Search Results (92)

The SHAGGY-like kinase (SK) gene family regulates diverse developmental and abiotic stress response processes in plants. Although genome-wide analyses of SKs have been conducted in model plants such as Arabidopsis thaliana and rice, their characterization in the economically important crop Brassica rapa remains limited. In this study, we conducted a systematic genome-wide analysis of SK genes in three Brassica species. A total of 18, 16, and 18 SK members were identified in B. rapa, B. nigra, and B. oleracea, respectively, and phylogenetic analysis classified them into four distinct clades. Expression profiling revealed that BrSKβ-1 and BrSKβ-2 were specifically expressed in fertile floral buds, suggesting their critical roles in pollen development. Furthermore, co-expression analysis indicated that both genes were co-expressed with key regulators involved in pollen development, pollen sperm cell differentiation and pollen tube growth. Loss of BrSKβ-2 via CRISPR/Cas9 resulted in 25–65% pollen abnormality and reduced the germination rate of normal-appearing pollen to only 10%, confirming its essential role in male fertility. Together, these findings provide a comprehensive characterization of the SK gene family in Brassica and position BrSKβ-2 as a promising candidate for gene editing-based male sterility systems in B. rapa and related crops. Full article

AGL6 genes are critical floral regulators in diverse angiosperms, yet their roles in legumes remain poorly understood. This study aimed to characterize GmAGL6 genes in soybean (Glycine max [L.] Merr. cv. Williams 82). We identified four homologs (GmAGL6a–d) featuring conserved MADS-box and K-box domains that cluster within the AGL6 lineage. Tissue-specific expression profiling revealed significant transcript enrichment during flower bud differentiation and maturation. Using CRISPR/Cas9, we generated quadruple knockout lines to evaluate gene function. Phenotypic analysis showed that, unlike the homeotic transformations typical of AGL6 loss in monocots, Gmagl6 quadruple mutants retained a standard papilionaceous floral structure without keel petal aberrations. However, the mutants did not show significant changes in floral height or width, but exhibited a significantly increased floral height-to-width ratio and smaller mature seeds, while vegetative architecture and podding capacity remained unaffected. These results suggest that GmAGL6 genes in soybean may function primarily in the regulation of floral proportion and seed development rather than floral organ identity. This research provides insights into the evolution of specialized legume flowers and suggests candidate genes for seed size improvement. Full article

Korean pine (Pinus koraiensis) is a vital woody oil tree species native to Northeast Asia, with its pine nuts serving as the primary global source of edible pine nuts globally due to their rich nutritional content. Currently, seed yield from Korean pine is low and unstable, failing to meet the market demand. The limited number of female cones is the primary factor restricting its yield. MADS-box family members are crucial in regulating the initiation, differentiation, and morphogenesis of floral organs. However, systematic identification and characterization of MADS-box proteins in Korean pine have not been reported. This study utilized transcriptome data from reproductive and vegetative buds during the flower bud differentiation stage of Korean pine to comprehensively identify MADS-box family members through bioinformatics analysis and molecular biology approaches. A total of 37 PkMADS-box genes were identified, including 6 type I and 31 type II (MIKC) genes, which were classified into 8 subfamilies. The physicochemical properties, conserved domains, conserved motifs, protein structures, gene expression profiles, and protein–protein interaction networks of these genes were analyzed. Key genes associated with physiological differentiation (flower induction) and sexual organogenesis were identified based on expression patterns during flower bud differentiation and flower organ development. Among these, PkMADS4 and PkMADS26 are likely involved in positively regulating flower induction, while PkMADS9 plays a role in the morphological differentiation of sexual organs in a dose-dependent manner and overexpression of PkMADS9 promoting early flowering in transgenic Arabidopsis. These genes were also identified as key candidates for regulating reproductive phase changes and strobilus development. This study provides a theoretical foundation for further investigation of MADS-box genes in reproduction and offers insights into genetic improvements aimed at enhancing the seed yield of Korean pine. Full article

Longan (Dimocarpus longan Lour.) is a commercially valuable tropical fruit crop that contains two antagonistic FLOWERING LOCUS T (FT) homologs involved in regulating flowering time. However, how these FT genes interact with flowering regulators FLOWERING LOCUS D (FD) and APETALA1 (AP1) remains unknown. Four flowering-related genes in longan, DlFT1, DlFT2, DlAP1 and DlFD, were successfully isolated. Expression profiling revealed that all four genes were expressed in leaves and buds across different stages of natural and KClO₃-induced floral bud differentiation. Functional characterization through heterologous overexpression in Arabidopsis thaliana showed that DlAP1 significantly promotes early flowering under long-day conditions and induced morphological changes in floral organs and leaves. In contrast, DlFD overexpression had no effect on flowering time. Subcellular localization assays revealed that DlFT1 and DlFT2 localized to both the nucleus and the plasma membrane, while DlAP1 and DlFD localized exclusively to the nucleus. Yeast two-hybrid and bimolecular fluorescence complementation (BiFC) analyses revealed a novel regulatory node: DlFT1 directly interacts with DlAP1, a finding that expands the classical FT-FD-AP1 flowering model. Additionally, DlFD interacts more strongly with DlFT1 than with DlFT2, whereas DlFT1 only interacts with DlAP1, but not DlFT2. These results demonstrate that DlFT1 promotes flowering not only via the conserved FD-dependent pathway but also through direct association with AP1. These findings advance our understanding of the regulatory mechanisms of flowering in longan and provide valuable insights into flowering pathways of perennial woody species. Full article

High temperature is a major environmental stress that severely limits passionfruit (Passiflora edulis) productivity by impairing floral initiation. However, the physiological and molecular mechanisms underlying this process remain poorly understood. In this study, we investigated the effects of varying durations and intensities of heat stress on flower bud differentiation in passionfruit. Our results showed that prolonged exposure to temperatures above 35 °C significantly delayed or completely inhibited bud formation, accompanied by altered carbohydrate and nitrogen metabolism, accumulation of osmolytes (soluble protein and proline), and dynamic changes in antioxidant enzyme activities (SOD, POD, CAT). Notably, short-term heat stress induced a transient increase in salicylic acid (SA) levels and upregulation of SA biosynthesis genes (PeEDS1.2, PeICS1) and WRKY transcription factors (PeWRKY11/15), which were associated with sustained floral initiation. In contrast, prolonged stress suppressed SA accumulation and signaling, leading to bud abortion. Comparative transcriptomic analysis further revealed enrichment of pathways related to secondary metabolite biosynthesis, plant hormone signal transduction, and phenylpropanoid biosynthesis under heat stress. These findings highlight the critical role of SA in balancing heat tolerance and reproductive development and provide candidate gene resources for the molecular breeding of heat-resistant passionfruit varieties. This study offers new insights into the thermotolerance mechanisms of fruit crops under sustained high-temperature stress. Full article

As a highly valued orchid species, Cymbidium ensifolium (C. ensifolium) exhibits a natural flowering period mainly from July to September, which does not align with the market demand and shows low flowering quality, thereby significantly constraining the development of the C. ensifolium floriculture industry. To address this key issue, the study used C. ensifolium ‘Longyan Su’ as the experimental material, with white light as the control and composite light with varying ratios of red and blue light as the treatments, and investigated the influence of light quality on flowering. The results showed that blue light could significantly advance the flowering time, while red light could markedly improve the flower quality. Blue light promoted the accumulation of soluble protein and soluble sugar during flower bud differentiation, while red light enhanced their accumulation during floral organ development. During the flower bud differentiation and development stage, blue light increased the synthesis of abscisic acid (ABA) in leaves, and red light promoted the production of gibberellic acid (GA₃) and zeatin riboside (ZR). The study provides an important foundation and reference for further analysis of the flowering mechanism of C. ensifolium under different light quality treatments, and also provides technical support for flowering regulation of orchids in practical production. Full article

Bougainvillea spp. is a well-known ornamental plant that is widely applied in urban landscaping construction. The colorful bracts of Bougainvillea in full bloom become important for urban landscape during special festivals. Although flowering regulation measures of Bougainvillea attracted much attention, the underlying mechanism of flower bud differentiation and development remains poorly understood. Here, we induced flowering of Bougainvillea glabra ‘Sao Paulo’ under 6-BA treatment and conducted RNA sequencing data analysis to characterize the molecular regulatory mechanism of flower development in response to 6-BA. Transcriptome analysis indicated that a series of genes and transcription factors of cytokinin metabolism, flowering and floral development regulation, and photoperiod regulation were upregulated by the 6-BA treatment, including COL, AP2, FT, SOC1, LFY, SPL4, SPL9, and SPL13. Moreover, the expression of these important genes exhibited relatively high levels of thorns compared to apical buds, suggesting that flower bud differentiation probably starts with the thorns in Bougainvillea. This study confirms that 6-BA treatment at certain concentrations can promote flowering of Bougainvillea and provides insight into the regulatory mechanism of the growth regulator acting on early flowering of Bougainvillea. Full article

The formation of plant flower buds is regulated by various genes occurring upstream in floral induction pathways. However, the precise regulatory roles and underlying molecular mechanisms of these pathways in Camellia flower bud formation remain unclear. This study investigated the annual periodicity pattern of flower bud formation in two Camellia species exhibiting distinct flowering phenotypes: Camellia azalea, which initiates flower buds continuously throughout the year, and Camellia japonica, which forms buds only between May and July. C. azalea helps address the lack of summer-flowering representatives within the Camellia genus. Elucidating its unique molecular mechanism of flowering regulation provides valuable guidance for breeding new cultivars with summer blooming traits. Comparative transcriptome analysis of mature leaves sampled annually from the two Camellia species revealed the highest number of differentially expressed genes (DEGs) in C. azalea between May and December, whereas in C. japonica, the peak number of DEGs occurred between June and December. Gene ontology analysis indicated that the most enriched category in the transcriptomes of both species was oxidoreductase activity, which was followed by cofactor binding in C. azalea, whereas in C. japonica, it was cellular amino acid metabolic process. Flowering-related genes were identified from the transcriptome database, yielding 248 transcripts in C. azalea and 257 in C. japonica. The transcriptome analysis also revealed that C. azalea lacks certain floral inhibitory pathways that are present in C. japonica, such as the photoperiod pathway genes including GI2, FKF1, and COL14 and the thermosensitive pathway gene SVP. The reliability of the transcriptome results was further validated by quantitative real-time PCR (qRT-PCR) analysis. These results suggest that differences in upstream regulatory mechanisms within the floral induction pathways of C. azalea and C. japonica may underlie the species-specific patterns in the annual distribution of flower bud formation. Full article

Southern highbush blueberry (SHB, Vaccinium corymbosum, Ericaceae) enables production in warm, low-chill regions, where breeding success depends on precisely timed pollinations. To support breeding in non-traditional environments, we characterized floral staging, anther wall ontogeny, tubule formation, and pollen development in two SHB cultivars (‘Emerald’, ‘Snowchaser’) grown in commercial orchards. Floral development was divided into seven stages: dormant buds (db), five successive floral-bud stages (botA–botE), and anthesis, based on bud size, corolla exposure and pigmentation, and anther/tubule coloration. Internal events were documented by light, confocal, and scanning electron microscopy. External cues reliably separated stages and tracked male-gametophyte phases: meiosis at botB; callose-encased tetrads at botC; permanent tetrahedral tetrads after callose dissolution at botD; bicellular tetrads from botE to anthesis, released intact via poricidal dehiscence. Anther-wall differentiation followed a consistent sequence and lacked a fibrous, lignified endothecium. We therefore propose a new Ericaceous pattern for blueberry anthers, defined by a transient non-lignified subepidermal stratum. Tubules originated apically as solid outgrowths, hollowed centrifugally to a beveled pore, developed a dorsal supportive zone, and mediated poricidal release of permanent tetrads. No qualitative cultivar differences were detected. The staging framework defines operational windows for pollination, emasculation, and pollen handling in low-chill systems. Full article

Michelia ‘Xin’ is an evergreen rare ornamental tree species that undergoes FBD only once but blooms twice a year. However, the molecular mechanisms controlling its FBD process remain largely unknown. This study characterized the FBD process and delved into the key molecular regulatory mechanisms through transcriptomic and metabolomic analyses of developing flower buds. FBD in Michelia ‘Xin’ was characterized into five stages, including vegetative (T1), floral meristem transition (T2), tepal primordia differentiation (T3), stamen primordia differentiation (T4), and pistil primordia differentiation (T5). Analyses revealed a stage-specific metabolic and transcriptional regulation of FBD, with increasing numbers of differential metabolites and a decreasing number of DEGs from T1 to T5. Most phytohormone and transcription factor-related DEGs were highly induced from T2. The down-regulation of dormancy-associated protein homologs and CONSTANS-LIKE proteins associated with significant induction of flowering-promoting factor, CLAVATA3, trichome birefringence-like, and GRAVITROPIC IN THE LIGHT proteins was essential for the induction and reproductive organs’ development. Porphyrin biosynthesis, chlorophyll a-b binding proteins, DNA replication, flavonoid biosynthesis, and starch and sucrose metabolism were also significantly induced from T2. Key pivotal candidate genes were screened out. Our results provide fundamental resources for dissecting the molecular network regulating FBD and molecular-assisted flowering control in Michelia ‘Xin’. Full article

Rosa rugosa is an important ornamental and edible species that is valued for its floral colors and essential oils in the cosmetic and pharmaceutical industries. Carotenoids, beyond their health-promoting roles, function as accessory pigments that influence petal coloration, flower quality, and stress responses. However, their accumulation patterns and molecular biosynthesis in R. rugosa remain poorly understood. Here, UPLC-APCI-MS/MS analysis across three developmental stages (bud, semi-open, and full bloom) revealed stage-specific carotenoid accumulation, with phytoene and phytofluene markedly increasing at the semi-open stage. In total, 11 carotenoids were identified, comprising four carotenes and seven xanthophylls. Differential accumulation of metabolites (DAMs) analysis indicated shifts in compounds, including (E/Z)-phytoene, phytofluene, and β-carotene across stages. Genetic complementation assays in Escherichia coli and transient overexpression in rose petals confirmed that RrPSY1 functions as a phytoene synthase. qRT-PCR results showed its upregulation under salt treatment, suggesting a role in enhancing stress tolerance through carotenoid-mediated antioxidant protection. Furthermore, sub-cellular localization experiments confirmed plastid targeting of RrPSY1. Together, these findings clarify the role of RrPSY1 in carotenoid biosynthesis and provide a foundation for future studies on metabolic regulation and biosynthesis of carotenoids in R. rugosa. Full article

Male sterility is an important trait in heterosis utilization and marigold (Tagetes erecta L.) breeding. Currently, most male-sterile lines used in production are derived from natural mutations. ABORTED MICROSPORES (AMS) is an important gene that regulates tapetum and microspore development. Therefore, the effect of AMS on fertility was studied. TeAMS was located in the nucleus and exhibited self-activation activity. TeAMS was highly expressed in the flower buds of T. erecta. The expression of this gene in fertile plants was higher than that in sterile plants, and the expression level gradually increased with the development of flower buds. The expression level of TeAMS was highest in the flower buds with a diameter of 1.2 cm at the floret differentiation stage, while the expression level was extremely low in the flower buds with a diameter of 1.6 cm. The expression trend of TeAMS in sterile plants was opposite to that in fertile plants. At the inflorescence primordium differentiation stage, flower buds with a diameter of 0.2 cm had the highest expression level, and the stem tip had the lowest expression level. In tobacco (Nicotiana tabacum L.), overexpression of the TeAMS gene resulted in shortened floral tubes, increased thousand-seed weight, a reduced flowering period, and decreased flower numbers. The pollen viability of transgenic tobacco was significantly lower than that of the wild type, and the pollen grains were smaller and showed irregular shapes. The pollen wall was dry and shrunk. Some pollen germinal furrows were distorted, and a few were almost invisible. Silencing TeAMS resulted in a longer flowering period in tobacco, reduced thousand-seed weight, and high pollen viability. Pollen morphology in silenced lines showed no significant differences compared to the wild-type and empty vector controls. Only a few pollen grains were smaller, shriveled, and shrunken. Therefore, the TeAMS gene plays an important role in regulating the fertility of marigolds. This study provides a theoretical foundation for breeding marigold male-sterile lines. Full article

Off-season flowering of Macadamia integrifolia has been observed in certain high-altitude regions; however, the endogenous hormonal mechanisms underlying this phenomenon remain unclear. In this study, the annual dynamics of four key endogenous phytohormones (ZT, GA₃, IAA, and ABA) were quantified in the leaves and branches of trees from both normal and off-season flowering sites using high-performance liquid chromatography (HPLC). Hormonal ratios and correlation network analyses were further performed to investigate their roles in flowering regulation. Floral bud differentiation at the off-season site occurred approximately 1 to 2 months earlier than at the normal site. This advancement was associated with sustained low levels of GA₃ (below 100 μg·g⁻¹ FW), while ZT and ABA levels peaked in September at 108.66 μg·g⁻¹ FW and 24.25 μg·g⁻¹ FW, respectively. The ratios of ABA to GA₃, ABA to IAA, and ZT to GA₃ increased significantly between July and September, indicating the early establishment of a hormonal environment favorable for floral induction. Correlation analysis revealed that IAA, GA₃, and ZT formed a synergistic module promoting flowering, whereas ABA functioned as an antagonistic regulator. These findings provide insight into the hormonal regulation of off-season flowering in macadamia and offer a theoretical basis for precision flowering control in high-altitude cultivation systems. Full article

Flowering is a key agronomic trait that directly influences the yield of the tea-oil tree (Camellia oleifera). Floral initiation, which precedes flower bud differentiation, represents a critical developmental stage affecting the flowering outcomes. However, the molecular mechanisms underlying floral initiation in C. oleifera remain poorly understood. In this study, buds from five key developmental stages of a 12-year-old C. oleifera cultivar ‘changlin53’ were collected as experimental samples. Scanning electron microscopy was employed to identify the stage of floral initiation. UPLC-MS/MS was used to analyze endogenous gibberellin (GA) concentrations, while transcriptomic analysis was performed to reveal the underlying transcriptional regulatory network. Six GA types were detected during floral initiation and petal development. GA₄ was exclusively detected at the sprouting stage (BII), while GA₃ was present in all samples but was significantly lower in BII and the flower bud primordium formation stage (BIII) than in the other samples. A total of 64 differentially expressed genes were concurrently enriched in flower development, reproductive shoot system development, and shoot system development. Weighted gene co-expression network analysis (WGCNA) identified eight specific modules significantly associated with different developmental stages. The magenta module, containing Unigene0084708 (CoFT) and Unigene0037067 (CoLEAFY), emerged as a key regulatory module driving floral initiation. Additionally, GA20OX1 and GA2OX8 were identified as candidate genes involved in GA-mediated regulation of floral initiation. Based on morphological and transcriptomic analyses, we conclude that floral initiation of C. oleifera is a continuous regulatory process governed by multiple genes, with the FT-LFY module playing a central role in the transition from apical meristem to floral meristem. Full article

Pear (Pyrus pyrifolia) is an important deciduous fruit tree that requires a specific period of low-temperature accumulation to trigger spring flowering. The warmer winter caused by global warming has led to insufficient winter chilling, disrupting floral initiation and significantly reducing pear yields in Southern China. In this study, we integrated targeted phytohormone metabolomics, full-length transcriptomics, and proteomics to explore the regulatory mechanisms of dormancy in ‘Mixue’, a pear cultivar with an extremely low chilling requirement. Comparative analyses across the multi-omics datasets revealed 30 differentially abundant phytohormone metabolites (DPMs), 2597 differentially expressed proteins (DEPs), and 7722 differentially expressed genes (DEGs). Integrated proteomic and transcriptomic expression clustering analysis identified five members of the dormancy-associated MADS-box (DAM) gene family among dormancy-specific differentially expressed proteins (DEPs) and differentially expressed genes (DEGs). Phytohormone correlation analysis and cis-regulatory element analysis suggest that DAM genes may mediate dormancy progression by responding to abscisic acid (ABA), gibberellin (GA), and salicylic acid (SA). A dormancy-associated transcriptional regulatory network centered on DAM genes and phytohormone signaling revealed 35 transcription factors (TFs): 19 TFs appear to directly regulate the expression of DAM genes, 18 TFs are transcriptionally regulated by DAM genes, and two TFs exhibit bidirectional regulatory interactions with DAM. Within this regulatory network, we identified a novel pathway involving REVEILLE 6 (RVE6), DAM, and CONSTANS-LIKE 8 (COL8), which might play a critical role in regulating bud dormancy in the ‘Mixue’ low-chilling pear cultivar. Furthermore, lncRNAs ONT.19912.1 and ONT.20662.7 exhibit potential cis-regulatory interactions with DAM1/2/3. This study expands the DAM-mediated transcriptional regulatory network associated with bud dormancy, providing new insights into its molecular regulatory mechanisms in pear and establishing a theoretical framework for future investigations into bud dormancy control. Full article