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The oil tree peony (Paeonia ostii) is widely cultivated for their high value seed oil, and its roots also have high medicinal value, but they are often discarded and wasted as by-products. In this study, a set of steam explosion (SE) and ultrasound (US)-assisted extraction/purification methods of insoluble bound phenols (IPs) from oil peony roots (PR) were explored and developed. The IPs were obtained through SE pre-treatment (120 °C, 15 min) and US-assisted alkaline extraction (0.25 W/cm2, 4 h and 4 M NaOH). Their total phenolic content (TPC) significantly increased from 112.26 mg gallic acid/g dry weight (mg GAE/g dw) with traditional method to 185.59 mg GAE/g dw. Subsequently, the IPs were purified into PIPs using LX-83 resin. The optimized purification conditions were pH = 4, 3.0 mg GAE/mL of IPs, 0.25 W/cm2 adsorption for 120 min, as well as 60 % ethanol desorption solution, and 0.25 W/cm2 desorption for 30 min. The TPC of the PIPs increased to 254.74 mg GAE/g dw. Notably, typical compounds in IPs and PIPs were identified and quantified by HPLC-MS and their antioxidant and anti-tyrosinase activities were also evaluated by chronometry. The results showed that paeoniflorin and benzoyl-paeoniflorin increased by about 10-fold in the PIPs. Additionally, they demonstrated superior antioxidant and tyrosinase inhibitory activities compared to IPs. Therefore, the innovative extraction and purification process greatly improved the yield of bound phenols and recovered paeoniflorin from non-medicinal PR. The process may also provide a reference for the in-depth development of medicinal PR, ultimately achieving more efficient PR development and utilization. [Display omitted] • The integrated process improves the yield of insoluble phenols from peony (IP). • IP are raised by steam explosion and ultrasound-assisted alkaline extraction. • US enhances adsorption/desorption of IPs using LX-83 resins. • The sum of 5 typical compounds increases from 0.47 (IPs) to 3.24 mg/g (PIPs). • PIPs showed higher antioxidant and anti-tyrosinase activities. [ABSTRACT FROM AUTHOR]

Due to high medicinal and economic value of Paeonia L., roots from 4-year-old, 5-year-old, and 6-year-old Paeonia ostii (4PO, 5PO, 6PO), as well as medicinal Paeonia suffruticosa (PS), Paeonia lactiflora (PL) and Paeonia vetchii Lynch (PV) were utilized to isolate and purify soluble activity substances. Through static and dynamic experiments, it was established that LX-83 macroporous resin effectively purified the crude extract of peony root (PR) under optimal conditions: Absorption to the column at 2 BV/h for 6 h, followed by desorption with 60 % ethanol at 5 BV/h for 0.8 h. After purification, the average total phenolic content of six PR crude extracts surged from 147.8 mg GAE/g dry weight (dw) to 397.5 mg GAE/g dw. Eight terpenes, 13 phenols, 6 flavonoids, and 4 tannins in crude PR extracts were identified by HPLC-MS. The content of paeoniflorin, pentagalloylglucose, mudanpioside C, benzoyloxidized paeoniflorin, benzoyl paeoniflorin, and paeonol was determined by HPLC, which increased by 3–5.2 times. The purified PO and PS extracts contain significantly abundant amounts of paeonol and paeoniflorin, exceeding the standards of 1.2 % and 1.6 % in the Chinese Pharmacopoeia, respectively. Moreover, the purified PR extracts exhibited enhanced antioxidant activity and anti-tyrosinase activity, with 5PO and 6PO extracts demonstrating the highest efficacy. This study successfully developed a versatile and effective method for purifying active substances in various PRs. It also provided theoretical and practical insights for upgrading and transforming the root industry of Paeonia plants. • A versatile and effective method for purifying active substances in various PRs. • The TPC and six typical compounds in purified PR extracts increased by over 3 times. • The extracts from Moutan contain high levels of both paeonol and paeoniflorin. • The extracts from Paeonia ostii roots exhibit superior anti-tyrosinase activity. [ABSTRACT FROM AUTHOR]

Adventitious root (AR) formation is a limiting factor in the vegetative propagation of tree peony (Paeonia suffruticosa Andr.). PoARRO-1 , which encodes an auxin oxidase involved in AR formation, plays a role in the root development of P. ostii , but its associated molecular regulatory mechanisms are not yet understood. In this study, we examined the role of PoARRO-1 in AR formation in P. ostii. The overexpression of PoARRO-1 in P. ostii test-tube plantlets led to a notable enhancement in both the rooting rate and the average number of ARs in vitro, as well as increased activities of peroxidase (POD), superoxide dismutase (SOD), and indoleacetic acid oxidase (IAAO). PoARRO-1 was involved in the conversion of IAA-Asp and IAA-Glu to OxIAA and promoted IAA oxidation. RNA sequencing analysis revealed that PoARRO-1 overexpression led to upregulation of enzyme activity, auxin metabolism related genes. Further analyses showed that PoARRO-1 interacted with the 1–175 aa position of PoIAA27b to regulate the formation of ARs. We therefore propose that PoARRO-1 interacts with PoIAA27b to promote AR formation, and it may be useful targets for enhancing the in vitro propagation of P. ostii. • Overexpression of PoARRO-1 increased the ARs number in Paeonia ostii test-tube plantlets. • PoARRO-1 was involved in the conversion of IAA-Asp and IAA-Glu to OxIAA and promoted IAA oxidation. • PoARRO-1 interacted with PoIAA27b to positively regulate the formation of ARs in P. ostii test-tube plantlets. [ABSTRACT FROM AUTHOR]

Tree peony (sect. Moutan) is a kind of Traditional Chinese Medicine and ornamental plant, which has been widely cultivated and utilized for thousands of years. To further study the active components of Paeonia ostii (Moutan , Fengdan), six fractions (soluble free (F), soluble esterification, soluble glycosylation, insoluble bound, insoluble esterification and insoluble glycosylation) were extracted from the leaves and roots by alkaline and acid treatment for the first time. Twenty-one typical compounds were identified and quantified by HPLC-MS. The results showed that total phenolic content (TPC) in peony roots (PR) and peony leaves (PL) were as high as 125.48 and 280.38 mg GAE·g−1 dw, which maximizes the extraction efficiency of phenolic compounds, especially leaves, compared with the conventional method. PR-F and PL-F had the highest TPC, antioxidant and anti-tyrosinase activities. Paeoniflorin was the main compounds in PL and PR. It and pentagalloylglucose (PGG) almost reached the anti-tyrosinase level of kojic acid, but they showed different inhibitory mechanisms by molecular docking. On the whole, PR-F, PL-F, PGG and paeoniflorin might be potential for skin whitening products. [Display omitted] • Paeonia ostii leaves contained high polyphenol may be underestimated for a long time. • PGG and paeoniflorin almost reached the tyrosinase inhibitory strength of kojic acid. • PR-F and PL-F had the highest TPC, antioxidant and anti-tyrosinase activities. • PR-F, PL-F, PGG and paeoniflorin might be potential materials for whitening products. • PGG, paeoniflorin and kojic acid show diverse anti-tyrosinase mechanisms by docking. [ABSTRACT FROM AUTHOR]

• A drought-related bZIP transcription factor PobZIP4 was identified in paeonia ostii. • PobZIP4 positively responded to drought stress with enhanced expression. • PobZIP4 enhanced drought tolerance in plants by scavenging ROS. Drought, as a natural disaster of force majeure, significantly disrupts the physiological balance of plants and crop yields. The basic leucine zipper (bZIP) transcription factors assume the pivotal role of paramount regulators in orchestrating drought response. In this study, a bZIP transcription factor PobZIP4 was isolated on the base of Paeonia ostii transcriptome, and its function in response to drought stress was verified. PobZIP4 had a 579 bp open reading frame, encoded 192 amino acids, and existed in a conserved structural domain typical of bZIP, and was highly expressed when P. ostii was stressed by drought. Moreover, the subcellular localization of PobZIP4 was observed with fluorescent protein labeling method and it was found that PobZIP4 localized in the Nicotiana benthamiana epidermal cell nucleus. Then, we silenced PobZIP4 in P. ostii using virus-induced gene silencing technology, and found that PobZIP4 -silenced plants showed significantly less tolerant to drought stress than the negative control. The accumulation of reactive oxygen species was found to be heightened, while the photosynthetic capacity, proline content, and protective enzyme activities exhibited a significant decline upon silencing PobZIP4 , which unequivocally demonstrated that PobZIP4 amplifies the drought tolerance of P. ostii. This study highlighted the positive role of PobZIP4 in mitigating drought stress in P. ostii , thereby establishing a molecular basis for enhancing the drought tolerance of P. ostii. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The effects of geographical differences on the characteristics of P. ostii seed and oil were studied. • The characterisations of P. ostii seeds and oil from different regions were extremely different. • Seeds of P. ostii could be clustered into three groups based on the main FAs and TCMFA contents. • Classification of P. ostii was associated to the geographical location of cultivation area. Abstract Paeonia ostii is one of the important woody oleaginous plants, and is cultivated on a large scale in China. The main purpose of this study is to evaluate the characteristic difference of P. ostii seed and oil sourced different geographical regions in China. The thousand seed weight (TSW), oil content and kernel content of the P. ostii seed, the composition and content of the main fatty acids, and the physicochemical characteristics of the seed oil of 62 P. ostii seed samples from different cultivation regions were monitored and evaluated in this study. The results showed that there were extremely significant difference among the TSW and the contents of the main fatty acids in P. ostii seed and oil. The geographical regions were related to the variability in TSW, the contents of the main fatty acids (FAs) and the total content of the main fatty acids (TCMFA), perhaps due to the influence of environmental factors, and the water, fertilizer application, crop management, or other factors. P. ostii would become a kind of woody oleaginous plant and an industrial crop with broad prospects for its high content of alpha-linolenic acid (ALA) and the high oil content of the seeds. [ABSTRACT FROM AUTHOR]

Abstract Paeonia ostii (Paeoniaceae), a famous traditional flowering plant, is an edible perennial shrub having medicinal uses. In recent decades, growing market demands and unprecedented damage to forests has caused severe degeneration of its natural habitat. As a result, land managers involved in conserving and restoring its habitat need to identify the environmental factors that shape its distribution. The present study predicted the potential distribution of this species and evaluated habitat suitable for it. The main environmental factors affecting this species were determined using 145 occurrence records, 30 environmental variables, MaxEnt modeling, and an analysis using ArcGIS 10.2 software. The results showed that the moderately and highly suitable habitat for P. ostii encompasses ca. 8.23 × 105 km2; the areas with a high suitability index (>0.6) for the distribution of this species were in southern Anhui, Henan (Kaifeng, Luoyang, Pingdingshan, Xuchang, and Zhengzhou), Hubei (Huanggang and Huangshi), and Shanxi (Yan'an) provinces. Annual mean temperature, mean UV-B of the lightest month, vapor pressure, and annual precipitation were the main environmental factors affecting the distribution of P. ostii. The results of this study can allow land managers to avoid wasted human effort and materials as well as the exhaustion of wild P. ostii resources that could result from the blind introduction of this species into unsuitable habitat while improving both the quality and yield of P. ostii. Highlights • Maxent modeling was used to predict the distribution of Paeonia ostii. • The moderate and highly suitable habitat for P. ostii encompass ca. 8.23 × 105 km2. • Annual mean temperature was the most critical factors shaping it distribution. [ABSTRACT FROM AUTHOR]

Drought is a detrimental environmental factor limiting sustainable agricultural development worldwide. Paeonia ostii , an oil-producing woody crop, while its endogenous mystery underlying this tolerance remains largely elusive to scholars. Herein, we reported that PoWRKY17, a WRKY transcription factor from IId subgroup, positively functioned in face of drought stress in P. ostii. PoWRKY17 expressed in significantly higher abundance when drought was applied. Silencing of PoWRKY17 substantially reduced drought resistance, with decreased leaf water content and protective enzyme activities, increased relative electric conductivity (REC), malondialdehyde (MDA) content, and reactive oxygen species (ROS) accumulation. On the contrary, overexpression of PoWRKY17 endowed plants with higher drought tolerance with opposite drought-relevant physiological indices. Notably, both PoWRKY17- silenced P. ostii and PoWRKY17- overexpressing plants showed changes in lignin content under drought stress. Based on this clue, we quantified the expression of lignin biosynthetic caffeoyl-CoA O -methyltransferase (CCoAOMT) gene in PoWRKY17 -silenced P. ostii and found that PoCCoAOMT expression was significantly repressed. Next, protein-gene interaction assays showed that PoWRKY17 interacted with PoCCoAOMT promoter by targeting the W-box element and activated PoCCoAOMT expression under drought stress, which has been early verified to act as a positive participant in P. ostii drought tolerance. This study broadens our understanding of WRKY-mediated lignin biosynthesis regulation in response to drought stress in plants. [Display omitted] • A drought-related WRKY transcription factor PoWRKY17 was identified in Paeonia ostii. • PoWRKY17 positively responded to drought stress with enhanced expression. • PoWRKY17 enhanced drought tolerance in plants by promoting lignin accumulation. • PoWRKY17 enhanced PoCCoAOMT expression by targeting the W-box element. [ABSTRACT FROM AUTHOR]

• Examine the effects of different temperature and durations on seed germination. • The seed germination of Paeonia ostii can be divided roughly into four stages. • Warm stratification broken physiological dormancy, allowing the embryo to grow and the radicle to emerge. • The physiological dormancy of the epicotyl was relieved by cold stratification. • By using variable temperature treatments, we greatly shortened the germination time. Paeonia ostii T. Hong & J. X. Zhang (Paeoniaceae) , a traditional ornamental and medicinal plant, is used as a new oil tree crop in China, but its cultivation is greatly hindered by seed dormancy. By using an alternating temperature stratification assay, the present study investigated seed germination of P. ostii. Seeds of P. ostii did not germinate under low temperature, and produced the root but not the shoot under continuous warm conditions. Seedling emergence of P. ostii was dependent on a warm (I) - cold - warm (II) sequence of temperature regimes. During warm (I) stratification, the embryo developed fully and the radicle emerged and grew; the activity of peroxidase increased in the embryo, the contents of soluble protein, IAA and ABA in the embryo decreased before radicle emerged and increased after radicle emerged, the contents of GA 3 and the GA 3 : ABA ratio in the embryo increased before radicle emerged and decreased after radicle emerged,and the content of starch decreased in the endosperm.Under cold stratification, the embryo and the root developed slowly, but the GA 3 : ABA ratio in embryo gradually increased. Subsequent warm (II) condition allowed the epicotyl to elongate and produce a shoot. These results indicate that seeds of P. ostii have morphophysiological dormancy. The radicle and shoot of the underdeveloped embryo have physiological dormancy (PD). Warm stratification breaks PD, allowing the embryo to grow and the radicle to emerge. Cold stratification is required to break dormancy of the epicotyl, but this treatment is not effective until after the radicle has emerged. [ABSTRACT FROM AUTHOR]

Tree peony is an economically important plant with nine wild species distributed in China. Among them, Paeonia ostii T. Hong ＆ J. X. Zhang is one of the most cultivated wild species for its ornamental, medicinal, and edible oil values. However, the biochemical composition and biological activities of hydrolate extracts from P. ostii are largely unknown. In this study, we investigated the potentials of various P. ostii organs for being used as antibacterial agents. The single-factor optimization and Box-Behnken Design (BBD) experiments were performed to determine the optimal hydrosol extraction conditions as follows: extraction duration of 4 h, temperature of 90 °C, pressure of 0.35 MPa, and ratio of 6:1. In total, 150 volatile chemicals were identified and quantified from P. ostii through gas chromatography-mass spectrometry (GC-MS). The antibacterial activities against eight Gram-positive and Gram-negative bacterial were examined. Among the volatile substances, mono-terpenoids (31.36–77.28 %) was of the highest content in P.ostii , followed by alcohols (17.69–26.82 %). The quantitative test demonstrated the P. ostii hydrosols being significantly effective against Staphylococcus aureus and Streptococcus hemolytis - β. In particular, the newly-grown leaf hydrosols displayed more pronounced antibacterial effects than those from other organ, with the inhibition zones and minimal inhibitory concentrations (MICs) being 10.65–17.5 mm and 0.78–12.5 mg/mL, respectively. The results indicate that the hydrolate extracts from P. ostii possessed remarkable antibacterial activities against some common skin-infecting and food-borne bacterial pathogens, implying that P. ostii could be a potential source for antibacterial agents for food, pharmaceutical, and cosmetics. [Display omitted] • Volatile chemical composition of hydrosols from different organs of Paeonia ostii was systematically identified. • Optimal hydrosol extraction conditions were determined by single-factor optimization and Box-Behnken Design experiments. • Antibacterial activities of P.ostii hydrosols against eight Gram-positive and Gram-negative bacteria were verified. • Antibacterial assay suggests that P. ostii may serve as a source of antibacterial agents for food, pharmaceutical, and cosmetic applications. [ABSTRACT FROM AUTHOR]

An efficient strategy for the extraction of total oligostilbenes extract (TOE) from oil peony seed shells was developed. The chemical constituents, the antimicrobial and antitumor activities of TOE were also measured. Based on the results, the optimum conditions were as follows: an ultrasonic extraction temperature of 64.0 °C, an ultrasonic extraction time of 25.0 min, a liquid-to-solid ratio of 25.0 mL/g, and an ethanol concentration of 66.0%. With these conditions, the extraction yield of TOE was 20.5%. Bioactivity assays showed that the TOE had varying degrees of antibacterial activity and strong antitumor activity in vitro. Twelve oligostilbenes were isolated from the TOE, and trans -gnetin H and suffruficosol B were the main compounds in the oil peony seed shells. These results suggested that the TOE from oil peony seed shells can be prepared as value-added products for their good antimicrobial and antitumor activities. [Display omitted] • RSM was used to optimize the UAE conditions for the extraction of TOE from oil peony seed shells. • The antimicrobial and antitumor activities of TOE were assessed. • Twelve oligostilbenes were isolated from the TOE of oil peony seed shells. • Oligostilbene compounds were the main active substances in oil peony seed shells. • The TOE might be developed into a food additives because of its good biological activities. [ABSTRACT FROM AUTHOR]

• Lipids of P. ostii seeds were stored in OBs. • P. ostii seed oil contained five dominant fatty acid compositions. • P. ostii seed oil yield and fatty acid content were in line with OB accumulation. • P. ostii OB stability was affected by NaCl concentration and pH value. • PoOLE17.5 was localized in OBs and regulated OB morphology and fatty acid content. Paeonia ostii is an emerging woody oil crop and cultivated on a large scale in China. This study attempted to characterize the characteristics of P. ostii seed oil body (OB) and found the key genes related to its morphology. The results showed that P. ostii seed oil contained five dominant fatty acid compositions that were stored in OBs. During the development of seeds, oil yield and fatty acid content were in line with OB accumulation. Moreover, NaCl concentration and pH value could influence P. ostii OB stability. Additionally, oleosins (OLEs) were identified as the most abundant proteins in OBs. Based on the expression levels of OLEs , PoOLE17.5 was isolated, which might be localized in OBs. And overexpression of PoOLE17.5 in tobacco obviously increased seed size and hundred-seed weight, altered OB morphology and increased fatty acid content. These results could provide a theoretical basis for improving oil yield of P. ostii seeds. [ABSTRACT FROM AUTHOR]