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Continuous flowering is a key horticultural trait in ornamental plants, whereas the specific molecular regulation mechanism remains largely unknown. In sweet osmanthus ( Osmanthus fragrans Lour.), plants based on their flowering characteristics are divided into once-flowering (OF) habit and continuous flowering (CF) habit. Here, we first described the flowering phenology shifts of OF and CF habits in sweet osmanthus through paraffin section and microscope assay. Phenotypic characterization showed that CF plants had constant new shoot growth, floral transition, and blooming for 1 year, which might lead to a continuous flowering trait. We performed the transcriptome sequencing of OF and CF sweet osmanthus and analyzed the transcriptional activity of flowering-related genes. Among the genes, three floral integrators, OfFT , OfTFL1 , and OfBFT , had a differential expression during the floral transition process in OF and CF habits. The expression patterns of the three genes in 1 year were revealed. The results suggested that their accumulations corresponded to the new shoots occurring and the floral transition process. Function studies suggested that OfFT acted as a flowering activator, whereas OfBFT was a flowering inhibitor. Yeast one-hybrid assay indicated that OfSPL8 was a common upstream transcription factor of OfFT and OfBFT , suggesting the vital role of OfSPL8 in continuous flowering regulation. These results provide a novel insight into the molecular mechanism of continuous flowering.

Background In Arabidopsis , a long day flowering plant, CONSTANS ( CO ) acts as a transcriptional activator of flowering under long day (LD) condition. In rice, a short day flowering plant, Hd1 , the ortholog of CO , plays dual functions in respond to day-length, activates flowering in short days and represses flowering in long days. In addition, alleles of Hd1 account for ~ 44% of the variation in flowering time observed in cultivated rice and sorghum. How does it work in bamboo? The function of CO in bamboo is similar to that in Arabidopsis ? Results Two CO homologous genes, PvCO1 and PvCO2 , in Phyllostachys violascens were identified. Alignment analysis showed that the two PvCOLs had the highest sequence similarity to rice Hd1. Both PvCO1 and PvCO2 expressed in specific tissues, mainly in leaf. The PvCO1 gene had low expression before flowering, high expression during the flowering stage, and then declined to low expression again after flowering. In contrast, expression of PvCO2 was low during the flowering stage, but rapidly increased to a high level after flowering. The mRNA levels of both PvCOs exhibited a diurnal rhythm. Both PvCO1 and PvCO2 proteins were localized in nucleus of cells. PvCO1 could interact with PvGF14c protein which belonged to 14–3-3 gene family through B-box domain. Overexpression of PvCO1 in Arabidopsis significantly caused late flowering by reducing the expression of AtFT , whereas, transgenic plants overexpressing PvCO2 showed a similar flowering time with WT under LD conditions. Taken together, these results suggested that PvCO1 was involved in the flowering regulation, and PvCO2 may either not have a role in regulating flowering or act redundantly with other flowering regulators in Arabidopsis . Our data also indicated regulatory divergence between PvCOLs in Ph. violascens and CO in Arabidopsis as well as Hd1 in Oryza sativa. Our results will provide useful information for elucidating the regulatory mechanism of COLs involved in the flowering. Conclusions Unlike to the CO gene in Arabidopsis , PvCO1 was a negative regulator of flowering in transgenic Arabidopsis under LD condition. It was likely that long period of vegetative growth of this bamboo species was related with the regulation of PvCO1.

The SET domain genes ( SDGs ) are significant contributors to various aspects of plant growth and development, mainly includes flowering, pollen development, root growth, regulation of the biological clock and branching patterns. To clarify the biological functions of the chrysanthemum SDG family, the SDG family members of four chrysanthemum cultivars and three related wild species were identified; their physical and chemical properties, protein domains and conserved motifs were predicted and analyzed. The results showed that 59, 67, 67, 102, 106, 114, and 123 SDGs were identified from Chrysanthemum nankingense , Chrysanthemum lavandulifolium , Chrysanthemum seticuspe , Chrysanthemum × morifolium cv. ‘Hechengxinghuo’, ‘Zhongshanzigui’, ‘Quanxiangshuichang’ and ‘Jinbeidahong’, respectively. The SDGs were divided into 5–7 subfamilies by cluster analysis; different conserved motifs were observed in particular families. The SDGs of C. lavandulifolium and C. seticuspe were distributed unevenly on 9 chromosomes. SDG promoters of different species include growth and development, photo-response, stress response and hormone responsive elements, among them, the cis-acting elements related to MeJA response had the largest proportion. The expression of chrysanthemum SDG genes was observed for most variable selected genes which has close association with important Arabidopsis thaliana genes related to flowering regulation. The qPCR results showed that the expression trend of SDG genes varied in different tissues at different growth stages with high expression in the flowering period. The ClSDG29 showed higher expression in the flower and bud tissues, which indicate that ClSDG29 might be associated with flowering regulation in chrysanthemum. In summary, the results of this study can provide a basis for subsequent research on chrysanthemum flowering time regulation.

Background The C-repeat binding factor (CBF)/dehydration-responsive element binding (DREB1) belongs to a subfamily of the AP2/ERF (APETALA2/ethylene-responsive factor) superfamily, which can regulate many physiological and biochemical processes in plants, such as plant growth and development, hormone signal transduction and response to abiotic stress. Although the CBF/DREB1 family has been identified in many plants, studies of the CBF/DREB1 family in alfalfa are insufficient. Results In this study, 25 MsCBF genes were identified in the genome of alfalfa (“Zhongmu No. 4”). These genes were distributed on chromosomes 1, 5, 6 and unassembled scaffolds. Phylogenetics divided the CBF members of Medicago sativa , Arabidopsis thaliana , and Medicago truncatula into six groups, of which group VI had the most MsCBFs members, reaching 52% (13/25). Gene duplication analysis showed that 64% (16/25) of MsCBFs formed tandem duplications, and 32% (8/25) formed segment duplications. The expression pattern of MsCBF9 under different hormone treatments was verified by RT-qPCR, and it was found that MsCBF9 responded to GA3, IAA, SA, and MeJA. Overexpression of MsCBF9 in Arabidopsis significantly delayed the flowering time of Arabidopsis . In contrast, the flowering time of the cbfs mutant was earlier, and overexpression of MsCBF9 also increased the number and size of Arabidopsis rosette leaves. Conclusion In this study, the CBF/DREB1 family of alfalfa was comprehensively identified and analyzed, and the function of MsCBF9 in regulating flowering time was studied. This study laid a foundation for further analysis of the function of the CBF family in alfalfa. Clinical trial number Not applicable.

In evergreen avocado ( Persea americana Mill.), flowering occurs in parallel with shedding of the previous season’s mature leaves, leaving partially leafless trees highly exposed to heat-induced damage in the spring. Foliar application of gibberellins (GAs) is known to increase vegetative growth while reducing flowering in various fruit trees. Here, we examined the effects of autumn GA 3 treatment on different growth parameters of young ‘Hass’ avocado trees over two years. Our results showed that 200 ppm GA₃ treatment applied in the fall slightly reduced flowering levels. In addition, both 100 and 200 ppm GA₃ treatments significantly increased foliar coverage and the indeterminate-to-determinate floral shoot ratio, changes that were associated with elevated expression of the floral repressor PaTFL1. Furthermore, GA 3 treatment also increased leaf area and chlorophyll content, enhanced fruitlet retention, and increased yield in subsequent seasons. In conjunction with field measurements, we acquired high-resolution unmanned aerial vehicle (UAV) imagery, including multispectral imagery and 3D point cloud data, at distinct time intervals after applying the GA₃ treatment. UAV imagery and random forest machine learning models were used to estimate flowering intensity, leaf area density, canopy volume, and chlorophyll content across orchards. The 3D point cloud data revealed significantly more developed canopies in GA₃-treated trees. Furthermore, UAV-derived estimates of flowering, canopy leaf area, and chlorophyll content closely matched field data measurements. Together, our results suggest that GA 3 treatment applied during the fall to young ‘Hass’ trees contributes to protection against heat damage in the spring, thereby increasing yield in the next season.

The phosphatidylethanolamine-binding protein (PEBP) gene family plays a crucial role in regulating key biological processes in plants, such as flowering time, morphological architecture, and seed germination. However, the diversity, expression patterns, and functions of PEBP genes in Nicotiana tabacum remain largely unexplored. In this study, 32 PEBP gene family members were identified in Nicotiana tabacum and systematically classified into four subfamilies: FT-like (17 members), TFL1-like (9 members), MFT-like (2 members), and YbhB-like (4 members). Conserved motifs DPDxP and GxHR, essential for anion-binding activity, were identified in NtPEBPs . Promoter cis -acting element analysis indicated that NtPEBPs are extensively involved in light response, hormone regulation, stress response, and growth and development in tobacco. Transcriptome data revealed that some genes exhibit tissue-specific expression patterns, with certain NtBFT and NtTSF members showing high expression levels in leaves and flowers, while some members of the MFT-like and YbhB-like subfamilies were significantly expressed in dry capsules. Subcellular localization confirmed that NtATC4, NtBFT1, and NtBFT4 are localized in the cytoplasm, while NtFT7 is localized in both the nucleus and cytoplasm. Yeast two-hybrid and bimolecular fluorescence complementation assays further demonstrated that NtATC4, NtFT7, NtBFT1, and NtBFT4 can all interact with the Nt14-3-3 protein, suggesting their potential involvement in the tobacco flowering process through the formation of flowering regulatory complexes. Virus-induced gene silencing (VIGS) assays revealed that silencing of NtATC4 delays flowering and promotes vegetative growth. In NtATC4 -silenced plants, the expression of flowering-related genes NbAP1 and NbSVP was upregulated, whereas NbSOC1 expression was downregulated. This study provides a comprehensive gene inventory and interaction dataset for further research on NtPEBPs and identifies candidate targets for molecular breeding in tobacco.

Flowering is a pivotal developmental transition in the life cycle of plants, and the precise timing of this process is crucial for successful reproduction. The flowering mechanism of the pineapple is influenced by a combination of genetic factors, environmental conditions and cultivation methods. Once pineapple plants have reached a certain number of leaves, the timing of floral bud differentiation can be regulated by applying plant growth regulators. This facilitates staggered fruit production and enables a balanced year-round supply. The timing, quantity and quality of floral bud differentiation directly affect pineapple fruit quality and yield, and also significantly impact the economic and social benefits of the pineapple industry. This paper provides a systematic review of the morphological characteristics of flowers, the patterns of floral bud differentiation, the mechanisms underlying natural and induced flowering, and the key factors influencing flowering in pineapples. This review establishes a theoretical foundation for regulating fruiting periods and optimising high-quality, high-efficiency cultivation practices.

The flower induction of Hydrangea macrophylla “Endless Summer” is regulated by a complex gene network that involves multiple signaling pathways to ensure continuous flowering throughout the growing season, but the molecular determinants of flower induction are not yet clear. In this study, genes potentially involved in signaling pathway mediating the regulatory mechanism of flower induction were identified through the transcriptomic profiles, and a hypothetical model for this regulatory mechanism was obtained by an analysis of the available transcriptomic data, suggesting that sugar-, hormone-, and flowering-related genes participated in the flower induction process of H. macrophylla “Endless Summer”. The expression profiles of the genes involved in the biosynthesis and metabolism of sugar showed that the beta-amylase gene BAM1 displayed a high expression level at the BS2 stage and implied the hydrolysis of starch. It may be a signaling molecule that promotes the transition from vegetative growth to reproductive growth in H. macrophylla “Endless Summer”. Complex hormone regulatory networks involved in abscisic acid (ABA), auxin (IAA), zeatin nucleoside (ZR), and gibberellin (GA) also induced flower formation in H. macrophylla. ABA participated in flower induction by regulating flowering genes. The high content of IAA and the high expression level of the auxin influx carrier gene LAX5 at the BS2 stage suggested that the flow of auxin between sources and sinks in H. macrophylla is involved in the regulation of floral induction as a signal. In addition, flowering-related genes were mainly involved in the photoperiodic pathway, the aging pathway, and the gibberellin pathway. As a result, multiple pathways, including the photoperiodic pathway, the aging pathway, and the gibberellin pathway, which were mainly mediated by crosstalk between sugar and hormone signals, regulated the molecular network involved in flower induction in H. macrophylla “Endless Summer”.