Water is one of the most important elements affecting the growth of ornamental plants. To investigate the effects of drought stress on the growth, ornamental values, and physiological properties of Begonia semperflorens, watering treatments with 250 mL (control check, CK), 200 mL (extremely light drought, ELD), 150 mL (light drought, LD), 100 mL (moderate drought, MD), 50 mL (severe drought, SD), and 25 mL (extremely severe drought, ESD) on the B. semperflorens variety “Chao Ao” were performed in this study. As a result, compared to the control (CK), the number of flowers, leaves, and branches, leaf size, plant height, crown diameter, as well as water content, transpiration rate, net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and chlorophyll content in leaves decreased, followed by an increased amount of drought stress. The contents of the osmotic adjustment substances, such as soluble sugar, soluble protein, proline, and betaine, were increased under drought stress. Indicators related to antioxidant activities, such as SOD activity, increased and then decreased. The POD activity, CAT activity, MDA content, and plasma membrane permeability of B. semperflorens were higher under increased drought stress than in the control condition. The APX activity decreased and then increased under drought stress. In conclusion, B. semperflorens responds to drought stress by increasing osmotic adjustment substances and antioxidant activities and reducing the water loss, growth potential, and photosynthetic rate. The correlation analysis showed that, except for APX, the drought resistance coefficients of 23 other indexes were correlated in different degrees. Therefore, this study suggests that B. semperflorens has a strong drought resistance ability, retaining high ornamental values in conditions of moderate drought stress, and can still survive under extremely high drought stress.

In nature, plants have rich and vivid colors. Flower color can confer economic and ornamental value to ornamental plants, and is one of the target traits for current directed breeding. Therefore, it is essential to understand the molecular regulatory mechanisms behind flower color formation in ornamental plants. However, in Cosmos bipinnata Cav., one of the most important ornamental plants, the metabolic pathways and molecular regulatory mechanisms underlying the formation of different flower colors are not yet clear, which greatly restricts the molecular breeding of flower color varieties. We selected three varieties of Cosmos bipinnata Cav. with white, pink, and red flowers as research materials, and identified significantly different metabolites among them through ultra performance liquid chromatography mass spectrometry (UPLC-MS/MS) analysis and principal component analysis (PCA). Then, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and transcriptome sequencing analysis in different colors flowers were used to reveal that the differential metabolites were enriched in flavonoid metabolic pathways and related structural genes were differentially expressed. Furthermore, we identified differentially expressed members of the MYB and bHLH transcription factor families, which play key roles in regulating the anthocyanin biosynthesis. By constructing a phylogenetic tree and performing a joint analysis of transcriptome and metabolome data, we further elucidated the molecular regulatory network underlying the formation of flower colors in Cosmos bipinnata Cav. This study not only provides a theoretical basis and gene resources for color-oriented breeding and the creation of new color varieties, but also offers new insights into the molecular mechanisms of flower color formation in plants.

Fragrance lotus (Nymphaea hybrid) is a tropical interspecific cultivar characterized by large flowers and high scent intensity, offering dual potential for ornamental commerce and natural fragrance extraction. Floral scent determines both economic value and pollinator attraction, yet the biosynthetic organs and metabolic routes remain undocumented. To fill this gap, single flowers of the high-aroma cultivar ‘Eldorado’ at full anthesis were dissected into petal (PE), stamen (ST) and pistil (PI); each organ was subjected to untargeted LC-MS/MS metabolomics and Illumina RNA-seq. Organ-specific gene–metabolite co-expression networks were constructed by pairwise integration of transcript and metabolite matrices. All three organs formed distinct clusters in principal-component space. Compared with PE, 6221, 3352 and 5891 differentially expressed genes (DEGs) together with 30, 24 and 39 differentially accumulated metabolites (DAMs) were identified in ST, PI and PE, respectively. The phenylpropanoid biosynthesis pathway (map00940) was the only route simultaneously enriched at both transcript and metabolite levels; 59 DEGs mapped to this pathway co-linearly with three scent-related DAMs. ST contained the highest concentration of scent-active volatiles; phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL) and benzaldehyde reductase (BAR) were all significantly up-regulated in this organ, driving the accumulation of p-coumaric acid that is subsequently channeled into benzyl alcohol via side-chain cleavage and BAR-mediated reduction, thereby generating the characteristic fragrance of Nymphaea. This study provides the first organ-level resolution of scent biosynthesis and metabolic flux partitioning in fragrance lotus, furnishing molecular targets for directed aroma improvement and efficient natural fragrance extraction.

The precious aquatic plant Nymphaea hybrid, is valued for its ornamental and economic importance but is highly sensitive to environmental fluctuations. However, the interactive effects of light and temperature, two critical abiotic factors, on its photosynthetic performance and underlying structural basis remain poorly understood. In this paper, we conducted a two-factorial experiment in which N. hybrid plants were exposed to five light–temperature regimes for 9 days: control (T0, 800 μmol·m⁻²·s⁻¹ + 25/20 °C); low light–low temperature—LLLT (T1, 200 μmol·m⁻²·s⁻¹ + 15/10 °C); low light–high temperature—LLHT (T2, 200 μmol·m⁻²·s⁻¹ + 35/30 °C); high light–low temperature—HLLT (T3, 1400 μmol·m⁻²·s⁻¹ + 15/10 °C); and high light–high temperature—HLHT (T4, 1400 μmol·m⁻²·s⁻¹ + 35/30 °C). We systematically investigated changes in photosynthetic pigments, gas exchange, chlorophyll fluorescence, and leaf ultrastructure by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that: The HLLT treatment (T3) inflicted the most severe damage, triggering a rapid decline in net photosynthetic rate (Pn), maximal photochemical efficiency (F_v/F_m), and chlorophyll content, coupled with a significant increase in intercellular CO₂ concentration (Ci). Ultrastructurally, T3 caused stomatal closure, disintegration of thylakoid membranes, and accumulation of large osmophilic granules, indicating severe photo-oxidative stress. In contrast, the LLHT treatment (T2) demonstrated remarkable resilience, with physiological and structural parameters closely resembling the control. The HLHT treatment (T4) caused intermediate damage, primarily through non-stomatal limitations over time. Our findings demonstrate a significant light–temperature interaction in N. hybrid. The thermophilic nature of N. hybrid was evident: high temperature mitigated the negative effects of low light, whereas low temperature, especially in combination with high light, acted synergistically to cause catastrophic damage to the photosynthetic apparatus. This study provides a mechanistic understanding of N. hybrid’s environmental adaptability, offering critical insights for its cultivation management under changing climate conditions, especially in high altitude and high latitude areas.