determined by the rosette leaf number and first flower open time. The expression levels of flowering-related genes were quantified by qRT-PCR, and the results suggested that CpWRKY75 had obvious influence on the expression level of MICRORNA156C (MIR156C), SQUAMOSA PROMOTER BINDING PROTEIN-LIKE3 (SPL3) and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 9 (SPL9), FLOWERING LOCUS T (FT), LEAFY (LFY), SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), APETALA1 (AP1), CAULIFLOWER (CAL), and FRUITFULL (FUL). These results suggest that CpWRKY75 might have a flowering time regulation function, and additionally provide a new gene resource for the genetic engineering of woody flowering plants.

The Chimonanthus salicifolius genome provides insight into magnoliid evolution and flavonoid biosynthesis.

Chimonanthus salicifolius, a member of the Calycanthaceae of magnoliids, is one of the most famous medicinal plants in Eastern China. Here, we report a chromosome-level genome assembly of C. salicifolius, comprising 820.1 Mb of genomic sequence with a contig N50 of 2.3 Mb and containing 36 651 annotated protein-coding genes. Phylogenetic analyses revealed that magnoliids were sister to the eudicots. Two rounds of ancient whole-genome duplication were inferred in the C. salicifolious genome. One is shared by Calycanthaceae after its divergence with Lauraceae, and the other is in the ancestry of Magnoliales and Laurales. Notably, long genes with > 20 kb in length were much more prevalent in the magnoliid genomes compared with other angiosperms, which could be caused by the length expansion of introns inserted by transposon elements. Homologous genes within the flavonoid pathway for C. salicifolius were identified, and correlation of the gene expression and the contents of flavonoid metabolites revealed potential critical genes involved in flavonoids biosynthesis. This study not only provides an additional whole-genome sequence from the magnoliids, but also opens the door to functional genomic research and molecular breeding of C. salicifolius.

Expression of the subgroup IIIf bHLH transcription factor CpbHLH1 from Chimonanthus praecox (L.) in transgenic model plants inhibits anthocyanin accumulation.

KEY MESSAGE: Overexpression of CpbHLH1 in Arabidopsis and tobacco resulted in a dramatic decrease in anthocyanin accumulation by repressing the expression of late biosynthesis genes in the flavonoid biosynthesis pathway. Many basic helix-loop-helix (bHLH) transcription factors (TFs) of subgroup IIIf have been characterized as anthocyanin-associated activators in higher plants, but information regarding bHLH TFs that inhibit anthocyanin accumulation remains scarce. In this study, the subgroup IIIf bHLH TF CpbHLH1 from Chimonanthus praecox (L.) was identified as a negative regulator of anthocyanin accumulation. Our results showed that overexpression of CpbHLH1 in model plant species, Arabidopsis and tobacco, resulted in a dramatic decrease in anthocyanin content, whereas the content of proanthocyanidin was little affected. Quantitative RT-PCR (qRT-PCR) assays of the structural genes in the flavonoid biosynthesis pathway revealed that CpbHLH1 inhibits anthocyanin accumulation mainly through repressing the expression of late biosynthesis genes (LBGs). Interactions between CpbHLH1 protein and AtPAP1/NtAN2 protein were detected via yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. This is the first bHLH repressor of anthocyanin biosynthesis identified in dicotyledons. These results can help us better understand the anthocyanin regulatory network in plants and may provide insights into the diverse functions of bHLH proteins.

Finding the fragrance genes of wintersweet.

Fragrant flowers emit a complex mixture of volatile organic compounds (VOCs) that we perceive as pleasant. While we know the chemical nature of these volatiles, the molecular traits that regulate their biosynthesis are poorly understood. In this issue, Tian et al. (2019) compare the transcriptomic and proteomic profiles of a scented genotype of wintersweet (Chimonanthus praecox) with a non-scented one. By correlating the differential gene expression profile with the observed differences in VOC profiles, they attempt to identify the genes that regulate the fragrance of wintersweet.

Transcriptomic and proteomic approaches to explore the differences in monoterpene and benzenoid biosynthesis between scented and unscented genotypes of wintersweet.

Wintersweet (Chimonanthus praecox L.) is an important ornamental plant in China with a pleasant floral scent. To explore the potential mechanisms underlying differences in the fragrances among genotypes of this plant, we analyzed floral volatile organic compounds (VOCs) from two different genotypes: SW001, which has little to no fragrance, and the scented genotype H29. The major VOCs in H29 were linalool, trans-ß-ocimene, benzyl acetate, methyl salicylate, benzyl alcohol (BAlc) and methyl benzoate. The most important aroma-active compound in H29, linalool, was emitted at a low concentration in SW001, which had markedly higher levels of trans-ß-ocimene than H29. Next, to investigate scent biosynthesis, we analyzed the transcriptome and proteome of fully open flowers of the two genotypes. A total of 14 443 differentially expressed unigenes and 196 differentially expressed proteins were identified. Further analyses indicated that 56 differentially expressed genes involved in the terpenoid and benzenoid biosynthesis pathways might play critical roles in regulating floral fragrance difference. Disequilibrium expression of four terpene synthase genes resulted in diverse emission of linalool and trans-ß-ocimene in both genotypes. In addition, the expressions of two CpMYC2 transcription factors were both upregulated in H29, implying that they may regulate linalool production. Notably, 16 of 20 genes in the benzenoid biosynthesis pathway were downregulated, corresponding to the relatively low level of benzenoid production in SW001. The lack of benzyl acetate might indicate that SW001 may lack substrate BAlc or functional acetyl-CoA:benzylalcohol acetyltransferase.

Comprehensive analysis of wintersweet flower reveals key structural genes involved in flavonoid biosynthetic pathway.

Wintersweet (Chimonanthus praecox (L.)), with an over-one-thousand-years long history in cultivation, is still a popular ornamental woody plant in China. The tepals of wintersweet flower are waxy in nature and the overall color of the flower is yellow, while the inner tepals range from yellow to red, which makes it an ideal plant to study floral color formation in ornamental shrubs. In our current work, HPLC analysis revealed that the principal pigments in tepals were the metabolite of flavonoids. All the tepals were containing quercetin, kaempferol 3­O­rutinoside and rutin while cyanidin­3­O­glucoside and cyanidin­3­O­rutinoside were only found in the in the red tepals. Moreover, we found the rutin as the principal component of all the pigments revealed. As well as in this study, a reference transcriptome library constructed from two varieties H29 and H64 flower. Further, 30 proteins of flavonoid biosynthesis pathway were identified in H29 flower using proteome analysis. Based on these dataset, the flavonoid biosynthesis pathway was also speculated. After quantitative analysis of gene expression, we found that ANS act as an on-off switch for the accumulation of red pigments and had positive correlations with various steps genes of the flavonoid pathway. This expression profiling demonstrates that no gene products compete for common substrates to redirect the metabolic flux in wintersweet. It is also demonstrated that high expression of F3'H would provide sufficient content of the precursor, dihydroquercetin, for both flavonol and anthocyanin biosynthesis. The results help us to deepen and enrich the gene resource of color formation in wintersweet flower, and provide specific breeding strategies for increasing diversity of flower color.

Water relations of Calycanthus flowers: Hydraulic conductance, capacitance, and embolism resistance.

For most angiosperms, producing and maintaining flowers is critical to sexual reproduction, yet little is known about the physiological processes involved in maintaining flowers throughout anthesis. Among extant species, flowers of the genus Calycanthus have the highest hydraulic conductance and vein densities of species measured to date, yet they can wilt by late morning under hot conditions. Here, we combine diurnal measurements of gas exchange and water potential, pressure-volume relations, functional responses of gas exchange, and characterization of embolism formation using high resolution X-ray computed microtomography to determine drought responses of Calycanthus flowers. Transpiration from flowers frequently exceeded transpiration from leaves, and flowers were unable to limit transpiration under conditions of high vapour pressure deficit. As a result, they rely heavily on hydraulic capacitance to prevent water potential declines. Despite having high water potentials at turgor loss, flowers were very resistant to embolism formation, with no embolism apparent until tepal water potentials had declined to -2 MPa. Although Calycanthus flowers remain connected to the stem xylem and have high hydraulic capacitance, their inability to curtail transpiration leads to turgor loss. These results suggest that extreme climate events may cause flower failure, potentially preventing successful reproduction.

Studies on the alkaloids of the calycanthaceae and their syntheses.

Plants of the Calycanthaceae family, which possesses four genera and about 15 species, are mainly distributed in China, North America and Australia. Chemical studies on the Calycanthaceae have led to the discovery of about 14 alkaloids of different skeletons, including dimeric piperidinoquinoline, dimeric pyrrolidinoindoline and/or trimeric pyrrolidinoindolines, which exhibit significant anti-convulsant, anti-fungal, anti-viral analgesic, anti-tumor, and anti-melanogenesis activities. As some of complex tryptamine-derived alkaloids exhibit promising biological activities, the syntheses of these alkaloids have also been a topic of interest in synthetic chemistry during the last decades. This review will focus on the structures and total syntheses of these alkaloids.

Correlation between pollen aperture pattern and callose deposition in late tetrad stage in three species producing atypical pollen grains.

PREMISE OF THE STUDY: Pollen grains of flowering plants display a fascinating diversity of forms, in spite of their minute size. The observed diversity is determined by the developmental mechanisms implicated in the establishment of pollen morphological features. Pollen grains are generally surrounded by an extremely resistant wall interrupted in places by apertures that play a key role in reproduction, being the places at which pollen tube growth is initiated. Aperture shape, number, and position are determined during microsporogenesis (male meiosis), the earliest step in pollen ontogeny. We investigate in detail the unfolding of microsporogenesis in three species that present uncommon aperture pattern (i.e., disulculate in Calycanthus floridus [Calycanthaceae, magnoliids], tetraporate in Hohenbergia stellata [Bromeliaceae, monocots], and monoporate in Typha latifolia [Typhaceae, monocots]). METHODS: We performed a comparative analysis of microsporogenesis and aperture distribution within tetrads in these species with contrasting aperture arrangements. This was done using aniline blue coloration and UV light microscope observations. KEYS RESULTS: We show that aperture localization and features of callose deposition on intersporal walls produced during cytokinesis coincide in all three species examined. Such a correlation suggests that patterns of callose deposition are strongly involved in determining aperture localization. CONCLUSION: In flowering plants, patterns of male meiosis and especially callose deposition following meiosis may be implicated in the diversity of pollen aperture patterns.

Molecular cloning and expression of Chimonanthus praecox farnesyl pyrophosphate synthase gene and its possible involvement in the biosynthesis of floral volatile sesquiterpenoids.

Farnesyl pyrophosphate (FPP) synthase catalyzes the biosynthesis of FPP, which is the precursors of sesquiterpenoids such as floral scent volatiles, from isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). cDNA encoding wintersweet (Chimonanthus praecox L.) FPP synthase was isolated by the RT-PCR and RACE methods. The deduced amino acid sequence showed a high identity to plant FPP synthases. Expression of the gene in Escherichia coli yielded FPPS activity that catalyzed the synthesis of FPP as a main product. Tissue-specific and developmental analyses of the mRNA levels of CpFPPS and volatile sesquiterpenoids levels in C. praecox flowers revealed that the FPPS may play a regulatory role in floral volatile sesquiterpenoids of wintersweet.

[Effects of water stress and temperature on gas exchange and chlorophyll fluorescence of Sinocalycanthus chinensis leaves].

Sinocalycanthus chinensis is an endangered species in Sinocalycanthus, and only distributed in Zhejiang Province of China. This paper studied the photosynthetic responses of 2-year-old pot-cultured S. chinensis to different levels of water stress and temperature. The results indicated that under mild and moderate water stress, the net photosynthetic rate (Pn) of S. chinensis leaves was decreased to 92.3% and 74.3% of the control, respectively, which was mainly attributed to stomatal limitation; and under severe water stress, the Pn was decreased to 44.4% of the control, which might be mainly linked to non-stomatal limitation. The appropriate temperature for S. chinensis photosynthesis was from 20 degrees C to 28 degrees C. At 39 degrees C, the Pn, water use efficiency (WUE), and maximal photochemistry efficiency (Fv/Fm) were decreased significantly, while the dark respiration rate (Rd) and transpiration rate (Tr) were enhanced significantly. With increasing water stress and temperature, some photosynthetic parameters including light saturation point (LSP), apparent quantum yield (AQY) and maximal CO2 assimilation rate (Pmax) decreased to certain extents, while light compensation point (LCP) increased, suggesting that both severe water stress and higher temperature were the important environmental factors affecting the survival of S. chinensis.