Ming Sun

Chrysanthemum is an important ornamental plant. However, long-term intrageneric hybridization has led to a narrow genetic background, hindering germplasm innovation and necessitating the introduction of new genes for genetic improvement. Ajania pacifica (Nakai) Bremer et Humphries, a species of the genus Ajania, offers a potential means to introduce its unique traits into chrysanthemums. In this study, hybrid populations were constructed by crossing A. pacifica (and its F₁ progeny) with ground-cover chrysanthemum. Genetic variations in 16 phenotypic traits, including plant height, plant crown, floral and leaf characteristics, were analyzed in two hybrid populations. The results demonstrated that hybrids exhibited extensive genetic variation across 16 phenotypic traits (2.76%–271.87%), with simultaneous occurrence of heterosis and hybrid decline, along with significant segregation in flower color. By applying Pearson correlation analysis, and major gene with polygene inheritance analysis, the genetic architecture and effects of these traits were elucidated. Except for disc flower diameter, which lacked major gene control, all other traits were governed by two pairs of major genes, predominantly through additive effects. This study reports for the first time, a systematic genetic analysis of the hybrid progeny between the F₁ generation of A. pacifica and modern cultivated chrysanthemums, revealing the potential genetic modes of 16 traits in the hybrid population. The results of the study not only expand the genetic reservoir of chrysanthemum but also clarify the inheritance patterns of phenotypic traits, providing critical theoretical support for developing novel chrysanthemum varieties with optimized phenotypic traits.

The chrysanthemum is a perennial herbaceous flower with a long history of cultivation dating back over 3000 years. The potted chrysanthemum is a significant type and is widely used in landscaping. Expensive substrate costs, complicated management of water and fertilizer, and uneven product quality currently plague the potted chrysanthemum industry. This study systematically investigated the growth status of potted chrysanthemums under different substrates, water, and fertilizer ratios and established a simplified cultivation system for potted chrysanthemums. The substitute substrate experiment demonstrated that coir: moss peat: perlite: pine needle mulch = 2:4:2:2 is the most suitable substitute substrate. Research on fertilizer ratios found that chrysanthemums’ best growth and flowering characteristics were achieved with nitrogen, phosphorus, and potassium concentrations of 336 mg/L, 93 mg/L, and 273 mg/L, respectively. A comprehensive, simplified cultivation system was established when utilizing T4 substitute substrate (2:4:2:2 ratios of coir, moss peat, perlite, and pine needle mulch), 40% water capacity, and F9 fertilizer (336 mg/L nitrogen, 93 mg/L phosphorus, and 273 mg/L potassium). This study comprehensively and systematically explored the cultivation and maintenance schemes in the production of potted chrysanthemums and built a light, simple, and efficient production technology system of potted chrysanthemums in the open field suitable for the climatic characteristics of northern China, which provides feasible technical specifications and a theoretical basis for the refinement and large-scale management of potted chrysanthemums. This experiment lays the foundations for cost reduction and efficiency in the potted chrysanthemum industry.

The construction of urban green spaces is a pivotal aspect of sustainable urban development. As societal preferences evolve, a shift from visually oriented landscapes to multi-sensory landscapes has emerged. However, scant attention has been given to the olfactory dimension of urban green spaces. This study addresses this gap by investigating the relationship between odor perception and park visit experiences, employing a combination of smellwalks and questionnaire surveys conducted in Purple Bamboo Park in Beijing. Natural odors, with most perception frequencies above 60%, are the most dominant odors in Purple Bamboo Park during the summer, including plant, water, and soil smells. The questionnaire survey results revealed a positive correlation between the perception of natural odors and tour experience. Notably, floral fragrances emerged as the predominant olfactory stimulus influencing the park’s olfactory ambiance. Furthermore, a remarkably strong association was observed between the degrees of olfactory, visual, and overall experiential satisfaction, which indicates that multi-sensory experiences in urban parks work as an organic whole. By recognizing the pivotal role of smell in shaping perceptions, urban planners and designers can now integrate olfactory considerations into their work, thereby elevating the overall quality and sustainability of urban green spaces.

Lilies (Lilium spp.) are famous bulb flowers worldwide, with high ornamental value. Aphid damage has seriously constrained the development of the lily industry. In this study, the aphid resistance of 16 lily cultivars and 2 wild lily species was characterized in the field and greenhouse. Leaf color parameters, stomatal density and size, thickness of leaf layers, leaf waxy content, and leaf water content were determined to explore the constitutive resistance of lilies. The results show that there was a significant positive correlation between the number of aphids in the field and in the greenhouse (p ≤ 0.05, r = 0.47). This indicated that the level of aphid infestation in both the field and the greenhouse is generally consistent across different types of lily plants. Among these 18 lilies, ‘Palazzo’, ‘Nymph’, ‘Cameleon’ and L. lancifolium were resistant to A. gossypii, while ‘Black Beauty’ and ‘Magnefique’ had poor resistance. The correlation analysis results showed that the number of aphids was negatively correlated with leaf abaxial surface a*, stomatal size, water content, and thickness of leaf palisade tissue and positively correlated with leaf distal axial surface b*, C*, and waxy content. Among them, the correlation between the number of aphids and the thickness of leaf palisade tissue reached a significant level (p ≤ 0.05, r = −0.521). This indicated that the thickness of the palisade tissue of lily leaves might be an important factor influencing the proliferation of aphids. This study not only screened out aphid-resistant lilies but also established a crucial research foundation for the targeted breeding and molecular breeding of lilies with aphid resistance.

Crossostephium chinense is a wild species with strong salt tolerance, which has great potential to improve the salt tolerance of cultivated chrysanthemums. Conversely, the unique salt-tolerant molecular mechanisms of Cr. chinense are still unclear. This study performed a comparative physiological and transcriptome analysis of Cr. chinense, Chrysanthemum lavandulifolium and their hybrids. The physiological results showed that Cr. chinense maintained a higher superoxide dismutase (SOD) activity, to alleviate the oxidative damage to membrane. KEGG enrichment analysis showed that the plant hormone signaling transduction and the MAPK signaling pathway were mostly enriched in Cr. chinense and hybrids under salt stress. Further weighted gene co-expression network analysis (WGCNA) of DEGs suggested that the abscisic acid (ABA) signaling transduction may play a significant role in the salt-tolerant mechanisms of Cr. chinense and hybrids. The tissue-specific expression patterns of the candidate genes related to ABA signaling transduction and MAPK signaling pathway indicated that genes related to ABA signaling transduction performed significant expression levels under salt stress. This study provides a theoretical foundation for future research into the molecular mechanism of salt tolerance in chrysanthemums under salt stress.

Titan arum (Amorphophallus titanum) is a rare and endangered plant in the world. It has a huge flower and releases a repulsive odor like a corpse. On the evening of 23 July 2022 (Beijing time), a titan arum in the north garden of the China National Botanical Garden in Beijing bloomed. In order to determine the components and contents of volatile compounds released by the titan arum during its flowering, the dynamic headspace adsorption method was utilized to collect the odor of the titan arum flower on the evening of 23 July (S1), the morning of 24 July (S2), the afternoon of 24 July (S3) and the evening of 24 July (S4). The volatile compounds were analyzed by automatic thermal desorption–gas chromatography/mass spectrometry. Sixty-three volatile compounds were detected in the titan arum flower in four periods. The comparison of the total volatile compounds released in four periods was S2 > S3 > S1 > S4. The highest content of volatile compounds in the S1 period were sulfur compounds (dimethyl disulfide and dimethyl trisulfide), and the sulfur compounds were released in large amounts only in the S1 period. Dimethyl disulfide was the volatile substance with the highest content in the S1 period (20.00%). The total volatile compounds content of titan arum flower in the S2 period was the highest among the four periods. From the S2 period, the relative content of sulfur compounds decreased significantly until the S4 period. Compared with the S1 period, 1-butanol and butyl acrylate increased significantly and 1-butanol became the highest relative component of volatile compounds in the S2 period. After the S3 period, the total amount of volatile compounds began to decline and reached the lowest level in the S4 period. It is worth noting that the contents of two terpenes, α-pinene and γ-terpinene, rose from the S1 period until their height in the S3 period. From the S4 period, the contents of most volatile compounds decreased significantly. This study revealed the varieties and contents of volatile compounds in the titan arum flower at different flowering periods. The changing trend and physiological significance of dimethyl oligosulfide from the evening of flowering (S1) to the second day (S2–S4) were emphatically discussed, and this research also provides a reference for the study of the release of volatile compounds and the molecular biology of the flower fragrance of titan arum.

Basic helix-loop-helix (bHLH) transcription factors (TFs) play irreplaceable roles in plant growth and development, especially in plant secondary metabolism. However, the functions of most bHLH TFs in Lilium ‘Siberia’ are still unknown, especially their roles in regulating floral fragrance. In this study, two bHLH TFs in lily, i.e., LibHLH22 and LibHLH63, were identified and functionally characterized. A bioinformatics analysis revealed that LibHLH22 and LibHLH63 were unstable proteins. Subcellular localization demonstrated that LibHLH22 and LibHLH63 proteins were in the cell nucleus. Quantitative real-time PCR showed that the highest expression level of LibHLH22 was at the initial flowering stage and in the stigma, and the highest expression level of LibHLH63 was at the budding stage and in the filaments. The results of transient overexpression and virus-induced gene silencing (VIGS) of LibHLH22 and LibHLH63 in lily petals showed that these two transcription factors significantly promoted the expression of LiDXR and LiTPS2, and thus, markedly enhanced the release of floral fragrance. Our results indicated that LibHLH22 and LibHLH63 could effectively regulate the fragrance of Lilium ‘Siberia’, laying the foundation for fragrance breeding and improving the terpenoid transcriptional regulatory pathway.

As one of the most destructive oligophagous pests, the chrysanthemum aphid (Macrosiphoniella sanborni) has seriously restricted the sustainable development of the chrysanthemum industry. Olfaction plays a critical role in the environmental perception of aphids, but very little is currently known about the chemosensory mechanism of M. sanborni. In this study, four MsanOBPs, four MsanCSPs, eight MsanORs, two MsanIRs and one MsanSNMP were identified among the 28,323 unigenes derived from the antennal transcriptome bioinformatic analysis of M. sanborni adults. Then, comprehensive phylogenetic analyses of these olfactory-related proteins in different aphid species were performed using multiple sequence alignment. Subsequently, the odor-specific and wing-specific expression profiles of these candidate chemosensory genes were investigated using quantitative real-time PCR. The data showed that most of these chemosensory genes exhibited higher expression levels in alate aphids. Among them, MsanOBP9, MsanOR2, MsanOR4, MsanOR43b-1, MsanCSP1, MsanCSP2, MsanCSP4, MsanIR25a and MsanIR40a in alate aphids showed remarkably higher expression levels than in apterous aphids under the effect of the host plant volatiles, indicating that these genes may take part in the specific behaviors of alate adults, such as host recognition, oviposition site selection and so on. This study lays the groundwork for future research into the molecular mechanism of olfactory recognition in M. sanborni.