Embryos Of Seeds Research Articles

Proteomic analysis reveals differential accumulation of small heat shock proteins and late embryogenesis abundant proteins between ABA-deficient mutant vp5 seeds and wild-type Vp5 seeds in maize.

ABA is a major plant hormone that plays important roles during many phases of plant life cycle, including seed development, maturity and dormancy, and especially the acquisition of desiccation tolerance. Understanding of the molecular basis of ABA-mediated plant response to stress is of interest not only in basic research on plant adaptation but also in applied research on plant productivity. Maize mutant viviparous-5 (vp5), deficient in ABA biosynthesis in seeds, is a useful material for studying ABA-mediated response in maize. Due to carotenoid deficiency, vp5 endosperm is white, compared to yellow Vp5 endosperm. However, the background difference at proteome level between vp5 and Vp5 seeds is unclear. This study aimed to characterize proteome alterations of maize vp5 seeds and to identify ABA-dependent proteins during seed maturation. We compared the embryo and endosperm proteomes of vp5 and Vp5 seeds by gel-based proteomics. Up to 46 protein spots, most in embryos, were found to be differentially accumulated between vp5 and Vp5. The identified proteins included small heat shock proteins (sHSPs), late embryogenesis abundant (LEA) proteins, stress proteins, storage proteins and enzymes among others. However, EMB564, the most abundant LEA protein in maize embryo, accumulated in comparable levels between vp5 and Vp5 embryos, which contrasted to previously characterized, greatly lowered expression of emb564 mRNA in vp5 embryos. Moreover, LEA proteins and sHSPs displayed differential accumulations in vp5 embryos: six out of eight identified LEA proteins decreased while nine sHSPs increased in abundance. Finally, we discussed the possible causes of global proteome alterations, especially the observed differential accumulation of identified LEA proteins and sHSPs in vp5 embryos. The data derived from this study provides new insight into ABA-dependent proteins and ABA-mediated response during maize seed maturation.

Phytochemical Profile and Biological Activity of Nelumbo nucifera.

Nelumbo nucifera Gaertn. (Nymphaeaceae) is a potential aquatic crop grown and consumed throughout Asia. All parts of N. nucifera have been used for various medicinal purposes in various systems of medicine including folk medicines, Ayurveda, Chinese traditional medicine, and oriental medicine. Many chemical constituents have been isolated till the date. However, the bioactive constituents of lotus are mainly alkaloids and flavonoids. Traditionally, the whole plant of lotus was used as astringent, emollient, and diuretic. It was used in the treatment of diarrhea, tissue inflammation, and homeostasis. The rhizome extract was used as antidiabetic and anti-inflammatory properties due to the presence of asteroidal triterpenoid. Leaves were used as an effective drug for hematemesis, epistaxis, hemoptysis, hematuria, and metrorrhagia. Flowers were used to treat diarrhea, cholera, fever, and hyperdipsia. In traditional medicine practice, seeds are used in the treatment of tissue inflammation, cancer and skin diseases, leprosy, and poison antidote. Embryo of lotus seeds is used in traditional Chinese medicine as Lian Zi Xin, which primarily helps to overcome nervous disorders, insomnia, and cardiovascular diseases (hypertension and arrhythmia). Nutritional value of lotus is as important as pharmaceutical value. These days' different parts of lotus have been consumed as functional foods. Thus, lotus can be regarded as a potential nutraceutical source.

Induced of Salt Tolerance Wheat (Triticum aestivum L.) Mutants with Gamma Radiation and Determining Molecular Analysis by ISSR

As result of world population's rapid increase, avaliable agricultural lands became insufficient to meet nutritional needs and it became quite important to conduct studies on increasing productivity of plants per unit area. Especially, in recent years, it's aimed to produce plants which are more resistant to abiotic stress factors and have high nutritional value, productivity.In this study, it's aimed to induce salt stress tolerant mutants of wheat (Triticum aestivum L.) which is one the most important agricultural products in the world, by gamma radiation. For this purpose, appropriate mutation doses determined by irradiating Guadalupe wheat seeds with various gamma radiation doses and then seeds irradiated by mutation dose and control planted to experimental land for 3 years to generate M2 and M3 generations.Mature embryos of seeds belonging to M3 generation experimental group which were harvested from experimental land. Then we have been focusing on selecting putative salt tolerant mutant under tissue culture conditions and characterizing them using ISSR markers.

The expression and roles of parent-of-origin genes in early embryogenesis of angiosperms.

Uniparental transcripts during embryogenesis may arise due to gamete delivery during fertilization or genomic imprinting. Such transcripts have been found in a number of plant species and appear critical for the early development of embryo or endosperm in seeds. Although the regulatory expression mechanism and function of these genes in embryogenesis require further elucidation, recent studies suggest stage-specific and highly dynamic features that might be essential for critical developmental events such as zygotic division and cell fate determination during embryogenesis. Here, we summarize the current work in this field and discuss future research directions.

Induction of tolerance to desiccation and to subzero temperatures in embryos of recalcitrant seeds of inga

Drying, widely used for storing orthodox seeds for prolonged periods, cannot be applied to recalcitrant seeds, which are sensitive to desiccation. Thus, inclusion of species with recalcitrant seeds, like inga, in reforestation programs or even for commercial use has been hindered by the lack of technology that would allow storage of these seeds. The remaining option, cryopreservation, is a method of high cost that requires a high level of technology. Knowledge of the processes involved in sensitivity to desiccation continues to be a great challenge for the seed sector. The aim of this study was to analyze the effects of osmotic treatments on tolerance to desiccation and storage capacity of recalcitrant seeds of inga. Embryos were subjected to osmotic stresses with PEG solution and subjected to progressive drying processes. In another experiment, the effects of these solutions on embryo conservation during storage were analyzed. From the results, it may be concluded that incubation of embryos in a solution with -2.0 MPa increases their tolerance to desiccation.

Tissue-specific hormonal profiling during dormancy release in macaw palm seeds.

Little is known about the control exerted by hormones in specific tissues during germination and post-germinative development in monocot seeds, whose embryos have complex structures and can remain dormant for long periods of time. Here the tissue-specific hormonal profile of macaw palm (Acrocomia aculeata) seeds overcoming dormancy and seedling during initial development was examined. Endogenous hormonal concentrations were determined in the cotyledonary petiole, haustorium, operculum, endosperm adjacent to the embryo and peripheral endosperm of dry dormant seeds, imbibed seeds trapped in phase I of germination, and germinating (phase 2 and phase 3) seeds 2, 5, 10 and 15 days after sowing. Evaluations were performed on seeds treated for overcoming dormancy by removal of the operculum and by immersion in a gibberellic acid (GA3 ) solution. Removal of the operculum effectively helped in overcoming dormancy, which was associated with the synthesis of active gibberellins (GAs) and cytokinins (CKs), as well as reductions of abscisic acid (ABA) in the cotyledonary petiole. In imbibed seeds trapped in phase I of germination, exogenous GA3 caused an increase in active GAs in the cotyledonary petiole and operculum and reduction in ABA in the operculum. Initial seedling development was associated with increases in the CK/auxin ratio in the haustorium and GA levels in the endosperm which is possibly related to the mobilization of metabolic reserves. Increases in salicylic acid (SA) and jasmonic acid (JA) concentrations were associated with the development of the vegetative axis. Hormones play a crucial tissue-specific role in the control of dormancy, germination and initial development of seedlings in macaw palm, including a central role not only for GAs and ABA, but also for CKs and other hormones.

Variation in the seed progeny of smooth brome grass, Bromus inermis Leyss., under conditions of chronic irradiation in the zone of the Eastern Ural Radioactive Trace

Long-term studies have been performed on the seed progeny of B. inermis from test plots established along the radioactive contamination gradient in the zone of the Eastern Ural Radioactive Trace (EURT), where dose loads on maternal plants and embryos of seeds from chronically irradiated cenopopulations (with natural background radiation taken into account) exceed control values by factors of 2 to 107. Interannual and individual variation in the viability, mutability, and radiosensitivity of the seed progeny has been revealed. Against the background of high interpopulation variation in test parameters in the EURT zone, weather conditions appear to have no significant effect on seed quality, while such effects are appreciable in background cenopopulations. It has been shown that a positive correlation exist between the initial viability of the seed progeny and their radioresistance. Chronic irradiation in a wide dose range induces an increased frequency of different mutations and morphological modifications. The contents of low-molecular antioxidants in seedlings from impact cenopopulations proved to be higher than in the background sample. The results obtained characterize the potential of protective and restorative mechanisms acquired in the course of evolution that allow plants to survive in the changing environment under exposure to technogenic stress.

Phosphate transporter OsPht1;8 in rice plays an important role in phosphorus redistribution from source to sink organs and allocation between embryo and endosperm of seeds

Phosphorus (P) redistribution from source to sink organs within plant is required for optimizing growth and development under P deficient condition. In this study, we knocked down expression of a phosphate transporter gene OsPht1;8 (OsPT8) selectively in shoot and/or in seed endosperm by RNA-interference using RISBZ1 and GluB-1 promoter (designate these transgenic lines as SSRi and EnSRi), respectively, to characterize the role of OsPT8 in P redistribution of rice. In comparison to wild type (WT) and EnSRi lines, SSRi lines under P deficient condition accumulated more P in old blades and less P in young blades, corresponding to attenuated and enriched transcripts of P-responsive genes in old and young blades, respectively. The ratio of total P in young blades to that in old blades decreased from 2.6 for WT to 0.9–1.2 for SSRi lines. During the grain-filling stage, relative to WT, SSRi lines showed the substantial decrease of total P content in both endosperm and embryo, while EnSRi lines showed 40–50% decrease of total P content in embryo but similar P content in endosperm. Taken together, our results demonstrate that OsPT8 plays a critical role in redistribution of P from source to sink organs and P homeostasis in seeds of rice.

Compatibility of inter-specific crosses between Capsicum chinense Jacq. and Capsicum baccatum L. at different fertilization stages

Interspecific barriers have been investigated in a direct and reciprocal cross between Capsicum chinense Jacq. (‘cv. C’) and Capsicum baccatum L. (‘cv. B’). Compatibilities of interspecific cross were examined at three different growth stages, i.e. pre-pollination, pre-fertilization and post-fertilization. At pre-pollination, higher pollen germination was obtained when the pollens were collected on the blooming day and germinated immediately without storage. In addition, ‘cv. C’ gave higher percentage germination than ‘cv. B’ under most combinations of three factors, i.e. flowering development stages, pollen incubation periods and different concentrations of sucrose. In both direct and reciprocal crosses, the pollen tubes were able to grow and reached the ovules within 48h indicating that there were no pre-fertilization barriers. For compatibility at post-fertilization, microscopic investigation of embryo development revealed normal features of embryo during various developmental stages in ‘C-selfed’, ‘B-selfed’ and ‘B/C’ resulting in mature healthy seeds. However, the ‘C/B’ embryos began to show abnormal growth patterns at the globular stage resulting in abnormal embryos in mature seeds. In conclusion, successful interspecific hybridization between C. chinense Jacq. and C. baccatum L. can be performed using the latter as the female parent.

MYB118 represses endosperm maturation in seeds of Arabidopsis.

In the exalbuminous species Arabidopsis thaliana, seed maturation is accompanied by the deposition of oil and storage proteins and the reduction of the endosperm to one cell layer. Here, we consider reserve partitioning between embryo and endosperm compartments. The pattern of deposition, final amount, and composition of these reserves differ between the two compartments, with the embryo representing the principal storage tissue in mature seeds. Complex regulatory mechanisms are known to prevent activation of maturation-related programs during embryo morphogenesis and, later, during vegetative growth. Here, we describe a regulator that represses the expression of maturation-related genes during maturation within the endosperm. MYB118 is transcriptionally induced in the maturing endosperm, and seeds of myb118 mutants exhibit an endosperm-specific derepression of maturation-related genes associated with a partial relocation of storage compounds from the embryo to the endosperm. Moreover, MYB118 activates endosperm-induced genes through the recognition of TAACGG elements. These results demonstrate that the differential partitioning of reserves between the embryo and endosperm in exalbuminous Arabidopsis seeds does not only result from developmental programs that establish the embryo as the preponderant tissue within seeds. This differential partitioning is also regulated by MYB118, which regulates the biosynthesis of reserves at the spatial level during maturation.

Intermediate complex morphophysiological dormancy in seeds of the cold desert sand dune geophyte Eremurus anisopterus (Xanthorrhoeaceae; Liliaceae s.l.).

Little is known about morphological (MD) or morphophysiological (MPD) dormancy in cold desert species and in particular those in Liliaceae sensu lato, an important floristic element in the cold deserts of Central Asia with underdeveloped embyos. The primary aim of this study was to determine if seeds of the cold desert liliaceous perennial ephemeral Eremurus anisopterus has MD or MPD, and, if it is MPD, then at what level. Embryo growth and germination was monitored in seeds subjected to natural and simulated natural temperature regimes and the effects of after-ripening and GA3 on dormancy break were tested. In addition, the temperature requirements for embryo growth and dormancy break were investigated. At the time of seed dispersal in summer, the embryo length:seed length (E:S) ratio was 0·73, but it increased to 0·87 before germination. Fresh seeds did not germinate during 1 month of incubation in either light or darkness over a range of temperatures. Thus, seeds have MPD, and, after >12 weeks incubation at 5/2 °C, both embryo growth and germination occurred, showing that they have a complex level of MPD. Since both after-ripening and GA3 increase the germination percentage, seeds have intermediate complex MPD. Embryos in after-ripened seeds of E. anisopterus can grow at low temperatures in late autumn, but if the soil is dry in autumn then growth is delayed until snowmelt wets the soil in early spring. The ecological advantage of embryo growth phenology is that seeds can germinate at a time (spring) when sand moisture conditions in the desert are suitable for seedling establishment.

Enzyme polymorphism of an antioxidant system in chronically irradiated Scots pine populations

This paper studies enzyme polymorphism of the antioxidant system in endosperms and embryos of Scots pine seeds from the areas of the Bryansk region that have been contaminated by the Chernobyl nuclear disaster. The mutation frequency in isozyme loci, the effective number of alleles, and the heterozygosity increase with the increasing dose absorbed in reproductive organs of pine. The experimental populations demonstrate the increased intrapopulation diversity and frequency of occurrence of rare alleles. The genetic differentiation of the studied populations is caused by the increased frequency of occurrence of rare alleles.

A comprehensive view of epicotyl dormancy in Viburnumfurcatum: combining field studies with laboratory studies using temperature sequences

AbstractSeeds with epicotyl dormancy reside in soil up to 15 months (or longer), being exposed to a sequence of temperatures, before seedlings completely emerge (i.e. with both roots and shoots). Heretofore, few studies have examined precise temperatures, especially in sequences, for promotion of radicle and cotyledon emergence and how they relate to environmental cues in nature. Viburnum is the best known genus to exhibit epicotyl dormancy and, as such, we investigated the Japanese V.furcatum, hypothesizing a similar kind and level of dormancy. The underdeveloped embryos in mature seeds in October were spatulate shaped, unlike those in other Viburnum species, and they elongated from late June to August of the following year. Radicles emerged after embryo growth until mid-October, followed by cotyledons from mid-April to mid-May. Temperatures required for embryo growth, radicle and cotyledon emergence in the laboratory approximated closely those in the field. Embryo elongation and radicle emergence occurred at warm temperature regimes, and gibberellic acid (GA3) did not substitute for this warm temperature requirements. Following a 120-d cold stratification of seeds with an emerged radicle, shoots emerged from seeds at 10, 15, 15/5, 20/10 and 25/15°C. We identified that seeds of V. furcatum have deep simple epicotyl morphophysiological dormancy like the majority of other Viburnum species. For propagation of the species from seeds, the nearly 2-year period for seedling emergence could be shortened to 8 months: start fresh seeds at 25/15°C (60 d) and then move them through a sequence of 15/5°C (30 d) → 0°C (120 d) → 20/10°C (30 d).

Genetic diversity in Scots pine populations along a radiation exposure gradient

Polymorphisms of antioxidant enzymes were studied in the endosperm and embryos of seeds from Scots pine populations inhabiting sites in the Bryansk region of Russia radioactively contaminated as a result of the Chernobyl accident. Chronic radiation exposure at dose rates from 0.8μGy/h led to a significant increase in the rate of enzymatic loci mutations. The main parameters of genetic variability of the affected Scots pine populations had considerably higher values than those from the reference site. Changes in the genetic makeup of Scots pine populations were observed at dose rates greater than 10.4μGy/h. However, the higher mutation rate had no effect on the activities of antioxidant enzymes.

Amylolytic activities and starch reserve mobilization during the germination of quinoa

Quinoa (Chenopodium quinoa) is a dicotyledonous plant producing perispermic seeds that is increasingly popular in the Western world due to its nutritional value. Germination can be used in food processing to alter the sensory, nutritional and functional properties of grains, and the increased enzyme activities may have beneficial influences in food applications. Knowledge about the germination of perispermic seeds is scarce. In this study, the development of amylolytic activities and subsequent changes in sugar profiles and starch content were followed in quinoa over a period of 72 h. The seeds germinated rapidly with radicle protrusion occurring 8 h after imbibition, when the seeds had reached a moisture content of 44 %. A low level of α-amylase activity (determined at pH 5.2 using blocked ρ-nitrophenyl-maltoheptaoside as substrate) was present in the embryo of non-germinating seeds, but emerged in the perisperm only after 24 h, followed by a sharp increase in activity in both tissues. The accumulation of glucose and fructose (determined with high pressure liquid chromatography) and the decrease in starch content (determined with an enzymatic assay) were observed after 24 and 36 h, respectively, indicating the onset of starch reserve mobilization. Overall, the levels of amylolytic activities remained very low compared with traditional malting cereals, suggesting the unsuitability of quinoa as a source of amylases in food applications. Scanning electron microscopy, used to visualize changes in starch granule morphology, showed mainly exocorrosion, suggesting a homogenous structure of the outer layers of quinoa starch.

Relationship between initiation of embryogenic suspensor mass (ESM) and zygotic embryo development in Pinus densiflora

To initiate embryogenic suspensor mass (ESM) in Pinus densiflora, immature seeds were collected on dates from 31 May to 20 July in 2004, 2005 and 2006, and their embryo developmental stages were checked. In materials from 2004, the highest frequency (0.88%) of ESM initiation was obtained with explants collected on 28 June, and the seeds contained zygotic embryos in the proembryo stage (100%). The highest ESM initiation frequencies were 0.88% (28 June 2004, Suwon), 1.4% (1 July 2005, Suwon), 2.31% (1 July 2005, Anmyeondo) and 0.91% (1 July 2006, Suwon) and all embryos were at the proembryo stage, regardless of seed collection year (2004, 2005 or 2006) or collection location (Suwon or Anmyeondo). Histological analysis from zygotic embryos (proembryos) of seeds, which were harvested at various times or locations, revealed no significant morphological differences at various developmental stages. These results show that seed collection time could be critical for obtaining the higher rate of ESM initiation.

Comprehensive Germination Quality Evaluation of Bupleurum chinense Seeds of Different Maturities from Qingchuan County with the Topsis Approach

Topsis approach,a multi-indexes evaluation method,can be used for comprehensive comparison of objects. This approach was used to investigate Bupleurum chinense seeds ' germination quality of different maturities from Qingchuan County. The anatomic structure of the seeds were observed with paraffin method,and their appearance was analyzed,and then the content of soluble sugar and soluble protein,thousand kernel weight(TKW),as well as the seeds' germination indexes were determined. Seeds of different maturities differed in appearance, TKW, bibulous performance, germination characteristics, nutrients content and anatomical structure. After being post-harvested for 4 weeks,the embryo of seeds of different maturities can be developed into a similar level; with the increasing of the seeds' maturity,seeds' dry weight increased,seedling quality enhanced. Being analyzed with Topsis approach, the green seeds, which possessed a good germination characteristic,were recognized to be the superior group,followed by the yellow,the brown and the black. Black seeds' TKW and embryo rate were greater than the others,but their germination rate was low,these may attribute to the highest contents of coumarins,which both inhabited the embryo growing and germination. Green seeds' comprehensive quality is better than the others;followed by the yellow,and then the brown and the black. In terms of agricultural technique,it is better to harvest the seeds in time,hereby obtaining a low proportion of overripen seeds,which are inferior.

Physiology of Desiccation-Sensitive (Recalcitrant) Seeds and the Implications for Cryopreservation

Desiccation-tolerant (orthodox) seeds can survive in the dry state for considerable periods and so can be stored successfully at low water content and subzero temperatures. Orthodox seeds possess a variety of protective processes and mechanisms that confer desiccation tolerance, important among them being metabolic shutdown and intracellular dedifferentiation. In contrast, desiccation-sensitive (recalcitrant) seeds cannot tolerate water loss and so cannot be stored using conventional seed bank conditions. Particularly with respect to storage, recalcitrant seeds do not undergo intracellular dedifferentiation nor any significant metabolic shutdown. Embryos of recalcitrant seeds remain metabolically active, with little or no reduction in extent of the extensive intracellular membranes. At the water content at which they are shed, with the ongoing metabolism in recalcitrant seeds, developmental phenomena grade imperceptibly into those associated with germination. Thus, recalcitrant seeds can be stored intact ...

Metabolism of aged seeds. Changes in rye embryo polyribosomes during seed aging

Germination, total dehydrogenase activity, ribosomal proteins and ribonucleic acids of embryos obtained from winter rye harvested in different years and of distinctly differing viability were studied. Diminishing viability was accompanied by declines in the amount of ribosome-bound mRNA and a drop in the intensity of its synthesis during germination. Electrophoretic analysis of control embryo (fully viable) ribosome proteins revealed 55 different bands: 10 acidic and 45 basic. The embryos of aged seeds had 43 different bands of which 8 were acidic, 35 basic and almost all of which had an altered electrophoretic mobility as compared with the control sample. As aging progressed, the percentages of lysine, histidine and arginine increased while those of tyrosine, methionine, proline and serine decreased.

Biochemical changes in embryos of dormant and after-ripened seeds of Caryophyllaceae

The dependence of <sup>14</sup>C-leucine, <sup>3</sup>H-uracil and <sup>3</sup>H-thymidine incorporation in dormat and after-ripened seeds is demonstrated and discussed together with other metabolic events. Striking differences in dependence on the physiological state in both types of seeds could only be found in the axes of after-ripened seeds.