【Objective】 The microbial community in the rhizosphere is produced by the interactions of the soil environment and root metabolic activities, and plays an important role in plant growth and development. Analysis of characteristics of bacterial community in the rhizosphere soil of wild tree peony species possesses important theoretical significance for the effective use of microbial resources to protect wild plant germplasm resources and lays a foundation for improving the soil environment of wild tree peony species and realizing the broad-spectrum planting of high-quality germplasm resources. 【Method】 In the present study, MiSeq high-throughput sequencing technology with 16S rRNA genes was employed to investigate bacterial community characteristics in the rhizosphere soil of nine wild tree peony species (Paeonia ludlowii, P. potaninii, P. delavayi, P. lutea, P. rockii, P. ostii, P. decomposita, P. jishanensis and P. qiui) as well as their relevance with physicochemical properties. 【Result】A total of 606 536 sequences and 99 OTU clusters were obtained by high-throughput sequencing, which belonged to 24 phyla, 84 classes, 154 orders, 280 families and 603 genera. Alpha diversity analysis revealed that the rhizosphere microbial community of P. ostii contained the highest number of species. Beta analysis revealed that the bacterial community structures in the rhizosphere soils of P. decomposita, P. rockii, P. lutea, P. ostii, P. delavayi and P. ludlowii were similar. Analysis of bacterial community compositions showed that the core and dominant bacteria in the rhizosphere soil were Proteobacteria, Acidobacteria, Actinobacteria and Chloroflexi. Significant differences were found in beneficial bacteria among different wild tree species, such as Acidobacteria, Chloroflexi, Nitrospirae, Gemmatimonadetes, Nitrosospira and Pseudomonas. Predicted functions of the rhizosphere bacterial community have mostly focused on metabolism, genetic information processing, and environmental information processing. The bacterial community in the rhizosphere of wild peony trees is significantly affected by soil organic matter and available potassium. 【Conclusion】These results indicated that the bacterial community structure in the rhizosphere soil of different wild tree peony species was different, and the formation of a bacterial community was closely related to the varieties of tree peony. The enrichment in beneficial bacteria (genera) promoted plant growth. In the future, rhizospheric microbial resources could be effectively utilized to improve the soil environment of wild tree peonies, to realize the broad-spectrum planting of high-quality germplasm resources, and to lay the foundation for the protection of wild planting resources.
【Objective】 Paeonia×suffruticosa (peony) is a traditional ornamental flower. Because its short flowering period greatly limits the ornamental value of peony, the PoERF4 gene of ostii ‘Feng Dan’ was cloned to study its sequence and expression characteristics in different flowering periods, tissues, varieties and hormone treatments. This study aimed to provide a theoretical reference for further research on the regulation of PoERF4 during the flowering, growth and development of tree peony. 【Method】 Using ‘Feng Dan’ as the material, based on the results of the three-generation full-length transcriptome sequencing of ‘Feng Dan’, the sequences with high homology were screened, the PoERF4 gene was cloned by RT-PCR technology, and bioinformatics and expression pattern analysis were performed. 【Result】The open read frame (ORF) of the PoERF4 gene was 747 bp, which encoded 248 amino acids. The molecular formula of PoERF4 was C2 217H3 689N747O933S174, which is a hydrophilic protein containing a conserved AP2 superfamily domain with no transmembrane structure. The secondary structure contained 28 amino acids in the α-helix, 48 amino acids in the extended chain, and six amino acids in the β-turn. Fluorescence quantitative analysis found that the PoERF4 gene was mainly expressed in the petals of the half-opening period of ‘Feng Dan’ and it was expressed in different tissues of ‘Feng Dan’ peony, but its expression was highest in the leaves, followed by in the petals and roots. The expression level was the highest in the late-flower cultivar ‘Lianhe’. Under auxin treatment, the PoERF4 gene could respond. 【Conclusion】The PoERF4 gene was successfully isolated from ‘Feng Dan’ and it was speculated that it plays an important regulatory role in the development of flowers and leaves and is involved in the auxin signal transduction process of ‘Feng Dan’.
【Objective】This study aimed to investigate and analyze the volatile components of three wild tree peony species and identify the key volatile components and aroma-releasing sites. This was done to provide a reference for future research, such as on the breeding and genetic regulation of the floral fragrance of tree peony, and for the development of related products. 【Method】The volatile components in different parts of flower organs (whole flower, petals and stamens) of Paeonia ludlowii, P. lutea and P. ostii were analyzed using headspace-gas chromatography-mass spectrometry, and based on the identified volatile components, three tree peony species were analyzed by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). 【Result】 A total of 147 volatile compounds were detected in the flowers of three species of tree peony. The main volatile components in P. ludlowii were ketones, alcohols, olefins and aldehydes. The main compounds in the whole flower of P. ludlowii were acetophenone, 6,6-dimethyl-bicyclo[3.1.1]heptane-2-carboxaldehyde and linalool, while β-copaene, acetophenone and linalool were the main compounds of petals, and acetophenone and linalool were the main compounds of stamens. The main components of P. lutea were olefins, alkanes and alcohols. α-pinene, β-copaene and linalool were the main compounds of the whole flower and petals in P. lutea, while 1-octane, β-copaene, and α-pinene were the main compounds of stamens. The main components of P. ostii were olefins and alkanes. The main compounds in the whole flower of P. ostii were α-pinene, ocimene and pentadecane; ocimene was the main compound of petals and its relative content was as high as 81.58%; and ocimene and pentadecane were the main compounds of stamens. These three tree peony species were effectively classified by the PCA and PLS-DA models based on their volatile components, and 15 differential components of the three peony species were identified using the PLS-DA model (VVIP > 1, P < 0.05). 【Conclusion】 There were significant differences among the types and relative contents of compounds among the three tree peony species and among different parts of the same tree peony species. The main aromatic components of P. ludlowii were acetophenone and linalool. The main aroma components of P. lutea were α-pinene, β-copaene and linalool. The main aroma components of P. ostii were ocimene, α-pinene and pentadecane. The relative alkane contents in the stamens of the three tree peony species were much higher than those in whole flowers and petals, suggesting that the stamen may be an important alkane synthesis site. Different volatile components formed the unique aroma characteristics of the three tree peony species, P. ludlowii and P. lutea showed intense floral attributes, whereas P. ostii had herbal and waxy attributes.
