After-ripening Treatment Research Articles

Complex Seed Dormancy in Parrotia subaequalis: Identification, Breaking Mechanisms, and Conservation Strategies for an Endangered Species in China

Parrotia subaequalis, an endangered plant unique to China, is highly valued for its significant ecological and ornamental value. The specific type of seed dormancy in this species has not been clearly reported, which limits its natural regeneration and artificial propagation, posing a challenge to its conservation and sustainable use. To address this, we conducted a comprehensive analysis of the seed dormancy mechanism of P. subaequalis and explored various methods to break dormancy, including cold and warm stratification, after-ripening, seed coat removal, and hormone soaking. Our analysis of the seeds’ physical properties, water absorption patterns, seed coat structure, embryo development, and endogenous inhibitors revealed that P. subaequalis seeds exhibit complex characteristics of physical and non-deep physiological dormancy. Experimental results showed that soaking the seeds in gibberellin (GA3) followed by seed coat removal effectively promoted germination. The optimal GA3 concentration for germination was 800 mg·L−1. Additionally, cold and warm stratification and after-ripening treatments significantly increased the germination percentage. These findings provide important technical support for dormancy release and seedling growth, which is crucial for the artificial propagation and population recovery of P. subaequalis.

Myosin-binding protein 13 mediates primary seed dormancy via abscisic acid biosynthesis and signaling in Arabidopsis.

Dormancy is an essential characteristic that enables seeds to survive in unfavorable conditions while germinating when conditions are favorable. Myosin-binding proteins (MyoBs) assist in the movement of organelles along actin microfilaments by attaching to both organelles and myosins. In contrast to studies on yeast and metazoans, research on plant MyoBs is still in its early stages and primarily focuses on tip-growing cells. In this study, we found that Arabidopsis MyoB13 is highly expressed in dry mature seeds. The myob13 mutant, created using CRISPR/Cas9, exhibits a preharvest sprouting phenotype, which can be mitigated by after-ripening treatment, indicating that MyoB13 plays a positive role in primary seed dormancy. Furthermore, we show that MyoB13 negatively regulates ABA biosynthesis and signaling pathways. Notably, the expression of MyoB13 orthologs from maize and soybean can completely restore the phenotype of the Arabidopsis myob13 mutant, suggesting that the function of MyoB13 in ABA-induced seed dormancy is evolutionarily conserved. Therefore, the functional characterization of MyoB13 offers an additional genetic resource to help prevent vivipary in crop species.

Fruit maturity & after-ripening improve seed physical and physiological quality of Solanum aethiopicum L.

In the absence of a reliable seed supply for the African eggplant (Solanum aethiopicum L.), farmers source their seeds from fruits harvested for fresh market (precocious harvests) but ripen later in the market. Some also source seeds from traders who extract seeds from unsold fruits. Fruits harvested at 20 days after anthesis (DAA) failed to germinate while those extracted from 34 DAA fruits had less than 10% germination in a preliminary study. This study was, therefore, conducted to determine whether the seeds within fruits harvested at 30 days after anthesis upwards could be after-ripened prior to seed extraction to improve seed physical and physiological quality characteristics. The treatments were laid in a randomized complete block design in a 2 x 5 x 4 factorial arrangement involving two cultivars, five harvest maturity stages: 30, 40, 50, 60 and 70 days after anthesis, four after-ripening periods: 0, 5, 10 and 15 days with four replications. Fruits were harvested at different maturity stages & seeds were extracted at 0, 5, 10 and 15 days of storage under ambient condition (24 ± 3°C) after each harvest. Seed dry weight, seed moisture content, 1000 seed weight, first germination count and germination percentage were determined. It was established that precocious harvest (30 days after anthesis, DAA) was not beneficial to physiological seed quality even when subjected to 15 days after-ripening. Fruits harvested 40 DAA failed to germinate while 50 DAA fruits had not more than 50% germination in both cultivars. However, when seeds extracted from these fruits were ripened for 15 days in storage, the germination percentage increased significantly by 63 to 72%. Seeds extracted from fruits harvested 60 or 70 DAA achieved the maximum germination, varying between 93 to 94% (cv. Oforiwa) & 78 to 96% (cv. Kpando) independent of after-ripening treatment. It is concluded that after-ripening is inconsequential & not necessary when seeds are harvested at physiological maturity (60 -70 DAA). For the purpose of seed production, it is recommended to harvest seeds of African eggplant at physiological maturity.

지황 종자의 형태 및 발아 특성

Background: This study was conducted to determine the effect of temperature, light, hormones, and after-ripening treatment on Rehmannia glutinosa seed germination to provide valuable information for its breeding and cultivation.BRMethods and Results: The seeds used in this study were harvested from the ‘Jihwang-1-ho’ cultivar. The seed length and width were 1.13 ± 0.03 ㎜ and 0.86 ± 0.02 ㎜, respectively, with a seed coat characterized by polygonal cells. The germination efficiency was evaluated at various temperatures (15, 20, 25, and 30℃) and light conditions (light/dark). The optimal germination condition was found to be 25℃ with light (91% germination). Pre-soaking the seeds with gibberellic acid (GA₃) increased germination, and the highest germination (72%) was observed with 1,000 ㎎/ℓ GA₃. Additionally, this also increased the mean germination time , germination uniformity, and germination index. The seeds that matured at 45% and 70% relative humidity showed the highest germination rates at 32 and 24 weeks, respectively.BRConclusions: The best method for R. glutinosa seed germination is maintaining 25℃ under light conditions with after-ripening treatment for over 16 weeks. Pre-soaking the seeds in 1,000 ㎎/ℓ GA₃ for 24 h further improved their germination. Rehmannia glutinosa seeds were classified under non-deep physiological dormancy.

Effects of Temperature, Scarification, Stratification, Phytohormones, and After-Ripening on the Dormancy and Germination of Eucommia ulmoides Oliv. Seeds

Eucommia ulmoides Oliv., the only member of the family Eucommiaceae, is endemic to China and has great development and utilization prospects. The seeds of E. ulmoides show dormancy but the underlying mechanism remains unknown. The aim of this study was to determine the cause of the seed dormancy and provide fundamental knowledge for the breeding, genetic improvement, and conservation of the germplasm resources of this species. According to the seed dormancy classification system developed by Jerry M. Baskin and Carol C. Baskin, we compared the germination percentage between intact seeds and isolated embryos, constructed water absorption curves, and evaluated the germination of seeds treated with scarification, cold/warm-moist stratification, after-ripening during dry storage, and gibberellic acid (GA3). The results showed that the intact seeds germinated only at 10 °C with a low germination percentage of 13.3% whereas the isolated embryos had a high normal germination percentage among a wider range of temperatures. According to the results from the scarified seeds, half seeds, and intact seeds, the seed coat significantly restricted the embryo water absorption. The scarification, after-ripening, cold/warm-moist stratification, and GA3 treatments promoted seed germination. Among them, cold-moist stratification was the most effective method and the temperature range of seed germination increased in both directions from 10 °C with prolonged stratification. The germination percentage increased significantly at constant temperatures with the highest germination percentage of 93.7 ± 0.3% at 10 °C and a light/dark cycle after 90 days of cold-moist stratification. Therefore, the freshly harvested E. ulmoides seeds exhibited a combinational dormancy comprising physical and Type 3 non-deep physiological dormancy, causing limited embryo water absorption by the seed coat and a low embryo growth potential. Given the unique phylogenetic characteristics and utility of E. ulmoides, our findings should promote studies of seed dormancy evolution and the development and application of E. ulmoides germplasm resources.

The effect of maturation stage and after-ripening on seed quality in organically- and conventionally-produced pepper (Capsicum annuum L.) seeds

High quality seed production is essential in organic production as well as in conventional production. Fruit maturity can be observed at different times due to the continuous flowering of pepper plant. Consequently, seeds with different maturity are obtained as the fruits are collected during once over-harvesting period. Immature seeds collected in once over-harvest may cause quality losses in the seed lot. Hence, this study was conducted to determine the effect of after-ripening on mature and immature pepper seeds produced in organic and conventional production systems. To see the effect of after-ripening treatment, seeds were harvested in two different periods (immature 45-50 day after anthesis(DAA) and mature 60-65DAA). After-ripening(AR) was performed by keeping the seeds in fruits for 7 days after harvesting the fruits. Effect of production systems and after-ripening on immature and mature pepper seed lots were assessed for four cultivars harvested in 2015 and 2016. After-ripening increased germination (AR:76.3%, C:28% for organic and AR:88%, C:53.8% for conventional), seedling emergence (AR:70.8%, C:44.3% for organic and AR:82.5%, C:53.8% for conventional) percentages and mean weight of 1000 seeds (AR:6.5, C:6.0g for organic and AR:6.5, C:6.2g for conventional) in both production systems of immature seed lots compared to control (C)(P<0.05) but did not have a similar effect on mature ones. Moreover, organically-produced seed lots have the same quality as conventionally-produced seeds. Consequently, obtained results indicate that after-ripening can be used to enhance the quality of immature seeds of pepper cultivars and seeds can be produced organically without any loss of quality.

Enhancing Conservation of a Globally Imperiled Rockland Herb (Linum arenicola) through Assessments of Seed Functional Traits and Multi-Dimensional Germination Niche Breadths.

Humans currently face an extraordinary period of plant biodiversity loss. One strategy to stem further losses involves the development of species-level recovery plans that guide conservation actions. Seeds represent an important component in the life history of plants and are crucial for conservation activities. Yet, most recovery plans contain meager seed biology information. We set out to examine seed functional traits and germination niche breadth of Linum arenicola seeds exposed to a range of thermal, photoperiodic, and salinity gradients to gain perspectives on the seed biology of this endangered species that may inform conservation decision making and assist recovery plan development. We found that fresh seeds possess non-deep physiological dormancy, which may be alleviated via a four-week dry after-ripening treatment. The germination response of non-dormant seeds is subsequently promoted by constant rather than alternating temperatures. The optimum germination temperature range is 20–22 °C. Non-dormant seeds do not possess an absolute light requirement for germination, but are sensitive to low levels of salinity (EC50 = 6.34 ppth NaCl). The narrow thermal and salinity germination niche breadths reported here suggest a specialized reproductive strategy that may require careful consideration when planning ex and in situ conservation activities.

Effect of maturity and after-ripening on the formation of gel in the syrup made from Japanese apricot ‘Suiko’ fruits

To process clear syrup from ‘Suiko’ Japanese apricots, the effect of fruit changes on the amount of gel with pectin characteristics formed upon natural ripening or after-ripening was investigated. Little gel was formed in the syrup extracted from early-mature fruits subjected to after-ripening for 0 to 4 days, and from moderately mature fruits subjected to after-ripening for 0 to 2 days; conversely, a large amount of gel was formed in the syrup extracted from fully mature drop fruits. Uronic acid was found at a higher concentration and had a higher degree of esterification in the gel than in the liquid phase. Moreover, the gel contained larger amounts of high-molecular-weight polysaccharides than the liquid phase. In raw fruits, an increase in the duration of natural ripening and after-ripening reduced high-molecular-weight water-soluble pectin content, and increased the low-molecular-weight polymer. This suggests that low-molecular-weight pectin would actively convert into syrup in ripened fruits, while high-methoxyl pectin would recombine under conditions of low pH and high soluble solid content, thus resulting in gel formation. We conclude that early-matured fruits after a 4-day after-ripening treatment were best suited for processing because they showed the least gel formation in the clarified syrup, while preserving aroma.

One Way to Achieve Germination: Common Molecular Mechanism Induced by Ethylene and After-Ripening in Sunflower Seeds

Dormancy is an adaptive trait that blocks seed germination until the environmental conditions become favorable for subsequent vegetative plant growth. Seed dormancy is defined as the inability to germinate in favorable conditions. Dormancy is alleviated during after-ripening, a dry storage period, during which dormant (D) seeds unable to germinate become non-dormant (ND), able to germinate in a wide range of environmental conditions. The treatment of dormant seeds with ethylene (D/ET) promotes seed germination, and abscisic acid (ABA) treatment reduces non-dormant (ND/ABA) seed germination in sunflowers (Helianthus annuus). Metabolomic and transcriptomic studies have been performed during imbibition to compare germinating seeds (ND and D/ET) and low-germinating seeds (D and ND/ABA). A PCA analysis of the metabolites content showed that imbibition did not trigger a significant change during the first hours (3 and 15 h). The metabolic changes associated with germination capacity occurred at 24 h and were related to hexoses, as their content was higher in ND and D/ET and was reduced by ABA treatment. At the transcriptional level, a large number of genes were altered oppositely in germinating, compared to the low-germinating seeds. The metabolomic and transcriptomic results were integrated in the interpretation of the processes involved in germination. Our results show that ethylene treatment triggers molecular changes comparable to that of after-ripening treatment, concerning sugar metabolism and ABA signaling inhibition.

After-Ripening Increased Seed Germination in Commercial Aubergine Seed Lots

This work tested the effect of after-ripening on seed germination of thirteen commercial seed lots from four open pollinated cultivars (Aydın Siyahı, Kemer, Pala and Topan) of aubergine (Solanum melongena L.). Seeds were stored (after-ripened) at 5 °C with at 9% seed moisture content over 14 days in the dark in hermetic conditions. After-ripened seeds were tested at 25 °C and 20/30 °C (16/8 h) together with a control at 20/30 °C for 14 days in petri dishes. Results indicated that after-ripening significantly (p < 0.05) increased total germination in six lots and normal germination in eight lots out of thirteen when germination was tested at 25 °C. Increases were also observed eleven lots in total and thirteen in normal germination percentages out of thirteen when seeds were tested at 20/30 °C. Cumulative germination showed that after-ripened seeds germinated faster than control either germinated at 25 or 20/30 °C. Results indicated that aubergine seed germination can be increased through after-ripening treatment which shows the presence of seed dormancy in this species.

Seed dormancy and germination in different populations of the Argentinan endemic halophyte grass, Sporobolus phleoides (Poaceae: Chloridoideae)

Sporobolus phleoides Hack. is an endemic grass of Argentina that is considered an important genetic resource for saline environments. Knowledge of its germination behaviour is an indispensable requirement for the future potential use of this species. Thus, the effects of different factors on germination were evaluated in six representative populations collected from plants cultivated in a uniform environment. In addition, we investigated how the different parts of the seed contributed to dormancy and intraspecific variability. S. phleoides has non-deep physiological dormancy that appeared to be related to its testa. Thereby, dormancy was completely removed with puncturing treatments. High levels of germination were also obtained in seeds stratified at 8°C over 100 days in a solution of nitrates. After-ripening treatment did not have a significant effect in breaking dormancy. Similar germination behaviour and dormancy levels were observed in the different populations, especially when they were subjected to cold stratification. Although further work is needed, cold stratification appears to be the major factor in determining the time of seedling establishment in natural environments for this species.

Environmental and maternal factors affecting on oriental mustard (Sisymbrium orientale L.) and musk weed (Myagrum perfoliatum L.) seed germination

The effects of environmental and maternal factors on seed germination of oriental mustard and musk weed factors were investigated through a series of laboratory and pot experiments. In experiment 1, the effect of seed coat removal on musk weed seed germination at 25/15 °C (day/night) was evaluated. In experiment 2, seeds of both weeds were subjected to temperature and after-ripening treatments. In experiment 3, oriental mustard and musk weed seeds were treated by gibberellic acid (GA3). Experiment 4 was set up to evaluate the effects of intra and interspecific competition and seed position on plant canopy on seed germination behavior of oriental mustard. Seed coat-inhibited germination of musk weed. Dry after-ripening and temperature fluctuations did not promote germination of musk weed seed, while oriental mustard seed germination was promoted by after-ripening and temperature treatments. The maximum germination of oriental mustard seed occurred at 25/15 °C temperature and 2 months after ripening. Except in chickpea treatment, intra and interspecific competitions reduced oriental mustard seed germination. Seed dormancy in different layers of oriental mustard canopy was varied. Also, seed position on mother plant influenced the seed germination behavior of oriental mustard.

Factors Affecting Seedling Emergence and Dry Matter Characteristics in Musa balbisiana Colla

The effects of storage duration (0, 2, 4, 6, 8, and 10 days), sterilization with sodium hypochlorite (0, 5, 10, 15, and 20%), and weaning media on seedling characteristics and dry matter content in Musa balbisiana seedlings were studied. The experiment was factorial in a completely randomized design with five replicates. The result indicates that increase in NaOCl concentration and number of days in storage significantly (P=0.5) increased the period of seedling emergence. Also, soaking in NaOCl for 20 min had significant effect on average seedling emergence at 15 and 20% concentrations, compared to 10 min soaking at the same concentrations. The combined effects of storage duration and sterilization resulted in a decrease in the duration of seedling emergence. Seeds previously sterilized with either water or NaOCl had no significant effect on seedling growth, leaf and corm dry weight, but affected almost all the dry matter traits. A mixture of poultry manure, top soil, and river sand as weaning media gave better seedling growth and increased dry matter characteristics. We conclude that M. balbisiana seeds require after-ripening treatment to enhance germination, sterilizing seeds with 5% NaOCl for 10 min and air-drying under ambient condition for 2–6 days were found most appropriate, and a mixture of poultry manure, top soil, and river sand is recommended as weaning medium for growth and dry matter composition in M. balbisiana seeds.

Effects of temperature, after-ripening, stratification, and scarification plus hormone treatments on dormancy release and germination of Acer truncatum seeds

Effects of temperature, after-ripening, stratification, and scarification plus hormone treatments on dormancy release and germination of Acer truncatum seeds

CHOTTO1, a Putative Double APETALA2 Repeat Transcription Factor, Is Involved in Abscisic Acid-Mediated Repression of Gibberellin Biosynthesis during Seed Germination in Arabidopsis

The phytohormones abscisic acid (ABA) and gibberellins (GAs) are the primary signals that regulate seed dormancy and germination. In this study, we investigated the role of a double APETALA2 repeat transcription factor, CHOTTO1 (CHO1), in seed dormancy, germination, and phytohormone metabolism of Arabidopsis (Arabidopsis thaliana). Wild-type seeds were dormant when freshly harvested seeds were sown, and these seeds were released from dormancy after a particular period of dry storage (after-ripening). The cho1 mutant seeds germinated easily even in a shorter period of storage than wild-type seeds. The cho1 mutants showed reduced responsiveness to ABA, whereas transgenic plants constitutively expressing CHO1 (p35SCHO1) showed an opposite phenotype. Notably, after-ripening reduced the ABA responsiveness of the wild type, cho1 mutants, and p35SCHO1 lines. Hormone profiling demonstrated that after-ripening treatment decreased the levels of ABA and salicylic acid and increased GA(4), jasmonic acid, and isopentenyl adenine when wild-type seeds were imbibed. Expression analysis showed that the transcript levels of genes for ABA and GA metabolism were altered in the wild type by after-ripening. Hormone profiling and expression analyses indicate that cho1 seeds, with a short period of storage, resembled fully after-ripened wild-type seeds. Genetic analysis showed that the cho1 mutation partially restored delayed seed germination and reduced GA biosynthesis activity in the ABA-overaccumulating cyp707a2-1 mutant background but did not restore seed germination in the GA-deficient ga1-3 mutant background. These results indicate that CHO1 acts downstream of ABA to repress GA biosynthesis during seed germination.

Pre- and post-harvest influences on physiological dormancy alleviation of an AustralianAsteraceaespecies:Actinobole uliginosum(A. Gray) H. Eichler

AbstractThe effects of maternal air temperature and soil moisture upon seed physiological dormancy (PD) alleviation of an Australian nativeAsteraceaewere investigated. From the onset of flowering,Actinobole uliginosumplants growingex situwere subjected to either a warm (mean 26°C) or cool (mean 17°C) temperature regime, with adequate or limited water availability. In the warm environment, the reproductive phase was accelerated, and plants yielded fewer seeds over a shorter, earlier harvest period, when compared to those in the cool environment. Initial germination of all seeds was low ( < 20% at 15°C) due to PD, which was gradually alleviated by a dry after-ripening (DAR) treatment (34/20°C, 40% relative humidity, in darkness). Seeds from plants grown in the warm environment were more responsive to DAR than seeds from the cool environment, but maternal plant water availability had little effect on dormancy status. Germination was higher at 15°C than at 25/15°C, reaching a plateau ofc.80% germination after 20 weeks DAR. Before DAR, application of GA3had little impact on seeds, which would consequently be classified as having deep PD if tested at the time of dispersal. However, DAR caused seeds to become increasingly responsive to GA3, reaching 97% germination at 15°C following just 4 weeks of DAR, which would indicate non-deep PD if seeds were tested following a period of warm, dry storage. Maternal air temperature regulates PD status ofA. uliginosum, such that seeds collected from a warmer environment are likely to be more responsive to DAR. Post-harvest storage in an environment suitable for DAR affects seed response to GA3, which has implications for germination stimulation and dormancy classification.

Environmental signals for seed germination reflect habitat adaptations in four temperate Caryophyllaceae

Summary 1Requirements for dormancy break and seed germination are specific for all species and depend chiefly on phylogeny, geographical distribution, habitat preference and life cycle. Studying germination requirements of closely related species with a similar geographic distribution allows one to attribute variation in germination requirements to differences in habitat preference between the species. 2We investigated requirements for dormancy break and the effect of environmental signals on induction of germination in seeds of four closely related Caryophyllaceae species growing in a variety of habitats (Moehringia trinervia, Stellaria holostea, S. nemorum and S. graminea). The species studied depend on disturbances in the vegetation for seed germination and subsequent seedling establishment. 3Seedlings of all four species emerged both in summer and spring. Stellaria nemorum and M. trinervia, both growing in temperate forests, emerged mainly in summer under a closed forest canopy. Seeds of S. graminea, occurring in grasslands, did germinate in summer at an open site, but could not germinate under a closed forest canopy. Seedlings of S. holostea were observed in late summer when buried at an open site or in early spring when sown in a forest patch. 4Seeds of S. holostea and M. trinervia were completely dormant at dispersal in early summer, while germination was low in fresh seeds of S. graminea and S. nemorum. Dormancy was broken, to a certain extent, during all three after-ripening treatments applied (dry storage, cold and warm stratification). 5The effect of three gap-detection signals (light, fluctuating temperatures, nitrates) on germination of fresh and dry stored seeds was tested. Seeds of S. holostea only germinated in response to daily fluctuating temperatures. Although light was the most important signal affecting germination of S. graminea and M. trinervia, we also observed a positive effect of fluctuating temperatures and nitrates on germination. The effect of fluctuating temperatures on germination of S. nemorum was small in both light and dark incubated seeds. Seed germination in this species generally occurred in response to addition of light and nitrates. 6This study on dormancy breaking and germination requirements of the four species enabled us to expose, sometimes subtle, differences in germination requirements. These contrasting germination patterns were related to differences in the species’ habitat preferences.

Surface sterilization and duration of seed storage influenced emergence and seedling quality of African breadfruit (Treculia africana Decne)

The effects of factorial combinations of four storage duration (in days after seed extraction) and surface sterilization with three dilution levels of sodium hypochlorite on seedling emergence and seedling quality of African breadfruit were studied. Storage duration significantly influenced days to seedling emergence, cumulative emergence and seedling quality traits. The effect of sterilization was, however, only significant on deformed seedlings and seedling foliage development. The combined effects of storage duration and sterilization were significant on all traits measured. Seedlings arising from previously sterilized seeds and planted within six days of extraction had fewer cases of deformity and had better foliage development. It was conclusive that after-ripening treatment was necessary to enhance the number of seedling emerging and quality of seedlings of African breadfruit. Sterilizing seeds with 10% dilution of NaOCl and air-drying under ambient tropical room condition for three to six days were found most appropriate, and thus, recommended.

Determination of Seed Germination Requirements in Nolana sp.

Nolana is a diverse genus native to coastal deserts of Peru and Chile, with great potential for developing new ornamental cultivars. Low germination has been an obstacle to breeding efforts at the University of New Hampshire (UNH). Nolana fruits are comprised of unusual sclerified mericarps, each containing one or more embryos. Germination occurs with opening of funicular plugs on the mericarps. Under normal greenhouse conditions at UNH, germination success in eight Nolana species (N. adansonii, N. aticoana, N. humifusa, N. laxa, N. ivaniana, N. plicata, N. elegans, and N. rupicola) ranged from 0 to 0.05 seedlings/mericarp. We analyzed mericarp morphology, imbibition, and the effect of chemical and environmental germination treatments. SEM showed that soaking treatments create physical changes in mericarp morphology, exposing tracheid tubes in the funicular plugs. Mericarps were soaked in dye to track imbibition, confirming that this occurs through the tracheid tubes, and that additional scarification is not required. The following chemical treatments were unsuccessful in increasing germination: 0.1 N HNO3, 0.2 KNO3, conc. H2SO4, 10 mM or 1 μM ethephon. Gibberellic acid (1000 ppm) effectively increased germination in some species (up to 0.47 seedlings/mericarp). Mericarps stored dry for 2 years had significantly higher germination than fresh mericarps (0.55 seedlings/mericarp). Mericarps of N. aticoana were subjected to after-ripening treatments. Mericarps stored for 7 weeks at 35 °C and 75% RH showed significantly higher germination (0.36 seedlings/mericarp) than mericarps stored dry, or stored moist for 1-6 or 8-12 weeks. Our findings facilitate development of larger hybrid populations, thus increasing the efficiency of Nolana breeding programs.

Gene expression analysis by cDNA-AFLP highlights a set of new signaling networks and translational control during seed dormancy breaking in Nicotiana plumbaginifolia

Seed dormancy in Nicotiana plumbaginifolia is characterized by an abscisic acid accumulation linked to a pronounced germination delay. Dormancy can be released by 1 year after-ripening treatment. Using a cDNA-amplified fragment length polymorphism (cDNA-AFLP) approach we compared the gene expression patterns of dormant and after-ripened seeds, air-dry or during one day imbibition and analyzed 15,000 cDNA fragments. Among them 1020 were found to be differentially regulated by dormancy. Of 412 sequenced cDNA fragments, 83 were assigned to a known function by search similarities to public databases. The functional categories of the identified dormancy maintenance and breaking responsive genes, give evidence that after-ripening turns in the air-dry seed to a new developmental program that modulates, at the RNA level, components of translational control, signaling networks, transcriptional control and regulated proteolysis.