Search Results (54)

Accurate determination of endodormancy release is essential for grapevine dormancy management. However, most phenological models are validated only against macroscopic budbreak dates, without physiological verification of predicted release dates. Here, we integrated phenological modeling with biochemical profiling to characterize endodormancy release in two table grape cultivars with contrasting chilling requirements: ‘Muscat Hamburg’ (Vitis vinifera L.) and ‘Shine Muscat’ (Vitis labrusca × V. vinifera). Endodormancy release dates were determined by forced budbreak assays, and chilling and heat requirements were estimated from 5 min temperature records using the Dynamic Model and Growing Degree Hours. ‘Muscat Hamburg’ released endodormancy on December 16 (10.95 Chill Portions), whereas ‘Shine Muscat’ released on January 6 (22.78 CP). Around these dates, coordinated biochemical changes occurred in buds, including starch depletion, hexose accumulation, ABA decline, GA₃ increase, and redox-related changes in H₂O₂ content and CAT activity. These changes were more pronounced in buds than in canes and were not identical across all biochemical indicators. Hydrogen cyanamide treatment induced biochemical changes similar to those observed during natural dormancy release, with cultivar-specific responses consistent across both conditions. These results indicate that experimentally determined endodormancy release dates are associated with population-level physiological changes, supporting the integration of phenological modeling with biochemical characterization in table grape production. Full article

Sugars play a pivotal regulatory role in floral bud dormancy release in Prunus mume, a process that critically determines subsequent flowering time. However, the precise molecular mechanisms linking sugar metabolism to this developmental transition remain poorly understood. To address this gap, we integrated physiological profiling and transcriptomic sequencing using two cultivars with contrasting flowering phenologies: the early-flowering ‘Chaotang Gongfen’ (CTGF) and the late-flowering ‘Shichu Jin’ (SCJ). Exogenous sugar treatments were applied separately to floral buds of the cultivar ‘Yilian’ to evaluate the effect of sugars on dormancy release. During dormancy release, glucose and sucrose contents increased progressively and showed significant positive correlations with bud break rates in both CTGF and SCJ (r > 0.75). Consistently, exogenous application of glucose and sucrose significantly accelerated bud break in ‘Yilian’, whereas mannose exhibited an inhibitory effect. Transcriptome analysis of CTGF and SCJ revealed significant enrichment of starch and sucrose metabolism, hormone signal transduction, and stress-responsive pathways. Key metabolic genes, notably the α-amylase gene PmAMY1-2 and the cell wall invertase genes PmCWINV1/4, were upregulated during this transition. Weighted gene co-expression network analysis (WGCNA) further identified PmFRK4, PmSUS6, and the aforementioned invertases as candidate genes within a sugar-associated regulatory module. Collectively, these findings support a model in which glucose and sucrose accumulation promotes endodormancy release via the transcriptional activation of starch and sucrose catabolic pathways. This study provides a theoretical framework for deciphering dormancy regulation in woody perennials and offers potential targets for the precise manipulation of flowering time. Full article

Potato tubers can be dormant for 1–15 weeks after harvest, and the germination of tuber eye-buds is suppressed by cold. Genetic mechanisms regulating bud dormancy at low temperatures are not completely understood. We performed RNA-seq to compare gene expression in tubers after 0.5, 3.5, and 6.5 months of cold storage. Differentially expressed genes (DEGs) in non-dormant (3.5/6.5 months) vs. dormant (0.5 months) tubers were associated with transcriptional and translational activation, cell growth, metabolism, hormonal signaling, meristem development, dormancy break, and reproduction, confirming the non-dormant state of the meristem in the middle of storage. DEGs encoding transcription factors (TFs) (CBF1, FLC, SVP, HY5, GI, CO, FT, SOC1, CDF1, POTM1) were associated with the regulation of dormancy, flowering, and tuberization. TF DEGs upregulated (78) or downregulated (224) over four times in non-dormant vs. dormant tubers are considered potential coordinators of the endo- to non-dormancy transition and upcoming tuber sprouting during cold storage. RT-qPCR analysis of non-dormant and germinating buds revealed the upregulation of tuberigens (StSP3D, StFTL1-1, StFTL1-2), anti-tuberigens (StSP5G-like), and TF genes positively associated with tuberization or flowering/germination (StFDL1, StFDL, StCDF1, StCO-like). Our results should further investigation of the mechanisms underlying tuber meristem dormancy release and sprouting during long-term cold storage. Full article

Global warming leads to premature dormancy release and untimely flowering in southern highbush blueberry during winter, resulting in chilling injury and yield losses. However, effective strategies to delay flowering by modulating dormancy progression without compromising fruit quality remain lacking. This study demonstrated through field trials that spraying 1 mg/mL ethephon (ETH) during the early endodormancy stage effectively delayed dormancy release and reduced the bud break rate of spring shoots by approximately 33.92% relative to the control, with no adverse effects on fruit quality. The treatment also reduces sucrose content in floral buds, a change potentially associated with dormancy maintenance. To explore the molecular basis of this process, we examined two ethylene-responsive transcription factors, VcERF112 and VcERF115, previously identified in our laboratory. Their expression was rapidly upregulated following ETH treatment. Heterologous expression of either gene in Arabidopsis delayed both seed germination and flowering, suggesting a conserved growth-suppressive function. Dual-luciferase reporter assays confirmed that VcERF112 and VcERF115 bind to the T2 region (−2310 to −1595 bp) of the VcBRC1 (VcBRANCHED1) promoter and enhance its expression. In contrast, sucrose treatment suppressed VcBRC1 expression. Collectively, these results propose that ethylene may sustain bud dormancy through a coordinated mechanism that operates independently of the classic abscisic acid (ABA)/gibberellins (GA) balance, a relationship not addressed in this study. This mechanism involves the induction of VcERF112/115 to activate VcBRC1, coupled with the reduction in sucrose levels to alleviate its repressive effect on VcBRC1. These findings provide new molecular insights into the ethylene-mediated regulatory network underlying bud dormancy in blueberry. Full article

Seed physical dormancy, also known as hard-seededness, is a characteristic commonly found in higher plants, which functions to prevent water and oxygen from passing through the impermeable seed coat. Background: Notably, seed dormancy has emerged as a critical factor in the domestication of leguminous plants. Alfalfa (Medicago sativa L.) is a globally cultivated high-quality legume forage crop, while the seeds from different varieties maintain varying degrees of hard-seededness. However, the molecular mechanisms underlying physical dormancy in alfalfa seeds remain poorly understood. In particular, the regulatory mechanisms at the transcriptomic level remain unclear, which has hindered the breeding process of varieties with low hard-seededness. Methods: In this study, we performed global transcriptome analysis to discover the genes specifically expressed in the alfalfa seed coat and provide insights into alfalfa seeds’ physical dormancy domestication traits. RNA sequencing was performed on various alfalfa tissues, including roots, stems, leaves, flowers, and seed coats. Results: This analysis led to the identification of 4740 seed coat-specific expressed genes, including key genes such as KNOX4 (a class II KNOTTED-like homeobox gene), qHs1 (encoding endo-1,4-β-glucanase), GmHs1-1 (encoding a calcineurin-like metallophosphoesterase), and KCS12 (β-ketoacyl-CoA synthase). In addition, several seed coat-specific transcription factor families were identified, including ERF, B3, and NAC, among others. Furthermore, a comparison of gene expression profiles between seeds with and without physical dormancy revealed 60 upregulated and 197 downregulated genes associated with physical dormancy. Crucially, functional enrichment analysis demonstrated that these genes are predominantly associated with lipid metabolism pathways, particularly those involved in the formation of “monolayer-surrounding lipid storage bodies.” Conclusions: This key finding suggests that the establishment of physical dormancy is closely linked to the biosynthesis and deposition of specialized lipid-based layers in the seed coat, which likely constitute the primary barrier to water penetration. Our study thus provides fundamental insights and a valuable genetic resource for future functional studies aimed at deciphering and manipulating physical dormancy in alfalfa. Full article

This study investigated the effects of elevated temperature on the phenology and morphology of the early-maturing peach cultivar ‘Mihong’. The experiment was conducted from 2019 to 2024 in a temperature-gradient chamber at the National Institute of Horticultural and Herbal Science, Wanju, Korea, with four warming treatments (+2.2 °C to +5.0 °C above ambient). Higher temperatures delayed the onset of endodormancy and markedly shortened the period from endodormancy release to full bloom. Elevated temperatures also increased the LD ratio, with the proportion of fruits exceeding an LD ratio of 1.0 rising significantly with temperature. The LD ratio showed strong correlations with November mean temperature (MT11) and March maximum temperature (HT3) (r = 0.81) and was also associated with the average temperature (Temp3, r = 0.51) and duration (P3, r = −0.54) of the endodormancy release to full bloom phase. Stepwise and PLS regression identified temperatures in May, November, and March as key predictors of the LD ratio, while PCA revealed that temperature variables (Temp3, Temp5) and stage durations (P3, P4) were major contributors. These results confirm that climate warming alters the phenology and morphology of ‘Mihong’, reducing fruit quality and marketability, while providing a basis for predictive modeling and highlighting the importance of adaptive strategies such as shading or growth regulator application. Full article

Postharvest losses and limited physiological knowledge restrict the conservation and year-round availability of underutilized crops such as Dioscorea trifida. This study characterized the postharvest behavior of Colombian purple D. trifida tubers and evaluated low-cost, GRAS-status technologies to improve storage performance in smallholder production systems. Tubers were stored for 34 days at ambient conditions (20 °C, 90% RH) and compared with treatments including cold storage, calcium pretreatments combined with Aloe vera-based coatings, and short-duration hot water immersion. Over storage, total carbohydrates increased, while potassium remained at substantial levels until the final day. Weight loss and respiration declined steadily, and sprouting was absent, suggesting extended endodormancy in this genotype. Major deterioration causes observed upon reception included fragmentation, insect damage, and surface molds, highlighting the importance of improved sanitation and mechanical protection during harvest, early postharvest stages, and transportation. Edible coatings enhanced antioxidant activity and increased malic and succinic acid concentrations. Cold storage at 3 °C reduced weight loss more effectively than storage at 12 or 20 °C, although citric acid accumulation was greater at the latter temperature. Among all treatments, immersion at 55 °C for 5 min was the most promising, offering a scalable, low-input option to extend shelf life in neglected yam species. Full article

Asian chestnut gall wasp (ACGW) (Dryocosmus kuriphilus Yasumatsu), native to China, is an invasive pest that causes significant economic losses in Castanea species. While some cultivars show full resistance by inhibiting insect development in buds, the underlying defense mechanisms remain unclear. In this study, the accumulation and distribution of hydrogen peroxide (H₂O₂) were investigated in dormant buds of chestnut cultivars that are resistant and susceptible to D. kuriphilus by using the 3,3′-diaminobenzidine (DAB) staining method. Buds were examined under a stereomicroscope during key stages of pest development, including oviposition, transition from egg to larva, gall induction, and gall development. Baseline levels of H₂O₂ were detected in all buds; however, these levels varied among cultivars, with resistant cultivars exhibiting lower basal levels. The degree of H₂O₂ accumulation was found to vary depending on plant–insect interaction, physiological processes, and cultivar-specific traits. Histochemical staining revealed that brown spots indicative of H₂O₂ accumulation were concentrated in the vascular bundles of leaf primordia and in the apical regions. In resistant hybrid cultivars, the defense response was activated at an earlier stage, while in resistant Castanea sativa Mill. cultivars, the response was delayed but more robust. Although consistently high levels of H₂O₂ were observed throughout the pest interaction in susceptible cultivars, gall development was not inhibited. During the onset of physiological bud break, increased H₂O₂ accumulation was observed across all cultivars. This increase was associated with endodormancy in susceptible cultivars and with both defense mechanisms and endodormancy processes in resistant cultivars. These findings highlight the significant role of H₂O₂ in plant defense responses, while also supporting its function as a multifunctional signaling molecule involved in gall development and the regulation of physiological processes. Full article

Dormancy is a vital adaptive strategy in temperate and boreal plants, particularly fruit trees, enabling them to withstand harsh winter conditions and ensure survival and synchronized growth resumption in spring. This review comprehensively examines dormancy, focusing on its physiological, environmental, and molecular mechanisms. Dormancy is characterized by two distinct phases: endodormancy, which is regulated by internal plant signals and requires cold temperatures for release, and ecodormancy, which is influenced by external environmental factors. These stages are intricately linked to seasonal temperature fluctuations and the plant’s ability to synchronize growth cycles, ensuring survival through harsh winters and optimal growth in warmer seasons. The review delves into the role of chilling requirements, temperature thresholds, and hormonal regulation in the dormancy process, highlighting how these factors influence critical growth events such as budbreak, flowering, and fruiting. Plant hormones, including abscisic acid, gibberellins, and cytokinins, regulate dormancy by modulating gene expression and growth activity. Additionally, we explore the historical development of dormancy research, from early observations of chilling requirements to the formulation of the chilling hours model. Considering ongoing climate change, the review examines how rising winter temperatures may disrupt dormancy cycles, potentially affecting the timing of flowering, fruiting, and overall crop productivity. This shift necessitates new strategies for managing dormancy, particularly in regions experiencing inconsistent or insufficient chilling. The review concludes by discussing practical approaches to enhance dormancy release and mitigate the impact of environmental stress on deciduous fruit tree growth, offering insights into improving agricultural practices amidst a changing climate. Full article

Morphophysiological dormancy (MPD) is considered one of the most primitive dormancy classes among seed plants. While extensive studies have examined the occurrence of endo-β-mannanase in seeds with physiological dormancy (PD) or non-dormancy, little is known about the activity of this enzyme in seeds with MPD. This study aimed to investigate the temporal and spatial patterns of endo-β-mannanase activity during dormancy break and germination. The research focused on Jeffersonia dubia, a species with deep simple MPD, by monitoring its morphological and biochemical characteristics under natural field conditions. Seeds were buried in the field and exhumed monthly over a year. Key parameters measured included germination, embryo elongation, endosperm weakening, and endo-β-mannanase activity in the exhumed seeds. Scanning electron microscopy was employed to observe structural changes in the endosperm. For the first three months after burial in May, endo-β-mannanase activity was undetectable, and the underdeveloped embryo exhibited minimal elongation. Starting in September, the embryo began to grow, accompanied by increased endo-β-mannanase activity in the micropylar endosperm. Erosion of the endosperm cell wall was observed in the lateral regions surrounding the embryo, whereas the micropylar endosperm showed no obvious signs of collapse or damage. The increase in enzyme activity coincided with moderate temperatures and a corresponding increase in embryo length. During the winter months, embryo elongation ceased for 2–3 months, and enzyme activity declined. However, as germination resumed in early March, enzyme activity increased again. This was followed by micropylar endosperm rupture and the completion of germination. The seasonal pattern of endo-β-mannanase activity observed in seeds with deep simple MPD was distinct from that of seeds with PD, MD, or non-deep MPD, highlighting the unique mechanisms underlying dormancy break and germination in J. dubia. Full article

The study of pear dormancy mechanisms is currently a major research area in pear production and has high economic significance for agricultural production. We selected the southern sand pear cultivar Pyrus pyrifolia ‘Huanghua’ as the test material to study the pear dormancy process through microscopic observation of pear flower buds. The endodormancy period is abbreviated as D_bud. Similarly, the endodormancy release initiation period and the ecodormancy period are referred to as DB_bud and G_bud, respectively. Meanwhile, RNA sequencing was used to obtain the gene expression profile of Pyrus pyrifolia ‘Huanghua’ flower buds. The RNA sequencing results indicated that there were 224 differentially expressed genes (DEGs) in endodormancy (D) vs. endodormancy release initiation period (DB), while 975 were identified between endodormancy and ecodormancy (G). Finally, a total of 868 DEGs were found in the DB vs. G comparison. The expression levels of the genes Pbr009498.1 (LAX1-1), Pbr012348.1 (LAX1-2), Pbr021158.1 (GH35), and Pbr031621.1 (LAX2) encoding IAA were significantly higher during the DB_bud than during the D_bud. The expression level of Pbr025864.2 (IAA13) during the D_bud was significantly higher than the DB_bud and G_bud. The Pbr041942.1 (GID1B) gene also showed a significant increase during ecodormancy. Taken together, these results suggest that these genes, annotated as LAX1, GH35, LAX2, IAA13, and GID1C, are involved in endodormancy maintenance and in the transition from endodormancy to ecodormancy in Pyrus pyrifolia ‘Huanghua’. Full article

Gene function verification is a crucial step in studying the molecular mechanisms regulating various plant life activities. However, a stable and efficient homologous genetic transgenic system for herbaceous peonies has not been established. In this study, using virus-induced gene silencing technology (VIGS), a highly efficient homologous transient verification system with distinctive advantages was proposed, which not only achieves true “intact-plant” infiltration but also minimizes the operation. One-year-old roots of the representative species, Paeonia lactiflora Pall., were used as the materials; prechilling (4 °C) treatment for 3–5 weeks was applied as a critical precondition for P. lactiflora to acquire a certain chilling accumulation. A dormancy-related gene named HOMEOBOX PROTEIN 31 (PlHB31), believed to negatively regulate bud endodormancy release (BER), was chosen as the target gene in this study. GFP fluorescence was detected in directly infiltrated and newly developed roots and buds; the transgenic plantlets exhibited remarkably earlier budbreak, and PlHB31 was significantly downregulated in silenced plantlets. This study established a homologous transient silencing system featuring intact-plant infiltration and minimized manipulation for gene function research, and also offers technical support and serves as a theoretical basis for gene function discovery in numerous other geophytes. Full article

Despite ample knowledge of the effect of warm-dry storage on breaking dormancy in chincuya (Annona purpurea Moc. & Sessé ex Dunal) seeds, this paper investigates an important new aspect of this process—the applicability of seed treatment with gibberellic acid and its influence on seed viability and fatty acid profile. Chincuya is an underutilized, tropical wild species native to Mexico, with potential as a biopesticide. The impact of warm-dry storage and gibberellic acid treatment on seed viability and germination was determined to improve that knowledge further. Also, the content and kinetics of fatty acids in chincuya seeds were profiled during warm-dry storage. Seed treatments included storage time (0, 3, 6, 9, and 12 months), seed imbibition for 72 h in gibberellic acid at 350 mg L⁻¹, and distilled water imbibition for 72 h for the control treatment. Seed viability was determined using the TTZ classic test. Imbibed seeds were germinated on paper towels and incubated at 30 °C during the day and 25 °C at night in a 12:12 h dark/light photoperiod. The lipid profile was obtained by gas chromatography. During the storage treatment, seeds stayed in darkness at 25 ± 3 °C. Results showed that high viability remained up to month 9 in storage when it significantly decreased. Freshly harvested seeds germinated at a statistically significantly lower rate (26.1%) than six-month-old seeds (65.6%). The profile of fatty acids breaks down as palmitic acid (33.41%), stearic acid (7.72%), and arachidic acid (1.30%), for a total of 42.44% of saturated fatty acids. The detected unsaturated fatty acids (52.15%) were palmitoleic acid (1.52%), oleic acid (43.37%), and linoleic acid (7.24%). No significant changes were detected in fatty acid content; however, the highest fatty acid content (92.84%) occurred with the highest germination rate. Regression analysis showed significant content changes: palmitoleic and palmitic acids increased while oleic acid decreased during dry storage. Arachidic acid showed a slight downward trend. Also, fatty acid content significantly differed between intact seeds (unstored and unincubated) and latent seeds (unstored, incubated, and ungerminated). The total fatty acids content for latent seeds was significantly lower. These results show that Annona purpurea seeds present morphophysiological dormancy. Also, we document the highest germination rate reported (65.6%) and report the presence of arachidic and palmitoleic acids in chincuya seeds. Full article

Bud endodormancy represents a pivotal and intricate biological process influenced by both genetic and epigenetic factors, the exact mechanism of which remains elusive. Hydrogen peroxide (H₂O₂) functions as a signalling molecule in the regulation of dormancy, with peroxidase (POD) playing a crucial role in governing H₂O₂ levels. Our prior transcriptomic and metabolomic investigations into diverse pear dormancy phases posited that POD predominantly oversees pear bud dormancy. In this study, we utilised qRT-PCR to screen the most significantly expressed gene, Pyrus pyrifolia POD4-like (PpPOD4-like), from seven POD genes. Subsequently, H₂O₂ test kits, overexpression methods, and subcellular localisation techniques were employed to assess changes in H₂O₂ content, POD activity, PpPOD4-like expression, and its cellular positioning during pear bud dormancy. Subcellular localisation experiments revealed that PpPOD4-like is situated on the cell membranes. Notably, H₂O₂ content exhibited a rapid increase during endodormancy and decreased swiftly after ecodormancy. The fluctuation pattern of POD activity aligned with that of H₂O₂ content. Additionally, PpPOD4-like expression was markedly upregulated, displaying an overall upward trajectory. Our findings indicate that PpPOD4-like modulates H₂O₂ levels by regulating POD activity, thereby actively participating in the intricate regulation of pear dormancy processes. Full article

Buffalobur (Solanum rostratum Dunal) is an invasive species that seriously endangers crop production and the ecological environment. Seeds are the primary source of infestation; therefore, understanding the molecular basis of buffalobur seed dormancy, and germination is crucial for precision weed management. In this study, high-throughput RNA-Seq was performed on buffalobur seeds, which imbibed under 0.35 mmol/L giberellic acid (GA) and 0.35 mmol/L abscisic acid (ABA). In total, 3658 differentially expressed genes (DEGs) were identified during seed germination. Gene annotation revealed that the DEGs were significantly enriched during the protein metabolic process, as well as the macromolecular complex and cytoplasmic part for ABA versus GA. Pathway analysis predicted that the DEGs were associated with metabolic pathways, the biosynthesis of secondary metabolites and ribosome. Nine germination-related genes involved in the biosynthesis and metabolism of the phytohormones and encoding of the endo-β-mannanase (EBM) were identified. Gene expression indicated that GA upregulated GA3OX1 and MAN2 expression to increase the EBM activity, which caused the endosperm cap to weaken and lowered the puncture force to trigger the germination of buffalobur. The obtained results would be helpful to clarify the regulation of seed dormancy and the germination of buffalobur, and could serve as a valuable resource when unravelling the genetic basis of seed biology of this weed species. Full article