Weak stem mechanical strength severely restrains cut flowers quality and stem weakness can be alleviated by calcium (Ca) treatment, but the mechanisms underlying Ca-mediated enhancement of stem mechanical strength remain largely unknown. In this study, we performed a comparative transcriptomic, proteomic, and metabolomic analysis of herbaceous peony (Paeonia lactiflora Pall.) inflorescence stems treated with nanometer Ca carbonate (Nano-CaCO₃). In total, 2643 differentially expressed genes (DEGs) and 892 differentially expressed proteins (DEPs) were detected between the Control and nano-CaCO₃ treatment. Among the 892 DEPs, 152 were coregulated at both the proteomic and transcriptomic levels, and 24 DEPs related to the secondary cell wall were involved in signal transduction, energy metabolism, carbohydrate metabolism and lignin biosynthesis, most of which were upregulated after nano-CaCO₃ treatment during the development of inflorescence stems. Among these four pathways, numerous differentially expressed metabolites (DEMs) related to lignin biosynthesis were identified. Furthermore, structural observations revealed the thickening of the sclerenchyma cell walls, and the main wall constitutive component lignin accumulated significantly in response to nano-CaCO₃ treatment, thereby indicating that Ca can enhance the mechanical strength of the inflorescence stems by increasing the lignin accumulation. These results provided insights into how Ca treatment enhances the mechanical strength of inflorescence stems in P. lactiflora.

Sorbus alnifolia (Siebold & Zucc.) K.Koch (Rosaceae) is an economically important tree in the temperate forests of Eastern China. In recent decades, ever-increasing use and modification of forestlands have resulted in major degeneration of the natural habitat of S. alnifolia. Moreover, S. alnifolia seeds germinate in a complicated way, leading to a high cost of propagation. The current study aimed to determine the requirements for breaking seed dormancy and for germination as well as to characterize the type of seed dormancy present in this species. Moreover, the roles of temperature, cold/warm stratification, and gibberellic acid (GA₃) in breaking dormancy were tested combined with a study of the soil seed bank. The results showed that intact seeds of S. alnifolia were dormant, requiring 150 days of cold stratification to achieve the maximum germination percentage at 5/15 °C. Exposure of the seeds to ranges of temperatures at 15/25 °C and 20/30 °C resulted in secondary dormancy. Scarifying seed coat and partial removal of the cotyledon promoted germination. Compared with long-term cold stratification, one month of warm stratification plus cold stratification was superior in breaking dormancy. Application of GA₃ did not break the dormancy during two months of incubation. Seeds of S. alnifolia formed a transient seed bank. The viability of freshly matured S. alnifolia seeds was 87.65% ± 11.67%, but this declined to 38.25% after 6-months of storage at room temperature. Seeds of S. alnifolia have a deep physiological dormancy; cold stratification will be useful in propagating this species. The long chilling requirements of S. alnifolia seeds would avoid seedling death in winter.

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.

Pothos (Epipremnum aureum) is a commonly used indoor ornamental foliage, particularly in the middle and lower regions of the Yangtze River in China. It typically grows in the tropical area, and it is yet unclear whether prolonged winter temperatures cause plant damage and impact its development. In this study, the E. aureum chilling injury response was explored by maintaining it at 1 °C. Based on the acquired results, low-temperature stress (LTS) induced wilting and yellowing of leaves and diminished chloroplast pigment concentrations, particularly the chlorophyll b content. LTS also induced overproduction of reactive oxygen species (ROS) within E. aureum and enhanced the relative electrical conductivity and superoxide dismutase activity. In addition, with prolonged LTS, the anatomical structure of E. aureum was severely damaged, resulting in a marked reduction in the photochemical activity of the photosystem Ⅱ reaction center and suppressed photosynthesis. Moreover, results of the transcriptomic analysis revealed that LTS induced the expression of genes involved in the α-linolenic acid metabolic pathway, plant hormone network, host plant–pathogen association, and MAPK axis, suggesting that LTS would activate its resistant response to cold stress. These results unraveled the physiological and transcriptomical response of E. aureum to chilling injury, which would lay a theoretical foundation for the cultivation of low-temperature-tolerant varieties of E. aureum.

Paeonia ostii is an emerging woody oil crop, but the high temperature in summer is extremely unfavorable for its growth and development. Understory intercropping cultivation would provide shaded environments which could effectively reduce the ambient temperature. In order to explore whether understory intercropping cultivation would reduce the effects of high-temperature stress on P. ostii, the changes of leaf physiological indicators and leaf microstructures of sole-cropping and intercropping P. ostii were investigated. P. ostii that intercropping cultivated under Illinois pecans (Carya illinoinensis (Wangenh.) K. Koch) with 4 m × 4 m and 4 m × 8 m rowing spaces were used as samples in this study. The results showed that with continuous high temperature, the high-temperature damage index of P. ostii kept increasing, whereas the leaf relative water content continued to decline. Compared to sole-cropping, the high-temperature damage index, relative electrical conductivity, proline content, antioxidant enzymes superoxide dismutase (SOD), and ascorbate peroxidase (APX) activities of intercropping P. ostii under C. illinoinensis were significantly decreased, whereas the leaf relative water content was higher. Moreover, compared to sole-cropping, intercropping P. ostii under C. illinoinensis increased SPAD and chlorophyll contents, made mesophyll cell ultrastructures more intact, and made the chloroplasts rounder and more filled with starch granules and lipid globules, leading to enhanced photosynthesis (Pn) and transpiration rates (Tr). Notably, the reduction of high-temperature damage on intercropping P. ostii under C. illinoinensis with 4 m × 4 m rowing spaces was more significant than that under C. illinoinensis with 4 m × 8 m rowing spaces. This research provides some reference values for efficient plantation of P. ostii in the middle and lower reaches of the Yangtze River in China.

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