Jinfen Wen

Chrysanthemum is one of the world’s four main cut flowers. However, postharvest drought stress severely disrupts water homeostasis, triggering reactive oxygen species burst and membrane lipid peroxidation, thereby reducing its ornamental quality and vase life. Melatonin serves as a multifunctional antioxidant and stress regulator. This study demonstrated that 200 μmol L⁻¹ melatonin effectively alleviated drought-induced leaf wilting, maintained relative water content, decreased the accumulation of MDA, H₂O₂, and O₂^•−, and enhanced the activities of SOD, CAT, POD, and APX. Concurrently, non-enzymatic antioxidants (proline, GSH, ASA) accumulated to high levels. RNA-seq analysis revealed that drought affects pathways closely related to the production of antioxidant and osmoprotectant metabolites, while melatonin initiated extensive transcriptional reprogramming and responded to drought stress through distinct pathways at the early (12 h) and late (24 h) treatment stages. Melatonin also modulated key transcription factor families, including bHLH, NAC, ERF, MYB, and bZIP. Collectively, exogenous MT mitigates drought damage in chrysanthemum cut flowers by coordinating antioxidant systems and complex transcriptional regulatory networks. This study provides a theoretical foundation for improving postharvest drought tolerance and prolonging the vase life of cut flowers.

(1) Background: The bHLH (basic helix-loop-helix) transcription factor family is one of the most abundant in plants and is involved in plant growth, development, and abiotic stress responses. Notably, the functions of most bHLH family members remain poorly characterized. (2) Results: CmbHLH112, a nuclear-localized bHLH transcription factor from chrysanthemum, exhibits transcriptional activation activity. Overexpression of CmbHLH112 in Arabidopsis significantly promotes flowering and enhances drought resistance. qRT-PCR analysis revealed that CmbHLH112 regulates flowering time by affecting the expression of key flowering genes, including FT, SOC1, LFY, and FLC. Under drought stress, CmbHLH112 overexpression plants showed reduced ROS accumulation compared with wild-type plants, accompanied by elevated activities of key antioxidant enzymes and increased proline content. Moreover, transgenic plants exhibited lower MDA concentrations and reduced water loss rates under drought conditions, further indicating enhanced stress resilience. Overexpression of CmbHLH112 also upregulates ABA levels under drought stress, while simultaneously promoting the expression of genes involved in ABA biosynthesis and ABA signaling pathways. (3) Conclusions: Our results demonstrate that heterologous overexpression of CmbHLH112 in Arabidopsis enhances drought tolerance and promotes flowering. Thus, CmbHLH112 is proposed to play a dual role in modulating flowering time and drought tolerance, at least partly by regulating ABA biosynthesis.

Hybrid tea roses (Rosa hybrida) are economically important horticultural crops and highly susceptible to heat stress, which significantly impacts flower quality and yield. As a key member of the heat shock protein (HSP) family, HSP70 protein acts as a molecular chaperone and exhibits diverse abiotic stress response functions in plants. A total of 113 HSP70 transcription factors (TFs) with varying physical and chemical properties were identified in the genome of hybrid tea rose. Phylogenetic analysis showed that the identified TFs could classify into three (I, II, and III) subfamilies, with most members (51 TFs) falling in subfamily II. Wide gene structural variations were observed among the three subfamilies, with group I and II members lacking introns, while group III members only harbored 1~4 exons and introns. Numerous cis-acting elements associated with abiotic stress, hormone response, growth and development responses, as well as light response were detected in the HSP70 gene promoters. In addition, protein interaction networks predicted a wide range of interactions between different hybrid tea rose HSP70 subfamilies. Gene expression analysis revealed that 57 HSP70 genes had strong organ specificity and response to heat stress in the hybrid tea rose plants. Notably, the expression levels of two RhHSP70 genes, RhHSP70-69 and RhHSP70-88, were significantly increased after heat stress, indicating that these two genes might be crucial for plant heat stress response. Subcellular localization of RhHSP70-69 and RhHSP70-88 revealed that their proteins were located in the nucleus. Our results are not only useful for future evaluation of the regulatory roles of RhHSP70 genes in the hybrid tea rose growth and development, but also provides key genes for future molecular breeding of heat tolerant plants.

Drought stress is an important factor that reduces plant biomass production and quality. The APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) gene family is widely involved in biological processes such as plant growth, development, and stress response. However, the characteristics of the AP2/ERF gene family in hybrid tea rose (Rosa × hybrida) and their potential functions in responding to drought stress are still unclear. In the current study, 127 AP2/ERF genes were identified in hybrid tea rose. Phylogenetic analysis showed that the corresponding 127 AP2/ERF transcription factors belonged to five subfamilies. There was a large number of cis-acting elements in the AP2/ERF gene promoters related to regulation of stress response, growth and development. By examining the RNA sequencing data in the PlantExp database, the RhAP2/ERF genes exhibiting tissue-specific and stress-responsive expression in rose were identified. Furthermore, three candidate RhAP2/ERF genes (RhDREB36, RhERF59, and RhDREB44) that might participate in drought response were determined via qRT-PCR analysis in rose cultivars under drought treatment. Subcellular localization analysis revealed that RhDREB44 was located in the nucleus. These results provide a foundation for exploring the regulatory functions of RhAP2/ERF genes in the growth and development of roses, as well as for selecting key genes for future molecular breeding.

Dried yellow chili is highly appreciated by consumers due to its excellent quality and flavor. The quality of products is determined by the drying and storage methods. In this study, dried yellow chilis were processed by natural air drying and hot air drying methods and then stored under three conditions: ambient temperature, ambient temperature with light avoidance, and at 10 °C with light avoidance for 12 months. The changes in the bioactive compounds during this period were analyzed attempting to reveal correlations between the different treatments and these compounds, with the aim of providing references for maintaining the bioactive compounds of pepper products. The results showed that samples treated with hot air had higher levels of fatty acids, resulting in a more pronounced flavor. During storage, samples stored at 10 °C with light avoidance were more effective in preserving soluble solids, total protein content, total phenols, capsaicinoids and most fatty acids.

Cuticular wax is the first barrier between plants and the environment. Here, the densities of cuticular wax crystals on the petals of eight rose cultivars were determined to be sparse; the crystals were mostly granular and only a few rod-shaped crystals were observed in ‘Sweet’. The total contents and chemical compositions of waxes were significantly different among the rose varieties. The waxes were mainly composed of n-alkanes, iso-alananes and alkenes. Under water-loss stress, ‘Diana’ and ‘Carola’ cultivars, having high petal wax contents, had low water permeability levels, long vase lives, high relative water contents and low relative conductivity levels. However, the low wax contents of the ‘Jubilance’ and ‘Candy Avalanche’ cultivars resulted in high water permeability levels and short vase lives. Pearson correlation analyses showed the total wax content in petal epidermis was positively correlated with vase life. The data provide novel insights into the compositional variances in the cuticular waxes of rose petals and their impacts on cut rose vase lives.

The WRKY gene family is a key transcription factor family for plant development and the stress response. However, few studies have investigated the WRKY gene family in Chinese rose (Rosa chinensis). In this study, 68 RcWRKY genes were identified from the Chinese rose genome and classified into three primary groups and five subgroups based on the structural and phylogenetic characteristics. The analysis of the conserved domains, motifs, and gene structure revealed that the RcWRKY genes within the same group had the same exon–intron organization and composition. Chromosome mapping and gene duplication revealed that the RcWRKY genes were randomly dispersed across seven chromosomes. Fragment duplication and refined selection may have influenced the evolution of the WRKY gene family in Chinese rose. The cis-acting elements in the WRKY promoter region revealed that the RcWRKY genes contained numerous abiotic stress response elements. The results of qRT-PCR revealed that the expression of RcWRKY was tissue-specific, with high expression being observed under drought, heat, and salt stress. Notably, RcWRKY49′s expression increased more than fivefold following salt stress, indicating that it is a crucial gene mediating the salt stress response of Chinese rose. These findings shed light on the regulatory role of RcWRKY in the growth and development of Chinese rose, and they serve as a foundation for future molecular breeding programs and gene discovery.

Heat shock proteins (HSPs) play important roles in plant stress resistance, but it is not clear whether small molecular HSPs (sHSPs) are involved in the cold stress resistance of lily flowers. In this study, we cloned LbHSP17.9 and found that its expression was up-regulated under cold stress. When LbHSP17.9 was silenced (TRV2::LbHSP17.9) using virus-induced gene silencing in cut lily flowers, the content of malondialdehyde was increased under 4 °C stress treatment. The catalase (CAT) activity in TRV2::LbHSP17.9 was significantly lower than in TRV2 in the first 7 days, and the peroxidase (POD) activity in TRV2::LbHSP17.9 was significantly lower than in TRV2 after 4 days of 4 °C stress. Further analysis showed that the transcription levels of LbCu/ZnSOD, LbMnSOD and LbCAT in TRV2::LbHSP17.9 were lower than those of TRV2 under 4 °C stress. When LbHSP17.9 was overexpressed in lily petal disks, the OE-LbHSP17.9 disks faded later than the controls at 4 °C and the relative conductivity decreased significantly. Overexpression of LbHSP17.9 in Arabidopsis thaliana resulted in fewer injury symptoms and lower MDA content than wild type under 4 °C stress. Therefore, we speculate that LbHSP17.9 can improve the resistance of lily flowers to cold stress.

In this study, LbCu/ZnSOD, LbFeSOD, and LbMnSOD genes were cloned, the role of strigolactones (SLs), a novel plant hormone that is ubiquitous in plants in modulating plant responses to abiotic stress, on the three superoxide dismutases (SODs) ...

Plant homeodomain (PHD) transcription factor genes are involved in plant development and in a plant’s response to stress. However, there are few reports about this gene family in peppers (Capsicum annuum L.). In this study, the pepper inbred line “Zunla-1” was used as the reference genome, and a total of 43 PHD genes were identified, and systematic analysis was performed to study the chromosomal location, evolutionary relationship, gene structure, domains, and upstream cis-regulatory elements of the CaPHD genes. The fewest CaPHD genes were located on chromosome 4, while the most were on chromosome 3. Genes with similar gene structures and domains were clustered together. Expression analysis showed that the expression of CaPHD genes was quite different in different tissues and in response to various stress treatments. The expression of CaPHD17 was different in the early stage of flower bud development in the near-isogenic cytoplasmic male-sterile inbred and the maintainer inbred lines. It is speculated that this gene is involved in the development of male sterility in pepper. CaPHD37 was significantly upregulated in leaves and roots after heat stress, and it is speculated that CaPHD37 plays an important role in tolerating heat stress in pepper; in addition, CaPHD9, CaPHD10, CaPHD11, CaPHD17, CaPHD19, CaPHD20, and CaPHD43 were not sensitive to abiotic stress or hormonal factors. This study will provide the basis for further research into the function of CaPHD genes in plant development and responses to abiotic stresses and hormones.