The benefits of urban green space are socially widely recognized as a direct link between plant–microbe interactions and the maintenance of biodiversity, community stability, and ecosystem functioning. Nevertheless, there is a lack of knowledge about the factors influencing microbial communities in urban green spaces, especially those related to phyllosphere epiphytes and stem epiphytes. In this study, we analyzed the microbial community assembly in leaf and stem bark samples collected from Square, Road, Campus, and Park. Illumina sequecing of 16S amplicons was performed to characterize microbial diversity and composition. The α-diversity was significantly higher in the bark epiphytic community, compared to the phyllosphere. Moreover, urban greenspaces'type altered the way communities gathered. The main soil and air properties factors of the urban greenhouse (e.g. soil temperature, atmospheric moisture, air temperature) were shaping the characteristics of bacterial communities on the leaf surface and bark epiphytic. In addition, in the co-occurrence network analysis, keystone taxa were not mostly observed in abundant species, which may be necessary to maintain ecosystem functions. Finally, our findings provide a deeper understanding of the ecological dynamics and microbial interactions within plant phyllosphere and stem epiphytes microbiomes.

Color and form are closely related to our daily lives and can directly and rapidly affect people’s emotions, and it is of great significance to study the effects of color and form of garden plants on the body and mind of urban residents. In this study, the shrub Camellia japonica L., which has rich germplasm resources, was selected as the research object. It aims to address the following research questions: how flower colors and flower types of Camellia japonica L. affect human physiology and psychology? In this study, we recruited 158 participants to participate in a controlled experiment to quantitatively measure and analyze physiological (heart rate, blood pressure, oxygen saturation, electroencephalogram [EEG]) and psychological (anger, panic, nervousness, energy, fatigue, depression, and self-esteem) indices before and after viewing pictures of Camellia japonica L. of all colors and flower types, as well as of them in different colony configurations. The results of evaluating physiological indexes and POMS values showed that different types of Camellia japonica L. images had different restorative benefits. From the physiological indicators, blood pressure metrics were more sensitive as an evaluation of recovery effects than those of heart rate and oxygen saturation, and stress recovery was more significant after color stimulation than petal category and landscape type. Color, petal type, and landscape configuration type affect relaxation, concentration restoration, and other moods differently reflected by α wave and β wave of EEG. POMS questionnaires showed that viewing different types of picture processes of Camellia sinensis significantly reduced nervousness, anger, fatigue, depression, panic, and self-esteem, and the effect was significant in males than in females. Our findings provide a theoretical basis and selection for the garden application of Camellia japonica L. in a broader sense, intending to improve their health benefits and maximize the restorative effects of urban environments.

Flower color is an important ornamental trait that influences plant growth and pollination. However, the molecular mechanisms of flower color variation in Camellia, a widely used ornamental woody flower for landscaping, remain unexplored. Here, we used an integrated transcriptomic and metabolomic approach to investigate the molecular regulatory mechanisms underlying petal coloration diversity in three Camellia species: Camellia amplexicaulis Cohen Stuart (red flower, RD), C. petelotii (Merr.) Sealy (yellow flower, YE), and C. oleifera Abel (white flower, WH). We found that in RD flowers, the anthocyanin content, which is closely associated with red flowers, was the highest. In YE flowers, compounds believed to play important roles in flower coloration, such as apigenin, vitexin and their derivatives, as well as quercetin and its derivatives, were significantly greater than those in flowers of other colors. Kaempferol and its derivative contents, which are considered white petal pigments, were greater in WH flowers. Additionally, we identified 139 structural genes involved in flavonoid biosynthesis and screened 29 key structural genes, including PAL, 4CL, CHI, CHS, ANS, ANR, LAR, CYP75B1, FLS, C12RT1, FG3, and CYP93B2_16. The expression patterns of these genes in flowers of different colors were closely related to the patterns of flavonoid metabolite accumulation, indicating that these genes play a key role in flower color development. Transcription factors (TFs) also play important roles in regulating flower color formation. We identified 3,181 TFs, including members of the MYB, bHLH, bZIP, and WRKY TF families, which play crucial roles in the flavonoid and anthocyanin biosynthetic pathways. According to the results of the correlation analysis, 66 TFs were highly correlated with the total flavonoid and anthocyanin contents, and these TFs directly or indirectly regulate flower color development. Moreover, we identified numerous potential metabolites, along with many candidate structural genes and TFs, that may cause flower color variations. Therefore, our findings provide new insights into the molecular regulatory network of Camellia flower color diversity and offer significant genetic insight and a theoretical foundation for the cultivation of Camellia varieties with desirable color characteristics. With further functional validation and breeding applications, these results may increase the ornamental value of Camellia species and contribute to the genetic improvement of the Camellia flower.

Camellia (Camellia japonica) is a semi-shaded plant that is highly vulnerable to heat stress. To investigate the mechanisms underlying heat stress in C. japonica, two C. japonica cultivars, “Xiaotaohong” and “Zhuapolian”, which exhibit significant differences in heat tolerance, were selected from four common cultivars. The selection methods included phenotypic observations and physiological index detection, including relative electric conductivity (REC), malondialdehyde (MDA) content, superoxide dismutase (SOD) enzyme activity, relative water content (RWC), and chlorophyll content. RNA-seq analysis yielded 980 million reads and identified 68,455 differentially expressed genes (DEGs) in the two C. japonica cultivars during heat stress compared to the control samples. Totals of 12,565 and 16,046 DEGs were differentially expressed at 16 h and 32 h, respectively, in “Xiaotaohong” during heat stress. In “Zhuapolian”, 40,280 and 37,539 DEGs were found at 16 h and 32 h, respectively. KEGG enrichment analysis revealed that both cultivars were enriched in the “plant hormone signal transduction” and “circadian rhythm” pathways at two stages, indicating the critical role these pathways play in the heat stress response. The differences in the tolerance between the two cultivars are likely linked to pathways such as “plant hormone signal transduction”, “photosynthesis”, and “circadian rhythm”. Some members of heat shock proteins (HSPs) are associated with the heat stress response. It is speculated that transcription factor families contributing to the tolerance differences include AP2/ERF, C3H, bHLH, bZIP, and MYB-related with a small number of heat shock factors (HSFs) also induced by the stress. In conclusion, these results reveal the changes in the physiological indices and molecular networks of two C. japonica cultivars under heat stress. This study lays the foundation for the breeding of superior heat-resistant C. japonica cultivars and for further molecular research.

Camellia’s ornamental value is constrained by its natural winter–spring flowering period. Although the discovery of Camellia azalea provides important germplasm resources for developing cultivars with year-round flowering, the molecular mechanisms underlying flowering time variation remain unclear. Here, we investigated three germplasms with distinct flowering patterns: winter–spring flowering Camellia japonica ‘Tieke Baozhu’, summer–autumn flowering Camellia azalea, and their hybrid Camellia ‘Lingnan Yuanbao’ inheriting the latter’s flowering traits. Integrated transcriptomic and metabolomic analyses revealed that differentially expressed genes (DEGs) and metabolites (DAMs) were mainly enriched in the pathways related to photoperiod regulation, plant hormone synthesis and signal transduction and flavonoid synthesis. The transcription factor (TF) analysis revealed that the bHLH and MYB TF families were significantly differentially expressed in different Camellia germplasm, suggesting their potential involvement in the regulation of flowering time through the plant hormone signal transduction and photoperiod pathway. Meanwhile, photoperiod regulation related genes, including Cryptochrome circadian regulator (CRY), Timing of CAB expression 1 (TOC1), and phytochrome interacting factor 3 (PIF3), showed significant expression differences, further confirming the photoperiod pathway’s crucial regulatory function. In terms of plant hormone levels, there were significant differences in the levels of gibberellin (GA), abscisic acid (ABA), and jasmonic acid (JA) among Camellia germplasm. The differential expression characteristics of DELLA (Asp-Glu-Leu-Leu-Ala) proteins indicated that the GA signal transduction pathway was one of the key factors regulating flowering time in Camellia. Additionally, metabolomics analyses showed significant differences in flavonoid metabolite content among Camellia germplasm, which was significantly correlated with the different developmental stages of the buds. Our findings provide a theoretical basis for the molecular breeding of everblooming Camellia cultivars, advancing the understanding of flowering regulation mechanism in ornamental species.