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Herbaceous peony (Paeonia lactiflora Pall) is resistant to drought but not waterlogging. The main production areas of peony are prone to waterlogging, seriously affecting the growth and development of herbaceous peony. Polyamines have been observed to significantly enhance the ability of plants to defend and repair adverse damage and affect the synthesis and accumulation of the endogenous growth hormones indole-3-acetic acid (IAA) and abscisic acid (ABA). In this study, two herbaceous peony varieties ('Lihong', 'Qihualushuang') with different waterlogging tolerances were selected for artificial simulated waterlogging treatment to observe their morphological indexes and to determine their endogenous polyamine and hormone contents. Simultaneously, transcriptome sequencing and bioinformatics analysis were performed, focusing on screening differentially expressed genes in the polyamine metabolism pathway. The results showed that flood-tolerant varieties of herbaceous peony respond to waterlogging stress by continuously synthesizing spermidine (Spd) and spermine (Spm) through putrescine (Put) to counteract adversity. In the waterlogging-intolerant varieties, the expression of polyamine oxidase-related genes was annotated; their response to waterlogging stress was the simultaneous degradation of Spm and Spd to Put in the process of synthesis, and a decrease in the accumulation of Spm and Spd led to the early appearance of the symptoms of damage. In addition, polyamines influence key hormones that respond to plant adversity (IAA; ABA). The objective of this work was to initially analyze the mechanism of the polyamine signaling pathway in response to flooding in herbaceous peonies for further in-depth research on the mechanism of flooding tolerance in herbaceous peony, screen flood-tolerant varieties, and promote of their use. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Paeonia peregrina Mill. is a protected, herbaceous species native to Southeastern Europe and Turkey. Due to its vulnerability, it has to be protected both in its natural habitats and through cultivation. Peonies are known to have a low potential for natural regeneration due to their seed dormancy, low germination rate, and long germination period. In this study, treatments with gibberellic acid (GA3 150, 200, 250, 300, and 350 mg L−1 GA3) and warm (at 20/16 °C day/night regime) and cold stratification (at 4 °C) were used to accelerate dormancy release and increase the germination rate. The seeds of P. peregrina from four natural habitats in Serbia and the Institute's collection were collected and analyzed. They showed an underdeveloped embryo that needs to grow inside the seed before it can germinate. The application of GA3 accelerated each stage of germination (seed coat rapturing, hypocotyl dormancy release, and epicotyl dormancy release) for approximately 10 days compared to the control. It was also found that two-day imbibition with 200 mg L−1 GA3 significantly accelerated and equalized germination. Higher GA3 concentrations had a more pronounced impact on each stage but also resulted in greater seed infection after the seed coat rupture, elongated and weak seedlings, while lower concentrations did not result in obtaining uniform seedlings. There were no significant differences observed between localities. Restoring P. peregrina through seeds and nursery-produced plants is crucial for conserving the genetic diversity of the tested species. [ABSTRACT FROM AUTHOR]

In July 2022, stem rot symptom was found in a peony plant grown in a pot under a greenhouse at Jinju, Gyeongnam Province, South Korea. Two fungal species were isolated from the infected peony stems and cultured on 1/2-strength potato dextrose agar for identification. The morphological characteristics of the fungal isolates were examined, and nucleotide sequences of the internal transcribed spacer region, β-tubulin and translation elongation factor 1-α were analysed. The pathogenicity of the two isolates was confirmed in detached peony leaves, according to Koch's postulates. To our knowledge, this is the report of Neopestalotiopsis clavispora and Sclerotinia sclerotiorum as the causal agents of peony stem rots. Antifungal activity of chemical fungicide propineb and rhizobacterium Bacillus siamensis H30-3 was shown against the two plant pathogenic fungi N. clavispora and S. sclerotiorum. Unidentified diffusible and volatile compounds from B. siamensis H30-3 could suppress in vitro mycelial growths of N. clavispora JJ 8-2-1 and S. sclerotiorum JJ 8-2-2.

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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. [ABSTRACT FROM AUTHOR]

Abstract There are replanting problems in the production of herbaceous peony. If ramet seedlings are replanted in the original planting hole, they weaken year-by-year until their death, which reduces the land utilisation rate and increases the production costs. In this study, exogenous lactic acid bacteria (LAB, the main component is Lactobacillus plantarum) were applied to improve the planting soil of herbaceous peony for the first time to alleviate the replanting problems, to reduce the production costs, and to provide a new way to promote the of the herbaceous peony industry. In this study, herbaceous peony main cultivars varieties ‘Dafugui’ ‘Hongxiuqiu’ and ‘Zifengyu’ were selected, and experiments were conducted using exogenous LAB. Morphological, rhizosphere soil, and root physiology indexes were measured by sampling at the end of the high-growth periods of herbaceous peony. The results showed that after LAB treatment, the plant height, flowering rate, other morphological indexes and root vitality of ‘Hongxiuqiu’ were increased, with a better promoting effect than that of ‘Dafugui’ and ‘Zifengyu’. The ‘Dafugui’ rhizosphere soil nutrient content and enzyme activity were improved, followed by ‘Hongxiuqiu’ and ‘Zifengyu’. The rhizosphere soil free salicylic acid content and root abscisic acid content decreased, whereas the soil bacterial abundance, root antioxidant enzyme activity, proline and paeoniflorin content increased in all varieties. This study found that LAB application can improve soil fertility and enzyme activity, promote the growth and development of herbaceous peony, increase the flowering rate and improve the ornamental value. However, the influence of LAB on different herbaceous peony varieties varied. Therefore, it is necessary to further expand the number of varieties, optimise the application concentration and frequency of LAB application, alleviate the replanting problems in herbaceous peony production, improve the utilisation rate of land, promote excellent varieties of herbaceous peony, and provide a new methods and references. Graphical abstract

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.

Herbaceous peony (Paeonia lactiflora Pall) is resistant to drought but not waterlogging. The main production areas of peony are prone to waterlogging, seriously affecting the growth and development of herbaceous peony. Polyamines have been observed to significantly enhance the ability of plants to defend and repair adverse damage and affect the synthesis and accumulation of the endogenous growth hormones indole-3-acetic acid (IAA) and abscisic acid (ABA). In this study, two herbaceous peony varieties (‘Lihong’, ‘Qihualushuang’) with different waterlogging tolerances were selected for artificial simulated waterlogging treatment to observe their morphological indexes and to determine their endogenous polyamine and hormone contents. Simultaneously, transcriptome sequencing and bioinformatics analysis were performed, focusing on screening differentially expressed genes in the polyamine metabolism pathway. The results showed that flood-tolerant varieties of herbaceous peony respond to waterlogging stress by continuously synthesizing spermidine (Spd) and spermine (Spm) through putrescine (Put) to counteract adversity. In the waterlogging-intolerant varieties, the expression of polyamine oxidase-related genes was annotated; their response to waterlogging stress was the simultaneous degradation of Spm and Spd to Put in the process of synthesis, and a decrease in the accumulation of Spm and Spd led to the early appearance of the symptoms of damage. In addition, polyamines influence key hormones that respond to plant adversity (IAA; ABA). The objective of this work was to initially analyze the mechanism of the polyamine signaling pathway in response to flooding in herbaceous peonies for further in-depth research on the mechanism of flooding tolerance in herbaceous peony, screen flood-tolerant varieties, and promote of their use.

Paeonia peregrina Mill. is a protected, herbaceous species native to Southeastern Europe and Turkey. Due to its vulnerability, it has to be protected both in its natural habitats and through cultivation. Peonies are known to have a low potential for natural regeneration due to their seed dormancy, low germination rate, and long germination period. In this study, treatments with gibberellic acid (GA3 150, 200, 250, 300, and 350 mg L−1 GA3) and warm (at 20/16 °C day/night regime) and cold stratification (at 4 °C) were used to accelerate dormancy release and increase the germination rate. The seeds of P. peregrina from four natural habitats in Serbia and the Institute’s collection were collected and analyzed. They showed an underdeveloped embryo that needs to grow inside the seed before it can germinate. The application of GA3 accelerated each stage of germination (seed coat rapturing, hypocotyl dormancy release, and epicotyl dormancy release) for approximately 10 days compared to the control. It was also found that two-day imbibition with 200 mg L−1 GA3 significantly accelerated and equalized germination. Higher GA3 concentrations had a more pronounced impact on each stage but also resulted in greater seed infection after the seed coat rupture, elongated and weak seedlings, while lower concentrations did not result in obtaining uniform seedlings. There were no significant differences observed between localities. Restoring P. peregrina through seeds and nursery-produced plants is crucial for conserving the genetic diversity of the tested species.

There are replanting problems in the production of herbaceous peony. If ramet seedlings are replanted in the original planting hole, they weaken year-by-year until their death, which reduces the land utilisation rate and increases the production costs. In this study, exogenous lactic acid bacteria (LAB, the main component is Lactobacillus plantarum) were applied to improve the planting soil of herbaceous peony for the first time to alleviate the replanting problems, to reduce the production costs, and to provide a new way to promote the of the herbaceous peony industry. In this study, herbaceous peony main cultivars varieties 'Dafugui' 'Hongxiuqiu' and 'Zifengyu' were selected, and experiments were conducted using exogenous LAB. Morphological, rhizosphere soil, and root physiology indexes were measured by sampling at the end of the high-growth periods of herbaceous peony. The results showed that after LAB treatment, the plant height, flowering rate, other morphological indexes and root vitality of 'Hongxiuqiu' were increased, with a better promoting effect than that of 'Dafugui' and 'Zifengyu'. The 'Dafugui' rhizosphere soil nutrient content and enzyme activity were improved, followed by 'Hongxiuqiu' and 'Zifengyu'. The rhizosphere soil free salicylic acid content and root abscisic acid content decreased, whereas the soil bacterial abundance, root antioxidant enzyme activity, proline and paeoniflorin content increased in all varieties. This study found that LAB application can improve soil fertility and enzyme activity, promote the growth and development of herbaceous peony, increase the flowering rate and improve the ornamental value. However, the influence of LAB on different herbaceous peony varieties varied. Therefore, it is necessary to further expand the number of varieties, optimise the application concentration and frequency of LAB application, alleviate the replanting problems in herbaceous peony production, improve the utilisation rate of land, promote excellent varieties of herbaceous peony, and provide a new methods and references. [ABSTRACT FROM AUTHOR]

To identify herbaceous peony cultivars with strong photosynthetic productivity, we compared the photosynthetic characteristics of 20 herbaceous peony cultivars based on four photosynthetic characteristics parameters and established light–response curves under a light intensity gradient, using CIRAS-3 portable photosynthetic dynamic monitoring. The net photosynthetic rate (Pn) showed a "unimodal" diurnal variation pattern, with a peak around 12:00. The diurnal pattern of the transpiration rate was the same as that of Pn. Stomatal conductance values (Gs) showed similar patterns among the cultivars, with only small differences. The daily variation in intracellular CO2 concentration (Ci) showed an opposite trend to that of Pn. When the photosynthetically active radiation was 0–400 μmol·m−2s−1, Pn increased linearly and gradually with increasing light intensity. 'Xueyuanhonghua', 'Qingwen', 'Taohuafeixue', 'Chifen', and 'Qihualushuang' showed high photosynthetic productivity. 'Xueyuanhonghua', 'Fushi', 'Qingwen', 'Tianshanhongxing', 'Qingtianlan', 'Dafugui', and 'Hongfushi' had high light saturation points and the highest light resistance. 'Xueyuanhonghua', 'Qingwen', 'Taohuafeixue', 'Tianshanhongxing', 'Qingtianlan', 'Guifeichacui', 'Chifen', and 'Hongxiuqiu' had low light compensation points. Thus, two cultivars with strong photosynthetic productivity, 'Xueyuanhonghua' and 'Qingwen', can be cross-bred to obtain both light- and shade-tolerant plants. This study provides a theoretical basis for breeding new cultivars with high photosynthetic productivity. [ABSTRACT FROM AUTHOR]

The herbaceous peony (Paeonia lactiflora Pall.) has high ornamental value. Replanting problems occur when seedlings are replanted into previous holes. We studied the root system and soil environment of the 'Dongjingnvlang' variety under a continuous planting regime of one, four, and seven years, and a replanting regime of one and four years. Under the condition of continuous planting, with the increase of number of years, pH, ammonium nitrogen, and nitrate nitrogen decreased in the rhizosphere and non-rhizosphere soils, whereas organic matter, available phosphorus and potassium, enzyme activities, and the number of bacteria, fungi, and actinomycetes increased. Under the condition of replanting, with the increase of number of years, fungi and actinomycetes in both soils increased, while pH, organic matter, nutrients, enzyme activities, and bacterial number decreased. pH, organic matter, nutrient content, enzyme activity and the number of bacterial were lower in soil replanted for four years, whereas the abundance of fungi and actinomycetes was higher, altering the soil from "bacterial high-fertility" to "fungal low-fertility" with increasing years of replanting. The activity of antioxidant enzymes and MDA content in roots of peony in replanting were higher than those in continuous planting, while the content of osmotic regulatory substances in replanting was lower than that in continuous planting. The results showed that there were no obvious adverse factors in soil during seven years of continuous planting, and herbaceous peony could maintain normal growth and development. However, soils after four years of replanting were not suitable for herbaceous peony growth. Benzoic acid increased with years of replanting, which potentially caused replanting problems. This study provides a theoretical basis for understanding the mechanism of replanting problems in the herbaceous peony. [ABSTRACT FROM AUTHOR]

Leaf spot disease caused by Alternaria pathogens seriously threatens peony production. The physiological mechanism of peony resistance to the pathogen is little reported. This study aimed to reveal the defensive mechanism of peonies in response to the pathogen Alternaria tenuissima. The disease-resistant (R) variety 'Zi Fengyu' and susceptible (S) variety 'Heihai Botao' were employed, and some parameters in the leaves were analyzed after inoculation with A. tenuissima, mainly including the hypersensitive response (HR), activity of defensive enzymes, and expression of disease-resistance genes. The results showed that compared with the responses in the S genotype, HR occurred more rapidly in the R genotype. Meanwhile, the activity of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) and other two defense enzymes (polyphenol oxidase and phenylalanine ammonia-lyase) increased more significantly, and the expression of pathogenesis-related (PR) genes (PlPR1, PlPR2, PlPR4B, PlPR5, and PlPR10) and two WRKY genes (PlWRKY13 and PlWRKY65) was more strongly induced. These responses collectively contributed to the disease resistance of the R genotype. These findings provided a theoretical basis for understanding the intrinsic mechanism of peony resistance to Alternaria leaf spot disease and breeding the disease-resistant peony varieties using a molecular approach. [ABSTRACT FROM AUTHOR]

Paeonia peregrina Mill. is a perennial herbaceous plant species, known for the medicinal value of all of its plant parts, although the chemical composition of the petals is unknown. This study aimed to determine the chemical fingerprint of the petals and also establish the optimal extraction parameters, extraction medium, and extraction method for petals collected from different localities in Serbia. The optimization was performed in order to acquire extracts that are rich in the contents of total polyphenol content (TPC) and total flavonoid content (TFC), and also exhibit strong antioxidant activity. In addition, the influence of the extracts on several human skin pathogens was evaluated, as well as their ability to aid wound closure and act as anti-inflammatory agents. Both the extraction medium and the applied technique significantly influenced the skin-beneficial biological activities, while methanol proved to be a more favorable extraction medium. In conclusion, the extraction conditions that yielded the extract with the richest phenolic content with satisfactory biological potential varied between the assays, while the most promising locality in Serbia for the collection of P. peregrina petals was Pančevo (South Banat). [ABSTRACT FROM AUTHOR]

Flower scent is one of the main ornamental characteristics of herbaceous peony, and the improvement of flower fragrance is a vital objective of herbaceous peony breeding. In this study, 87 herbaceous peony cultivars were divided into three groups (no/light fragrance, medium fragrance, and strong fragrance) based on their sensory evaluation scores, and 16 strong fragrance cultivars and one no fragrance cultivar were selected for subsequent analysis. Sixty-eight volatile components were detected in these 17 cultivars based on solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS), and 26 types were identified as important scent components. They were composed of terpenoids, benzenoids/phenylpropanoids, and fatty acid derivatives. According to the content and odor threshold of these main aroma components, the characteristic aroma substances of herbaceous peony were identified, including linalool, geraniol, citronellol, and phenylethyl alcohol (2-PE). The cultivars of strong scented herbaceous peony were divided into three types: rose scent, lily scent, and mixed scent. We explored the possible key genes of characteristic aroma substances in herbaceous peony petals with different odors through the qRT-PCR. The key genes encoding monoterpene biosynthesis were found to be PlDXS2, PlDXR1, PlMDS1, PlHDR1, PlGPPS3, and PlGPPS4. In addition, the linalool synthase (LIS) gene and the geraniol synthase (GES) gene were also found. PlAADC1, PlPAR1, and PlMAO1, related to the biosynthesis of 2-PE were detected, and the synthetic pathway of 2-PE was speculated. In conclusion, these findings revealed that the difference in gene expression of monoterpene and 2-PE synthesis pathway was related to the difference in the fragrance of herbaceous peony. This study explored the releasing pathway of herbaceous peony characteristic aroma substances and provided key genetic resources for fragrance improvement. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) has emerged in the cut flower market due to its beautiful appearance. The bending flower stems caused by a lack of mechanical strength is the main problem restricting the development of the cut P. lactiflora industry. So it is of great worth to reveal the basis of stem development changes in P. lactiflora to improve its cut flower quality. Quantitative research on gene expression characteristics can provide clues for understanding their biological functions, and the screening of relatively stable expression genes is a prerequisite for the quantitative study of gene expression characteristics. Thus, it is necessary to find appropriate genes during stem development so as to analyze the qRT‒PCR results. In this study, 10 genes were screened, and these genes expressed stably in stems of different stem strengths at three different developmental stages. Then, their expressions were evaluated by RefFinder, BestKeeper, NormFinder, and GeNorm programs. The results demonstrated that γ-tubulin (γ-TUB) was the most suitable gene, followed by α-tubulin (α-TUB) and β-D-glucosidase (β-GUS), whereas histone H3 (His) was the least suitable gene. Besides, the temporal and spatial expression characteristics of PlCOMT1, the key gene concerned with the synthesis of cell wall fillers in P. lactiflora, were also used to evaluate the suitability of genes. Consequently, γ-TUB and α-TUB are the two best combinations during stem development, and their combination can be used for the stem development of P. lactiflora. These findings will provide a reference for the selection of genes related to stem development and the study of molecular mechanisms related to stem development in P. lactiflora. [ABSTRACT FROM AUTHOR]

When used for ornamental purposes, the herbaceous peony is usually propagated by root ramets, but the replanting of divided seedlings in the original planting area results in poor growth and development. No research has reported on a compound microbial agent used for herbaceous peony. The purpose of this experiment is to provide a reference for low–cost soil improvement in production, promote the growth and development of herbaceous peony, and solve the problem of planting back obstacles. In this study, 3–year–old seedlings of herbaceous peony 'Zifengyu' were selected and planted into an ordinary garden and replanted soils. Four root irrigation treatments were conducted using the compound microbial agent 'Junzhongjun' to determine the physicochemical properties of rhizosphere soil, root physiology, and growth and development of 'Zifengyu' under different soil conditions. The growth and development of the aboveground parts of herbaceous peony were promoted by the treatment of the compound microbial agent in the following order: garden soil > sieved–root soil > unsieved–root soil. Root vigour was enhanced in the following sequence: sieved–root soil > unsieved–root soil > garden soil. The organic matter and available potassium in the rhizosphere soil of herbaceous peony increased, and the promotional effect in the sieved–root soil was significantly better than that in the other two soils. The results show that the compound microbial agent is low in cost and has a stimulating effect on the growth and development of herbaceous peony. In the process of production, the residual broken roots in the soil can be sieved and combined with the application of the compound microbial agent to further alleviate the barriers of replanting. The concentration and frequency of agent application should be further optimized at a later stage. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is a famous ornamental plant, and the study of its flower color is of great significance for cultivating new flower varieties. To explore the factors driving the formation and change of herbaceous peony flower color, we selected five herbaceous peony varieties at four flowering stages to determine the change in flower color, petal area, and microstructure. We also examined the composition and content of petal pigments, soluble sugar and soluble protein content, pH value of cell fluid, and water content. Finally, we analyzed the correlations between each factor. We found that Pn3G5G, Pg3G5G, and Cy3G5G were the main anthocyanin components in red and purple petals. Qu3G, Qu7G, Is3G, and lutein play important roles in yellow petal formation. The change in herbaceous peony flower color during the flowering process is directly caused by changes in the anthocyanin and carotenoid content in petals. In addition, changes in other physiological indices also influence the change in flower color. This study explored the physiological and biochemical factors affecting the color of herbaceous peony petals, which has an important practical significance for studying the physiological mechanism of herbaceous peony flower color formation and color breeding of new flowers. [ABSTRACT FROM AUTHOR]

SUMMARY: Stem strength is an important agronomic trait affecting plant lodging, and plays an essential role in the quality and yield of plants. Thickened secondary cell walls in stems provide mechanical strength that allows plants to stand upright, but the regulatory mechanism of secondary cell wall thickening and stem strength in cut flowers remains unclear. In this study, first, a total of 11 non‐redundant Paeonia lactiflora R2R3‐MYBs related to stem strength were identified and isolated from cut‐flower herbaceous peony, among which PlMYB43, PlMYB83 and PlMYB103 were the most upregulated differentially expressed genes. Then, the expression characteristics revealed that these three R2R3‐MYBs were specifically expressed in stems and acted as transcriptional activators. Next, biological function verification showed that these P. lactiflora R2R3‐MYBs positively regulated stem strength, secondary cell wall thickness and lignin deposition. Furthermore, yeast‐one‐hybrid and dual luciferase reporter assays demonstrated that they could bind to the promoter of caffeic acid O‐methyltransferase gene (PlCOMT2) and/or laccase gene (PlLAC4), two key genes involved in lignin biosynthesis. In addition, the function of PlLAC4 in increasing lignin deposition was confirmed by virus‐induced gene silencing and overexpression. Moreover, PlMYB83 could also act as a transcriptional activator of PlMYB43. The findings of the study propose a regulatory network of R2R3‐MYBs modulating lignin biosynthesis and secondary cell wall thickening for improving stem lodging resistance, and provide a resource for molecular genetic engineering breeding of cut flowers. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.), as a high-end cut flower in the international market, has high ornamental and medicinal values. But in Northern China, drought is a major environmental factor influencing the growth and development of P. lactiflora. Quantitative real-time polymerase chain reaction (qRT-PCR) can evaluate gene expression levels under different stress conditions, and stable internal reference is the key for qRT-PCR. At present, there is no systematic screening of internal reference for correcting gene expressions of P. lactiflora in response to drought stress. In this study, 10 candidate genes [ubiquitin (UBQ2), UBQ1, elongation factor 1-α (EF-1α), Histidine (His), eukaryotic initiation factor (eIF), tubulin (TUB), actin (ACT), UBQ3, ACT2, RNA polymerase II (RNA Pol II)] were chosen, and 4 analysis methods were used to compare the stabilities for these 10 genes coping with drought stress. Due to the difference of operation methods, the results of different analysis were distinct, and the final comprehensive analysis indicated that EF-1α was a relatively stable internal reference gene for P. lactiflora under drought stress. Also, UBQ1 and UBQ2 were the best reference gene combination according to GeNorm analysis. This study will lay a foundation for screening the key genes of P. lactiflora in response to drought stress. [ABSTRACT FROM AUTHOR]

To identify herbaceous peony cultivars with strong photosynthetic productivity, we compared the photosynthetic characteristics of 20 herbaceous peony cultivars based on four photosynthetic characteristics parameters and established light–response curves under a light intensity gradient, using CIRAS-3 portable photosynthetic dynamic monitoring. The net photosynthetic rate (Pn) showed a “unimodal” diurnal variation pattern, with a peak around 12:00. The diurnal pattern of the transpiration rate was the same as that of Pn. Stomatal conductance values (Gs) showed similar patterns among the cultivars, with only small differences. The daily variation in intracellular CO2 concentration (Ci) showed an opposite trend to that of Pn. When the photosynthetically active radiation was 0–400 μmol·m−2s−1, Pn increased linearly and gradually with increasing light intensity. ‘Xueyuanhonghua’, ‘Qingwen’, ‘Taohuafeixue’, ‘Chifen’, and ‘Qihualushuang’ showed high photosynthetic productivity. ‘Xueyuanhonghua’, ‘Fushi’, ‘Qingwen’, ‘Tianshanhongxing’, ‘Qingtianlan’, ‘Dafugui’, and ‘Hongfushi’ had high light saturation points and the highest light resistance. ‘Xueyuanhonghua’, ‘Qingwen’, ‘Taohuafeixue’, ‘Tianshanhongxing’, ‘Qingtianlan’, ‘Guifeichacui’, ‘Chifen’, and ‘Hongxiuqiu’ had low light compensation points. Thus, two cultivars with strong photosynthetic productivity, ‘Xueyuanhonghua’ and ‘Qingwen’, can be cross-bred to obtain both light- and shade-tolerant plants. This study provides a theoretical basis for breeding new cultivars with high photosynthetic productivity.

Using SSR, a molecular marker, this study aimed to evaluate the genetic diversity and genetic relationship among 55 herbaceous peony (Paeonia lactiflora Pall.) cultivars belonging to the Lactiflora, Hybrid and Itoh Groups to lay a foundation for the molecular classification of peony cultivars, as well as for genetic background analysis and breeding of new cultivars. Our results show that 86 alleles, 76 of which were polymorphic, were obtained by screening 13 pairs of polymorphic primers from 100 initially tested primers, each of them having an average of 6.615 alleles. The range of variation of the effective alleles was 2.243-7.800, PIC content was 0.554-0.872 and Shannon's genetic diversity index was 1.701-3.126. The 55 herbaceous peony cultivars were divided into nine groups based on UPGMA. This analysis indicates that the 55 cultivars have rich genetic diversity while a phylogenetic relationship of most cultivars was identified. This molecular-based classification is a useful and simple reference molecular method to differentiate peony cultivars in crossbreeding programs. [ABSTRACT FROM AUTHOR]

Paeonia lactiflora Pall. is an important ornamental plant with high economic and medicinal value, which has considerable development prospects worldwide. The lack of efficient tissue culture techniques and genetic transformation systems has become a master obstacle for P. lactiflora research. The purpose of the present study focuses on obtaining an efficient and stable genetic transformation method using callus as the receptor and exploring an efficient protocol for callus induction and proliferation associated with P. lactiflora. Callus induction and proliferation were performed using MS medium with various concentrations of 2,4-Dichlorophenoxyacetic acid (2,4-D), 1-Naphthaleneacetic acid (NAA), 6- Benzylaminopurine (6-BA) and thidiazuron (TDZ). The sensitivity of callus to kanamycin and cefotaxime was determined. Several parameters such as Agrobacterium cell density, infection time and co-culture duration were studied to optimize transformation efficiency. Agrobacterium strains EHA105 and pBI121 binary vector harboring the b-glucuronidase (GUS) gene were used for transformation. Expression of the GUS reporter gene was detected by GUS assay, polymerase chain reaction (PCR) and Quantitative Real-time PCR (RTqPCR). The MS medium containing 1.0 mg·L-1 NAA, 0.5 mg·L-1 2,4-D and 0.5 mg·L-1 TDZ was optimal for callus induction and MS medium containing 0.5 mg·L-1 NAA, 1.0 mg·L-1 2,4-D and 0.5 mg·L-1 TDZ was the best for callus proliferation. The concentrations of kanamycin and cefotaxime used for screening positive callus were 125 mg·L-1 and 200 mg·L-1, respectively. Among various combinations analyzed, the best transformation result was obtained via the 25 min of infection of Agrobacterium at 0.6 OD600 and 3 d of co-culture. Overall, this study provided technical support and theoretical guidance for improving the callus induction and proliferation efficiency and the study of gene function in P. lactiflora. [ABSTRACT FROM AUTHOR]

Without being aware of its chemical makeup, many ancient societies have used Steppe peony in their traditional medicine. Given that modern phytopreparation intended for use on human skin requires, above all, knowledge of its chemical composition, the goal of this study was to make a screening of the composition of aqueous and methanolic extracts of the petals of P. tenuifolia L. and to examine them for various skin-beneficial properties. The extracts were prepared by maceration, ultrasound-assisted, and microwave-assisted extraction procedures. The chemical profiling was conducted by the use of UHPLC-LTQ-OrbiTrap MS and UHPLC/MS, and spectrophotometric methods for the determination of total polyphenol and total flavonoid contents. The biological activities entailed antioxidant ABTS, DPPH, CUPRAC (Cupric Ion Reducing Antioxidant Capacity), and FRAP (Ferric Reducing Antioxidant Power) assays, antimicrobial (antibacterial and antifungal) and antibiofilm activities, cytotoxicity, wound healing potential, as well as the adhesion and invasion of Staphylococcus lugdunensis. The results showed that the petals are rich in phenolic acids and flavonoids, which are commonly associated with numerous biological activities. The aqueous extracts were more efficient in the majority of the bioactivity assays then the methanolic ones, whereas the optimal extraction method varied between the assays. This study is the first step towards the safe use of the aqueous extracts of P. tenuifolia petals for therapeutic skin treatments. [ABSTRACT FROM AUTHOR]

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The growing region of herbaceous peony (Paeonia lactiflora) has been severely constrained due to the intensification of global warming and extreme weather events, especially at low latitudes. Assessing and selecting stress-tolerant and high-quality peony germplasm is essential for maintaining the normal growth and application of peonies under adverse conditions. This study proposed a modified multi-criteria decision-making (MCDM) model for assessing peonies adapted to low-latitude climates based on our previous study. This model is low-cost, timesaving and suitable for screening the adapted peony germplasm under hot and humid climates. The evaluation was conducted through the analytic hierarchy process (AHP), three major criteria, including adaptability-related, ornamental feature-related and growth habits-related criteria, and eighteen sub-criteria were proposed and constructed in this study. The model was validated on fifteen herbaceous peonies cultivars from different latitudes. The results showed that 'Meiju', 'Hang Baishao', 'Hongpan Tuojin' and 'Bo Baishao' were assessed as Level I, which have strong growth adaptability and high ornamental values, and were recommended for promotion and application at low latitudes. The reliability and stability of the MCDM model were further confirmed by measuring the chlorophyll fluorescence of the selected adaptive cultivars 'Meiju' and 'Hang Baishao' and one maladaptive cultivar 'Zhuguang'. This study could provide a reference for the introduction, breeding and application of perennials under everchanging unfavorable climatic conditions. [ABSTRACT FROM AUTHOR]

[Objective] To establish a comprehensive evaluation system of herbaceous peony cultivars, screen cultivars suitable for outdoor cultivation in Suqian City, Jiangsu Province, and provide reference for large-scale introduction and landscape application of herbaceous peony. [Methods] Using 104 herbaceous peony cultivars as the experimental materials, the quantitative evaluation of 11 key traits was carried out from three aspects, adaptability, plant characteristics and ornamental quality by analytic hierarchy process (AHP). [Results] The weight of adaptability was the largest at 0.539 0, which was more important than plant characteristics and ornamental. 104 cultivars were divided into four grades. 12 cultivars, including Zijinlian, Saifugui and Zifengyu, were at Grade Ⅰ, superior, and were recommended for preferentially application in Suqian City. 45 cultivars, including Dahongpao, Huangyuqiu, and Shaonnyuzhuang, were at Grade Ⅱ, fine, could be used conservatively. 29 cultivars were at Grade Ⅲ and could be used appropriately, including Fencijinyu, Yanzhihong, and Caozhouhong. 18 cultivars, including Tieganzi, Kunshanxiaguang and Luxihong were evaluated as Grade Ⅳ and deemed unsuitable for development and utilization in Suqian City. [Conclusion] 12 herbaceous peony cultivars including Zijinlian, Saifugui, Zifengyu, Hongyanyuchun, Xingguangcanlan, Furongronghua, Jiguanzi, Lanchongmeng, Shuiyingchunlan, Yinxianxiuhongpao, Liantaizi and Meiju were selected out of 104 cultivars as being suitable for outdoor cultivation in Suqian City, Jiangsu Province. [ABSTRACT FROM AUTHOR]

The ornamental and commercial values of herbaceous peony (Paeonia lactiflora Pall.) are directly related to its flower pattern. However, the molecular mechanisms underlying the type formation of P. lactiflora flowers have not been studied in great detail. Previous studies identified, using integrated multipleomics analysis, revealed that APETALA2 (AP2) is an important candidate gene that modulates type formation of P. lactiflora flowers. To further reveal the expression mechanism of AP2 in P. lactiflora petals, we examined the profile of AP2 expression in the inner and outer petals of 'ZiFengyu' at various developmental stages using qRT-PCR and BSP+Miseq methylation analysis. Based on our data, the AP2 levels in the outer petals were obviously increased, relative to the inner petals. In addition, the S3 levels at the bloom stage were significantly higher than at the flower-bud stage S1, thereby promoting bloom stage S2, while declining stage S4. Using chromosome walking, the 2000 bp of the 5'-end upstream promoter region was achieved. This region harbored a CpG island (-665∼-872 bp), with multiple essential transcription factor binding sites (TFBS) such as NF-kappa B, GATA-1, Sp1, and C/EBP. Methylation sequencing revealed 7 methylated CpG sites in the CpG island region of the AP2 promoter, thereinto, the methylation ratio of the CpG-3 site in the inner petals was significantly higher than in the outer petals. Correlation analysis revealed a negative association between the level of methylation (CpG-3, CpG-6), and AP2 mRNA expression. CpG-3 was located on the Sp1 transcription factor binding site. Thus, we speculated that the CpG-3 methylation may inhibit transcription factor Sp1 binding to the gene promoter, thereby regulating AP2 expression. Herein, we examined the role of AP2 in the determination of flower patterns in P. lactiflora. Our conclusion will provide theoretical guidance for the molecular breeding of the flower pattern in P. lactiflora. [ABSTRACT FROM AUTHOR]

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., (© 2024 John Wiley & Sons Ltd.)

Leaf spot disease caused by Alternaria pathogens seriously threatens peony production. The physiological mechanism of peony resistance to the pathogen is little reported. This study aimed to reveal the defensive mechanism of peonies in response to the pathogen Alternaria tenuissima. The disease-resistant (R) variety ‘Zi Fengyu’ and susceptible (S) variety ‘Heihai Botao’ were employed, and some parameters in the leaves were analyzed after inoculation with A. tenuissima, mainly including the hypersensitive response (HR), activity of defensive enzymes, and expression of disease-resistance genes. The results showed that compared with the responses in the S genotype, HR occurred more rapidly in the R genotype. Meanwhile, the activity of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) and other two defense enzymes (polyphenol oxidase and phenylalanine ammonia-lyase) increased more significantly, and the expression of pathogenesis-related (PR) genes (PlPR1, PlPR2, PlPR4B, PlPR5, and PlPR10) and two WRKY genes (PlWRKY13 and PlWRKY65) was more strongly induced. These responses collectively contributed to the disease resistance of the R genotype. These findings provided a theoretical basis for understanding the intrinsic mechanism of peony resistance to Alternaria leaf spot disease and breeding the disease-resistant peony varieties using a molecular approach.

Paeonia peregrina Mill. is a perennial herbaceous plant species, known for the medicinal value of all of its plant parts, although the chemical composition of the petals is unknown. This study aimed to determine the chemical fingerprint of the petals and also establish the optimal extraction parameters, extraction medium, and extraction method for petals collected from different localities in Serbia. The optimization was performed in order to acquire extracts that are rich in the contents of total polyphenol content (TPC) and total flavonoid content (TFC), and also exhibit strong antioxidant activity. In addition, the influence of the extracts on several human skin pathogens was evaluated, as well as their ability to aid wound closure and act as anti-inflammatory agents. Both the extraction medium and the applied technique significantly influenced the skin-beneficial biological activities, while methanol proved to be a more favorable extraction medium. In conclusion, the extraction conditions that yielded the extract with the richest phenolic content with satisfactory biological potential varied between the assays, while the most promising locality in Serbia for the collection of P. peregrina petals was Pančevo (South Banat).

Flower scent is one of the main ornamental characteristics of herbaceous peony, and the improvement of flower fragrance is a vital objective of herbaceous peony breeding. In this study, 87 herbaceous peony cultivars were divided into three groups (no/light fragrance, medium fragrance, and strong fragrance) based on their sensory evaluation scores, and 16 strong fragrance cultivars and one no fragrance cultivar were selected for subsequent analysis. Sixty-eight volatile components were detected in these 17 cultivars based on solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS), and 26 types were identified as important scent components. They were composed of terpenoids, benzenoids/phenylpropanoids, and fatty acid derivatives. According to the content and odor threshold of these main aroma components, the characteristic aroma substances of herbaceous peony were identified, including linalool, geraniol, citronellol, and phenylethyl alcohol (2-PE). The cultivars of strong scented herbaceous peony were divided into three types: rose scent, lily scent, and mixed scent. We explored the possible key genes of characteristic aroma substances in herbaceous peony petals with different odors through the qRT-PCR. The key genes encoding monoterpene biosynthesis were found to be PlDXS2, PlDXR1, PlMDS1, PlHDR1, PlGPPS3, and PlGPPS4. In addition, the linalool synthase (LIS) gene and the geraniol synthase (GES) gene were also found. PlAADC1, PlPAR1, and PlMAO1, related to the biosynthesis of 2-PE were detected, and the synthetic pathway of 2-PE was speculated. In conclusion, these findings revealed that the difference in gene expression of monoterpene and 2-PE synthesis pathway was related to the difference in the fragrance of herbaceous peony. This study explored the releasing pathway of herbaceous peony characteristic aroma substances and provided key genetic resources for fragrance improvement.

When used for ornamental purposes, the herbaceous peony is usually propagated by root ramets, but the replanting of divided seedlings in the original planting area results in poor growth and development. No research has reported on a compound microbial agent used for herbaceous peony. The purpose of this experiment is to provide a reference for low–cost soil improvement in production, promote the growth and development of herbaceous peony, and solve the problem of planting back obstacles. In this study, 3–year–old seedlings of herbaceous peony ‘Zifengyu’ were selected and planted into an ordinary garden and replanted soils. Four root irrigation treatments were conducted using the compound microbial agent ‘Junzhongjun’ to determine the physicochemical properties of rhizosphere soil, root physiology, and growth and development of ‘Zifengyu’ under different soil conditions. The growth and development of the aboveground parts of herbaceous peony were promoted by the treatment of the compound microbial agent in the following order: garden soil > sieved–root soil > unsieved–root soil. Root vigour was enhanced in the following sequence: sieved–root soil > unsieved–root soil > garden soil. The organic matter and available potassium in the rhizosphere soil of herbaceous peony increased, and the promotional effect in the sieved–root soil was significantly better than that in the other two soils. The results show that the compound microbial agent is low in cost and has a stimulating effect on the growth and development of herbaceous peony. In the process of production, the residual broken roots in the soil can be sieved and combined with the application of the compound microbial agent to further alleviate the barriers of replanting. The concentration and frequency of agent application should be further optimized at a later stage.

Herbaceous peony is an important cut-flower plant cultivated worldwide, but its short vase life substantially restricts its economic value. It is well established that endogenous hormones regulate the senescence process, but their molecular mechanism in flower senescence remains unclear. Here, we isolated a MYB transcription factor gene, PlMYB308 , from herbaceous peony flowers, based on transcriptome data. Quantitative real-time PCR analysis showed that PlMYB308 is strongly up-regulated in senescing petals, and its expression was induced by abscisic acid or ethylene and reduced by gibberellin in petals. Treatment with abscisic acid or ethylene accelerated herbaceous peony petal senescence, and gibberellin delayed the process. PlMYB308 silencing delayed peony flower senescence and dramatically increased gibberellin, but reduced ethylene and abscisic acid levels in petals. PlMYB308 ectopic overexpression in tobacco accelerated flower senescence and reduced gibberellin, but increased ethylene and abscisic acid accumulation. Correspondingly, five endogenous hormone biosynthetic genes showed variable expression levels in petals after PlMYB308 silencing or overexpression. A dual-luciferase assay and yeast one-hybrid analysis showed that PlMYB308 specifically binds the PlACO1 promoter. Moreover, treatment with ethylene and 1-MCP can accelerate PlMYB308 silencing-reduced senescence and delay PlMYB308 - overexpression-induced senescence. We also found that PlACO1 silencing delayed senescence in herbaceous peony petals. Taken together, our results suggest that the PlMYB308- PlACO1 regulatory checkpoints positively mediate the production of ethylene, and thus contribute to senescence in herbaceous peony flowers. [ABSTRACT FROM AUTHOR]

We reconstructed April mean temperatures in Kyoto since the fifteenth century by investigating historical documents such as diaries and chronicles and compiling phenological data series of the full bloom date for herbaceous peony. In order to fill gaps in phenological data series, we used the full bloom date of rabbit-ear iris, an herbaceous plant that flowers at about the same time of the year as an herbaceous peony. We obtained floral phenological data covering a total of 278 years. Calibration using modern temperature data showed herbaceous peony phenology to be the preferred data source for April temperature estimation. Variations in the reconstructed April temperatures in Kyoto were synchronous with changes in the solar cycle. In particular, April temperatures were about 2 ℃ lower than at present around the ends of the Spoerer and Maunder grand solar minima, from 1550 to 1590 and from 1690 to 1730, respectively. In addition, the reconstructed April temperatures suggested a time lag in the climate response to solar activity changes that was about 10 years longer than the previously estimated lags in the responses of wintertime and March temperatures. However, further research is needed to accurately quantify this time lag. [ABSTRACT FROM AUTHOR]

• PlMYB42, an AMYB42-like R2R3-MYB TF, was associated with stem strength. • PlMYB42, which highly expressed in stems, would act as a transcriptional activator. • PlMYB42 was characterized to positively control stem strength during stem development. • PlMYB42 regulated stem strength via modulating lignin accumulation in stems. 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. [ABSTRACT FROM AUTHOR]

Herbaceous peony is an important cut-flower plant cultivated worldwide, but its short vase life substantially restricts its economic value. It is well established that endogenous hormones regulate the senescence process, but their molecular mechanism in flower senescence remains unclear. Here, we isolated a MYB transcription factor gene, PlMYB308, from herbaceous peony flowers, based on transcriptome data. Quantitative real-time PCR analysis showed that PlMYB308 is strongly up-regulated in senescing petals, and its expression was induced by abscisic acid or ethylene and reduced by gibberellin in petals. Treatment with abscisic acid or ethylene accelerated herbaceous peony petal senescence, and gibberellin delayed the process. PlMYB308 silencing delayed peony flower senescence and dramatically increased gibberellin, but reduced ethylene and abscisic acid levels in petals. PlMYB308 ectopic overexpression in tobacco accelerated flower senescence and reduced gibberellin, but increased ethylene and abscisic acid accumulation. Correspondingly, five endogenous hormone biosynthetic genes showed variable expression levels in petals after PlMYB308 silencing or overexpression. A dual-luciferase assay and yeast one-hybrid analysis showed that PlMYB308 specifically binds the PlACO1 promoter. Moreover, treatment with ethylene and 1-MCP can accelerate PlMYB308 silencing-reduced senescence and delay PlMYB308- overexpression-induced senescence. We also found that PlACO1 silencing delayed senescence in herbaceous peony petals. Taken together, our results suggest that the PlMYB308-PlACO1 regulatory checkpoints positively mediate the production of ethylene, and thus contribute to senescence in herbaceous peony flowers.

The postharvest response of two peony cultivars, 'Qi Hua Lu Shuang' and 'Da Fu Gui', to exogenous treatment with three concentrations (25, 50, and 75 μmol·L−1) of melatonin (MT) was evaluated. Both cultivars demonstrated a similar response to MT treatment in terms of delayed senescence, albeit with differing efficacies. The optimal concentration of MT (50 μmol·L−1) extended the vase life of 'Qi Hua Lu Shuang' and 'Da Fu Gui' by 1.6 and 1.2 days, respectively, relative to the control. This treatment also increased maximum flower diameter by 11.76% and 21.26%, respectively, and improved water balance, with 'Qi Hua Lu Shuang' maintaining stability for 6.0 days and 'Da Fu Gui' for 5.7 days longer than the control. Relative electrical conductivity and malondialdehyde (MDA) content, when treated with 50 μmol·L−1 MT, were reduced by 25.25% and 18.03% for 'Qi Hua Lu Shuang', and by 33.96% and 21.47% for 'Da Fu Gui', respectively. At this MT concentration, soluble sugar content peaked at 6.91 mg·g−1 FW for 'Qi Hua Lu Shuang' and 8.12 mg·g−1 FW for 'Da Fu Gui', while soluble protein content reached 5.07 mg·g−1 FW and 7.93 mg·g−1 FW, respectively. Additionally, at the same concentration of MT, the activities of antioxidant enzymes activities (SOD and CAT) were significantly enhanced. SOD activity peaked at 749.61 U·g−1 FW in 'Qi Hua Lu Shuang' and at 652.77 U·g−1 FW in 'Da Fu Gui', while CAT activity showed increases of 31.86% in 'Qi Hua Lu Shuang' and 44.46% in 'Da Fu Gui', compared to the control. These results demonstrate that 50 μmol·L−1 MT optimally delays senescence and preserves the postharvest quality of cut peonies, offering valuable insight for the floral industry. • Melatonin significantly enhances vase life and quality in two peony cultivars. • 50 μmol·L−1 melatonin optimally delays senescence in peony cut flowers. • Melatonin treatment effectively improves water balance and reduces cell membrane damage in peonies. • Melatonin treatment increases soluble sugars, proteins, and antioxidant activity, supporting flower quality. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is a famous ornamental plant, and the study of its flower color is of great significance for cultivating new flower varieties. To explore the factors driving the formation and change of herbaceous peony flower color, we selected five herbaceous peony varieties at four flowering stages to determine the change in flower color, petal area, and microstructure. We also examined the composition and content of petal pigments, soluble sugar and soluble protein content, pH value of cell fluid, and water content. Finally, we analyzed the correlations between each factor. We found that Pn3G5G, Pg3G5G, and Cy3G5G were the main anthocyanin components in red and purple petals. Qu3G, Qu7G, Is3G, and lutein play important roles in yellow petal formation. The change in herbaceous peony flower color during the flowering process is directly caused by changes in the anthocyanin and carotenoid content in petals. In addition, changes in other physiological indices also influence the change in flower color. This study explored the physiological and biochemical factors affecting the color of herbaceous peony petals, which has an important practical significance for studying the physiological mechanism of herbaceous peony flower color formation and color breeding of new flowers.

Herbaceous peony (Paeonia lactiflora Pall.) is an ornamental plant with huge potential in the international flower market. Similar to the flowers of most other ornamental plants, the top sellers of P. lactiflora are those with red or pink flowers. However, most studies on flower colors have focused on the novel colors and have neglected the most common red flowers. In this study, a red cultivar of P. lactiflora ('Dafugui') and a pink cultivar ('Qingwen') were selected in order to study the discrepancy in the red color of the flowers. The results demonstrate that these two cultivars have the same compositions as anthocyanins, flavones, and flavonols but different contents. 'Dafugui' was found to have a high accumulation of upstream substances due to the higher expression of the early genes encoding phenylalanine ammonialyase (PlPAL) and flavonoid 3′-hydroxylase (PlF3′H). Moreover, the anthocyanidin synthase gene (PlANS) and UDP-glucose flavonoid 3-O-glucosyltransferase gene (PlUF3GT) encoding enzymes catalyze these upstream substances into anthocyanins, resulting in more redness in 'Dafugui' than in 'Qingwen'. Our study thus provides a better understanding of the anthocyanin accumulation and coloring mechanism of P. lactiflora and can serve as a theoretical basis for breeding more red flowers using genetic engineering techniques to cater to consumers' preferences. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is a popular high-end cut flower, but stem bending caused by low stem strength severely decreases its quality. To enhance stem strength, the regulatory effects of exogenous silicon were investigated in P. lactiflora. The results showed that silicon application enhanced stem strength by increasing the thickness of secondary cell walls and the layers of thickened secondary cells. Moreover, more lignin accumulated, particularly G-lignin and S-lignin, and the activities of lignin biosynthetic enzymes increased with silicon application. In addition, based on transcriptome analysis, silicon application induced the expression of genes participating in lignin biosynthesis pathway. Among them, hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase gene (HCT1) was isolated from P. lactiflora and found to be mainly localized in the cytoplasm of cells. Overexpression of PlHCT1 increased the layers of thickened secondary cells and lignin accumulation in tobacco, resulting in enhanced stem strength and demonstrably straight stems. Finally, silicon content, lignin content and PlHCT1 expression in P. lactiflora cultivars with high stem strengths were totally higher than those in cultivars with low stem strengths. These results indicated that silicon application enhanced stem strength by promoting lignin accumulation in P. lactiflora , which has prospects for stem quality improvement in general. [Display omitted] • Silicon increased the net photosynthesis rate and SPAD value. • Silicon enhanced stem strength by promoting lignin accumulation. • Silicon increased lignin biosynthetic enzyme activities and gene expression. • HCT1 expression was induced and localized in the cytoplasm of cells. • Overexpression of HCT1 increased lignin, resulting in enhanced stem strength. [ABSTRACT FROM AUTHOR]

Abstract: Seeds of many peony species contain a large amount of oil. However, the exploiting of its potential for oil production is hampered by a lack of basic information regarding the developmental biology of the seeds. Our aim was to obtain a detailed relationship between seed development and accumulation of various storage compounds of Paeonia lactiflora ‘Hangshao’ seed. Seeds were collected at five developmental stages including 30 days after flowering (DAF), 45 DAF, 60 DAF, 75 DAF and 90 DAF. Anatomical and histological analysis, seed weight and water content, proteins, starch, and fatty acids contents were determinated. The time span of seed development for P. lactiflora ‘Hangshao’ was 90 DAF. Seeds were physiologically mature by 75 DAF, with maximum dry matter content. During seed development, the starch and lipid content showed an increased and then decrease pattern, while they reached their maximum content differed with starch for 60 DAF and lipid for 75 DAF. Protein content showed a slight decreased and then increased pattern. Lipid was the main storage reserve of mature seeds. A total of 26 kinds of fatty acid were detected and among which, seven kinds was all more than 100 mg.Kg-1 in all developmental seeds. Those seven fatty acids were palmitic acid, stearic acid, oleic acid, trans-oleic acid, linoleic acid, α-linolenic acid, and erucic acid. Besides, the content of α-linolenic acid accounted for more than 40% of the total fatty acid content in each stage.

Without being aware of its chemical makeup, many ancient societies have used Steppe peony in their traditional medicine. Given that modern phytopreparation intended for use on human skin requires, above all, knowledge of its chemical composition, the goal of this study was to make a screening of the composition of aqueous and methanolic extracts of the petals of P. tenuifolia L. and to examine them for various skin-beneficial properties. The extracts were prepared by maceration, ultrasound-assisted, and microwave-assisted extraction procedures. The chemical profiling was conducted by the use of UHPLC-LTQ-OrbiTrap MS and UHPLC/MS, and spectrophotometric methods for the determination of total polyphenol and total flavonoid contents. The biological activities entailed antioxidant ABTS, DPPH, CUPRAC (Cupric Ion Reducing Antioxidant Capacity), and FRAP (Ferric Reducing Antioxidant Power) assays, antimicrobial (antibacterial and antifungal) and antibiofilm activities, cytotoxicity, wound healing potential, as well as the adhesion and invasion of Staphylococcus lugdunensis. The results showed that the petals are rich in phenolic acids and flavonoids, which are commonly associated with numerous biological activities. The aqueous extracts were more efficient in the majority of the bioactivity assays then the methanolic ones, whereas the optimal extraction method varied between the assays. This study is the first step towards the safe use of the aqueous extracts of P. tenuifolia petals for therapeutic skin treatments.

The growing region of herbaceous peony (Paeonia lactiflora) has been severely constrained due to the intensification of global warming and extreme weather events, especially at low latitudes. Assessing and selecting stress-tolerant and high-quality peony germplasm is essential for maintaining the normal growth and application of peonies under adverse conditions. This study proposed a modified multi-criteria decision-making (MCDM) model for assessing peonies adapted to low-latitude climates based on our previous study. This model is low-cost, timesaving and suitable for screening the adapted peony germplasm under hot and humid climates. The evaluation was conducted through the analytic hierarchy process (AHP), three major criteria, including adaptability-related, ornamental feature-related and growth habits-related criteria, and eighteen sub-criteria were proposed and constructed in this study. The model was validated on fifteen herbaceous peonies cultivars from different latitudes. The results showed that ‘Meiju’, ‘Hang Baishao’, ‘Hongpan Tuojin’ and ‘Bo Baishao’ were assessed as Level I, which have strong growth adaptability and high ornamental values, and were recommended for promotion and application at low latitudes. The reliability and stability of the MCDM model were further confirmed by measuring the chlorophyll fluorescence of the selected adaptive cultivars ‘Meiju’ and ‘Hang Baishao’ and one maladaptive cultivar ‘Zhuguang’. This study could provide a reference for the introduction, breeding and application of perennials under everchanging unfavorable climatic conditions.

In order to use plant growth regulators more efficiently and rationally, we conducted a comprehensive study on the dwarfing effect of uniconazole on Paeonia lactiflora. The leaves of 'Dafugui' cultivar were sprayed with uniconazole at different concentrations (0, 20, 40 and 60 mg·L-1) to explore its effects on physiological and biochemical characteristics of the potted plant. Compared with control, uniconazole (40 mg·L-1) increased the activities of superoxide dismutase, peroxidase and catalase, but had no significant effect on the accumulation of malondialdehyde. Soluble protein content was significantly highest in all four growth stages. Soluble sugar, sucrose and reducing sugar contents were significantly highest at the full-flowering stage. The treatment also decreased indole-3-acetic acid, gibberellic acid and trans-zeatin riboside contents of leaves by 5.78%, 4.82% and 22.03% respectively, but increased abscisic acid content by 67.58%. This suggests that the stress resistance of the potted plant was enhanced. [ABSTRACT FROM AUTHOR]

Petaloid stamens in Paeonia lactiflora constitute an important developmental phenomenon that explain double flower formation. Although research on stamen development in model plants has progressed considerably, the underlying molecular mechanism in P. lactiflora petaloid stamens is still unclear. In this study, acomparative transcriptomic analysis was performed on two cultivars of P. lactiflora ('Fen Yu Nu' and 'Lian Tai') with different stamen developmental patterns. Following transcriptome sequencing, 89,393 unigenes were identified in P. lactiflora. Trend analysis and weighted gene co-expression network analysis (WGCNA) indicated that 18 candidate genes were likely involved in the formation and development of petaloid stamens, including seven MADS-box genes, PlAP3, PlDEFA, PlPI2, PlAG-1, PlSEP3, PlSEP1-1, and PlSEP1-2, and 11 other transcription factors (TFs), PlTCP2, PlTCP4, PlTCP9, PlbHLH36, PlICE1, PlLBD38, PlNAC083, PlBLH11, PlPDF2, PlGBF1, and PlIIIA. Using these 18 selected candidate genes, we propose ahypothetical model of gene expression network that regulates the development of petaloid stamens. Our results provide acollection of candidate genes that are useful for the analysis of P. lactiflora petaloid stamens, allowing for in-depth studies of the development pattern of P. lactiflora flower organs, and providing atheoretical basis for related research on petaloid stamens of flowers in other herbaceous plants. [ABSTRACT FROM AUTHOR]

Drought is an environmental stress that limits agricultural and horticultural production worldwide. Paeonia lactiflora Pall. is a perennial flowering plant with strong environmental adaptability and a good candidate for production in arid areas. Using the Illumina Hiseq platform to study the transcriptome of P. lactiflora leaves under drought stress, 62.27 Gb of clean data was obtained and 87,099 unigenes (N50 = 1,352 bp; mean length = 790.66 bp) were obtained by transcriptome sequencing. After screening 4,198 differentially expressed genes, genes that may be related to the response of P. lactiflora to drought stress were identified: 28 signal transduction genes, 12 protein kinase genes, 14 transcription factor genes, 35 osmotic adjustment genes, 14 antioxidase enzyme genes, 22 photosynthesis genes, 9 AQP genes, 20 HSP genes, and 17 LEA genes. Transcriptomics analysis revealed that transcription factors, such as ERF, WRKY, and NAC transcription factor family members regulate the synthesis of hormones that play a role in signal transduction pathways of peony in response to drought stress. These results enrich currently available herbaceous peony gene sequence resources, fortify the identification of candidate genes and molecular regulatory mechanisms in response to drought stress, allowing genetic engineering to be used to create drought-tolerant plants. [ABSTRACT FROM AUTHOR]

To clarify drought-stress-induced molecular changes in herbaceous peony (Paeonia lactiflora), we construct small RNA libraries by high-throughput sequencing. A total of 58 known miRNAs and 83 novel miRNAs are identified. Among them, 61 miRNAs are differentially expressed. In addition, differentially expressed miRNAs predict 122 target genes, 68 of which are annotated. When combined with gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis, 35 miRNAs and 67 target transcripts that might be associated with drought stress are detected. Expression analysis of some miRNAs are performed, which is consistent with the results of targets of transcription factors and functional genes. These results provide a better understanding of the roles of miRNAs under drought stress in herbaceous peony. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is a renowned traditional Chinese flower, which has been cherished by people since ancient times. It holds significant value as both an agricultural cash crop and an ornamental and medicinal plant. However, the lack of in vitro propagation system has been long hindered the commercial production of this species and the development of new cultivars. In this study, the low chilling requirement cultivar Paeonia lactiflora 'Hang Baishao' that originated from low latitudes of China, was used to study the in vitro culture of embryos. The results of our experiment showed that the optimal medium for in vitro culture of embryos was a 1/2 Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 6-benzyladenine (6-BA), 1.0 mg/L gibberellic acid (GA 3) and 2.0 g/L polyvinyl pyrrolidone (PVP). Additionally, histological observations revealed the crucial role of vascular bundle development in the survival of transplants. Plants with well-developed vascular tissue exhibited better transplanting success. This study presents, for the first time, a protocol for embryos propagation and transplanting of 'Hang Baishao', a cultivar with low chilling requirement (CR) during winter. This study provides an efficient method for in vitro culture of 'Hang Baishao', and makes it possible for large-scale production, utilization, and germplasm preservation of this species. [ABSTRACT FROM AUTHOR]