Ungerminated Seeds Research Articles

Germination and Dormancy in Annual Halophyte <i>Juncus ranarius</i> Song & Perr.

The effects of cold stratification and gibberellic acid (GA3) on dormancy breaking for seeds of the annual halophyte species Juncus ranarius were tested. Germination percentage and recovery responses of salt stressed seeds were also tested. Freshly collected seeds germinated slowly under all incubation conditions. Thus, the seeds of J. ranarius have physiological dormancy, e.g. they are water permeable, have a fully developed embryo and require cold stratification to come out of dormancy. Furthermore, promotion of germination by GA3 after-ripening in dry storage also indicated that these seeds have non-deep physiological dormancy. In general, the higher the GA3 concentration, the more germination occurred within the studied range. Juncus ranarius demonstrated a germination preference for light. The highest germination percentage and rate of germination were recorded under constant light conditions at 22 °C after 24 weeks of cold stratification. In saline solutions, the highest percentage of germination was obtained at 25 mM L-1 NaCl, and further increase in salinity resulted in a gradual decrease in germination. However, ungerminated seeds were not damaged by salt, showing a high level of recovery. The greater the reduction in salinity, the better the germination rate became. It was concluded that dormancy could be completely broken by cold stratification, indicating spring germination. Juncus ranarius can grow well at lower NaCl concentrations under constant light conditions at 22 °C.

Seed germination of Brazilian Aldama species (Asteraceae)

Brazilian samples from the Aldama genus (Asteraceae) could not propagate vegetatively despite their thickened underground system; thus, this study on sexual propagation is critical given the lack of data on reproductive strategies for such species. The aim for this research was to assess the optimal temperature for Aldama arenaria, A. filifolia, A. linearifolia, A. robustaand A. trichophylla seed germination. Seed germination was evaluated at the constant temperatures 20, 25 and 30 °C and the alternating temperatures 15-35, 20-30 and 20-35 °C with an 8-h daily photoperiod, using fluorescent-lamp. The ungerminated seeds were evaluated for embryo viability. The A. filifolia seed health was also evaluated. The optimal temperatures for germination are 20 and 25 °C for Aldama arenaria, A. filifolia, A. robusta and A. trichophylla seeds and 20 °C for A. linearifoliaseeds. The alternating temperature 15-35 °C is not recommended for germinating seeds from these species. The six fungi taxa studied herein did not affect A. filifolia seed germination.

Ample germination ability under wide‐ranging environmental conditions in a common understory tropical palm

AbstractAlthough palms play an important ecological role in tropical forests, characteristics related to their germinative niche remain largely unknown. We evaluated the seed germination characteristics of Geonoma schottiana, an abundant palm in the understory of different ecosystems of the Atlantic Rain Forest biome and the gallery forests of the Cerrado biome. We conducted experiments under light and dark conditions at Ψ = 0 MPa, and under two low‐water‐potential conditions and a flooded condition. Seed germination was highest at Ψ = 0 MPa under light (72%) and dark (67%) conditions. We observed moderate (51%) and low (18%) seed germination at Ψ = −0.4 and −0.8 MPa. About 20% of ungerminated seeds subjected to low water potentials for 300 days remained viable. No seeds germinated under flooded conditions; however, 23% of them maintained germinability. A delay in seed germination time was observed at low water potentials and an increase in synchrony occurred at Ψ = −0.8 MPa. G. schottiana seeds did not require specific light conditions to germinate, and the species possesses germinative characteristics to cope with deficit and excess of water. Probably, this wide germination niche allows for its seeds to germinate over a wide range of habitats in different types of ecosystems.

Proteomics를 이용한 콩의 발아 전 침종처리에 따른 단백질 발현 양상 비교 분석

Soybean is very useful crop to supply vegetable protein for human. However, cultivation arear of this economically important crop is gradually diminished in upland field. Hence, cultivation area of soybean is increased in paddy field. During the growth duration of soybean, excessive moisture injury is serious problem for sustainable production and supply. We investigated protein expression according to different period of seed soaking and germination after seed soaking. For comparison on expression of protein according to different condition, we performed two-dimensional electrophoresis. After electrophoresis analysis, we selected differentially expressed protein spots according to different condition such as soaking period and germination after soaking to identify protein function by using MALDI-TOF. Results revealed that pattern of expression of protein according to soaking period and germination after soaking were generally not different in major spots. However, degree of expression of protein in some protein spots was increased in accordance with decrease of soaking period. Especially, in Hwangkeum-Kong, Danyeop-Kon, and Pecking, the degree of expression of protein was remarkably increased for 4 days after soaking. But, according to germination after soaking, degree of expression of protein in germinated seeds of all cultivars was higher than un-germinated seeds. In results of MALDI-TOF analysis, specific proteins were identified by different soaking period such as Allergen Gly m Bd 28K, P24 oleosin isoform B. Also, in accordance with germination, degree of protein expression of the related protein, Gibberellin was increased in un-germinated seeds of Iksan-Kong. In ungerminated seeds of Sinpaldal-kong, proteins were identified as down-regulated by soaking such as ATP binding and Inhibitor II`, proteinase.

ACE-I inhibitory properties of hydrolysates from germinated and ungerminated Phaseolus lunatus proteins

Phaseolus lunatus protein concentrates and the proteases Alcalase(R) and Pepsin-Pancreatin were used for the production of protein hydrolysates that inhibit angiotensin-I converting enzyme (ACE). Protein concentrate obtained from germinated and ungerminated seeds flour was hydrolyzed with Alcalase(R) at enzyme/substrate ratio (E/S) 1/10 and during 0.5 and 2.0 h, respectively. On the other hand, protein concentrate obtained from ungerminated (E/S: 1/10) and germinated (E/S: 1/50) seeds flour was sequentially hydrolyzed with Pepsin-Pancreatin during 1.0 and 3.0 h, respectively. Peptide fractions with ACE inhibitory activity in a range of 0.9 to 3.8 µg/mL were obtained by G-50 gel filtration chromatography and high- performance liquid chromatography C18 reverse phase chromatography. The observed amino acid composition suggests a substantial contribution of hydrophobic residues to the peptides’ inhibitory potency, which potentially acts via blocking of angiotensin II production. These results show that P. lunatus seed proteins are a potential source of ACE inhibitory peptides when hydrolyzed with Alcalase(R) and Pepsin-Pancreatin.

Aerial seed bank affects germination in two small-seeded halophytes in Arab Gulf desert

Aerial seed banks protect seeds against granivores, help seed dispersal over time and maintain seeds in a favorable microhabitat. We hypothesized that the aerial seed bank in maternal tissues could protect halophyte seeds from lethal salinity effects of soils. Effects of aerial (in plant canopy) and room-temperature (lab) storage on subsequent germination behavior were assessed for two small-seeded halophytes: Halocnemum strobilaceum (known to be salt tolerant, with a short-term aerial seed bank –less than 9 months) and Halopeplis perfoliata (less salt tolerant, with a long-term aerial seed bank more than 17 months). Seeds were germinated in different salinities in both light/dark regime and darkness treatments. Ungerminated seeds from the different salinities were transferred to distilled water to assess their ability to recover germination capacity. Salinity tolerance during germination was much greater in H. strobilaceum, compared to H. perfoliata. Storage in the aerial seed bank resulted in significant germination-reduction in H. strobilaceum, but not in H. perfoliata. In H. strobilaceum aerial-stored seeds were less tolerant of the salinity than were the room-temperature-stored seeds. These results support the notion that an aerial seed bank protects salt-sensitive seeds from effects of high soil salinity, especially in species that have short-term aerial seed banks.

Evidence of Protaphorura fimata (Collembola: Poduromorpha: Onychiuridae) feeding on germinating lettuce in the Salinas Valley of California.

A series of experiments were conducted to determine the impact of Protaphorura fimata Gisin (Family: Onychiuridae) feeding on seeds and germinating seedlings of lettuce, Lactuca sativa L. (Asteraceae). First, various densities of P. fimata were incubated with 25 lettuce seeds for 7 d and feeding injury was evaluated in three soilless arena experiments. As a second step, 100 P. fimata were incubated with 25 lettuce seeds in three arena experiments with soil media. Finally, in a commercial field the incidence and impact of P. fimata on recently planted lettuce was assessed following applications of pyrethroid-insecticides: 2 d before planting, at planting, and 20 d later. In experiments without soil, the number of ungerminated seeds, feeding injury sites, and plants with injury were significantly greater in arenas with P. fimata than without. Similarly, the number of germinated seedlings, shoot fresh, and dry weights, and the length and width of fully opened-leaves were greater in arenas without than with P. fimata in assays with soil. In the field, P. fimata densities were significantly lower in beds that received insecticides at 2 d before and at planting than in untreated beds. Also, the fresh and dry weights of lettuce plants were significantly greater in the beds that received insecticide than in untreated. The results clearly show that P. fimata is a pest of lettuce and can cause severe feeding injury to germinating seeds or seedlings, thereby reducing their growth rate. The potential implications of P. fimata feeding and feeding injury characteristics are discussed.

Efectos del quitosano en hongos fitopátogenos y en la germinación de semillas de Jatropha curcas L.

Jatropha curcas es una planta con gran potencial agrícola e industrial. En este estudio se aislaron dos hongos de semillas no germinadas. Los aislamientos fúngicos se identificaron morfológica y molecularmente como Fusarium equiseti y Curvularia lunata. Los efectos del quitosano se evaluaron sobre el crecimiento micelial, esporulación y germinación de esporas de F. equiseti y C. lunata. Además, se estudió el efecto sobre la germinación de las semillas de J. curcas. Los resultados demostraron que todas las concentraciones probadas de quitosano (0.5, 1.0, 2.0 y 4.0 mg·mL-1) inhibieron el crecimiento micelial de los hongos. Las respuestas de esporulación y germinación de esporas fueron diferentes dependiendo de la especie fúngica; el quitosano inhibió completamente la esporulación C. lunata y la germinación de esporas de F. equiseti. La inoculación con F. equiseti y C. lunata redujo la germinación de semillas de J. curcas 20 y 26.6 %, respectivamente; sin embargo, la aplicación de quitosano antes de la inoculación inhibió la actividad patogénica. En conclusión, el quitosano no afectó la germinación de las semillas y causó efectos inhibitorios en F. equiseti y C. lunata. Este es el primer reporte del efecto del quitosano en J. curcas.

Evaluation of two fruit ecotypes (totai and sclerocarpa) of macaúba (Acrocomia aculeata)

Macaúba (Acrocomia aculeata) fruit has great potential for oil production, surpassed only by the African oil palm (Elaeis guineensis). Studies of the use of macaúba oil for biodiesel are on-going, and the co-products of oil processing are excellent nutritional sources when used in food and feed. Several ecotypes of macaúba occur, but their oil production potential remains to be verified. Thus, in this study, fruits of two ecotypes of macaúba were evaluated to determine their mineral and proximate compositions, biometric characteristics, the physicochemical composition of the nut oil, and their germination characteristics. Mineral analyses consisted of the evaluation of N, P, K, Ca, Mg, Cu, Zn, and Mn. Proximate analyses included measurements of moisture, dry matter, crude protein, crude fibre, lipids, mineral matter, ash, and carbohydrates. Biometric characterisation included the masses of the endocarp, nut, mesocarp, epicarp and fruit, the longitudinal diameter of the fruit and nut, the endocarp thickness, and the fruit volume. Progibb® (0, 50, 100, and 200mgL−1) was used at temperatures of 25°C and 35°C to evaluate germination. The acidity, iodine content, saponification properties, and humidity of the nut oil were analysed. For the mineral, proximate, biometric and nut oil analyses, the means of the sclerocarpa ecotype were higher than those of the totai ecotype. In the biometric evaluations, the percentages of each part of the fruit of the totai ecotype were higher than those of the sclerocarpa ecotype, although the averages were lower in relation to fruit. The seed lot used in this study did not produce good germination, but the use of Progibb® was effective at 35°C for the totai ecotype; both evaluated ecotypes exhibited high levels of contaminated and ungerminated seeds.

Salt tolerance during seed germination and early seedling stages of 12 halophytes

Most studies on plant responses to salt stress have focused on one salt (e.g., NaCl). The aim of this study was to investigate the salt tolerance of halophytes with different seed masses to three different salts during germination and early seedling growth stages. Seeds of 12 halophytes were imbibed with five concentrations of NaCl, NaHCO3, or Na2SO4 solutions or with distilled water. Germination was recorded for 20 days. Un-germinated seeds were transferred to distilled water and recovery of germination was recorded for another 20 days. We measured the Na+ and K+ concentrations in the seedlings after the germination experiments. Most species showed higher germination percentages in NaCl than in NaHCO3 or Na2SO4 solutions. There were only significant differences in regressions of germination rates and salt concentrations for Anabasis salsa and Kalidium foliatum, between Na2SO4 solutions and the other salts. The Na+ concentration in the seedlings increased with increasing salt concentrations, while the K+ concentration was unchanged. Seed mass was significantly negatively correlated with the Na+/K+ ratio, and with decreasing germination percentage and decreasing germination rate at high salt concentrations. The halophytes showed species-specific responses to different salts. Some species were salt tolerators, while some were salt avoiders, as indicated by a high percentage recovery of germination in water after the alleviation of salinity. Seed mass was positively related to salt tolerance at high salinities.

Colchicine-induced polyploidy in loquat (Eriobotrya japonica (Thunb.) Lindl.)

The induction of polyploids in loquat (Eriobotrya japonica (Thunb.) Lindl.) is of great interest for producing larger and seedless fruits according to market demands. Under this premise, this work was aimed to obtain tetraploid plants of loquat using the antimitotic agent colchicine. Experiments consisted in applying colchicine on shoot apex from in vitro-grown plants, in vitro-grown whole plants and ungerminated seeds. Treatments on the shoot apex or submerging whole plants produced no stable polyploids. Conversely, subjecting ungerminated seeds to colchicine produced two triploids in the 0.5 % (w/v) solution after 24 h and one tetraploid after 48 h. The triploids obtained among treated seeds make us believe that these plants were present in the hybrids original seedlot. Polyploidy levels were firstly detected by flow cytometry and later confirmed by chromosome counting and morphological characteristics. The relative fluorescence was 1.5-fold higher in triploids and twofold higher in tetraploids as compared to diploids. As expected, the chromosome number was 2n = 34 in diploids, 2n = 51 in triploids and 2n = 68 in the tetraploid. Moreover, differences in morphological characteristics between diploid and polyploid plants were significant. The tetraploid plant was more compact than triploids or diploids. Particularly, stomata of polyploids were larger with lower density than diploids. Results indicate that induction of polyploidy in loquat species is a reliable tool for breeding new loquat varieties.

Seed storage and germination in Kumara plicatilis, a tree aloe endemic to mountain fynbos in the Boland, south-western Cape, South Africa

Seed storage under appropriate conditions is a relatively inexpensive means of safeguarding plant genetic material for ex situ conservation. Post-storage germination trials are used to determine the viability of stored seeds, and hence the efficacy of the particular storage treatment. Kumara plicatilis (=Aloe plicatilis) is a tree aloe endemic to mountain fynbos in the Boland, south-western Cape. The viability and germination behaviour of K. plicatilis seeds were assessed for seeds stored for four and nine months at −80°C, 4°C, 25°C and under ambient conditions in a laboratory. Seeds were germinated under controlled conditions and germination rates and percentages determined. Ungerminated seeds were tested for viability using tetrazolium salt. Seed viability was not significantly reduced during storage. Seeds stored at −80°C for four and nine months exhibited the fastest germination rate overall (both 5.9±0.3 weeks, mean±S.E.), and slowest was for seeds stored under ambient conditions for four and nine months (both 7.8±0.4 weeks). All seed lots showed similar percentage germination after four months of storage (78.0–90.4%). The highest percentage germination overall was for seeds stored at −80°C for four months (90.4%) and the lowest was for seeds kept at 4°C and −80°C for nine months (39.2 and 39.6%, respectively). Respective percentage viability for ungerminated seeds in these two treatments was 82% and 87%, respectively, indicating the induction of secondary dormancy. Induced dormancy triggered by protracted cold temperatures may be an adaptation that enables seeds to survive prolonged extreme conditions that are unfavourable for germination. Further research on the long-term storage of aloe seeds would be beneficial for developing long-term seed storage and germination testing protocols for ex situ conservation.

The Hypoglycemic Effect of Pumpkin Seeds, Trigonelline (TRG), Nicotinic Acid (NA), and D-Chiro-inositol (DCI) in Controlling Glycemic Levels in Diabetes Mellitus

In the contemporary society, diabetes mellitus is considered as a common, growing, serious, costly, and potentially preventable public health problem. It is forecasted that in 2030, the number of people with diabetes will go up from 117 million in 2000 to 366 million in 2030. The prevalence of diabetes will place a huge burden on health and financial structures of countries, and these will impact on individuals, as well as families and nations. Polysaccharides, para-aminobenzoic acid, fixed oils, sterol, proteins, and peptides are biologically active ingredients, which are found in pumpkins. The chemicals within pumpkins such as the fruit pulp, oil from ungerminated seeds, and protein from germinated seeds have hypoglycemic properties. Preliminary investigation showed that pumpkin seeds, and the macromolecules, therein, such as Trigonelline (TRG), Nicotinic acid (NA), and dchiro-inositol (DCI), possess hypoglycemic properties and could assist in maintaining glycemic control.

外来杂草小花山桃草种子休眠萌发特性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 外来杂草小花山桃草种子休眠萌发特性 DOI: 10.5846/stxb201303150425 作者: 作者单位: 河南科技大学林学院,浙江农林大学林业与生物技术学院,河南科技大学林学院,浙江农林大学林业与生物技术学院,河南科技大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 河南科技大学博士基金资助(09001076); 河南科技大学科学研究基金项目(2007ZY025) Seed dormancy and germination characteristics of Gaura parviflora, an exotic weed species in China Author: Affiliation: Forestry College,Henan University of Science＆Technology,School of Forestry and Biotechnology, Zhejiang A,Forestry College,Henan University of Science＆Technology,School of Forestry and Biotechnology, Zhejiang A,Forestry College,Henan University of Science＆Technology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:种子萌发和出苗是植物一生中对环境胁迫最为敏感的阶段,外来植物在这一时期对环境条件的适应能力是决定其入侵能力大小的关键因素之一.通过室内外试验研究了小花山桃草种子休眠特性以及贮藏时间、果皮、温度、pH 值、水势、盐分和埋土深度对其种子萌发、幼苗生长和出苗的影响.结果表明:小花山桃草蒴果中4 粒种子的大小差异显著(P < 0.01),但它们的活力和萌发率差别不大,4 粒种子活力均高达96%以上.休眠解除后,萌发率均高达98%以上;坚硬果皮的机械阻碍是引起种子休眠的主要原因;在室温储藏条件下,种子萌发率随贮藏时间的增加先增加后降低.贮藏1个月,萌发率提高到54%(贮藏前为0).贮藏3-6 个月时,萌发率达最大值(98.5%-99%).贮藏1a后,萌发率和萌发速度显著下降,但萌发率仍高达90%以上;在室外,有10.5%的蒴果前两粒种子(果实柱头端)同时萌发出苗.室外埋藏1a后,蒴果中未萌发的3 粒种子的发芽率分别为45.5%、90.5%和88.5%;小花山桃草种子萌发的温度范围为5-35 ℃,15-25 ℃最适于种子萌发,25 ℃最有利于幼苗生长;小花山桃草能忍受一定的盐胁迫和干旱胁迫,盐浓度和水势为0.15 mol/L和-0.5 MPa时,种子萌发率分别为33.5%和9%.种子萌发和幼苗生长最适宜的土壤含水量为50%;小花山桃草对pH 值具有较广泛的适应性,在pH 值为5-9范围内均可萌发;小花山桃草种子在土壤表面的出苗率为43%,埋土深度2 cm时,出苗率最高(89.5%),埋土深度大于10 cm时,不再出苗.小花山桃草种子休眠萌发特征以及出苗特点是其快速入侵的基础.研究结果为预测小花山桃草潜在分布范围以及提出科学合理的综合治理措施提供了理论依据. Abstract:Seed germination and early seedling growth are the stages in a plant's life cycle during which it is most sensitive to environmental stresses. The adaptability of an alien plant at this stage to unfavorable environmental conditions is one of the key factors determining its invasiveness. In this study, experiments were conducted to evaluate the effects of dormancy features, storage time, pericarp, temperature, pH, osmotic stress, salt stress and seed burial depth on seed germination, seedling growth and seedling emergence in Gaura parviflora. Although the four seeds of each capsule were found to differ significantly with respect to weight (P < 0.01), their vigor and germination rates were similar to one another. Seed vigor was greater than 96%, and germination was higher than 98% after release from dormancy. The pericarp of G. parviflora affected seed germination via physical obstruction, and was the major cause of seed dormancy. After storage at room temperature, G. parviflora seed germination initially increased; at longer storage times, however, it decreased. Prior to storage, no germination occurred. After one month of storage, germination rates as high as 54% were observed, with maximum germination (98.5%-99%) taking place after 3-6 months of storage. Germination rate and germination speed decreased significantly after one year of storage, although the germination rate was still greater than 90%. The first two seeds of G. parviflora capsules germinated (10.5%) and emerged at the same time under outdoor conditions. After one year of burial in the soil, germination rates of the remaining second, third and fourth ungerminated seeds averaged 45.5%, 90.5% and 88.5%, respectively. Gaura parviflora seeds germinated at temperatures ranging from 5 ℃ to 35 ℃, with optimum germination occurring at 15-25 ℃, and optimum seedling growth taking place at 25 ℃. Gaura parviflora seeds were fairly tolerant of high salt stress and low water potential, with germination rates of 33.5% and 9% observed at a salinity level of 0.15 mol/L and an osmotic potential of -0.5 MPa, respectively. The optimum soil moisture content for seed germination and seedling growth was 50%. Gaura parviflora seeds were able to germinate over a broad range of pH values, ranging from pH 5 to 9. When seeds were placed on the soil surface, the seedling emergence rate was 43%. Maximum seedling emergence (89.5%) occurred at a burial depth of 2 cm. No seedlings emerged when a burial depth of 10 cm was used. Seed dormancy, seed germination and seedling emergence are the critical factors responsible for the rapid invasion characteristics of this species. Our results should be helpful for predicting potential distribution areas of G. parviflora and for developing effective management strategies for this species. 参考文献 相似文献 引证文献

Examination quality seed perennial ryegrass, Italian ryegrass and red fescue

Examination is seed quality of perennial ryegrass (Lolium perenne), italian ryegrass (Lolium multiflorum) and red fescue (Festuca rubra) during the five years 2010 - 2014. The average established seed purity was over 98.40%, with varying by year from 96.7% to 99.2%. The greatest part of the impurities was inert matter, which are varied over the years in the range from 0.0% to 2.30%. Presence of weed seeds by year varied in the range from 0.0% to 0.50%. In the seeds of the tested grasses dominate the weeds from the family Asteraceae, Caryophillaceae, Chenopodiaceae and Polygonaceae. The most common weeds in the investigated grasses were Amaranthus retroflexus and Chenopodium album. Participation of other species by year ranged from 0.0% to 1.8%. Seed germination varied from 75 to 88%, the average was 83%. The number of abnormal seedlings was 4%, while the average number of ungerminated seeds was 13%.

Genetic effects on seed quality in diallel crosses of popcorn

The failure to obtain the ideal stand is one of the causes of decreased crop yields, in this sense it is important to investigate the genetic effects related to seed quality. The aim of this study was to measure the general combining ability (GCA), the specific combining ability (SCA) and the reciprocal effects (RE) for popcorn seed quality in addition to evaluate the association between germination and vigor tests with field emergencein order to identify hybrids with better germination and vigour. Ten inbred lines were evaluated using a complete diallel cross with reciprocals. Seed quality was measured by germination tests (GT) and by modified cold vigour tests (MCV). In the GT, the numbers of strong normal seedlings (SNS), weak normal (WNS), abnormal (AS) and ungerminated seeds (UGS) were counted. In the MCV, the numbers of normal seedlings (NPC), abnormal (ASC) and ungerminated seeds (UGSC) were counted, and the plants' dry matter (DM) was measured. Analysis of variance for GCA, SCA and RE were significant for all variables. The quadratic components for SCA were higher than those for GCA for the SNS, AS, UGS, ASC and UGSC traits, which indicates higher significance for the non-additive effects. The most favourable GCA estimates, were found in lines P3 and L70. The best hybrids were P1xL70, P3xP6 and P8xL70. The RE results showed that L70 and P3 should be used as the female parent in the P1xL70 and P3xP6 hybrid crosses, respectively. The MCV was the test that was most strongly correlated with field emergence, with a magnitude of 0.667.

Secondary dormancy of seeds in relation to the Bromus tectorum-Pyrenophora semeniperda pathosystem

Bromus tectorum is a highly invasive annual grass. The fungal pathogen Pyrenophora semeniperda can kill a large fraction of B. tectorum seeds. Outcomes in this pathosystem are often determined by the speed of seed germination. In this paper we extend previous efforts to describe the pathosystem by characterising secondary dormancy acquisition of B. tectorum. In the laboratory approximately 80% of seeds incubated at &amp;ndash;1.0 MPa became dormant. In the field, seeds were placed in the seed bank in late autumn, retrieved monthly and dormancy status determined. The field study confirmed the laboratory results; ungerminated seeds became increasingly dormant. Our data suggest that secondary dormancy is much more likely to occur at xeric sites.

ESTs analysis reveals putative genes involved in symbiotic seed germination in Dendrobium officinale.

Dendrobium officinale (Orchidaceae) is one of the world’s most endangered plants with great medicinal value. In nature, D . officinale seeds must establish symbiotic relationships with fungi to germinate. However, the molecular events involved in the interaction between fungus and plant during this process are poorly understood. To isolate the genes involved in symbiotic germination, a suppression subtractive hybridization (SSH) cDNA library of symbiotically germinated D . officinale seeds was constructed. From this library, 1437 expressed sequence tags (ESTs) were clustered to 1074 Unigenes (including 902 singletons and 172 contigs), which were searched against the NCBI non-redundant (NR) protein database (E-value cutoff, e-5). Based on sequence similarity with known proteins, 579 differentially expressed genes in D . officinale were identified and classified into different functional categories by Gene Ontology (GO), Clusters of orthologous Groups of proteins (COGs) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The expression levels of 15 selected genes emblematic of symbiotic germination were confirmed via real-time quantitative PCR. These genes were classified into various categories, including defense and stress response, metabolism, transcriptional regulation, transport process and signal transduction pathways. All transcripts were upregulated in the symbiotically germinated seeds (SGS). The functions of these genes in symbiotic germination were predicted. Furthermore, two fungus-induced calcium-dependent protein kinases (CDPKs), which were upregulated 6.76- and 26.69-fold in SGS compared with un-germinated seeds (UGS), were cloned from D . officinale and characterized for the first time. This study provides the first global overview of genes putatively involved in D . officinale symbiotic seed germination and provides a foundation for further functional research regarding symbiotic relationships in orchids.

Changes in Lipid Content of Ungerminated and Germinated Seeds of &lt;i&gt;Capsicum Annuum&lt;/i&gt; L. and &lt;i&gt;Aframonum Melequeta&lt;/i&gt; K. Schum

The lipid contents of ungerminated and germinated seeds of Capsicunl srmuurn and Atremomum melequeta were studied to determine the level of total lipids, neutral lipids and phospholipids. The percentage germination of Capsicum annuum and Aframomum melequeta were 95+2.0% and 90+1.5% respectively. The total lipids of ungerminated and genninated seeds of C. annuum were 37.50% and 26.44% respectively. The neutral lipid, glycolipid and phospholipids of ungerminated seeds of C .annuum were 30.75%, 2.3% and 4.45% respectively while that of qerrnlnated seeds of C annuum was neutral lipid 21.65%, glycolipid 1.27% and phospholipids 3.49%. The neutral lipid, glycolipid and phospholipids of ungerminated seeds of A. melequeta were 67.72%, 3.75% and 13.68% respectively while that of germinated seeds were neutral lipid 50.0%, glycolipid 2.38% and phospholipids 10.12%. Neutral lipids were the major components while glycolipids and phospholipids formed the minor components. The colour of C. annuum lipid extracted was brownish and solid at room temperature while that of A. melequeta was also brownish but oily at room temperature. Both lipids were aromatic. Thin layer chromatographic analysis revealed three lipid classes which were oleic acid, palmitic acid and cholesterol. The seed lipids of C. annuum and A. melequeta can be used as edible oil and for industrial purposes. KEYWORD: Lipid, Capsicum annuum and Aframomum melequeta

The effects of litter accumulation through succession on seed bank formation for small‐ and large‐seeded species

AbstractQuestionsHow does litter accumulation through succession affect secondary seed dispersal and buried seed viability and consequently control seed bank formation for small‐ and large‐seeded species?LocationA post‐mined peatland in northern Japan (45°06′ N, 141°42′ E) where the chronological sequence of plant community succession is known.MethodsThe movements of seeds after reaching the ground surface and the availability of viable seeds potentially contributing to seed bank formation at various depths were experimentally investigated for 1 yr in four species that produce different‐sized seeds: Drosera rotundifolia (seed mass 0.01 mg), Lobelia sessilifolia (0.25 mg), Rhynchospora alba (0.87 mg) and Moliniopsis japonica (1.82 mg). The experiments were conducted in three successional stages with 0‐, 4‐ and 9‐cm thick litter layers.ResultsSeed emigration decreased and seed retention increased with an increase in litter thickness. Large seeds were retained within the litter throughout the experimental period, and fewer seeds were buried in peat compared to small seeds trapped by thick litter, which had shifted downward by the following early spring. Litter contributed to increasing the number of viable and ungerminated seeds. The number of viable seeds for all species was nearly zero on the bare peat surface. The numbers of viable seeds on and beneath the peat surface increased with increases in litter cover thickness.ConclusionsThe patterns of secondary seed dispersal and the availability of viable seeds were altered by litter accumulation through the progress of succession. Moreover, the effects of litter on seeds varied among species for which seed size differed. Overall, our results suggest that temporal changes in litter thickness through the progress of succession can play an important role in seed bank formation, which has potential impacts on the long‐term dynamics of plant populations and the whole community.