Search Results (163)

Cremastra appendiculata, a rare medicinal orchid, has extremely low natural seed germination due to immature embryos and dense seed coats, impeding its conservation. Commensal germination with fungi is effective, but the action pathways remain unclear. This study combined morphological observation (scanning electron microscopy and section observation), physiological–biochemical detection (lignocellulolytic enzyme activities, nutrient/hormone contents, FTIR analysis) and transcriptomics to explore Coprinellus radians’ role in C. appendiculata seed germination, with commensal and non-commensal cultures on OMA medium set as experimental and control groups. Results showed C. radians significantly promoted C. appendiculata seed germination and protocorm development (superior to non-commensal conditions). Morphologically, C. radians hyphae invaded seed coats at 6 days post-inoculation; embryos broke through coats and formed apical meristems at 12 days, developing into peloton-containing protocorms at 25 days (breaking dormancy). Physiologically, C. radians secreted lignocellulolytic enzymes (laccase, cellulase, xylanase) to degrade coats, enhancing permeability and water uptake, while driving nutrient accumulation (starch, soluble sugars) and hormone balance. Transcriptomically, symbiosis activated carbon/energy metabolism genes, enriching starch-sucrose metabolism and glycolysis pathways. This study clarifies C. radians’ multi-dimensional action pathways in promoting C. appendiculata germination, providing support for rare orchid conservation. Full article

This study investigates the influence of varying cold stratification durations (0–165 days) on the germination performance and early seedling development of Rudbeckia fulgida. Seeds were divided into 11 groups at 15-day intervals, using a total of 1320 seeds. For each stratification duration, an equivalent number of seeds stored at room temperature served as non-stratified controls. Results demonstrated a clear and significant increase in germination percentage with longer stratification periods (Kruskal–Wallis, H = 57.03, p < 0.001), with the highest germination observed at 135 and 165 days (96.7%). In contrast, seeds kept at room temperature exhibited low and inconsistent germination. Strong positive correlations were detected between stratification duration and both germination percentage (r = 0.914) and post-stratification seed weight (r = 0.419). Furthermore, a Response Surface Methodology (RSM) model was developed to predict germination behavior, achieving an exceptionally high 99% predictive accuracy. The RSM analysis confirmed that cold stratification duration is the dominant factor shaping germination responses in Rudbeckia fulgida Aiton. Overall, the study demonstrates that cold stratification is essential for breaking seed dormancy in R. fulgida, substantially improving propagation efficiency and offering valuable insights for nursery production, landscape practices, and restoration ecology. Full article

The lack of protocols for breaking seed dormancy, inconsistent seed quality, and abiotic stress factors such as drought impede large-scale restoration efforts of pollinator-friendly native plant species. This research explores the germination response, dormancy-breaking techniques, and water stress tolerance in selected pollinator-friendly plant species with characteristics facilitating mechanized rehabilitation protocols and biodiversity enhancement. Forty-two commercial seed lots representing seven plant families with 28 species were evaluated under two alternating temperature regimes (15/25 °C and 20/30 °C) with and without gibberellic acid (GA₃) priming treatments. Six of the twenty-eight species were selected based on pollinator requirements for the monarch butterfly (Danaus plexippus L.) and further examined by priming seeds for 24 h in solutions containing GA₃, kinetin (KIN), and hydrogen peroxide (H₂O₂), or their combinations, to evaluate their dormancy-breaking responses. The effect of water stress on seed germination was assessed in controlled chambers at soil water potentials of −1.08, −0.75, −0.13, and 0 MPa. Initial seed quality of the 42 seed lots revealed that only 62% had greater than 50% germination, while of the same 42 lots, 98% had greater than 50% viability based on the commercial seed label. The difference was largely attributed to seed dormancy. In laboratory studies of the 42 seed lots, GA₃ significantly enhanced germination percentage, and reduced T₅₀ (time to 50% germination) across most seed lots. Overall, germination was higher and faster at 20/30 °C than 15/25 °C. Priming the six selected species with 1.0 mM GA₃ in 0.3% H₂O₂ consistently improved germination compared to the non-primed control after 14 days. Asclepias species (A. incarnata, A. syriaca, and A. tuberosa) exhibited consistently high germination across a broad moisture range of −0.75 to 0 MPa. In contrast, Echinacea purpurea required high moisture levels (−0.13 to 0 MPa) for optimal germination. Monarda fistulosa and Rudbeckia hirta showed their best performance under moderate moisture conditions (−0.13 MPa). Collectively, the use of GA₃ priming to break physiological seed dormancy offers a promising approach to enhance germination and improving the establishment potential of native pollinator species in restoration programs. Full article

Cytokinin- and Auxin-Based Plant Growth Regulators (PGRs) are commonly employed to increase fruit size due to their ability to modulate cellular structure. This study aimed to evaluate the effects of different PGR application protocols on histological parameters, yield components, and fruit quality in ‘Maxi Gala’ apple. The experiments were carried out under humid subtropical conditions of southern Brazil across two growing seasons (2021/22 and 2022/23), allowing comparison of treatment performance under distinct climatic patterns. Data from common treatments were combined across years for integrated analysis. The PGRs used included 6-benzyladenine (BA) as a cytokinin source; naphthalene acetic acid (NAA) as an auxin source; and tryptophan, a precursor of auxin biosynthesis. PGRs were applied in various combinations and concentrations between 10 days after dormancy break (BBCH 01) and fruit diameters of 25–27 mm (BBCH 74), following a randomized block design with four replicates of twelve trees each. The multivariate analysis of treatments was performed using Principal Component Analysis (PCA). Additionally, an analysis of variance was performed for flesh firmness loss, with means compared using Tukey’s test (p < 0.05). PGRs significantly influenced only the histological parameters of the fruit flesh tissues. BA and tryptophan had the greatest effects on cell size and cell number in the fruit flesh, respectively, both reducing intercellular spaces. Tryptophan was associated with a higher number of smaller cells, whereas NAA promoted larger cell sizes. The combination of BA and NAA, as well as a single application of BA at petal fall, resulted in the highest yield performances and increased the proportion of large fruits. Furthermore, BA enhanced the percentage of red skin coloration and improved flesh firmness during storage. Full article

Seed dormancy and germination is regulated by internal hormones and exogenous environment cues. Ethylene is one of the hormones that break seed dormancy and induce seed germination. Our previous study showed that N-degron pathway gene, proteolysis6 (PRT6) was involved in dormancy release by ethylene, the defection of which exhibiting ethylene-insensitivity in Arabidopsis thaliana. In the present study, through screening an ethyl methyl sulfonate-mutagenized (EMS) population of prt6−1, we isolated a recessive mutant that acted as a suppressor of prt6 that rescued its insensitivity to ethylene as well as a phenotype of shorter silique length. Further bulk segregant analysis on F2 population identified a premature termination located in the third exon of LONGIFOLIA1 (LNG1), previously reported in the regulation of longitudinal cell elongation. Mutation of LNG1 in prt6−1 background by CRISPR-Cas9 confirmed that LNG1 was epistatic to PRT6 in seed responsiveness to ethylene. Our finding proposed the pleiotropic effect of LNG1 in seed dormancy breakage by ethylene via PRT6, providing novel functional component at the downstream of the coordinated PRT6 and ethylene signaling pathway. Full article

There is an urgent and constant need for land reclamation and to restore self-sustaining, stable, and resilient ecosystems. It is necessary to enhance the frequency, consistency, and success rates of applying native plant seed for ecological restoration. Smoke-water can affect seed germination of plants, regardless of whether they occur in fire-prone ecosystems. Germination trials of 18 native species of Indigenous value in the southern interior grasslands of British Columbia, Canada were conducted using a smoke aqueous solution. Locally sourced parent plant material was burned to produce smoke-water. Seeds were collected from multiple populations of the species across a wide geographic range within the B.C. southern interior to increase the genetic diversity of the seed stock. Seeds were soaked in smoke aqueous solution in various concentrates, including 0% (control), 1% (1:100), 10% (1:10), 20% (1:5), and 100%. The results indicate that germination rates in the presence of smoke-water are species-specific. Five species showed an increase in germination with smoke-water (Erythronium grandiflorum, Calochortus macrocarpus, Arnica latifolia, Lomatium nudicaule, and Shepherdia canadensis); four species showed no change (Rosa woodsii, Crataegus douglasii, Lewisia rediviva, and Prunus virginiana); and nine species showed some level of decrease (Fritillaria affinis, Fritillaria pudica, Berberis aquifolium, Claytonia lanceolata, Gaillardia aristate, Balsamorhiza sagittata, Allium cernuum, Amelanchier alnifolia, and Lomatium macrocarpum). Smoke-water also affected germination rate by plant form (herbs > shrubs), plant phenology (spring ephemeral and protracted > summer quiescent and summer mature) and plant dispersal mechanism (wind > animal). The treatments applied to encourage the germination of seeds from interior grassland forbs and shrubs have demonstrated that smoke-water can effectively break dormancy and enhance the germination rate from certain native plant species. Full article

Globally, biodiversity is declining, meaning that many endemic plants are under threat; therefore, it is essential to develop conservation strategies. Scutellaria indica var. coccinea has great potential as an ornamental ground cover plant, but it is a plant that requires ex situ conservation. This study was conducted in order to investigate the seed germination characteristics and classify the dormancy type of S. indica var. coccinea seeds, with the aim of developing mass propagation protocols for ex situ conservation and preservation of their genetic diversity. Fresh and mature seeds of S. indica var. coccinea are in a dormant state, which is released by low temperatures during winter, resulting in radicle and seedling emergence the following spring. At the time of dispersal, the seeds had fully developed embryos, and the seed coat was permeable. When the seeds were incubated under four different temperature regimes (4, 15/6, 20/10, or 25/15 °C), they showed a low germination percentage (≤20%), indicating that a substantial proportion of the seeds remained in a dormant state. In the cold stratification experiment (0, 4, 8, or 12 weeks at 4 °C), germination increased, and the time required for germination shortened as the duration of cold treatment lengthened. This suggests that low temperatures are the primary environmental signal that induces germination. In the gibberellic acid (GA₃) treatment (GA₃ 0, 10, 100, or 1000 mg·L⁻¹), relatively high concentrations (100 and 1000 mg·L⁻¹) were effective in promoting germination. The highest germination was obtained in GA₃ 1000 mg·L⁻¹ with 100.0%, which is about 7 times higher than the control (13.6%). Therefore, seeds of S. indica var. coccinea were classified as having non-deep physiological dormancy (PD). Additionally, because the minimum germinable temperature range of the seeds was extended to lower temperatures, the seeds were classified as having type 2 non-deep PD. Full article

Seeds in soil are often exposed to cycles of hydration and dehydration, which can prime them by triggering physiological activation without leading to germination. While this phenomenon has been scarcely studied in wild species, it may play a critical role in enhancing drought resilience and maintaining seed viability under the warmer conditions predicted by climate change. In this study, I investigated the effects of hydration–dehydration cycles on germination response under water stress in eight Cistus species typical of Mediterranean shrublands. First, seeds were exposed to a heat shock to break physical dormancy, simulating fire conditions. Subsequently, they underwent one of two hydration–dehydration treatments (24 or 48 h) and were germinated under a range of water potentials (0, –0.2, –0.4, –0.6, and –0.8 MPa). Six out of eight species showed enhanced germination responses following hydration–dehydration treatments, including higher final germination percentages, earlier germination onset (T₀), or increased tolerance to water stress. These findings highlight the role of water availability as a key factor regulating germination in Cistus species and evidence a hydration memory mechanism that may contribute in different ways to post-fire regeneration in Mediterranean ecosystems. Full article

The hard-seed coat of Ormosia henryi significantly impedes germination efficiency in massive propagation, while conventional physical dormancy-breaking methods often result in compromised seed vigor, asynchronous seedling emergence, and diminished stress tolerance. Seed biopriming, an innovative technique involving the inoculation of beneficial microorganisms onto seed surfaces or into germination substrates, enhances germination kinetics and emergence uniformity through microbial metabolic functions and synergistic interactions with seed exudates. Notably, spermosphere-derived functional bacteria isolated from native spermosphere soil demonstrate superior colonization capacity and sustained bioactivity. This investigation employed selective inoculation of these indigenous functional strains to systematically analyze dynamic changes in endogenous phytohormones, enzymatic activities, and storage substances during critical germination phases, thereby elucidating the physiological mechanisms underlying biopriming-enhanced germination. The experimental results demonstrated significant improvements in germination parameters through biopriming. Inoculation with the Bacillus sp. strain achieved a peak germination rate (76.19%), representing a 16.19% increase over the control (p < 0.05). The biopriming treatment effectively improved the seed vigor, broke the impermeability of the seed coat, accelerated the germination speed, and positively regulated physiological indicators, especially amylase activity and the ratio of gibberellic acid to abscisic acid. This study establishes a theoretical framework for microbial chemotaxis and rhizocompetence in seed priming applications while providing an eco-technological solution for overcoming germination constraints in O. henryi cultivation. The optimized biopriming protocol addresses both low germination rates and post-germination growth limitations, providing technical support for the seedling cultivation of O. henryi. Full article

Salicornia brachiata Roxb., an economically and ecologically significant halophytic species native to Sri Lanka, produces dimorphic seeds. Despite their importance for commercial cultivation and conservation, germination studies of these dimorphic seeds remain limited. This study investigated the effects of temperature (25 °C, 30 °C, 35 °C), gibberellic acid (GA₃) treatment, geographic location of seed source (Jaffna vs. Puttalam coastal regions), seed type (central vs. lateral), and perianth presence/absence on germination under controlled conditions. Our results show that temperature, GA₃, and geographic location of the seed source significantly influenced seed germination. This study presents the first documented evidence of physiological dormancy (PD) in S. brachiata seeds, with successful dormancy breaking achieved using GA₃ treatment at 25 °C. Although perianth and seed type alone had no significant direct effects on germination, they were involved in multiple significant interactions—two-, three-, and four-way—with other factors. These findings highlight the multifactorial regulation of S. brachiata seed germination, suggesting that tailored propagation strategies, incorporating environmental and physiological variables, can optimize germination. These findings offer practical solutions for enhancing germination in saline agriculture and habitat restoration efforts of S. brachiata. Full article

Polygonatum cyrtonema Hua (P. cyrtonema) is a medicinal plant with high pharmaceutical value. Due to morphological and physiological dormancy mechanisms in P. cyrtonema seeds, natural germination rates remain exceptionally low. This biological constraint necessitates the development of protocols to shorten germination timelines and improve germination efficiency, which are critical requirements for advancing P. cyrtonema breeding programs. In this study, exogenous gibberellin A4 + A7 (GA₄₊₇) was applied to break dormancy in P. cyrtonema seeds. Transcriptomic, hormone metabolomic, and physiological analyses were then employed to investigate the underlying mechanisms. Germination tests revealed that 50 mg·L⁻¹ GA₄₊₇ was the optimal concentration to break dormancy in P. cyrtonema seeds. Transcriptome analysis indicated that exogenous GA₄₊₇ induced the expression of genes involved in GA and ABA biosynthesis and signaling. A total of 19 differential hormone metabolites were identified through hormone metabolomics, with significantly increased levels of active GA₁ and GA₄, but decreased levels of ABA content. These findings were consistent with the up-regulation of transcript levels of GA biosynthesis-related genes and the down-regulation of ABA biosynthesis-related genes, which resulted in an increase in active GA/ABA ratio. At the same time, it was found that exogenous GA₄₊₇ treatment induced sucrose and starch metabolism and pectin catabolic pathways. We measured the relevant physiological indicators and found that the content of soluble sugar and α-amylase activity increased, but the pectin content decreased. These findings establish a theoretical foundation for applying GA₄₊₇ in the standardized production of P. cyrtonema, particularly for accelerating breeding cycles in medicinal germplasm development. Full article

Alfalfa (Medicago sativa L.) is a globally significant forage crop with notable economic value. Gibberellins (GA₃) promote dormancy breaking and early germination whereas auxins (IAA) predominantly influence bud regeneration. This study investigated the effects of exogenous gibberellins and indole acetic acid on the regeneration and biomass of crown buds in two alfalfa varieties with different dormancy levels. The experiment involved five concentrations each of gibberellins (0 mg/L, 10 mg/L, 20 mg/L, 30 mg/L, and 40 mg/L) and auxins (0 mg/L, 5 mg/L, 10 mg/L, 15 mg/L, and 20 mg/L). The results indicated that both exogenous gibberellins and auxins significantly increased the endogenous levels of these hormones in the crown buds, while decreasing abscisic acid (ABA) levels. There was also a significant increase in sugar and total nitrogen content in the buds. Treatments with exogenous gibberellins enhanced the number of crown buds and the aboveground biomass per plant, with the best results at 30 mg/L. Auxin treatments showed the largest increase in aboveground biomass per plant at 15 mg/L. In summary, 30 mg/L gibberellins or 15 mg/L auxins is recommended as the optimal spraying concentration. This research provides practical evidence for the regulation of exogenous growth regulators in alfalfa cultivation. Full article

Dormancy is a physiological state that enables cells to survive under adverse conditions by halting their proliferation while retaining the capacity to resume growth when conditions become favorable. This remarkable transition between dormant and proliferative states occurs across a wide range of species, including bacteria, fungi, plants, and tardigrades. Among these organisms, yeast cells have emerged as powerful model systems for elucidating the molecular and biophysical principles governing dormancy and dormancy breaking. In this review, we provide a comprehensive summary of current knowledge on the molecular mechanisms underlying cellular dormancy, with particular focus on the two major model yeasts: Saccharomyces cerevisiae and Schizosaccharomyces pombe. Recent advances in multifaceted approaches—such as single-cell RNA-seq, proteomic analysis, and live-cell imaging—have revealed dynamic changes in gene expression, proteome composition, and viability. Furthermore, insights into the biophysical properties of the cytoplasm have offered new understanding of dormant cell regulation through changes in cytoplasmic fluidity. These properties contribute to both the remarkable stability of dormant cells and their capacity to exit dormancy upon environmental cues, deepening our understanding of fundamental cellular survival strategies across diverse species. Full article

Acacia species are important trees in arid ecosystems due to their diverse ecological roles, such as providing vegetation cover, community structures, food resources for animals, soil stabilization, and erosion prevention. However, in the Arabian Peninsula, Acacia species are declining due to climate change, overgrazing, and fuelwood harvesting. This study evaluates the effectiveness of various pre-sowing treatments—sulfuric acid soaking and tap and hot water soaking—on breaking seed dormancy to enhance germination in nine Acacia species native to the Al-Baha region of Saudi Arabia. The key germination indicators assessed were the mean germination time (MGT), germination percentage (GP), and germination index (GI). Sulfuric acid treatments for 10–15 min reduced the MGT and increased the GP for A. etbaica, A. hamoulosa, and A. tortilis, while A. origena responded best to 1 min of hot water soaking. Conversely, A. asak, A. ehrenbergiana, and A. johnwoodii showed little to no germination improvement with treatment and A. oerfota and A. gerrardii showed no germination improvement, indicating the need for alternative methods. These findings indicate that the seed germination requirements vary within Acacia spp. from the same geographic region and similar climatic conditions. Further work is required for five of the species tested to develop better seed germination techniques, given the potential utility of Acacia spp., in ecological restoration and sustainable land management in arid regions. Full article

The success of double cropping in Vitis vinifera L. cultivated in temperate climates relies on bud forcing efficiency, which requires the prompt unlocking of apical dormant buds with sufficient fruitfulness. Chemical dormancy-breaking strategies need to be tested to enhance dormant bud forcing in summer pruning, as hydrogen cyanamide, the most used agent, could damage green organs. This study tested whether foliar applications of cytokinins and auxins could modulate dormancy release, potentially affecting bud forcing dynamics and shoot fruitfulness. The forcing treatments involved trimming primary shoots at the eighth node, removing lateral shoots, and retaining the main leaves and inflorescences. Five treatments were investigated: unforced control, control + 6-Benzyladenine application, forcing (FR), forcing + 6-Benzyladenine application (FBA), and forcing + Naphthaleneacetic acid application (FNAA). Phenological evolution, vegetative and productive parameters, and physiological characteristics have been assessed. Results showed that among the forcing treatments, FBA showed the highest forced/primary shoots ratio (106%), followed by FR (94%) and FNAA (21%). Primary yields were similar across treatments (2.74 kg), but total yield was highest in FBA (4.78 kg, including 2.02 kg from forced grapes), followed by FR (3.62 kg, with 1.09 kg forced). FNAA yielded no forced crop. During forced grapes maturation, photosynthesis rates were higher in forced leaves (11.1 μmol m⁻² s⁻¹, as FR and FBA average) than primary leaves (−32%). Forced grapes ripened 47 days later and achieved higher sugar content (21.7 °Brix) and titratable acidity (10.6 g/L) than primary grapes. The findings suggest cytokinins application enhances bud forcing, supporting the feasibility of double cropping, while auxins limited it. Full article