Dormancy Breaking Research Articles

Transcriptome Analysis of Seed in Dormancy and Dormancy Release State of Epimedium koreanum Nakai

Epimedium koreanum is a perennial herb of the Berberidaceae family, which is a traditional tonic in Chinese medicine. Seed germination of E. koreanum is difficult. Dormancy is an intrinsic factor that affects seed germination. Elucidating the molecular mechanism of seed dormancy and the lifting process of E. koreanum is of great significance for the breeding, conservation, and utilization of E. koreanum. Previous studies have concluded that E. koreanum seed dormancy breakage requires warm-temperature stratification followed by low-temperature stratification treatments. Therefore, we performed transcriptome sequencing using freshly harvested, untreated seeds (NS), seeds that developed a cotyledonary embryo after 90 d of constant-temperature stratification at 15 °C (CS), and seeds that broke dormancy by 90 d of stratification at 15 °C and 60 d of stratification at 5 °C (ND) in order to find the responsive genes and regulatory genes that regulate dormancy. A total of 92,867 genes with differential expression were identified. GO enrichment analysis highlighted redox processes, as well as structural components of the nucleus and ribosomes. KEGG enrichment analysis revealed a significant enrichment of phytohormone signaling pathways, which play a crucial role in seed dormancy release. Additionally, protein–protein interactions (PPIs) were predicted with starch and sucrose metabolic pathways. This study introduces a novel concept for a more profound comprehension of the molecular regulatory mechanism of E. koreanum and lays a theoretical foundation for the screening of E. koreanum candidate genes.

Transcriptome analysis of apical meristem enriched bud samples for size dependent flowering commitment in Crocus sativus reveal role of sugar and auxin signalling.

Cultivation of Crocus sativus (saffron) faces challenges due to inconsistent flowering patterns and variations in yield. Flowering takes place in a graded way with smaller corms unable to produce flowers. Enhancing the productivity requires a comprehensive understanding of the underlying genetic mechanisms that govern this size-based flowering initiation and commitment. Therefore, samples enriched with non-flowering and flowering apical buds from small (< 6g) and large (> 14g) corms were sequenced. Apical bud enriched samples from small and large corms were collected immediately after dormancy break in July. RNA sequencing was performed using Illumina Novaseq 6000 to access the gene expression profiles associated with size dependent flowering. De novo transcriptome assembly and analysis using flowering committed buds from large corms at post-dormancy and their comparison with vegetative shoot primordia from small corms pointed out the major role of starch and sucrose metabolism, Auxin and ABA hormonal regulation. Many genes with known dual responses in flowering development and circadian rhythm like Flowering locus T and Cryptochrome 1 along with a transcript showing homology with small auxin upregulated RNA (SAUR) exhibited induced expression in flowering buds. Thorough prediction of Crocus sativus non-coding RNA repertoire has been carried out for the first time. Enolase was found to be acting as a major hub with protein-protein interaction analysis using Arabidopsis counterparts. Transcripts belong to key pathways including phenylpropanoid biosynthesis, hormone signaling and carbon metabolism were found significantly modulated. KEGG assessment and protein-protein interaction analysis confirm the expression data. Findings unravel the genetic determinants driving the size dependent flowering in Crocus sativus.

Response of lettuce seeds undergoing dormancy break and early senescence to plasma irradiation

This study reports the response of lettuce seeds undergoing dormancy breaking and early senescence to DBD plasma irradiation. A heat map of germination percentages at 12 h reveals that dormancy has broken at 39 days' storage, and that one minute of plasma irradiation enhances germination in dormant seeds. Plasma irradiation does not affect those seeds where dormancy has already broken. Early senescence via storage was estimated using ESR measurements and the molecular modification of quercetin. This study reveals that lettuce seed susceptibility to plasma irradiation depends on storage duration and conditions, with dormancy state as a critical variable modulating the impact of plasma irradiation.

What we really know about the dormancy, reproduction, germination and cultivation of charophytes (Characeae)

This expanded review aims to provide information on previous basic research by charophyte experts in the areas of reproduction, dormancy, germination of oospores and cultivation. Therefore, published information, the author’s PhD thesis and further results have been combined to summarise the current state of knowledge for Characeae of permanent and temporary waterbodies. The understanding of evolutionary, systematic and molecular pathways require multidimensional approaches using combined results of morphology, anatomy, physiology, genetics, geobotanics and ecology. The application of zonobioms from geobotanies for performed germination studies resulted in a linkage between environmental conditions and dormancy breakage treatment. Besides this, the combination of environmental logger data and species-specific cultivation knowledge resulted in an optimised in-vitro system that allow the successful gametangia initiation and maturation under artificial laboratory conditions in monoecious diplostichous Chara species.

Identification of a key signaling network regulating perennating bud dormancy in Panax ginseng

BackgroundThe cycle of seasonal dormancy of perennating buds is an essential adaptation of perennial plants to unfavorable winter conditions. Plant hormones are key regulators of this critical biological process, which is intricately connected with diverse internal and external factors. Recently, global warming has increased the frequency of aberrant temperature events that negatively affect the dormancy cycle of perennials. Although many studies have been conducted on the perennating organs of Panax ginseng, the molecular aspects of bud dormancy in this species remain largely unknown. MethodsIn this study, the molecular physiological responses of three P. ginseng cultivars with different dormancy break phenotypes in the spring were dissected using comparative genome-wide RNA-seq and network analyses. These analyses identified a key role for abscisic acid (ABA) activity in the regulation of bud dormancy. Gene set enrichment analysis revealed that a transcriptional network comprising stress-related hormone responses made a major contribution to the maintenance of dormancy. ResultsIncreased expression levels of cold response and photosynthesis-related genes were associated with the transition from dormancy to active growth in perennating buds. Finally, the expression patterns of genes encoding ABA transporters, receptors (PYRs/PYLs), PROTEIN PHOSPHATASE 2Cs (PP2Cs), and DELLAs were highly correlated with different dormancy states in three P. ginseng cultivars. ConclusionThis study provides evidence that ABA and stress signaling outputs are intricately connected with a key signaling network to regulate bud dormancy under seasonal conditions in the perennial plant P. ginseng.

Mechanisms of seed persistence in blackgrass (Alopecurus myosuroides Huds.)

AbstractSeed dormancy is the key factor determining weed emergence in agricultural fields and there is growing interest in weed seeds as a target for weed management. A foremost limitation to this approach is the lack of molecular insight into the mechanisms regulating dormancy in weed seeds. Alopecurus myosuroides (blackgrass) seeds were collected from a wheat field in the UK. At low temperatures, dormant (D) and after‐ripened (AR) seeds germinate similarly and at warm temperatures dormancy is enforced. RNAseq analysis at both temperatures for D and AR seeds demonstrated distinct mechanisms, involving abscisic acid and gibberellin signalling, are involved in after‐ripening and cold‐induced dormancy release. Exogenous application of selected plant growth regulators provided further insight into the phytohormone processes involved in seed dormancy in blackgrass. An untargeted analysis of the transcriptome revealed dormancy‐related processes beyond the regulation of germination, such as seed defence processes, which may have potential as targets for weed seedbank management. Our findings suggest that dormancy breaking can occur via multiple independent but connected hormone‐mediated mechanisms and provide a case study for the use of next‐generation sequencing to uncover the mechanisms involved in seed dormancy in weed and non‐model species.

Gundelia tournefortii L. (Akkoub): a review of a valuable wild vegetable from Eastern Mediterranean

AbstractGundelia tournefortii L. (Asteraceae) is an artichoke-like wild edible vegetable that grows in the semi-arid climate of the East Mediterranean. Due to its high cultural and economic values for culinary and therapeutic uses, this plant is exposed to overharvesting driven by household consumption and trade, threatening the survival of natural populations. Some limited data on the nutrient composition of G. tournefortii exists indicating presence of folic acid and several essential amino acids. Research on seed germination reports that mechanical scarification, gibberellic acid, and cold stratification are all effective treatments for seed dormancy breaking and therefore to propagate plants from seed. Successful vegetative propagation from the plant meristems is also available. However, despite some exceptions, the species is still not widely cultivated due to its thorny habit and complex seed germination requirements, and the ability to ensure seed germination under natural field conditions remains to be addressed.

A Review on Flower Bulb Micropropagation: Challenges and Opportunities

This comprehensive review scrutinizes tissue culture and micropropagation methodologies in geophytes, focusing on bulbous plants. The examination encompasses key stages, including somatic embryogenesis, bulb growth, dormancy breaking, and planting. Studies underscore the pivotal role of plant growth regulators (PGRs) in plant regeneration and bulb growth. Bioreactor systems for healthy plant regeneration, rooting methods, acclimatization strategies, and considerations for ex vitro survival are elucidated. The review also delves into somaclonal variation dynamics and acknowledges the burgeoning field of gene editing, particularly Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) studies, as a promising avenue for enhancing valuable compound content in geophytes. In addition to addressing challenges in flower bulb micropropagation, this review briefly highlights emerging opportunities, including the potential integration of artificial intelligence (AI) to optimize culture conditions, predict growth parameters, and enhance efficiency in bulb production. The conclusion emphasizes the necessity of a multifaceted approach integrating biochemistry, physiology, and molecular biology to address existing challenges and improve tissue culture protocols for diverse geophyte species. This review article also intends to highlight how tissue culture techniques could contribute to the development and valorization of flower bulbs in today’s scenario of the ornamental industry.

Dormancy of Macadamia Nut Seeds (Macadamia Integrifolia) by Drying and Soaking Water

Macadamia nut seeds are orthodox seeds that result in a dormancy period, so breaking the seed dormancy period is necessary. This study aims to determine the effect of drying and water immersion on dormancy breaking and macadamia bean seed germination and which drying and water immersion had the best impact on dormancy breaking and macadamia bean seed germination. The research was conducted in the soil laboratory and screen house of the Faculty of Agriculture, Winaya Mukti University, Tanjungsari District, Sumedang Regency, from June to November 2022. The experimental design used was a simple randomized block design (RBD) with a combination of drying and soaking seeds with nine treatment combinations. Each was repeated three times, so there were 27 experimental units. A = P 40oC + PA 45oC, B = P 45oC + PA 50oC, C = P 50oC + PA 55oC, D = P 50oC + PA 45oC, E = P 40oC + PA 50oC, F = P 45oC + PA 55oC, G = P 45oC + PA 45oC, H = P 40oC + PA 55oC, I = P 50oC + PA 50oC. The results showed that drying and soaking in water treatments at different temperatures had no significant effect on seed moisture content, seed cracking percentage, germination percentage, radicle length, and plumula length.

Dormancy Resistance of Macadamia Bean Seeds (Macadamia Integrifolia) by Drying and Water Immersion

Macadamia nut seeds are orthodox seeds that result in a dormancy period, so breaking the seed dormancy period is necessary. This study aims to determine the effect of drying and water immersion on dormancy breaking and macadamia bean seed germination and to determine which drying and water immersion had the best effect on dormancy breaking and macadamia bean seed germination. The research was carried out in the soil laboratory and screen house of the Faculty of Agriculture, Winaya Mukti University, Tanjungsari District, Sumedang Regency, from June to November 2022. The experimental design used was a simple randomized block design (RBD) with a combination of drying and soaking seeds with nine treatment combinations. Each was repeated three times, so there were 27 experimental units. A = P 40oC + PA 45oC, B = P 45oC + PA 50oC, C = P 50oC + PA 55oC, D = P 50oC + PA 45oC, E = P 40oC + PA 50oC, F = P 45oC + PA 55oC, G = P 45oC + PA 45oC, H = P 40oC + PA 55oC, I = P 50oC + PA 50oC. The results showed that drying and soaking in water treatments at different temperatures had no significant effect on seed moisture content, seed cracking percentage, germination percentage, radicle length, and plumula length.

Overcoming Dormancy in Prunus Species under Conditions of Insufficient Winter Chilling in Israel.

The phenomenon of dormancy and the evolutionary causes for its development are presented together with the effects of the climatic factors: temperature and light. Shade and darkness have been found to enhance bud breaking in peach. The effects of various temperatures on chilling accumulation, chilling negation and chilling enhancement are described. The way these are computed in the face of global warming is explained, using the dynamic model. When natural chilling is less than that required, there are ways of compensation, up to a certain level. Various horticultural, physical and chemical means to achieve this are described, including bending branches, reducing vegetative vigor, shading the orchard, sprinkling to reduce daytime temperature and the application of various chemicals to break dormancy. When winter chilling is markedly reduced and temperatures increase considerably, the use of dormancy avoidance is suggested in frost-free places. This technique can induce a new growing cycle by avoiding dormancy altogether. However, the best approach is to breed high-quality cultivars requiring much less chilling. Another aspect discussed in this work, independent of the chilling requirement, is the negative effect of heat spells in winter and spring on the abnormal development of flower buds, leading to a low level of the stone fruit set and a reduced yield.

Breaking Dormancy of Shallot (Allium ascolonicum L.) Bulb Using Hydrogen Peroxide

Shallot bulbs have a dormancy period, so they must be stored for 3-4 months. This condition inhibits the acceleration of planting, which has a short time, so efforts are needed to accelerate the dormancy period by using hydrogen peroxide. This research was carried out from June to July 2023 at the Screen House, Teaching Farm, Faculty of Agriculture, Hasanuddin University. The study was arranged in a randomized block design with a two-factor factorial design. The first factor is the variety of Mentes, Rubaru, Violetta 2 Agrihorti, Kramat 1, and Ambassador 3 Agrihorti. The second factor is hydrogen peroxide concentration with three levels, namely 0%, 10% and 20%. The results showed that breaking the dormancy of shallot bulbs using hydrogen peroxide at a concentration of 20% effectively triggered the process of bulb growth in the various shallot varieties tested, marked by an increase in the percentage of rooted and sprouted bulbs. The Rubaru and Mentes varieties had an excellent response to 20% hydrogen peroxide immersion, indicated by a shorter rooting and sprouting time, compared to other varieties and concentrations of hydrogen peroxide. Therefore, hydrogen peroxide with a concentration of 20% can be used to break dormancy in shallot bulbs. However, further studies are needed on growth and production in the field and the quality and safety of shallot bulbs. Keywords: Bulb, Dormancy, Hydrogen peroxide, Shallot.

Suitable areas for temperate fruit trees in a Brazilian hotspot area: Changes driven by new IPCC scenarios

Chilling accumulation and sufficient water availability are mandatory requirements for most temperate fruit trees (TFT) productivity. Given the strong dependence of these crops on air temperature and water availability, it is imperative to analyze the impacts of climate change on TFT, especially in areas considered persistent climate change hotspots. This study analyzed the impacts of climate change on suitable areas for planting TFT in a Brazilian state considered a hotspot for future climate changes - Minas Gerais, using an Agroclimatic Zoning (AZ) method, and outlined adaptation measures for the sustainable cultivation of the main TFT under future climate scenarios. Daily near-surface air temperature (minimum and maximum) and precipitation data were used from 10 Earth System Models (ESMs) from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP), which are derived from the Coupled Model Intercomparison Project Phase 6 (CMIP6), in two Shared Socioeconomic Pathways scenarios (SSP2–4.5 and SSP5–8.5). The AZ method was applied for the current climate simulations (1995–2014), as well as for projections by the near (2041–2060) and far future (2081 – 2100) climate conditions considering two base temperature values (Tb = 7ºC and 13ºC). Given intense and persistent increases in air temperature, water deficit, and reduced chilling accumulation, TFT plantations will be restricted and economically unfeasible for about 69% (SSP2.4–5) to 86% (SSP5.8–5) of Minas Gerais in the far future for both Tb values. Only ∼6% (near future) and ∼2% (far future) of the study area located in a small portion of the Southern region of Minas Gerais will be suitable for TFT plantations. However, the future of TFT plantations in places classified as regular will depend on adopting adaptation measures to reduce vulnerability to these crops, including low-chill genotypes selection, improvements in breeding programs, using strategies to break dormancy artificially, and intensifying irrigation with less water-demanding techniques.

The Effect of Heat Shock on Seed Dormancy Release and Germination in Two Rare and Endangered Astragalus L. Species (Fabaceae).

Many Astragalus species exhibit seeds with physical dormancy (PY), but little is known about the ecological context of this dormancy. We focused on A. maritimus and A. verrucosus, two threatened Sardinian endemic species inside the subgenus Trimeniaeus Bunge. Fresh seeds collected from the only two respective known populations were used to investigate the effect of mechanical scarification, heat shock, and water imbibition processes on PY release and germination. PY can be overcome through mechanical scarification of the water-impermeable seed coats, while no dormancy break was detected, nor a subsequent increase in seed germination due to fire-induced heat. This suggests that fire does not trigger dormancy release and seed germination in these species. The seeds tolerate relatively high heat shock temperatures (up to 120 and 100 °C for A. verrucosus and A. maritimus, respectively), but after 120 °C for 10 min, the number of dead seeds increases in both species. These facts suggest the capacity to develop a soil seed bank that can persist after fires and delay germination until the occurrence of optimal conditions. As regards water imbibition, both Astragalus species did not show the typical triphasic pattern, as germination started without further water uptake. This study emphasizes the significance of understanding germination processes and dormancy in threatened species. In fire-prone ecosystems, PY dormancy plays a crucial role in soil seed bank persistence, and it may be selectively influenced by post-fire conditions. Understanding such adaptations provides useful insights into conservation strategies.

Dormancy break, sprouting and later tuber reproduction in response to different tuber sizes of tiger nut (Cyperus esculentus L.).

Dormancy release pattern, sprout growth and later reproduction were studied among various tuber sizes of Cyperus esculentus to determine effective methods to release dormancy and further to select suitable tuber size of this species in production. The results showed that medium tubers performed better during sprouting than large and small tubers under all pre-sprouting treatments. Pre-sprouting treatments at 25°C, 35°C, RT (room temperature) and -2°C were effective in relieving dormancy in medium tubers. Tiller number from medium tubers were significantly higher under 25°C, RT and 45°C than under 35°C and -2°C. Shoot and root mass from medium tubers were significantly higher under the 25°C, 35°C and RT than under other treatments. Tiller and tuber numbers both decreased with decreasing tuber size, as did tuber yield after three months of growth. Furthermore, leftover mass decreased with decreasing tuber mass and remained unchanged at sprouting and maturity periods. A significantly negative allometric correlation was found between plant mass and tuber mass from small tubers. However, a significantly positive allometric correlation was found between tuber size and tuber number from large tubers. In conclusion, medium tubers had a competitive advantage in sprouting, growth and reproduction.

Catalyzing Germination: Exploring Scarification and Hot Water Treatments for Dormancy Breaking and Enhanced Storage in Ficus Benjamina L., Thespesia populnea L., Phyllanthus emblica L., Tectona grandis L.f. seeds

A seed is a significant stage in the plant life cycle and is often referred to as the dispersal unit of the plant. There are two types of seeds: dormant seeds and non-dormant seeds. A dormant seed is one that does not have the capacity to germinate within a definite period under any combination of normal, physical and environmental factors. The other type is favourable for germination and when the seed becomes non-dormant, the circumstances that break dormancy and the location of water gaps in seeds, remain unclear. In the present study, we consider the adaptive role of impermeable coats in the seeds of Ficus Benjamina L., Thespesia populnea L., Phyllanthus emblica L. and Tectona grandis L.f. The study was particularly designed to analyze the conditions that break dormancy and the location of the primary water gap during dormancy breaking. Each seed was treated separately to break its dormancy and it was observed that water entered only through the lens due to the dislodgement of the palisade layer. Additionally, the storage life of Ficus Benjamina L. and Phyllanthus emblica L., seeds was extended as evidenced by the analysis of low moisture content decreasing from 6.02% to 5.31%. This study concludes that the impermeable seed coat of seeds with low moisture content increases storage life and regulates seed imbibition, thus influencing germination with the growing season.

Breaking of seed dormancy in ash gourd (&lt;i&gt;Benincasa pruriens&lt;/i&gt;) through fruit storage and seed treatments

The dormancy in seeds collected from freshly harvested ash gourd [Benincasa pruriens f. hispida (Thunb.) de Wilde &amp; Duyfjes] fruits reduces the seed quality and field performance viz. early germination, faster seedling establishment and vigorous seedling growth. Post harvest storage of fruits and different physical and chemical methods are useful in breaking seed dormancy in cucurbits. The present study was carried out during winter (rabi) 2020–21 and rainy (kharif) seasons of 2021–22 at the Agricultural Research Station (Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu), Vaigai Dam, Tamil Nadu to identify the optimal duration of post-harvest fruit storage and dormancy-breaking method for reducing seed dormancy in ash gourd cv. CO 1. Experiment was conducted in a randomized block design (RBD) with 3 replications. Firstly, the results revealed that the seeds extracted from the fruits, which were stored for 60 days after harvest, exhibited the best field performance, viz. early emergence, higher field emergence, faster rate of emergence and more seedling length, seedling dry weight, seedling vigour index, and viability indicating that prolonged storage can effectively reduce seed dormancy. Secondly, among different dormancy-breaking treatments, warm stratification of seeds at 40–50°C for 5 days and soaking of seeds in 500 ppm ethrel for 16 h remarkably improved the field performance, indicating the usefulness of these methods in improving seed quality characteristics in ash gourd. Farmers can use ethrel to break dormancy in ash gourd.

Hydrogened cyanamide promotes dormancy breakage in pear tree grown in a subtropical region

Hydrogened cyanamide promotes dormancy breakage in pear tree grown in a subtropical region

Tempo de imersão em ácido sulfúrico para superar a dormência de sementes de batata-doce

ABSTRACT To increase genetic variability, sweet potato needs to be sexually propagated in breeding programs. However, its seeds have a hard and thick integument, requiring some dormancy breaking method. Chemical treatment of seeds allows greater efficiency of the relationship between seeds obtained in crosses and those that germinate, providing genotypes to be tested for their potential, aiming at developing a new commercial cultivar. Thus, the objective of this study was to identify the effects of immersion times of seeds in sulfuric acid (98%) on the germination and initial growth of sweet potato seedlings. The seeds were immersed for five different times: 0 (control), 20, 40, 60, and 80 min. The experiment was carried out in a completely randomized design with ten repetitions consisting of 25 seeds each experimental plot. The germination percentage, germination speed index (GSI), dry mass of whole seedlings, and length of the largest root and shoot of the seedlings were evaluated. The germination percentage and GSI increased with immersion time until 53.30 min, with maximum estimated values of 85.39 and 25.10%, respectively. For the parameters dry mass of whole seedlings, length of the largest root, and shoot length, increases were observed up to 55.00, 37.63, and 44.44 min, respectively. In conclusion, the immersion of sweet potato seeds in sulfuric acid (98%) for 53 min is ideal for breaking dormancy and providing better conditions for the initial development of seedlings.

Caracterização físico-química de frutos, biometria e dormência de sementes de marula

ABSTRACT: This study recorded the physicochemical properties of the marula fruits, the biometry and breaking the dormancy in the marula seeds. Using 200 ripe fruits, the physicochemical characterization was done. From a random sample of 400 seeds, an assessment of the biometrics was performed, and the weight, length, width and thickness of the fruits and seeds were evaluated. Two experiments were conducted to study dormancy breaking using pre-germination treatments, which included immersing the marula seeds five times (0, 15, 30, 45 and 60 minutes) in concentrated sulfuric acid (96%) and water, at 65 ºC temperature. The control was time zero, using plain distilled water, with 25 seeds per treatment and four replications. The marula fruits revealed average values of 21.65 ± 3.44 g, 35.5 ± 2.38 and 34.8 ± 2.73, respectively, for weight, diameter and length. The soluble solids (SS), Hydrogenonic Potential (pH), titratable acidity (AT) and ratio (AT/SS) were 14.74 ± 1.0º Brix, 3.93 ± 0.49 pH, 0.63 ± 0.22 and 27.07 ± 12.10, respectively. For the weight of one thousand seeds, the average value was 3.576 ± 188.4 g. The mean values for the dimensions of the width, length and diameter of the seeds were 22.9 ± 2.11; 23.7 ± 2.04; and 14.9 ± 2.09 mm, respectively. The physiological quality of these seeds was enhanced by immersing the seeds from freshly picked fruits in sulfuric acid for a maximum of 30 minutes and storing them for six months.