Search Results (43)

Peonies (Paeonia spp.) are renowned for their beautiful ornamental flowers and significant cultural, medicinal, and economic values. Based on growth habit, peonies are categorized into herbaceous and tree peonies. Viral infections in peonies, historically referred to as “peony ringspot” or “peony mosaic” diseases, have been reported worldwide over decades. Infections symptoms typically include leaf discoloration and diminished flowering, substantially reducing both ornamental and commercial quality. In severe cases, viral diseases can cause stunted plant growth and impaired flowering, directly affecting peony cultivation and the floriculture profitability. This review systematically summarizes the current research on key viral diseases in peonies, addressing disease classification, symptomatology, causative viruses, pathogenesis, molecular virus–host interactions, and contemporary approaches for prevention and management. The insights provided in this review offer a theoretical foundation and practical guidelines to facilitate effective control of peony viral diseases, potentially promoting sustainable development within the peony industry. Full article

The tree peony holds significant historical, cultural, and practical value. P. ostii is extensively cultivated in China, where it represents the primary oil-producing variety of tree peonies. However, the current nutrient supplementation system for P. ostii lacks an empirical basis, resulting in frequent wastage of nutrients during daily production. In this study, varying ratios and quantities of nitrogen, phosphorus, and potassium were administered to P. ostii at distinct phases of its annual growth cycle, specifically during the bud sprouting, post-flowering, and dormancy periods. The results showed that during the bud sprouting period, the plants treated with a high nitrogen and potassium ratio (a high N&K ratio, N–P–K = 35%–20%–35%) had better flowering traits than those treated with a high phosphorus ratio (a high P ratio, N–P–K = 20%–35%–20%). Under the standard application amount, plants treated with a high N&K ratio outperformed those treated with a high P ratio in terms of flowering duration, net photosynthetic rate, and flowering biomass, with increases of 20.9%, 10.7%, and 32.9%, respectively. During the post-flowering period, all plants died when treated with 1.5 × standard amounts of the above ratios. At this period, the all-high ratio with N–P–K = 45%–45%–45% resulted in a 70.4% increase in fruit set, a 43.8% increase in seed number, and a 153.8% increase in biomass compared with the high N&K ratio. During the dormancy period, nutrient supplementation with the standard amount of P led to higher increases in ground diameter and biomass. Therefore, in subsequent tree peony production, particular attention should be paid to nutrient supplementation during the post-flowering period to prevent excessive fertilizer application and safeguard the plants’ normal growth and development. Full article

Paeonia ludlowii is a threatened and valuable germplasm in the cultivated tree peony gene pool, with distinctive traits such as tall stature, pure yellow flowers, and scarlet foliage in autumn. However, the crossability barrier limits gene transfer from P. ludlowii to cultivated tree peony. Therefore, our study investigated the reasons for the lack of crossability between P. ludlowii and Paeonia ostii ‘Fengdan’. Distant cross pollination (DH) resulted in the formation of many calloses at the ends of the pollen tubes, which grew non-polar, twisted, entangled, and often stopped in the style. Pollen tubes elongated the fastest in self-pollination (CK), and pollen tubes elongated faster and fewer pollen tube abnormalities were observed in stigmas treated with KCl solution before pollination (KH) than in DH. During pollen–pistil interactions, the absence of stigma exudates, high levels of H₂O₂, O₂⁻, MDA, ^•OH, ABA, and MeJA, and lower levels of BR and GA₃ may negatively affect pollen germination and pollen tube elongation in the pistil of P. ostii ‘Fengdan’. Pollen tubes in CK and KH penetrated the ovule into the embryo sac at 24 h after pollination, whereas only a few pollen tubes in DH penetrated the ovule at 36 h after pollination. Pre-embryo abnormalities and the inhibition of free nuclear endosperm division resulted in embryo abortion in most of the fruits of DH and many fruits of KH, which occurred between 10 and 20 days after pollination, whereas embryos in CK developed well. Early embryo abortion and endosperm abortion in most of the fruits of DH and KH led to seed abortion. Seed abortion in KH and DH was mainly due to an insufficient supply of auxins and gibberellins and lower content of soluble protein and soluble sugars. The cross failure between P. ludlowii and P. ostii ‘Fengdan’ is mostly caused by a pre-fertilization barrier. KH treatment can effectively promote pollen tube growth and facilitate normal development of hybrid embryos. These findings provide new insights into overcoming the interspecific hybridization barrier between cultivated tree peony varieties and wild species. Full article

Gibberellin (GA₃) plays a crucial role in regulating the flowering time of tree peony (Paeonia suffruticosa Andr.). However, its function on flower opening after dormancy release remains unclear, and its molecular mechanism need further study. We investigated the effects of exogenous GA₃ treatments at 800 mg/L, 900 mg/L, and 1000 mg/L on the flowering process of five-year-old peony plants (‘Luhehong’) under greenhouse conditions. Our results showed that exogenous GA₃ significantly accelerated the flower opening process. Specifically, flower buds treated with 800 mg/L and 900 mg/L GA₃ bloomed after 42 and 45 days, respectively. In contrast, all flower buds treated with 1000 mg/L GA₃ aborted, while only one flower bud in the control group bloomed after 56 days. Furthermore, analysis of endogenous hormone levels revealed that GA₃ treatment rapidly increased endogenous GA₃ levels, decreased ABA levels, and gradually increased IAA levels. Transcriptomic analysis of flower buds released from dormancy following GA₃ treatment identified multiple key genes involved in the flower opening process of peony. Notably, members of the C2H2, C3H, ERF, bHLH, MYB, bZIP, NAC, and WRKY families showed significant differential expression. Moreover, several key genes involved in GA₃, ABA, and IAA hormone signaling pathways were also differentially expressed. Our findings suggested that an appropriate concentration of exogenous GA₃ treatment could accelerate the flower opening process in tree peony through multiple pathways, which would provide valuable insights into the molecular mechanisms underlying the gibberellin-mediated flower opening process in tree peony. Full article

Paeonia suffruticosa Andr. (tree peony) and Paeonia lactiflora Pall. (herbaceous peony) are traditional Chinese flowers with great ornamental value. To maintain the aesthetic value and show the characteristics of these species, preserved flowers named ‘germplasm display balls’ were developed. Firstly, dried flowers were obtained by vacuum freeze-drying. Secondly, to embed dried flowers and develop germplasm display balls, highly transparent crystal glue (in wrapped display balls type 1 and drop-type display balls type 2) and highly transparent silicone gel (in wrapped display balls, type 3) were used. Finally, the first pass yield (FPY), labor productivity (LP), average cost (AC), and popularity of three kinds of germplasm display balls were compared. The results showed that with the support of a paper cup, the deformation rate of flowers significantly decreased by 91.11%. The FPY of dried flowers was as high as 98.89% at 18 °C. The optimal process for type 1 and type 2 was a glue dosage of 20 g, stirring time of 3 min, and room temperature of 25 °C. Although there was a higher AC in type 3 display ball process, moderate LP and higher FPY and popularity than in other two types, accompanied by high durability, render it the best choice. Full article

Tree peony (Paeonia suffruticosa Andr.), which is a traditional flower cultivated in China, is rapidly becoming an important species in the cut flower industry. Thus, extending the vase life of tree peony cut flowers is a major goal in the cut flower industry. Melatonin, which is a new type of antioxidant, plays an important regulatory role in the preservation of cut flowers. Therefore, this study employed the cut flower of tree peony “Diguan” as the test material to investigate the preservative effects of the antioxidant melatonin on the cut flower of tree peony “Diguan”. We examined tree peony cut flowers in terms of their morphology, lifespan, relative fresh weight, relative diameter, and water balance value after treatments with different melatonin concentrations (0.2, 0.3, 0.4, and 0.5 mg·L⁻¹) to select the optimal treatment concentration. Considered together, these analyses clarified the effects of melatonin on the preservation of “Diguan” tree peony cut flowers. Specifically, the exogenous application of melatonin positively affected the preservation of tree peony cut flowers by improving the water balance value and increasing the soluble protein content and antioxidant enzyme activities, thereby prolonging the ornamental period of tree peony cut flowers. The fresh weight of flower branches is significantly positively correlated with soluble protein, and cut flower lifespan increases with the values of soluble protein and the fresh weight of flower branches, with a large correlation coefficient. It can be used as an important indicator to measure cut flower lifespan in subsequent research. The 0.4 mg L⁻¹ melatonin treatment was optimal for preserving tree peony cut flowers because of its positive effects on the duration of the ornamental period and ornamental quality. Full article

Tree peony (Paeonia suffruticosa), as a popular ornamental plant worldwide, has a unique floral fragrance, and it is important in the pollination, ornamental, food, and fragrance product industries. However, the underlying molecular mechanisms for the synthesis of floral fragrance terpenoids in tree peony are not well understood, constraining their exploitation. P. suffruticosa ‘Oukan’ produces strong floral fragrance terpenoids with high ornamental value and excellent stress resistance and is considered a valuable model for studying tree peony floral fragrance formation. Based on transcriptome data analysis, the PsHMGR1 and PsTPS1 genes associated with floral terpene synthesis were cloned. Then, PsHMGR1 and PsTPS1 were functionally characterized by amino acid sequence analysis, multiple sequence alignment, phylogenetic tree construction, qRT-PCR, and transgenic assay. PsHMGR1 contains two transmembrane structures and a conserved HMG-CoA_reductase_class I domain, and PsTPS1 belongs to TPS-a subfamily. The qRT-PCR analysis showed that the expression levels of PsHMGR1 and PsTPS1 increased and then decreased at different flower development stages, and both were significantly higher in flowers than in roots, stems, and leaves. In addition, the linalool content in PsHMGR1 transgenic lines was significantly higher than that of WT. Germacrene D, which was not found in WT, was detected in the flowers of PsTPS1 transgenic lines. These results indicate that PsHMGR1 and PsTPS1 promote terpene synthesis in plants and provide ideas for the molecular mechanism of enhancing terpene synthesis in tree peony floral fragrance. Full article

As a plant-specific gene family, class III peroxidases (PODs) play an important role in plant growth, development, and stress responses. However, the POD gene family has not been systematically studied in Paeonia ostii. In this study, a total of 57 PoPOD genes were identified in the P. ostii genome. Subsequently, phylogenetic analysis and chromosome mapping revealed that PoPODs were classified into six subgroups and were unevenly distributed across five chromosomes. The gene structure and conserved motifs indicated the potential for functional divergence among the different subgroups. Meanwhile, four PoPODs were identified as tandem duplicated genes, with no evidence of segmental duplication. Using RNA-seq data from eight different tissues, multiple PoPODs exhibited enhanced expression in apical and adventitious roots (ARs). Next, RNA-seq data from AR development combined with trend analysis showed that PoPOD30/34/43/46/47/57 are implicated in the formation of ARs in tree peony. Through WGCNA based on RNA-seq, two key genes, PoPOD5/15, might be involved in heat tolerance via ABA and MeJA signaling. In addition, real-time quantitative PCR (qRT-PCR) analysis indicated that PoPOD23 may play an important role in flower senescence. These findings deepened our understanding of POD-mediated AR development, heat tolerance, and petal senescence in tree peony. Full article

(1) Tree peony (Paeonia suffruticosa Andrews) is a woody ornamental plant originating from China, and beloved by people worldwide. Non-structural carbohydrates (NSCs) play a crucial role in regulating the flowering quality of tree peonies in both field and potted conditions. However, the effects of NSCs accumulation and allocation in various organs during the vegetative growth stage on the flowering quality of tree peony under forcing culture remains unclear. (2) Two-year-old grafted seedlings of tree peony cv. ‘Luoyanghong’ were subjected to orthogonal treatments to investigate the role of NSCs accumulation in plants’ developmental process. We measured leaf photosynthetic capacity, NSCs accumulation in the organs of seedlings, observed key ornamental characteristics of flowering quality under forcing culture conditions, and evaluated the qualities of seedlings and flowers using the seedling index (SI) and flowering index (FI), respectively. (3) There was a significant positive correlation between leaf photosynthetic capacity and NSCs accumulation in both the whole plant and roots of potted tree peony. Roots were identified as the primary organs for NSCs accumulation in potted tree peonies. Sufficient NSCs accumulation in the plant, particularly in the roots during the defoliation period, was essential not only for enhancing the seedling quality of potted tree peonies but also for improving the flowering quality under forcing culture conditions. Both the seedling index (SI) and flowering index (FI) exhibited a significant dose-response with increasing root NSCs accumulation at defoliation. The T3 group, which involved slight root pruning (by 25%), combined with a high-concentration rooting agent (750 mg·L⁻¹) and Metarhizium anisopliae (20 million U·mL⁻¹), resulted in the highest photosynthetic capacity, SI, FI and NSCs accumulation status (NSCAR), making it the optimal treatment combination. (4) This finding indicates that increasing NSCs accumulation in the roots of potted tree peonies is a crucial biological foundation for producing high-quality potted flowers under forcing culture conditions, which provide new insights into the importance of NSCs in tree peony flowering and may improve the production technology for high-quality potted tree peony flowers under forcing culture conditions. Full article

SERK is a marker gene for early somatic embryogenesis. We screened and functionally verified a SERK-interacting protein to gain insights into tree-peony somatic embryogenesis. Using PoSERK as bait, we identified PorbcL (i.e., the large subunit of Rubisco) as a SERK-interacting protein from a yeast two-hybrid (Y2H) library of cDNA from developing tree-peony somatic embryos. The interaction between PorbcL and PoSERK was verified by Y2H and bimolecular fluorescence complementation analyses. PorbcL encodes a 586-amino-acid acidic non-secreted hydrophobic non-transmembrane protein that is mainly localized in the chloroplast and plasma membrane. PorbcL was highly expressed in tree-peony roots and flowers and was up-regulated during zygotic embryo development. PorbcL overexpression caused the up-regulation of PoSERK (encoding somatic embryogenesis receptor-like kinase), PoAGL15 (encoding agamous-like 15), and PoGPT1 (encoding glucose-6-phosphate translocator), while it caused the down-regulation of PoLEC1 (encoding leafy cotyledon 1) in tree-peony callus. PorbcL overexpression led to increased indole-3-acetic acid (IAA) content but decreasing contents of abscisic acid (ABA) and 6-benzyladenosine (BAPR). The changes in gene expression, high IAA levels, and increased ratio of IAA to ABA, BAPR, 1-Aminocyclopropanecarboxylic acid (ACC), 5-Deoxystrigol (5DS), and brassinolide (BL) promoted embryogenesis. These results provide a foundation for establishing a tree-peony embryogenic callus system. Full article

(1) Background: Tree peonies display extensive cultivar diversity due to widespread hybridization, resulting in a complex genetic architecture. This complexity complicates the selection of universal reference genes across different cultivars for qRT-PCR analyses. Paeonia suffruticosa ‘Doulv’, notable for its unique green blooms in China, exhibits chlorosis post-flowering and features petaloid stamens and pistils. (2) Methods: Based on published literature and RNA-seq data from ‘Doulv’, nine candidate reference genes—ACT (Actin), TUB (β-Tubulin), UBC (Ubiquitin Conjugating Enzyme), UBQ (Ubiquitin), UPL (Ubiquitin Protein Ligase), PP2A (Protein Phosphatase 2A), PP2C (Protein Phosphatase 2C), MBF1A (Multiprotein Bridging Factor 1A), and GAPDH (Glyceraldehyde-3-Phosphate Dehydrogenase)—were selected. Their expression stability was assessed across various tissues and developmental stages of ‘Doulv’ flowers using qRT-PCR, with evaluations conducted via GeNorm_v3.5, NormFinder_v20, and BestKeeper_v1.0. Gene cloning and expression analyses of PsCUC3, including its subcellular localization, were performed. (3) Results: GAPDH and ACT were identified as the most stable reference genes in petaloid stamens across various developmental stages of ‘Doulv’, whereas UBC and MBF1A were optimal across different tissues. Notably, specific conserved amino acids in PsCUC3 from ‘Doulv’ diverged from those in NAM/CUC3 proteins of other species, impacting its protein structure. PsCUC3 expression analysis revealed no correlation with chlorophyll content in petaloid stamens but an association with petaloid organ development. Furthermore, PsCUC3 was predominantly localized in the nucleus. (4) Conclusions: This study comprehensively evaluated suitable reference genes using GeNorm_v3.5, NormFinder_v20, and BestKeeper_v1.0 software, establishing a robust qRT-PCR detection system for ‘Doulv’ peony. These results provide a solid experimental foundation for further research on ‘Doulv’ peony. Building on this experimental foundation, the functional analysis of the PsCUC3 gene was conducted. The findings suggest a potential association between the PsCUC3 gene and floral morphology alterations in ‘Doulv’, identifying PsCUC3 as crucial for understanding the molecular mechanisms influencing floral structure in tree peonies. Full article

The tree peony, a traditional flower in China, has a short and concentrated flowering period, restricting the development of the tree peony industry. To explore the molecular mechanism of tree peony flowering-stage regulation, PoEP1, which regulated the flowering period, was identified and cloned based on the transcriptome and degradome data of the early-flowering mutant Paeonia ostii ‘Fengdan’ (MU) and Paeonia ostii ‘Fengdan’ (FD). Through bioinformatics analysis, expression pattern analysis, and transgene function verification, the role of PoEP1 in the regulation of tree peony flowering was explored. The open-reading frame of PoEP1 is 1161 bp, encoding 386 amino acids, containing two conserved domains. PoEP1 was homologous to the EP1 of other species. Subcellular localization results showed that the protein was localized in the cell wall and that PoEP1 expression was highest in the initial decay stage of the tree peony. The overexpression of PoEP1 in transgenic plants advanced and shortened the flowering time, indicating that PoEP1 overexpression promotes flowering and senescence and shorten the flowering time of plants. The results of this study provide a theoretical basis for exploring the role of PoEP1 in the regulation of tree peony flowering. Full article

The brief longevity of tree peony blossoms constrains its ornamental value and economic worth. Gibberellins (GAs) are crucial in the modulation of flower senescence, and GA 20-oxidase (GA20ox), GA 3-oxidase (GA3ox), and GA 2-oxidase (GA2ox) catalyze the synthesis and deactivation of bioactive GAs. In Paeonia ostii, a total of three PoGA20ox, ten PoGA3ox, and twelve PoGA2ox proteins were identified and comprehensively analyzed. The analysis of the gene structures, conserved domains, and motifs revealed structural similarities and variances among the GA20ox, GA3ox, GA2ox-A, and GA2ox-B subfamilies. The synteny analysis indicated a scarcity of collinear blocks within the P. ostii genome, with no tandem or whole-genome duplication/segmental duplications found in PoGAoxs. The investigation into the binding of transcription factors to PoGAox promoters and the assessments of the expression levels suggest that PoGA2ox1 and PoGA2ox8.1 are promising candidate genes implicated in the regulation of floral senescence. Further, Pos.gene61099 (BPC6) and Pos.gene61094 (CIL2) appear to modulate PoGA2ox1 transcription in a positive and negative manner, respectively, while Pos.gene38359 (DDF1) and Pos.gene17639 (DREB1C) likely enhance PoGA2ox8.1’s expression. This study lays a foundation for an in-depth understanding of PoGAox functions and the development of strategies to delay flower senescence in tree peony. Full article

Tree peony (Paeonia suffruticosa Andr.) is a traditional Chinese flower with significant ornamental and medicinal value. Its growth and development process is regulated by some internal and external factors, and the related regulatory mechanism is largely unknown. Myelocytomatosis transcription factors (MYCs) play significant roles in various processes such as plant growth and development, the phytohormone response, and the stress response. As the identification and understanding of the MYC family in tree peony remains limited, this study aimed to address this gap by identifying a total of 15 PsMYCs in tree peony and categorizing them into six subgroups based on bioinformatics methods. Furthermore, the gene structure, conservative domains, cis-elements, and expression patterns of the PsMYCs were thoroughly analyzed to provide a comprehensive overview of their characteristics. An analysis in terms of gene structure and conserved motif composition suggested that each subtribe had similarities in function. An analysis of the promoter sequence revealed the presence of numerous cis-elements associated with plant growth and development, the hormone response, and the stress response. qRT-PCR results and the protein interaction network further demonstrated the potential functions of PsMYCs in the growth and development process. While in comparison to the control, only PsMYC2 exhibited a statistically significant variation in expression levels in response to exogenous hormone treatments and abiotic stress. A promoter activity analysis of PsMYC2 revealed its sensitivity to Flu and high temperatures, but exhibited no discernible difference under exogenous GA treatment. These findings help establish a basis for comprehending the molecular mechanism by which PsMYCs regulate the growth and development of tree peony. Full article

Tree peony (Paeonia section Moutan DC.) is a traditional ornamental flower of China, which has thousands of varieties with different flower colors and types after a long history of natural selection and artificial breeding. However, tree peony is a perennial woody plant with a long breeding, and there are still significant challenges to accelerate the process of genetic improvement of important ornamental traits. In this study, a total of sixteen primer pairs with high polymorphism and good universality were selected from the initial pool of 115 SSR markers. The SSR marker set was derived from published papers on the genetic linkage map and association analysis of tree peony. Furthermore, we conducted a genetic diversity and population structure analysis on 322 tree peony cultivars using molecular markers with functional. These SSRs amplified a total of 391 alleles, the average number of different alleles was 5.113 alleles across all loci. The average Shannon’s information index, gene diversity and polymorphism information content were 0.842, 0.532, and 0.503 over all loci, respectively. Population genetic diversity analysis indicated that the average expected heterozygosity of the total population was larger than the observed heterozygosity, showing the presence of a certain degree of heterozygous deletion phenomenon. The Japan varieties had the richest diversity with the highest H (0.508) and PIC (0.479) values. The Zhongyuan varieties showed the greatest variation may be related to its longstanding cultivation history. Moreover, the STRUCTURE and principal coordinate analyses indicated that 322 tree peony individuals from five populations were grouped into two clusters. An analysis of molecular variance demonstrated significant genetic diversity among different populations. This research may contribute to the sustainable management, conservation, and utilization of tree peony resources. Full article