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.

Global climate change and widespread unsustainable agricultural practices increasingly impose both biotic and abiotic stresses on the production of horticultural plants. Lilies (Lilium spp.) are globally renowned ornamental plants, with some species also possessing medicinal, edible, and cosmetic value. However, their quality and yield are often negatively affected by various stresses. Conventional breeding methods are often inefficient due to the long juvenile phase, complex genetic background, and large genome size of lilies. While numerous emerging technologies provide opportunities for resistance breeding in lilies, their successful application relies on a thorough understanding of the resistance response mechanisms. This review systematically summarizes recent advances in lily stress resistance research, delineating the physiological and molecular response mechanisms of lilies under abiotic stresses (extreme temperature, drought, high salinity), biotic stresses (pathogens, pests), and continuous cropping obstacles. Furthermore, it discusses current challenges and limitations, and explores the potential applications of emerging technologies in improving the stress adaptability of lilies. These findings provide important insights for advancing stress resistance research and breeding stress-tolerant lily cultivars.

Lily is one of the most important cut flowers in the world, with a rich floral fragrance. To further explore the fragrance emission mechanisms of lily cultivars, headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) and organic solvent extraction–gas chromatography–mass spectrometry (OSE-GC-MS) were used to unveil the volatile organic compounds (VOCs) and endogenous extracts of seven lily cultivars. Furthermore, real-time quantitative PCR (qRT-PCR) was used to determine the expression levels of two key genes (TPS and BSMT) related to the biosynthesis of monoterpenoids and methyl benzoate. The results show that forty-five VOCs were detected in the petals of seven lily cultivars, and the main compounds were monoterpenoids and phenylpropanoids/benzenoids. Dichloromethane was the best solvent for extracting the endogenous extracts of Lilium ‘Viviana’ petals and eighteen endogenous extracts were detected using dichloromethane to extract the petals of seven lily cultivars. Each compound’s emission ratio (natural logarithm of the ratio of VOC content to endogenous extract content) was calculated, and linear regression analyses between emission ratios and boiling points were conducted. Significant linear negative correlations existed between the emission ratios and boiling points of compounds, and the regression equations’ coefficients of determination (R²) were all greater than 0.7. TPS was expressed highly in ‘Viviana’, ‘Pink News’, and ‘Palazzo’, and BSMT was expressed highly in ‘Pink News’ and ‘Palazzo’. Correlation analyses between the gene expression levels and the monoterpenoids and methyl benzoate contents found that the TPS expression levels have strong positive correlations with monoterpenoids content, while no correlations were found between the expression levels of BSMT and the contents of methyl benzoate. This study lays the foundation for research on the release patterns of VOCs in the flowers of Lilium, and the breeding of lilies for their floral fragrance.

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.

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.