Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Germination”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed2005

Effect of germination temperature on characteristics of phytase production from barley.

The effects of germination temperature on the growth of barley seedlings for phytase production were studied at 15, 20 and 25 degrees C for 6-10 days. The growth rate of the barley seedlings was increased as the germination temperature was increased. The initial rate of total protein production was closely coupled to that of the barley growth, and the rate of total protein production tended to increase as the germination temperature was increased. SDS-PAGE analysis of total protein from the barley seedlings showed time-dependent appearance and disappearance of protein bands. Although no significant phytase activity was detected at zero time of germination, a significant increase in phytase activity up to 7.9-fold occurred during the first several days of germination then decreased. Phosphate production (viz. phytate degradation) in the barley seedlings occurred rapidly at the beginning of germination. However, the rate of production continued to decrease with further germination. A time lag of about 1-2 days between the rate of total protein production and that of phytase production was observed. Unlike the extent of total protein production, that of phytase production was similar irrespective of germination temperature. Partial purification of a crude enzyme extract by hydrophobic interaction chromatography resulted in two phytase fractions (PI and PII). Zymogram analysis demonstrated that PI had two bands with molecular masses of about 66 and 123 kDa while PII had one band corresponding to a molecular mass of about 96 kDa. The optimal temperature for PI was found to be 55 degrees C, while it was 50 degrees C for PII. The enzyme fraction PI had a pH optimum at 6.0, whereas the optimum pH for PII was found to be 5.0. Addition of 0.1% (v/v) Tween 80 was found to increase enzyme activity significantly (i.e., 167% for PI and 137% for PII). Phytate in cereals including barley, rice, corn and soybean degraded effectively by the treatment of the barley phytases.

6-Phytase↗
PubMed2004

Assessment of application-rate dependent effects of a long-term fire retardant chemical (Fire Trol 934) on Typha domingensis germination.

Although long-term fire retardants (LTR) gain increasingly acceptance as effective tools for wildfire management, recent studies indicate their potential harmfulness in the environment, especially in aquatic ecosystems. This study comprises a first laboratory impact assessment of LTR action in temporal Mediterranean wetlands, using seed germination of Typha domingensis as indicator of impact. Our aim was to identify application rates upon which seed germination could be significantly affected. We tested for low (1 l m(-2)) and high (3 l m(-2)) application rates of Fire Trol 934 which are recommended by the manufacturers as a function of fuel characteristics. In addition, we simulated the impact of a higher application rate of 5 l m(-2) because inhomogeneous dispersal of the LTR during fire control and prevention operations can result in locally elevated applications. Results of a microcosm experiment indicate that application rates of 1 or 3 l m(-2) can impact Typha germination rates in the short-term via indirect LTR-mediated effects on water quality, which suppressed necessary cues for germination. However, a subsequent experiment with Petri dishes, using seeds isolated from the LTR treated sediments did not show significantly different germination rates between the control and the treatments with application rates of 1 or 3 l m(-2). This suggests that retardant pre-application germination success could be recovered in nature once the retardant is eliminated. By contrast, seeds almost completely failed to germinate in the microcosm experiment and the subsequent Petri dish essay when an application rate of 5 l m(-2) was used. This suggests a critical level upon which Typha seed germination may be perpetually limited. Research should be extended to other plant species to provide fire managers with guidelines for environmentally safe use of LTR in the Mediterranean region.

Dose-Response Relationship, Drug↗
PubMed2004

cAMP regulation of "pathogenic" and "saprophytic" fungal spore germination.

We report on the elucidation of two separate pathways of spore germination in a plant pathogenic fungus Colletotrichum gloeosporioides f. sp. aeschynomene. Conidia of the fungus can germinate either from one side or from both sides, depending on external conditions. In shake culture that includes an extract made up from fresh peas, the unicellular conidium divides and one of the two cells develops a germ tube. On a solid surface this germ tube differentiates an appressorium. In rich medium without pea extract, germination is highly similar to Aspergillus spore germination: the conidium swells, forms a single germ tube and then divides and forms a second germ tube. Conidia that germinate in a rich medium do not form appressoria even on a solid surface and are non-pathogenic. In rich medium, cAMP stimulates germination in rich liquid cultures and induces appressoria formation on a hard surface. In pea extract cAMP induces swelling and formation of irregular germ tubes and appressoria. Our results suggest that plant surface signals induce pathogenic-specific spore germination in a cAMP-independent manner. cAMP is required for saprophytic germination and for appressorium formation.

Colletotrichum↗
PubMed2004

IAA production during germination of Orobanche spp. seeds.

Broomrapes (Orobanche spp.) are parasitic plants, whose growth and development fully depend on the nutritional connection established between the parasite and the roots of the respective host plant. Phytohormones are known to play a role in establishing the specific Orobanche-host plant interaction. The first step in the interaction is seed germination triggered by a germination stimulant secreted by the host-plant roots. We quantified indole-3-acetic acid (IAA) and abscisic acid (ABA) during the seed germination of tobacco broomrape (Orobanche ramosa) and sunflower broomrape (O. cumana). IAA was mainly released from Orobanche seeds in host-parasite interactions as compared to non-host-parasite interactions. Moreover, germinating seeds of O. ramosa released IAA as early as 24 h after the seeds were exposed to the germination stimulant, even before development of the germ tube. ABA levels remained unchanged during the germination of the parasites' seeds. The results presented here show that IAA production is probably part of a mechanism triggering germination upon the induction by the host factor, thus resulting in seed germination.

Abscisic Acid↗
PubMed2005

Nutritional assessment of raw and germinated pea (Pisum sativum L.) protein and carbohydrate by in vitro and in vivo techniques.

OBJECTIVE: We assessed the effect of germinating Pisum sativum L. variant Arvense cv. Esla for 3 and 6 d in darkness on the chemical composition and nutritive utilization of protein and carbohydrates. METHODS: Nutritional assessment of protein and carbohydrates was based on chemical analysis of raw and germinated pea flours and in vitro and in vivo rat balance methodologies. RESULTS: Germination caused a notable decrease in alpha-galactoside content and significant increases in sucrose, glucose, and fructose. The ratio of available starch to total starch increased as a consequence of processing. The content of vitamin B2 increased significantly, whereas no significant change was observed in vitamin B1 content in germinated peas. Protein digestibility assessed with an in vivo technique (apparent digestibility coefficient) or as the percentage of dialyzable nitrogen increased significantly as a result of germination in contrast to what was observed with the in vitro pH-drop methodology. Daily food intake, nitrogen absorption and balance, percentage of retained versus absorbed nitrogen, protein efficiency ratio, and the index of available carbohydrates were significantly improved by germination for 3 d and significantly decreased by germination for 6 d. CONCLUSIONS: Germination of pea seeds for 3 d significantly improves palatability of these seeds and the nutritive utilization of protein and carbohydrates.

Animal Nutritional Physiological Phenomena↗
PubMed1998

A comparative study of germinal center: fowls and mammals.

The mammalian germinal center is organized into a dark zone containing proliferating centroblasts and a light zone filled with nondividing B cells (called centrocytes), follicular dendritic cells and a few scattered T cells. We clarified these two zones in the chicken germinal center with immunohistology. Proliferating cells and immunoglobulin negative cells were detected in the circumference ring of the chicken germinal center. The central part of the chicken germinal center contained B cells expressing immunoglobulin, follicular dendritic cells and a few T cells. Most of the B cells in the central part of the chicken germinal center did not enter into the S phase. These results suggest that the chicken germinal center is also organized into the dark zone (the circumference ring of germinal center) and the light zone (the central part of germinal center).

Animals↗
PubMed2003

Oxygen requirement of germinating flax seeds.

Plant experiments in earth orbit are typically prepared on the ground and germinated in orbit to study gravity effects on the developing seedlings. Germination requires the breakdown of storage compounds, and this metabolism depends upon respiration, making oxygen one of the limiting factors in seed germination. In microgravity lack of run-off of excess water requires careful testing of water dispensation and oxygen availability. In preparation for a shuttle experiment (MICRO on STS-107) we studied germination and growth of flax (Linum usitatissimum L.) seedlings in the developed hardware (Magnetic Field Chamber, MFC). We tested between four to 32 seeds per chamber (air volume=14 mL) and after 36 h measured the root length. At 90 microliters O2 per seed (32 seeds/chamber), the germination decreased from 94 to 69%, and the root length was reduced by 20%, compared to 8 seeds per chamber. Based on the percent germination and root length obtained in controlled gas mixtures between 3.6 and 21.6% O2 we determined the lower limit of reliable germination to be 10 vol. % O2 at atmospheric pressure. Although the oxygen available in the MFC's can support the intended number of seeds, the data show that seed storage and microgravity-related limitations may reduce germination.

Dose-Response Relationship, Drug↗
PubMed2003

Proteases associated with programmed cell death of megagametophyte cells after germination of white spruce (Picea glauca) seeds.

During post-germinative seedling growth, the major storage organ of the white spruce (Picea glauca) seed, the megagametophyte, undergoes programmed cell death (PCD). Protease activities in megagametophyte cells that arise post-germinatively were investigated. The accumulation of protease activities can be divided into two phases: the first phase correlated with degradation of storage proteins while the second phase was temporally associated with cell death, although some of the early proteases were also active during the later phase. Proteases induced during PCD were mainly serine and cysteine proteases. One of the PCD-associated cysteine proteases had homology to Cys-EP, a PCD-related cysteine protease of the castor bean endosperm. Transcripts encoding a Cys-EP-related protein were not present in megagametophytes when seeds were imbibed, nor were they present during germination and early post-germinative growth (radicle length ca. 2-5 mm). At a later post-germinative stage (i.e when the seed's radicle was ca. 15 mm), the Cys-EP-related transcripts (ca. 1.3 kb) became abundant and, at this time, the 48 kDa proform of the enzyme first appeared. The mature form of the Cys-EP (ca. 38 kDa) was predominant at a very late stage of post-germinative growth. Immunocytochemistry showed that the Cys-EP-related protein was localized to spherical organelles (ca. 2 microm) that may be equivalent to the 'ricinosomes' of castor bean endosperm cells. Caspase-like protease (CLP) activities were first detected 3 days after germination with the caspase-specific substrate Ac-DEVD-AMC; maximum activities occurred when the seed's radicle was ca. 20-25 mm. When germinated seeds were treated with a caspase-3 inhibitor, both the peak of CLP activities and the death of megagametophyte cells were delayed. We propose that the Cys-EP-related protein and CLP activity are involved in PCD of white spruce megagametophyte cells.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Distinct cell-specific expression patterns of early and late gibberellin biosynthetic genes during Arabidopsis seed germination.

Gibberellins (GAs) are biosynthesized through a complex pathway that involves several classes of enzymes. To predict sites of individual GA biosynthetic steps, we studied cell type-specific expression of genes encoding early and late GA biosynthetic enzymes in germinating Arabidopsis seeds. We showed that expression of two genes, AtGA3ox1 and AtGA3ox2, encoding GA 3-oxidase, which catalyzes the terminal biosynthetic step, was mainly localized in the cortex and endodermis of embryo axes in germinating seeds. Because another GA biosynthetic gene, AtKO1, coding for ent-kaurene oxidase, exhibited a similar cell-specific expression pattern, we predicted that the synthesis of bioactive GAs from ent-kaurene oxidation occurs in the same cell types during seed germination. We also showed that the cortical cells expand during germination, suggesting a spatial correlation between GA production and response. However, promoter activity of the AtCPS1 gene, responsible for the first committed step in GA biosynthesis, was detected exclusively in the embryo provasculature in germinating seeds. When the AtCPS1 cDNA was expressed only in the cortex and endodermis of non-germinating ga1-3 seeds (deficient in AtCPS1) using the AtGA3ox2 promoter, germination was not as resistant to a GA biosynthesis inhibitor as expression in the provasculature. These results suggest that the biosynthesis of GAs during seed germination takes place in two separate locations with the early step occurring in the provasculature and the later steps in the cortex and endodermis. This implies that intercellular transport of an intermediate of the GA biosynthetic pathway is required to produce bioactive GAs.

Arabidopsis↗
PubMed2005

Strategies for adaptation of Suaeda physophora, Haloxylon ammodendron and Haloxylon persicum to a saline environment during seed-germination stage.

BACKGROUND AND AIMS: Germination is very important for plant establishment in arid regions. The strategies taken by halophytes during the seed germination stage to adapt to saline environments in an arid zone were investigated in Suaeda physophora (euhalophyte), Haloxylon ammodendron (xero-halophyte) and Haloxylon persicum (xerophyte). METHODS: Seeds of S. physophora, H. ammodendron and H. persicum were exposed to a range of iso-osmotic NaCl and PEG solutions. Seed germination in, and recovery germination from, high NaCl were recorded. The effects of iso-osmotic NaCl and PEG on seed water uptake and changes in ion content were measured. In addition, the structure of seeds and Na+ distribution in the seed coat and embryos of dry seeds were investigated. KEY RESULTS: The relative increase in fresh weight of germinating seeds was markedly reduced in -2.24 MPa PEG compared with that in -2.24 MPa NaCl, while the opposite trend was found in concentration of K+ during the initial 9 h for all species. Haloxylon ammodendron and S. physophora had a higher recovery germination from -3.13 MPa NaCl compared with H. persicum. Seeds of all species had no endosperm. More Na+ was compartmentalized in the seed coats of the two halophytic species compared with that in the xerophyte H. persicum. CONCLUSIONS: The effect of NaCl on seed germination was due to both osmotic stress and ion toxicity for the three species. High soil salinity and a high content of Na+ in seeds may induce more seeds to remain ungerminated in S. physophora and H. ammodendron. Morphological structure and adaptation to salinity during seed germination may determine the geographical distribution of H. ammodendron and S. physophora in certain saline regions.

Adaptation, Physiological↗
PubMed2006

Effects of Neotyphodium fungi on Lolium multiflorum seed germination in relation to water availability.

BACKGROUND AND AIMS: Temperate endophyte-infected (Neotyphodium sp.) grasses have been shown to exhibit an ecological advantage over endophyte-uninfected grasses under abiotic stressful conditions. It is predicted that endophyte-infected plant populations will display higher rates of germination and proportion of germinated seeds under limiting water conditions. METHODS: The hydrotime regression model was used to describe the effect of Neotyphodium endophyte on seed germination of Lolium multiflorum at different water potentials. Additionally, seed mortality after water stress exposure was estimated in endophyte-infected and -uninfected seeds. KEY RESULTS: Endophyte infection inhibited seed germination at all water potentials. The hydrotime model described satisfactorily the germination responses, and revealed that endophyte-free seeds exhibited higher rates of and final percentage germination, probably due to a lower base water potential compared with endophyte-infected seeds. However, Neotyphodium endophyte conferred a higher rate of survival in those seeds that remained ungerminated when exposed to highly water stress conditions. CONCLUSIONS: Changes produced by Neotyphodium endophyte in L. multiflorum seeds might affect fitness in particular ecological scenarios. For example, the presence of the endophyte may curtail seed germination when water is limiting, reducing the risk of seedling death. Conversely, endophyte-free seeds would display an enhanced germination, ensuring a more rapid seedling establishment if later water conditions do not restrict plant growth.

Germination↗
PubMed2002

Effects of mechanical vibration on seed germination of Arabidopsis thaliana (L.) Heynh.

The effects of sinusoidal vibration (40-120 Hz, amplitude equal to or smaller than 0.42 mm) on seed germination of Arabidopsis thaliana were examined. When the amplitude of vibration was fixed at 0.42 mm, vibration with frequencies higher than 70 Hz increased the rate of seed germination. When the frequency of vibration was fixed at 100 Hz, vibration with amplitudes larger than 0.33 mm also increased the rate of germination. The increase in the rate of germination appeared dependent on acceleration calculated from the frequency and amplitude of vibration. Vibration with a maximum acceleration of 70 m s(-2) increased the rate of germination, but the promotive effects leveled off at higher accelerations. Vibration had little effect on seed germination in a starch-deficient mutant, pgm. Thus, the amyloplasts appeared to act as a susceptor that senses mechanical vibrations. No vibration-induced promotion of germination was seen in an ethylene-insensitive mutant, etr1, or in the wild type in the presence of aminoethoxyvinylglycine, an inhibitor of ethylene synthesis, suggesting that vibration increased the rate of seed germination through the action of ethylene.

Arabidopsis↗
PubMed1999

Mannose inhibits Arabidopsis germination via a hexokinase-mediated step.

Low concentrations of the glucose (Glc) analog mannose (Man) inhibit germination of Arabidopsis seeds. Man is phosphorylated by hexokinase (HXK), but the absence of germination was not due to ATP or phosphate depletion. The addition of metabolizable sugars reversed the Man-mediated inhibition of germination. Carbohydrate-mediated regulation of gene expression involving a HXK-mediated pathway is known to be activated by Glc, Man, and other monosaccharides. Therefore, we investigated whether Man blocks germination through this system. By testing other Glc analogs, we found that 2-deoxyglucose, which, like Man, is phosphorylated by HXK, also blocked germination; no inhibition was observed with 6-deoxyglucose or 3-O-methylglucose, which are not substrates for HXK. Since these latter two sugars are taken up at a rate similar to that of Man, uptake is unlikely to be involved in the inhibition of germination. Furthermore, we show that mannoheptulose, a specific HXK inhibitor, restores germination of seeds grown in the presence of Man. We conclude that HXK is involved in the Man-mediated repression of germination of Arabidopsis seeds, possibly via energy depletion.

3-O-Methylglucose↗
PubMed2005

Effect of individual amino acids and glucose on activation and germination of Rhizopus oligosporus sporangiospores in tempe starter.

AIM: To understand the conditions promoting activation and germination of spores, and to contribute to the control of tempe starters. METHODS AND RESULTS: Using microscopic counts of fluorescent labelled spores, the following results were obtained: (1) L-alanine plays an important role (of the same order as that of peptone) in stimulation of germination of dormant spores. Alanine can satisfy the requirements of carbon as well as nitrogen for spore germination; (2) L-proline, on the other hand, inhibits alanine uptake presumably by blocking/congesting transporters of spore cells, resulting in apparent low viability on agar media; (3) L-leucine and L-isoleucine slightly favour spore germination while L-arginine and L-lysine do not have any stimulating effect; (4) The stimulatory role of glucose was only evident in the presence of phosphate (in minimal medium); when glucose is used in the absence of phosphate, either alone or in combination with single amino acids its role is hardly distinguishable; (5) Phosphate plays a facilitating role in spore germination. CONCLUSIONS: Glucose and amino acids play important roles in activation and germination of sporangiospores of Rhizopus oligosporus in tempe starter (stored for 12 months). The ability and rate of germination of dormant/old sporangiospores of R. oligosporus, depend on their ability for uptake of individual amino acids and/or glucose. SIGNIFICANCE AND IMPACT OF STUDY: New light was shed on the counteractive role of proline and the stimulating effect of phosphate. Soybeans subjected to traditional preparation for tempe making are heavily leached; germination of starter spores on such beans is sub-optimal, and bean processing could be optimized.

Alanine↗
PubMed2004

The germinal center response.

The germinal center reaction is the foundation of T-cell-dependent humoral responses. Antigen-specific B cells recruited into germinal centers undergo a complex cellular program that allows for extensive expansion, isotype switching, somatic hypermutation, and differentiation into antibody-forming cells and memory cells. Importantly, the germinal center environment filters the repertoire of differentiating B cells such that high affinity variants are preferentially selected while low affinity or self-reactive clones are eliminated by apoptosis. The present article reviews the many processes that govern germinal center B-cell differentiation, as well as the cellular and molecular elements necessary to initiate and sustain a germinal center response. The major histologic features of the germinal center are also discussed, as well as the current dominant models of the germinal center reaction in humans and mice. Finally, a new model of murine B-cell differentiation is described on the basis of a multiparameter flow cytometric kinetic analysis of germinal center B cells.

Animals↗
PubMed2003

Experiment of seed germination with low pressure environment simulator.

Seeds of Brassica campestris germinated in low pressure environment at the pressures of 100, 50, 30, 20 kPa. The germination rates of 7 days after seeding were more than 90% without the rate at the pressures of 20 kPa. As the pressure was less, the germination was slower. The results showed that seeds of Brassica campestris normally germinated at the pressure of more than 30 kPa. The germination rate at the pressures of 20 kPa was about 60%. The germination rate was not normal. However, it was possible to germinate. The germination at the pressure of less than 20 kPa is expected.

Atmospheric Pressure↗
PubMed2005

[Effect of acid rain on seed germination of rice, wheat and rape].

Rice, wheat and rape seeds were treated with simulated acid rain at pH 2.0, 2.5, 3.0, 3.5, 4.0 and 5.0 levels for 7 days in order to understand the effects of acid rain on seed germination of various acid-fast plant. The germination test showed that seed germination was absolutely inhibited at pH 2.0 for three species. Rice and wheat seeds germinated abnormally at pH 2.5. WhenpH values above 3.0, percentage germination, germination energy, germination index, vigor index of rice, wheat and rape seeds increased in relation with decreased acidity levels. In contrast, the percentage of abnormal germination of rice and wheat decreased. The experiment data about physiological aspect demonstrated that water absorption rate, respiratory rate and storage reserve transformation rate of rice, wheat and rape seeds also increased with increased pH values. The storage loss of rice and wheat increased with increased pH values but that of rape decreased. Inhibition index of shoot and root length of three kinds of seeds decreased in relation with increased pH values. The amplitude difference of index of rice was lower than that of wheat, and wheat was lower than that of rape. The experiment data showed that rice had stronger fastness than wheat and rape, wheat had stronger fastness than rape under acid rain stress.

Acid Rain↗
PubMed2005

[Effects of polyethylene glycol (PEG)-simulated drought stress on Pinus sylvestris var. mongolica seed germination on sandy land].

With introduced sandy land Mongolian pine (Pinus sylvestris var. mongolica) seeds as test material, this paper studied the effects of polyethylene glycol (PEG)-simulated drought stress on their germination. The results showed that PEG could retard the germination of stressed seeds, and the germination rate, germination index, and germination potential were all decreased with increasing PEG concentration. The seeds treated with 30% PEG (about -1.20 MPa water potential) could not germinate at all throughout the experiment period, suggesting that 30% PEG or -1.20 MPa water potential was the threshold for the germination of Mongolian pine seeds. Under 10% PEG stress (about -0.20 MPa water potential), the lengths of radicle and hypocotyl were shorter, illustrating their growth be more sensitive to PEG-simulated drought stress, while the radicle/hypocotyl ratio was increased with increasing PEG concentration, indicating that Mongolian pine seeds had a stronger resistance to drought stress after germination. Drought stress might be a possible cause that inhibited the natural regeneration of Mongolian pine on sandy land.

Desert Climate↗