Peony Research Articles

Identification and characterization of terpene synthase genes accounting for volatile terpene emissions in the flower of Paeonia lactiflora

Emergence of floral scents marked a significant milestone in biological development of plant, letting out olfactory signals that enable them to induce pollinators. In this research, molecular and metabolomics methodologies were used to explore terpene synthase (TPS) genes, which are responsible for synthesis of floral fragrance in Paeonia lactiflora ‘Wu Hua Long Yu’. Analyses on transcriptome data identified 11 PlTPS genes, among them 7 genes were isolated, and the functions of 5 genes were confirmed. PlTPS1 was identified as a single-product enzyme; PlTPS4, 8 and 9 were identified as bifunctional enzymes, capable of recognizing farnesyl pyrophosphate and geranyl pyrophosphate; PlTPS6 generated multiple products by recognizing farnesyl pyrophosphate. Enzymatic products of these PlTPS proteins closely matched the volatile terpenes emitted by flowers, revealing the relation between PlTPS genes and the release of such volatile compounds. Functions of five PlTPS genes in herbaceous peony were further elucidated through virus-induced gene silencing experiments, as well as overexpression in tobacco. PlTPS1 catalyzes geraniol production, while PlTPS4 catalyzes linalool. PlTPS6 is responsible for producing two sesquiterpenes, caryophyllene and α-humulene. PlTPS8, with the most varied products, mainly catalyzes the production of α-pinene, linalool, and germacrene D. Based on these findings, graphical models summarizing the biosynthesis of floral volatile terpenes in herbaceous peony have been proposed. The characterization of PlTPS genes has elucidated their specific roles in the synthesis of herbaceous peony fragrance, opening up possibilities for introducing or enhancing floral scents in herbaceous peony and other plants.

Identification and Analysis of the Superoxide Dismutase (SOD) Gene Family and Potential Roles in High-Temperature Stress Response of Herbaceous Peony (Paeonia lactiflora Pall.).

The herbaceous peony (Paeonia lactiflora Pall.) plant is world-renowned for its ornamental, medicinal, edible, and oil values. As global warming intensifies, its growth and development are often affected by high-temperature stress, especially in low-latitude regions. Superoxide dismutase (SOD) is an important enzyme in the plant antioxidant systems and plays vital roles in stress response by maintaining the dynamic balance of reactive oxygen species (ROS) concentrations. To reveal the members of then SOD gene family and their potential roles under high-temperature stress, we performed a comprehensive identification of the SOD gene family in the low-latitude cultivar 'Hang Baishao' and analyzed the expression patterns of SOD family genes (PlSODs) in response to high-temperature stress and exogenous hormones. The present study identified ten potential PlSOD genes, encoding 145-261 amino acids, and their molecular weights varied from 15.319 to 29.973 kDa. Phylogenetic analysis indicated that PlSOD genes were categorized into three sub-families, and members within each sub-family exhibited similar conserved motifs. Gene expression analysis suggested that SOD genes were highly expressed in leaves, stems, and dormancy buds. Moreover, RNA-seq data revealed that PlCSD1-1, PlCSD3, and PlFSD1 may be related to high-temperature stress response. Finally, based on the Quantitative Real-time PCR (qRT-PCR) results, seven SOD genes were significantly upregulated in response to high-temperature stress, and exogenous EBR and ABA treatments can enhance high-temperature tolerance in P. lactiflora. Overall, these discoveries lay the foundation for elucidating the function of PlSOD genes for the thermotolerance of herbaceous peony and facilitating the genetic breeding of herbaceous peony cultivars with strong high-temperature resistance.

PlLAC15 Facilitates Syringyl Lignin Deposition to Enhance Stem Strength in Herbaceous Peony

Stems are prone to bending or lodging due to inadequate stem strength, which seriously reduces the cut-flower ornamental quality of herbaceous peony (Paeonia lactiflora Pall.). Plant LACCASE (LAC), a copper-containing polyphenol oxidase, has been shown to participate in the polymerization process of monolignols; however, the role of LAC in regulating the stem strength of P. lactiflora remains unclear. Here, the full-length cDNA of PlLAC15, which demonstrated a positive association with stem strength, was isolated. It consisted of 1790 nucleotides, encoding 565 amino acids that had four typical laccase copper ion-binding domains. Moreover, PlLAC15 was highly expressed in the stem, and its expression level gradually significantly increased during stem development. Furthermore, PlLAC15 was found to be localized specifically to the cell wall, and its recombinant protein exhibited laccase activity. Additionally, the role of PlLAC15 in regulating the stem strength of P. lactiflora was confirmed by transgenic studies. When PlLAC15 was overexpressed in tobacco, stem strength increased by more than 50%, S-lignin was significantly deposited, and the lignification degree of stem xylem fiber cells increased. These results suggested that PlLAC15 facilitated S-lignin deposition to enhance stem strength in P. lactiflora, which would provide precious information that benefits future exploration of stem bending or lodging resistance in plants.

PlWRKY47 Coordinates With Cytosolic Glyceraldehyde-3-Phosphate Dehydrogenase 2 Gene to Improve Thermotolerance Through Inhibiting Reactive Oxygen Species Generation in Herbaceous Peony.

Although WRKY transcription factors play crucial roles in plant responses to high-temperature stress, little is known about Group IIb WRKY family members. Here, we identified the WRKY-IIb protein PlWRKY47 from herbaceous peony (Paeonia lactiflora Pall.), which functioned as a nuclear-localized transcriptional activator. The expression level of PlWRKY47 was positively correlated with high-temperature tolerance. Silencing of PlWRKY47 in P. lactiflora resulted in the decreased tolerance to high-temperature stress by accumulating reactive oxygen species (ROS). Overexpression of PlWRKY47 improved plant high-temperature tolerance through decreasing ROS accumulation. Moreover, PlWRKY47 directly bound to the promoter of cytosolic glyceraldehyde-3-phosphate dehydrogenase 2 (PlGAPC2) gene and activated its transcription. PlGAPC2 was also positively regulated high-temperature tolerance in P. lactiflora by increasing NAD+ content to inhibit ROS generation. Additionally, PlWRKY47 physically interacted with itself to form a homodimer, and PlWRKY47 could also interact with one Group IIb WRKY family member PlWRKY72 to form a heterodimer, they all promoted PlWRKY47 to bind to and activate PlGAPC2. These data support that the PlWRKY47-PlWRKY47 homodimer and PlWRKY72-PlWRKY47 heterodimer can directly activate PlGAPC2 expression to improve high-temperature tolerance by inhibiting ROS generation in P. lactiflora. These results will provide important insights into the plant high-temperature stress response by WRKY-IIb transcription factors.

PlPOD45 positively regulates high-temperature tolerance of herbaceous peony by scavenging reactive oxygen species.

The online version contains supplementary material available at 10.1007/s12298-024-01505-x.

Molecular dissection of the parental contribution in Paeonia Itoh hybrids.

Hybrid breeding between herbaceous peonies (the maternal parent) and tree peonies (the paternal parent) results in Paeonia Itoh hybrids (Itoh peonies), a triploid species that combines advantageous traits from both parental species, thus offering great economic value. However, the exact genetic contribution of the two parents is unclear. In this study, we introduce a straightforward approach utilizing heterozygous SNPs and Sanger sequencing of targeted gene fragments to trace the original bases back to their parents in Itoh peonies. Our results indicate that in triploid Itoh peonies, only one set of genes are derived from herbaceous peonies, and two sets of genes are derived from the tree peonies. Notably, the presence of three distinct bases of heterozygous SNPs across multiple Itoh cultivars suggests that the gametes from the paternal parents carry two sets of heterozygous homologous chromosomes, which could be due to meiosis I failure during gamete formation. To validate our method's effectiveness in parentage determination, we analyzed two Itoh hybrids and their parents, confirming its practical utility. This research presents a method to reveal the parental genetic contribution in Itoh peonies, which could enhance the efficiency and precision of hybrid breeding programs of triploids in Paeonia and other plant species.

Identification and Functional Studies on the Role of PlSPL14 in Herbaceous Peony Stem Development.

Stem strength plays a crucial role in the growth and development of plants, as well as in their flowering and fruiting. It not only impacts the lodging resistance of crops, but also influences the ornamental value of ornamental plants. Stem development is closely linked to stem strength; however, the roles of the SPL transcription factors in the stem development of herbaceous peony (Paeonia lactiflora Pall.) are not yet fully elucidated. In this study, we obtained and cloned the full-length sequence of PlSPL14, encoding 1085 amino acids. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression level of PlSPL14 gradually increased with the stem development of P. lactiflora and was significantly expressed in vascular bundles. Subsequently, utilizing the techniques of virus-induced gene silencing (VIGS) and heterologous overexpression in tobacco (Nicotiana tabacum L.), it was determined that PlSPL14-silenced P. lactiflora had a thinner xylem thickness, a decreased stem diameter, and weakened stem strength, while PlSPL14-overexpressing tobacco resulted in a thicker xylem thickness, an increased stem diameter, and enhanced stem strength. Further screening of the interacting proteins of PlSPL14 using a yeast two-hybrid (Y2H) assay revealed an interactive relationship between PlSPL14 and PlSLR1 protein, which acts as a negative regulator of gibberellin (GA). Additionally, the expression level of PlSLR1 gradually decreased during the stem development of P. lactiflora. The above results suggest that PlSPL14 may play a positive regulatory role in stem development and act in the xylem, making it a potential candidate gene for enhancing stem straightness in plants.

First Report of 'Candidatus Phytoplasma ziziphi'-Related Strains Infecting Peony (Paeonia suffruticosa Andr.) Showing Leaf Yellows Symptoms in China.

Peony (Paeonia suffruticosa Andr.), belonging to family Paeoniaceae, is an important medicinal and ornamental plant. During August of each year from 2016 to 2023, peony plants at Heze city were found to exhibit leaf yellows symptoms. The incidence rate of the symptomatic plant was recorded from 10% to 30% in four peony gardens with about 200 acres. Total DNA was extracted from 0.10 g fresh plant leaf tissues from 24 symptomatic and 8 asymptomatic samples using rapid plant genomic DNA isolation kit (Aidlab Biotechnology, Beijing, China). The extracted DNA was amplified by nested polymerase chain reaction using universal primers R16mF2/R16mR1 followed by R16F2/R16R2 (Lee et al., 1993; Gundersen and Lee, 1996) specific for the 16S rRNA gene and new designed tuf gene specific primers JWB-tuforfF1 (5'-ATGGCTGAAATATTTTCAAGAG-3') and JWB-tuforfR1 (5'-TTATTCTATGATTTTAATAACAG-3') followed by JWB-tuforfF2 (5'-ATGTAAACGTAGGAACTATTGG-3') and JWB-tuforfR2 (5'- TCCGATAGTTCTTCCACCTTCAC-3'). Amplicons of about 1.25 kb and 1.02 kb (16S rRNA gene and tuf gene, respectively) were obtained in 8 symptomatic samples from four peony gardens. However, no amplification was obtained in any of the asymptomatic samples. The representative amplicons of 16S rRNA and tuf genes of three positive samples (Heze-9, -18 and -27) were cloned into a zero background pLB-simple vector (Tiangen Biotechnology, Beijing, China) and sequenced by Taihe Biotechnology, Beijing, China. Sequences obtained in the study were deposited in NCBI GenBank with accession numbers PP504882, PP504883 and PP504884 for the 16S rRNA gene as well as PP530237, PP530238 and PP530239 for the tuf gene. The phytoplasma strain under the study was described as peony yellows (PeY) phytoplasma, PeY-Heze strain. Alignment analysis by DNAMAN software showed that three 16S rRNA gene sequences obtained in the study shared 99.36% to 99.60% sequence identity and three tuf gene sequences obtained in the study were identical. BLAST analysis of the 16S rRNA gene sequences of the PeY-Heze phytoplasma strains showed 99.60%-99.84% sequence identity with 'Candidatus Phytoplasma ziziphi' (GenBank accession: CP025121). And tuf sequences of the strains showed 100% similarity with 'Ca. P. ziziphi' (CP025121). Interestingly, the virtual RFLP patterns derived from three 16Sr RNA gene sequences obtained in the study by iPhyClassifier (Zhao et al., 2009) were different from the reference patterns of all previously established 16Sr groups/subgroups. The most similar are the reference pattern of the 16Sr group VII, subgroup E (AY741531), with a similarity coefficient of 0.72, which is less than 0.85. These phytoplasma strains may represent a new 16Sr group. Phylogenetic analysis based on 16S rRNA genes using MEGA 7.0 by neighbor-joining (NJ) method with 1000 bootstrap value indicated that PeY-Heze strains clustered into one clade with the phytoplasma strains of 'Ca. P. ziziphi' with 68% bootstrap value. Although there are several reports available on 'Ca. P. solani' infecting peony in Shandong Province, China (Gao et al., 2013). To our knowledge, this is the first report of 'Ca. P. ziziphi'-related strains infecting peony in China. The findings in this study will be beneficial to the detection, quarantine, and prevention of peony yellows phytoplasmas in China.

The Genus Paeonia: A Review of the Targeted Signaling Pathways and Underlying Mechanisms of Pharmacological and Clinical Properties.

The Paeoniaceae family contains only the Paeonia genus and is considered the major group of flowering plants. Several traditional and pharmacological applications of Paeoniaceae herbs have been described. The current paper aimed to determine the pharmacological activities of the most prevalent herbs from the genus Paeonia by focusing on the underlying mechanism of action and signaling pathways to provide insight for further in-depth research on the medicinal resources of Paeonia. The "Paeoniaceae" keyword was searched from 1st January 1995 to 15th May 2024 through the PubMed and Scopus databases. Only papers related to pharmacology, pharmaceutics, and toxicology were extracted. The possible pharmacological activity of the Paeonia plants underlying their mechanism of action and signaling pathways was subsequently discussed. Following our venture, only 15 Paeonia herbs were adequately evaluated for their pharmacological applications. Paeonia lactiflora Pall., Paeonia suffruticosa Andrews, and Paeonia emodi Royle are among the most prevalent Paeonia plants that have attracted increased amounts of attention in modern pharmacological studies. Paeonia herbs possess various pharmacological applications, such as anti-inflammatory, anti-allergic, anticancer, antimicrobial, cardiovascular protective, cosmetic and skincare, radical scavenging, hepatoprotective and anti-ulcerative, anti-diabetic, musculoskeletal, and neuroprotective effects, and can be used as alternative therapies under critical medical conditions. Among the applications of Paeonia herbs, anti-inflammatory and antioxidant activities are critical, as most of the other pharmacological effects are attributed to them. In other words, nuclear factor (NF)-κB and nuclear factor erythroid 2-related factor 2 (Nrf2) can be considered the most important signaling pathways involved in the pharmacological activity of Paeonia herbs.

Isolation and functional analysis of R2R3-MYB transcription factor PlMYB42 associated with stem strength in herbaceous peony

Lodging resistance is a vital agronomic trait of plants, which affects plant architecture, yield and quality. Herbaceous peony (Paeonia lactiflora Pall.) is considered a high-end cut flowers due to its unique color, pattern, and aroma of flowers, but the traditional cultivated varieties of P. lactiflora have stem lodging. Although several regulatory factors participated in stem development have been identified in other plants, few involved in P. lactiflora have been reported. Here, PlMYB42, a transcription factor isolated from P. lactiflora, was found associated with stem strength and belonged to R2R3-MYB subfamily. PlMYB42 was highly expressed in stems, and showed a rise trend along with stem development. PlMYB42 protein was located in the nucleus and exhibited transcriptional activation activity. Silence of PlMYB42 in P. lactiflora suppressed lignin accumulation and weakened stem strength, while overexpression of PlMYB42 in tobacco promoted stem lignification and increased stem strength. Expression levels of lignin biosynthesis related genes were significantly decreased in PlMYB42 silence lines. These results indicated that PlMYB42 might promote stem strength through lignin accumulation. This work would reveal the genetic basis of lignin accumulation and stem development in P. lactiflora, and provide new insights into plant stem development.

Identification of key genes for triacylglycerol biosynthesis and storage in herbaceous peony (Paeonia lactifolra Pall.) seeds based on full-length transcriptome

BackgroundThe herbaceous peony (Paeonia lactiflora Pall.) is extensively cultivated in China due to its root being used as a traditional Chinese medicine known as ‘Radix Paeoniae Alba’. In recent years, it has been discovered that its seeds incorporate abundant unsaturated fatty acids, thereby presenting a potential new oilseed plant. Surprisingly, little is known about the full-length transcriptome sequencing of Paeonia lactiflora, limiting research into its gene function and molecular mechanisms.ResultsA total of 484,931 Reads of Inserts (ROI) sequences and 1,455,771 full-Length non-chimeric reads (FLNC) sequences were obtained for CDS prediction, TF analysis, SSR analysis and lncRNA identification. In addition, gene function annotation and gene structure analysis were performed. A total of 4905 transcripts were related to lipid metabolism biosynthesis pathway, belonging to 28 enzymes. We use these data to identify 10 oleosin (OLE) and 5 diacylglycerol acyltransferase (DGAT) gene members after de-redundancy. The analysis of physicochemical properties and secondary structure showed them similarity in gene family respectively. The phylogenetic analysis showed that the distribution of OLE and DGAT family members was roughly the same as that of Arabidopsis. Quantitative real-time polymerase chain reaction (qRT–PCR) analyses revealed expression changes in different seed development stages, and showed a trend of increasing and then decreasing.ConclusionIn summary, these results provide new insights into the molecular mechanism of triacylglycerol (TAG) biosynthesis and storage during the seedling stage in Paeonia lactiflora. It provides theoretical references for selecting and breeding oil varieties and understanding the functions of oil storage as well as lipid synthesis related genes in Paeonia lactiflora.

Integration of RNA-Seq and Metabolite Analysis Reveals the Key Floral Scent Biosynthetic Genes in Herbaceous Peony

Floral scent is an essential and genetically complex trait in herbaceous peonies (Paeonia lactiflora Pall.); however, specific genes related to metabolic and regulatory networks remain scantily studied. Our study integrated metabolite profiling and RNA-sequencing to screen floral scent biosynthetic genes. Hence, the major molecules identified by headspace collection combined with cultivar-specific GC-MS analysis were geraniol, β-caryophyllene, 2-phenylethanol (2-PE), citronellol, and 1,8-cineole. Genes related to terpenoids and 2-PE biosynthesis were identified after the assembly and annotation of the P. lactiflora transcriptomes. Eight angiosperm-specific terpene synthases (TPSs) from the TPS-a and TPS-b clades, as well as enzymes linked to 2-PE synthesis such as aromatic amino acid decarboxylase (AADC), phenylacetaldehyde reductase (PAR), and geranial reductase (GER) were identified. The biochemical analysis of the enzymes encoded by PlPAR1 and PlGER1 generated 2-PE from phenylacetaldehyde (PAld). The pairwise alignment of AADC1 reveals a splice variant lacking a 124 bp fragment, thus highlighting the possible role of alternative splicing in modulating floral scent composition. This study offers insights into the molecular-level biosynthesis of terpenoids and 2-PE in Peonia taxa, and provides the basis for the functional characterization, breeding, and bioengineering of prospective candidate genes for the production of floral volatiles in the Paeonia genus.

Exploring miRNA-target modules in Paeonia lactiflora stamen petalization through integrated miRNAome, transcriptome, and degradome analysis

Variation in floral organ number in plants is triggered by extremely complex transcriptional and post-transcriptional regulatory processes. MicroRNAs (miRNAs) play a pivotal role in the post-transcriptional regulation of floral organs. Paeonia lactiflora Pall., originating from China, is a precious herbaceous plant with ornamental, medicinal, and oil properties. Building on previous transcriptional studies, this work examined post-transcriptional regulation of peony stamen petalization using critical-stage flower buds. Using high-throughput small RNA sequencing, a miRNA expression profile was constructed. This was used to identify 10 known, 334 conserved, and 255 novel miRNAs, 155, 151, and 44 of which were differentially expressed at three developmental stages (stamen primordium, stamen primordium partly petaloid, and stamen primordium completely petaloid). Degradome analysis identified 55 miRNAs and 127 potential target genes. A miRNA-target network suggested that miR172-PlRAP2, miR160-PlARF, miR396-PlGRF, miR319-PlTCP4, and miR384\\394-PlFBOX modules are key regulators of peony stamen petalization. The regulation of miR319 and PlTCP4 during peony flower development was validated through transient expression in tobacco. This study provides insight into miRNA-mediated regulation of petalized stamen formation in herbaceous peony and refines the post-transcriptional network at critical stages of this process.

A novel source of biologically active compounds – The leaves of Serbian herbaceous peonies

In order to gain further insight into how various extraction techniques (maceration, microwave-, and ultrasound-assisted extractions) affect the chemical profile and biological activities of leaf extracts from Paeonia tenuifolia L., Paeonia peregrina Mill., and Paeonia officinalis L., this research was performed. The targeted chemical characterization of the extracts was achieved using the Ultra-High-Performance-Liquid-Chromatography-Linear-Trap-Mass-Spectrometry OrbiTrap instrumental technique, while Fourier Transform Infrared Spectroscopy was conducted to investigate the structural properties of the examined leaf extracts. According to the results, the species P. officinalis, Božurna locality as the origin of the plant material, and microwave-assisted extraction produced the maximum polyphenol yield, (491.9 ± 2.7 mg gallic acid equivalent (GAE)/mL).The ethanolic extracts exhibited moderate antioxidant activity as evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) and phosphomolybdenum tests. With MIC values of 0.125 mg/mL, the leaf extracts produced by ultrasound-assisted extraction and maceration (Deliblato sands and Bogovo gumno) had the best antibacterial activity against Pseudomonas aeruginosa and Salmonella Typhimurium. Ultrasound-assisted extraction has proven to produce the most effective antimicrobial agents. Inhibitory potential towards glucosidase, amylase, cholinesterases, and tyrosinase was evaluated in enzyme inhibition assays and molecular docking simulations. Results show that leaves of P. tenuifolia L. obtained by ultrasound-assisted extraction had the highest acetylcholinesterase and butyrylcholinesterase inhibitory activity. Namely, the complexity of the polyphenol structures, the extraction method, the used locality, and the different mechanisms of the reactions between bioactives from leaf extracts and other components (free radicals, microorganisms, and enzymes) are the main factors that influence the results of the antioxidant tests, as well as the antibacterial and enzyme-inhibitory activities of the extracts. Hydroxymethyl-phenyl pentosyl-hexoside and acetyl-hydroxyphenyl-hexoside were the first time identified in the leaf extract of the Paeonia species. Due to their proven biological activities and the confirmed existence of bioactive compounds, leaf extracts may find use in foodstuffs, functional foods, and pharmaceutical products.

Establishment of a Homologous Silencing System with Intact-Plant Infiltration and Minimized Operation for Studying Gene Function in Herbaceous Peonies.

Gene function verification is a crucial step in studying the molecular mechanisms regulating various plant life activities. However, a stable and efficient homologous genetic transgenic system for herbaceous peonies has not been established. In this study, using virus-induced gene silencing technology (VIGS), a highly efficient homologous transient verification system with distinctive advantages was proposed, which not only achieves true "intact-plant" infiltration but also minimizes the operation. One-year-old roots of the representative species, Paeonia lactiflora Pall., were used as the materials; prechilling (4 °C) treatment for 3-5 weeks was applied as a critical precondition for P. lactiflora to acquire a certain chilling accumulation. A dormancy-related gene named HOMEOBOX PROTEIN 31 (PlHB31), believed to negatively regulate bud endodormancy release (BER), was chosen as the target gene in this study. GFP fluorescence was detected in directly infiltrated and newly developed roots and buds; the transgenic plantlets exhibited remarkably earlier budbreak, and PlHB31 was significantly downregulated in silenced plantlets. This study established a homologous transient silencing system featuring intact-plant infiltration and minimized manipulation for gene function research, and also offers technical support and serves as a theoretical basis for gene function discovery in numerous other geophytes.

Phytochemical Analysis, Biological Activities, and Molecular Docking Studies of Root Extracts from Paeonia Species in Serbia.

Without being aware of their chemical composition, many cultures have used herbaceous peony roots for medicinal purposes. Modern phytopreparations intended for use in human therapy require specific knowledge about the chemistry of peony roots and their biological activities. In this study, ethanol-water extracts were prepared by maceration and microwave- and ultrasound-assisted extractions (MAE and UAE, respectively) in order to obtain bioactive molecules from the roots of Paeonia tenuifolia L., Paeonia peregrina Mill., and Paeonia officinalis L. wild growing in Serbia. Chemical characterization; polyphenol and flavonoid content; antioxidant, multianti-enzymatic, and antibacterial activities of extracts; and in vitro gastrointestinal digestion (GID) of hot water extracts were performed. The strongest anti-cholinesterase activity was observed in PT extracts. The highest anti-ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical potential was observed in PP extracts, whereas against DPPH (2,2-diphenyl-1-picrylhydrazyl radicals), the best results were achieved with PO extracts. Regarding antibacterial activity, extracts were strongly potent against Bacillus cereus. A molecular docking simulation was conducted to gather insights into the binding affinity and interactions of polyphenols and other Paeonia-specific molecules in the active sites of tested enzymes. In vitro GID of Paeonia teas showed a different recovery and behavior of the individual bioactives, with an increased recovery of methyl gallate and digallate and a decreased recovery of paeoniflorin and its derivatives. PT (Gulenovci) and PP (Pirot) extracts obtained by UAE and M were more efficient in the majority of the bioactivity assays. This study represents an initial step toward the possible application of Paeonia root extracts in pharmacy, medicine, and food technologies.

Morphological, cytological, physiological, and molecular evidence to explain how underground fleshy roots expand in herbaceous peony (Paeonia lactiflora Pall.)

The fleshy roots of herbaceous peonies serve as vital storage organs and are the primary source material for Chinese herbal medicine. Moreover, in certain cultivars, these roots can be propagated by root cuttings. However, the specific mechanisms governing the expansion and development of fleshy roots in herbaceous peonies currently remain unclear. To elucidate patterns of changes during the enlargement and development of herbaceous peony fleshy roots, this study assessed fleshy roots in six growth and development periods (P1–P6). By integrating environmental monitoring data, morphological, cytological, physiological and biochemical, as well as molecular characteristics across these developmental periods were compared. Both precipitation and temperature influenced the development of fleshy roots. The fastest enlargement of fleshy roots occurred under the following growth conditions: daily average precipitation = 5.6 mm; monthly average air temperature = 25.6°C; monthly average soil temperature = 26.3°C. Phloem and xylem, produced by the activity of vascular cambium, are important components of fleshy roots. Secondary xylem thickness consistently increased across the six developmental periods, resulting in the radial expansion of fleshy roots. When average monthly air and soil temperatures were about 26°C, starch accumulated gradually in fleshy roots, and carbohydrates were mostly starch-based. However, when the average monthly air and soil temperatures decreased to about 11.0°C, soluble sugar content increased. Endogenous hormones such as IAA, ZR, GA3, MeJA, and ABA played regulatory roles throughout the development of fleshy roots, and their levels and dynamic equilibrium were correlated with expansion rate. Elevated IAA and ZR content, and stabilized IAA/ABA and MeJA/ABA ratios, favored fleshy root expansion. Trends in the expression of three genes that play key roles in the expansion of fleshy roots (PlEXLB3, PlAUX1 and PlWRKY13) were consistent with morphological and physiological data, but PlHXK1 and PlIPT3 also play important roles. These findings lay a foundation for studying, in greater depth, the regulatory mechanisms governing the enlargement of herbaceous peony fleshy roots, and offer practical advice pertaining to field cultivation and management practices of this ornamental plant.

Transcriptome Sequencing Provides Insights into High-Temperature-Induced Leaf Senescence in Herbaceous Peony

Global warming causes frequent high temperatures in summer; which negatively impacts herbaceous peonies (Paeonia lactiflora Pall.) by accelerating leaf senescence and reducing biomass accumulation, leading to reduced flower quality in the subsequent year. Our findings revealed that as heat stress progressed, the high-temperature-sensitive cultivar ‘Meigui Zi’ (MGZ) exhibited a higher rate of chlorophyll content reduction and more pronounced premature aging symptoms than the high-temperature-tolerant cultivar ‘Chi Fen’ (CF). To investigate gene expression differences between CF and MGZ under high-temperature stress, we combined PacBio Iso-Seq sequencing (Iso-Seq) with next-generation sequencing (RNA-seq). Iso-seq yielded 352,891 full-length transcripts ranging from 61 bp to 49,022 bp in length. RNA-seq generated 257,562 transcripts across all samples. Further analysis revealed that differentially expressed genes (DEGs) between CF and MGZ were primarily enriched in “Photosynthesis”, with most photosynthesis-related DEGs highly expressed in CF. This indicates that CF has higher stability in its photosystem compared with MGZ, which is crucial for mitigating leaf senescence caused by high temperatures. Additionally, the highly expressed chlorophyll degradation genes stay-green (SGR) and stay-green-like (SGRL) in MGZ may be involved in chlorophyll content reduction induced by high temperature. This study preliminarily revealed the molecular mechanism of high-temperature-induced leaf senescence of in herbaceous peony and provided candidate genes for further studies of the regulation mechanism of high -temperature-induced leaf senescence.

Cytogenetic analysis reveals a mechanism of compatibility in distant hybridization between tree peony and herbaceous peony

Cytogenetic analysis reveals a mechanism of compatibility in distant hybridization between tree peony and herbaceous peony

Transcriptome and volatile compounds analyses of floral development provide insight into floral scent formation in Paeonia lactiflora 'Wu Hua Long Yu'.

Herbaceous peony (Paeonia lactiflora) is a well-known ornamental plant in China, celebrated for its beautiful flowers that can emit fragrances. However, exact molecular mechanisms governing synthesis of floral volatiles within herbaceous peony remain unclear. To address this gap in knowledge, our study focused on analyzing the transcriptome and the levels of floral volatile compounds in P. lactiflora 'Wu Hua Long Yu' at different stages of flower development. Using gas chromatography-mass spectrometry (GC-MS), we obtained eighteen major volatile compounds, with monoterpenes being the dominant components among them. Our transcriptome analysis, based on pooled sequencing data, revealed the most differentially expressed genes (DEGs) existed between stages S1 and S3 of flower development. Among these DEGs, we identified 89 functional genes associated with the synthesis of volatile monoterpenes, with 28 of these genes showing a positive correlation with the release of monoterpenes. Specifically, key regulators of monoterpene synthesis in herbaceous peony appear to be 1-deoxy-D-xylulose 5-phosphate synthase (DXS), geranyl pyrophosphate synthase (GPPS), and terpene synthase (TPS). Additionally, our study identified some transcription factors (TFs) that may be involved in the biosynthesis of monoterpenes. These discoveries offer invaluable illumination into the intricate molecular underpinnings orchestrating the generation of floral fragrances in herbaceous peonies, and they offer a foundation for further research to identify and utilize candidate gene resources for this purpose.