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 271 records · Page 15Linked to original sources
PubMed1990

Progressive transformation of germinal centers with and without association to Hodgkin's disease.

Progressively transformed germinal centers occurred in about 3.5% of cases of chronic nonspecific lymphadenitis. They are larger than germinal centers and are composed of follicular mantle lymphocytes, small clusters of proliferating mainly medium-sized B- and T-cells, as well as an extensive network of follicular dendritic cells. Sixty-six patients with lymph node enlargement containing progressively transformed germinal centers and staging and sequential biopsies of 213 patients with Hodgkin's disease (mixed and nodular sclerosis type) were investigated with special reference to the relationship of this lesion to Hodgkin's disease. In most cases, progressively transformed germinal centers developed without any obvious signs of illness and seemed to have no association with Hodgkin's disease. The patients could be differentiated into two groups. The larger group, Group 1 (n = 55 of 66) consisted of patients showing progressively transformed germinal centers without association to Hodgkin's disease. The smaller group, Group 2 (n = 11 of 66) showed progressively transformed germinal centers obviously with association to nodular paragranuloma (Hodgkin's disease lymphocytic predominance type). Progressively transformed germinal centers preceding (n = 3), simultaneously (n = 4), and after development of nodular paragranuloma (n = 4) were found. With regard to subtypes of Hodgkin's disease other than paragranuloma, progressively transformed germinal centers also could be found in sequential biopsies of Hodgkin's disease of mixed and nodular sclerosis type. In one case, progressively transformed germinal centers preceded, in another case they occurred simultaneously in mixed type of Hodgkin's disease, and in two cases of nodular sclerosis type progressively transformed germinal centers developed after the onset of Hodgkin's disease. These findings suggest that progressively transformed germinal centers may be a result of different processes that may be occasionally related not only to nodular paragranuloma, but also in rare cases to nodular sclerosis and mixed type of Hodgkin's disease.

Adolescent↗
PubMed1992

A Role for the Surrounding Fruit Tissues in Preventing the Germination of Tomato (Lycopersicon esculentum) Seeds : A Consideration of the Osmotic Environment and Abscisic Acid.

During tomato seed development the endogenous abscisic acid (ABA) concentration peaks at about 50 d after pollination (DAP) and then declines at later stages (60-70 DAP) of maturation. The ABA concentration in the sheath tissue immediately surrounding the seed increases with time of development, whereas that of the locule declines. The water contents of the seed and fruit tissues are similar during early development (20-30 DAP), but decline in the seed tissues between 30 and 40 DAP. The water potential and the osmotic potential of the embryo are lower than that of the locular tissue after 35 DAP also. Seeds removed from the fruit at 30, 35, and 60 DAP and placed ex situ on 35 and 60 DAP sheath and locular tissue are prevented from germinating. Development of 30 DAP seeds is maintained or promoted by the ex situ fruit tissue with which they are in contact. Their germination is inhibited until subsequent transfer to water, and germination is normal, i.e. by radicle protrusion, and viable seedlings are produced, compared with 30 DAP seeds transferred directly to water; more of these seeds germinate, but by hypocotyl extension, and seedling viability is very poor. Isolated seeds at 35 and 60 DAP re-placed in contact with fruit tissues only germinate when transferred to water after 7 d. At 30 DAP, isolated seeds are insensitive to ABA at physiological concentrations in that they germinate as if on water, albeit by hypocotyl extension. At higher concentrations germination occurs by radicle protrusion. Osmoticum prevents germination, but there is some recovery upon subsequent transfer to water. Seeds at 35 DAP are very sensitive to ABA and exhibit little or no germination, even upon transfer to water. The response of the isolated seeds to osmoticum more closely approximates that to incubation on the ex situ fruit tissues than does their response to ABA. This is also the case for isolated 60 DAP seeds, whose germination is not prevented by ABA, but only by the osmoticum; these seeds are inhibited when in contact with ex situ fruit tissues also. It is proposed that the osmotic environment within the tissues of the tomato fruit plays a greater role than endogenous ABA in preventing precocious germination of the developing seeds.

Journal Article↗
PubMed1996

Effect of Salt Stress on Germin Gene Expression in Barley Roots.

Germin gene expression in barley (Hordeum vulgare L.) seedlings responds to developmental and environmental cues. During seed germination, germin mRNA levels were maximal 2 d after the start of imbibition in control seedlings and declined to low levels by 6 d. When seeds were sown in the presence of 200 mM NaCl, germin mRNA levels were also maximal after 2 d, but NaCl treatment, which slowed seedling growth, prolonged germin gene expression for an additional 1 d. In 4-d-old seedlings, germin mRNA levels were highest in roots and higher in the vascular transition region than in shoots. In roots of 6-d-old seedlings, germin gene expression was regulated by salt shock and plant growth regulators. Induced germin mRNA levels were maximal 8 h after treatment with NaCl, salicylate, methyl salicylate, or methyl jasmonate and 4 h after treatment with abscisic acid and indoleacetic acid. Like germin mRNA, dehydrin mRNA levels were maximal 8 h after NaCl treatment. In contrast, peroxidase mRNA levels declined to less than control levels within 30 min of treatment. Germin gene expression is regulated developmentally by salt stress and by treatments with plant hormones. Since germin is an oxalate oxidase, these result imply that oxalate has important roles in plant development and homeostasis.

Journal Article↗
PubMed1992

Involvement of calcium in germination of coat-modified spores of Bacillus cereus T.

The effect of calcium on germination of coat-modified Bacillus cereus T spores was investigated. Coat-modified spores produced either by chemical extraction (SDS-DTT-treated spores) or by mutagenesis (10LD mutant spores) were unable to germinate in response to inosine. While SDS-DTT-treated spores could germinate slowly in the presence of L-alanine, 10LD mutant spores could not germinate at all. The lost or reduced germinability of coat-modified spores was restored when exogenous Ca2+ was supplemented to the germination media. The calcium requirement of coat-modified spores for germination was fairly specific. The simultaneous presence of germinant with Ca2+ was also required for germination of coat-modified spores. The optimal recovery of germinability was observed in the presence of 1.0 mM of calcium acetate. The calcium requirement itself was remarkably diminished under the condition in which L-alanine and a certain purine nucleoside analog, adenosine or inosine, coexisted. The lost or diminished germinability observed in SDS-DTT-treated spores or 10LD mutant spores may be attributed to the loss of calcium associated with the spore integuments.

Alanine↗
PubMed1985

Multiple modes of inhibition of spore germination and outgrowth by reduced pH and sorbate.

Germination and outgrowth of three strains of Clostridium botulinum in PYEG medium were measured by phase contrast microscopy. Reduction in pH from 7 to 5.5 completely inhibited germination of strain 12885A, reduced the extent of germination of strain 62A and had no effect on the extent of germination of strain 53B. At pH 5.5, 225 mg/l of undissociated sorbic acid had no effect on the germination of strain 53B, while at pH 6.5, 225 mg/l of undissociated sorbic acid completely inhibited germination of strains 62A and 12885A. Outgrowth of germinated spores of strains 62A and 53B was not inhibited at pH 5.5, but the addition of sorbate (225 mg/l undissociated sorbic acid) completely inhibited outgrowth. Sorbate inhibited germination of Cl. botulinum and Bacillus cereus spores triggered to germinate by amino acids. Inhibition occurred after germinant binding, as measured by commitment to germinate.

Bacillus cereus↗
PubMed2004

Mechanism of the hydrolysis of 4-methylumbelliferyl-beta-D-glucoside by germinating and outgrowing spores of Bacillus species.

AIMS: To determine the mechanism of the hydrolysis of 4-methylumbelliferyl-beta-D-glucopyranoside (beta-MUG) by germinating and outgrowing spores of Bacillus species. METHODS AND RESULTS: Spores of B. atrophaeus (formerly B. subtilis var. niger, Fritze and Pukall 2001) are used as biological indicators of the efficacy of ethylene oxide sterilization by measurement of beta-MUG hydrolysis during spore germination and outgrowth. It was previously shown that beta-MUG is hydrolysed to 4-methylumbelliferone (MU) during the germination and outgrowth of B. atrophaeus spores (Chandrapati and Woodson 2003), and this was also the case with spores of B. subtilis 168. Germination of spores of either B. atrophaeus or B. subtilis with chloramphenicol reduced beta-MUG hydrolysis by almost 99%, indicating that proteins needed for rapid beta-MUG hydrolysis are synthesized during spore outgrowth. However, the residual beta-MUG hydrolysis during spore germination with chloramphenicol indicated that dormant spores contain low levels of proteins needed for beta-MUG uptake and hydrolysis. With B. subtilis 168 spores that lacked several general proteins of the phosphotransferase system (PTS) for sugar uptake, beta-MUG hydrolysis during spore germination and outgrowth was decreased >99.9%. This indicated that beta-MUG is taken up by the PTS, resulting in the intracellular accumulation of the phosphorylated form of beta-MUG, beta-MUG-6-phosphate (beta-MUG-P). This was further demonstrated by the lack of detectable glucosidase activity on beta-MUG in dormant, germinated and outgrowing spore extracts, while phosphoglucosidase active on beta-MUG-P was readily detected. Dormant B. subtilis 168 spores had low levels of at least four phosphoglucosidases active on beta-MUG-P: BglA, BglH, BglC (originally called YckE) and BglD (originally called YdhP). These enzymes were also detected in spores germinating and outgrowing with beta-MUG, but levels of BglH were the highest, as this enzyme's synthesis was induced ca 100-fold during spore outgrowth in the presence of beta-MUG. Deletion of the genes coding for BglA, BglH, BglC and BglD reduced beta-MUG hydrolysis by germinating and outgrowing spores of B. subtilis 168 at least 99.7%. Assay of glucosidases active on beta-MUG or beta-MUG-P in extracts of dormant and outgrowing spores of B. atrophaeus revealed no enzyme active on beta-MUG and one enzyme that comprised > or =90% of the phosphoglucosidase active on beta-MUG-P. Partial purification and amino-terminal sequence analysis of this phosphoglucosidase identified this enzyme as BglH. CONCLUSIONS: Generation of MU from beta-MUG by germinating and outgrowing spores of B. atrophaeus and B. subtilis is mediated by the PTS-driven uptake and phosphorylation of beta-MUG, followed by phosphoglucosidase action on the intracellular beta-MUG-P. The major phosphoglucosidase catalyzing MU generation from beta-MUG-P in spores of both species is probably BglH. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides new insight into the mechanism of uptake and hydrolysis of beta-MUG by germinating and outgrowing spores of Bacillus species, in particular B. atrophaeus. The research reported here provides a biological basis for a Rapid Readout Biological Indicator that is used to monitor the efficacy of ethylene oxide sterilization.

Amino Acid Sequence↗
PubMed1981

Mechanisms of sorbate inhibition of Bacillus cereus T and Clostridium botulinum 62A spore germination.

The mechanism by which potassium sorbate inhibits Bacillus cereus T and Clostridium botulinum 62A spore germination was investigated. Spores of B. cereus T were germinated at 35 degrees C in 0.08 M sodium-potassium phosphate buffers (pH 5.7 and 6.7) containing various germinants (L-alanine, L-alpha-NH2-n-butyric acid, and inosine) and potassium sorbate. Spores of C. botulinum 62A were germinated in the same buffers but with 10 mM L-lactic acid, 20 mM sodium bicarbonate, L-alanine or L-cysteine, and potassium sorbate. Spore germination was monitored by optical density measurements at 600 nm and phase-contrast microscopy. Inhibition of B. cereus T spore germination was observed when 3,900 micrograms of potassium sorbate per ml was added at various time intervals during the first 2 min of spore exposure to the pH 5.7 germination medium. C. botulinum 62A spore germination was inhibited when 5,200 micrograms of potassium sorbate per ml was added during the first 30 min of spore exposure to the pH 5.7 medium. Potassium sorbate inhibition of germination was reversible for both B. cereus T and C. botulinum 62A spores. Potassium sorbate inhibition of B. cereus T spore germination induced by L-alanine and L-alpha-NH2-n-butyric acid was shown to be competitive in nature. Potassium sorbate was also a competitive inhibitor of L-alanine- and L-cysteine-induced germination of C. botulinum 62A spores.

Alanine↗
PubMed1971

Regulation and self-inhibition of Microsporum gypseum Macroconidia germination.

Germination of Microsporum gypseum macroconidia was accompanied by the release of alkaline protease, calcium ions, and inorganic phosphate into the germination fluid. The rate of germination was greatest during the first 2 hr, decreasing thereafter. This decrease in rate was accompanied by a decrease in protease activity, which was caused by an interaction of the enzyme with the inorganic phosphate released from the spores and accumulated in the germination medium after 2 hr. Germination of high spore densities was regulated by the ratio of released phosphate to protease protein, resulting in a constant percentage of germination at both high and low spore densities. A germination-defective mutant strain failed to germinate normally and released excessively high concentrations of phosphate into the germination medium during the initial 2 hr of incubation. Addition of calcium ions to germination mutant macroconidia stabilized spore morphology, prevented protease inactivation, and allowed normal germ-tube outgrowth. The germination of macroconidia appears to be regulated by the release of phosphate ions, which then inhibit the alkaline protease.

Calcium↗
PubMed1972

Characterization of L-leucine-induced germination of Trichophyton mentagrophytes microconidia.

l-Leucine and several amino acids were effective germination inducers of microconidia of Trichophyton mentagrophytes. During germination, phase-darkening and swelling occurred concomitantly with the loss of resistance to heat and stain, reduction of dry weight and specific gravity, and development of active glucose utilization. Germination induced by l-leucine was significantly stimulated by a pretreatment of the spores with sublethal doses of heat. No nucleosides or nucleotides were stimulatory to the l-leucine-induced germination of the microconidia. d-Leucine was almost an equally effective germinant as its l form. No carbohydrates, salts, vitamins, or other compounds tested induced germination of the fungus spore. Other factors that affected l-leucine-induced germination of the microconidia included the concentration of leucine, the inoculum size of the spores, temperature, and pH. The anaerobic condition and the presence or absence of carbon dioxide had no significant effects on the germination. Short germ tubes usually developed when the germinated spores were further incubated either in the presence or absence of l-leucine. The cytological study of the germinating microconidia revealed that the fragmentation of lipid granules was the major structural change associated with the germination.

Amino Acids↗
PubMed1962

Conditions affecting Bacillus megaterium spore germination in glucose or various nitrogenous compounds.

Hyatt, Mildred T. (Quartermaster Research and Engineering Center, Natick, Mass.) and Hillel S. Levinson. Conditions affecting Bacillus megaterium spore germination in glucose or various nitrogenous compounds. J. Bacteriol. 83:1231-1237. 1962.-The possibility that there is more than one metabolic pathway for triggering germination of Bacillus megaterium spores was investigated. Spores were germinated in seven different "physiological germinants" under varying conditions of concentration, pH, combinations of germinants, temperature before and during germination, and chemical inhibition. l-Alanine and l-valine appear to induce germination via the same metabolic pathway (same inhibitors are effective, similar germination rate and temperature requirements); and glucose and glucosamine also appear to act similarly, but by a different pathway than l-alanine and l-valine. The other germinants, l-leucine, l-proline, and KNO(3), do not correspond in all respects either to the glucose-glucosamine or to the alanine-valine pair in response to the different germination conditions. It is concluded that B. megaterium spore germination occurs via more than one pathway.

Alanine↗
PubMed1966

Response of Bacillus spores to combinations of germinative compounds.

Foerster, Harold F. (University of Texas, Austin), and J. W. Foster. Response of Bacillus spores to combinations of germinative compounds. J. Bacteriol. 91:1168-1177. 1966.-Spores of 21 strains of Bacillus megaterium and 25 other strains representing 13 species of Bacillus were produced under standardized conditions. The germination of a washed spore suspension of each strain was measured as a response to various combinations of 30 different germinative compounds. The strains were first typed with respect to their response to "primary" germination compounds, i.e., glucose, l-alanine, inosine, and l-alanine-inosine mixture, and also Na(+) and K(+). The second stage was the determination of the response to various organic and inorganic anions and cations, each strain being supplied with the "primary" compounds best for it. Marked differences in germination patterns were observed among species and strains of the same species. No relation to established taxonomic lines was evident. A nonspecific requirement for ions was found for all strains, but not all ions were effective. A striking degree of interchangeability of germinative chemicals was found. "Fractional germination" was very common. A mixture of l-alanine and inosine and various ions was the best germinative solution for most strains. Some anomalous germination patterns were encountered. Those studied included a strain whose cells lysed spontaneously upon germination and other strains for which l-leucine had striking germinative powers.

Alanine↗
PubMedDate not supplied

[The organization of germinal material and dynamics of mother sporocyst reproduction in the genus Echinostoma (Trematoda: Echinostomatidae)].

The reproduction in the first parthenogenetic generation--mother sporocyst (MS) in two species of echinostomes (E. caproni, E. paraensei) is investigated. A group of densely packed cells, which noticeably differ from others, occupies the posterior part of the miracidium. They are characterized by large sizes and a large bubble-shaped nucleus with heterogeneous nucleolus and strong dispersed chromatin. The use of histological and electron microscopic methods has shown that with observed similarity these cells are classified in two tyoes and have a completely different origin. First of all, large secretory cells stand out. In E. caproni miracidia their number averages 6.8 +/- 0.2 and linear sizes is 10-12 microns. Secretory cells possess a large bubble-shaped nucleus. The caryoplasm looks optically empty because of strong dispersion of chromatin. A large nucleolus occupies a bit eccentric position. Eosinophilic cytoplasm contains poorly noticeable at light-optical level accumulation of small granules. The second group of cells is represented by typical germinal cells (GC). The number of GC does not exceed six. Their polymorphy is well above that of secretory cells. The sizes of GC vary from 5.4 to 9 microns. The largest cells (8.1-9 microns) occupy the front position and usually are located between secretory cells. Intensively basophilic cytoplasm surrounds bubble-shaped nucleus with a large nucleolus like border with uniforming thickness. The heterochromatin is evenly distributed over the caryoplasm. Its content of nuclei is more than that in nuclei of secretory cells. That is why they do not look optically empty. So, it is "mature" germinal cells. Four or five cells are located directly behind "mature" cells. Their sizes are gradually decrease towards the posterior of the miracidium (the diameter of the smallest cells reaches 5.4 microns). Nuclei with a centrally located nucleolus are characterized by larger amount and more condensation of the heterochromatin than those in "mature" cells. Meanwhile, they concern to nuclei of bubble-shaped type. In general, all cells of second type represent the primary germinal cells distinguished by the stage of their differentiation. Also, 2-3 undifferentiated cells occupy the most posterior part of the miracidium. Their sizes average 5.55 +/- 0.18 microns. The nucleus contains a lot of densely packed heterochromatin. On parasitic phase of MS development undifferentiated cells give rise to secondary GC. Electron microscopic data in details confirm the situation described above. The essentially similar results were received during the investigation of E. Paraensei miracidia. The differences are observed in parameterical characteristics of germinal material and in small variability of the extent of germinal material development. With E. paraensei, germinal material may be represented by not only GC and undifferentiated cells, but one germ as well. So, our investigation has shown that germinal material of echinostomes represents typical germinal mass. The germinal material condition does not change on parasitic phase of E. caproni MS development during the first day of post infection (PI). The activization of germinal material coincides in the time with the beginning of schizocoel formation in 2 Days PI. On the 3rd day of PI, the proliferation of undifferentiated cells begins and the first germs are free to float in enormous schizocoel. After 8 days of PI, MS release the first rediae. During the following 2-3 days the other rediae formed by primary GC left MS. The release of rediae derived from secondary GC was observed later. So, E. caproni MS give rise to 12-16 rediae which is much less than the number of GC formed in MS. The earlier release of the first E. paraensei rediae by MS is predetermined by the difference in the structure of germinal mass in E. paraensei miracidia. Therefore, Echinostomatidae is intermediate between two groups of trematodes. The first group has MS that completely realize reproductive function in the time of miracidial formation; but the second group includes higher trematodes characterized by the transfer of reproductive time on a parasitic phase of MS development. The question concerning to so-called "pedogenetic larvae of trematodes" is discussed.

Animals↗
PubMed1990

Covalently bonded and adventitious glycans in germin.

Germin was previously shown to contain covalently bonded and adventitious glycans. The object of the present investigation was to characterize the two types of glycan. The presence of N- but not O-glycans in germin is indicated by the biosynthesis of altered forms, including an unglycosylated form of germin when wheat embryos are germinated in the presence of tunicamycin. After treating the doublet of germin pentamers (G and G') from normally germinated embryos with beta-N-acetylglucosaminidase, G is converted to a form that co-migrates with G' during electrophoresis in sodium dodecyl sulfate-polyacrylamide, but G' is unaffected. This suggests that the N-glycans in G contain antennary N-acetylglucosamine but that those in G' do not. This conclusion has been confirmed and elaborated by doubly labeling G and G' in vivo with [3H]glucosamine and [35S]methionine, and by characterizing sugar-labeled glycopeptides from G and G' by gel filtration, before and after their degradation by exoglycosidases. In the context of proven structures for the complex N-glycans in other plant glycoproteins, the findings, when combined with monosaccharide analyses of G and G', permit plausible speculation about the structure of the single N-glycan that is likely present in each G monomer (GlcNAc2(Man)2(Man-Xyl)(GlcNAc)(GlcNAc-Fuc] and G' monomer ((Man)2(Man-Xyl)(GlcNAc)(GlcNAc-Fuc)). The adventitious glycans, which can be removed by phenolic extraction of germin, have a composition similar to that expected for the characteristic hemicelluloses and pectins in monocot cell walls. The possible significance of this finding is discussed in relation to our continuing efforts to define the biochemical involvements of germin. In allied studies, affinity of its N-linked glycans for concanavalin A has been used to concentrate small amounts of germin from large volumes of wheat extract and to fractionate germin from tunicamycin-treated and normally germinated wheat embryos.

Electrophoresis, Polyacrylamide Gel↗
PubMed1985

[Biochemical and nutritional studies of germinated soybean seeds].

The purpose of this work was to determine the biochemical and nutritional changes of soybean seeds during germination. Soybean seeds were soaked for a period of eight hours and then germinated for 0, 1, 3 and 5 days. Part of them was subjected to an autoclave process. Then, both the raw and cooked seeds were dried, ground and analyzed. During the germination process an increase in the percentage content of protein and fiber in the seeds occurred; cooked seeds, in contrast, showed a slight decrease with respect to the former. Ether extract increased in percentage until the third day, and then decreased on the fifth. In the cooked seeds, higher values than in the raw seeds were obtained, due to the fact that when seeds were autoclaved, protein and carbohydrate losses occur. In regard to ash content, this diminished in percentage as germination advanced; the same happened to the free-protein extract. The raffinose and stachyose sugars, factors which cause flatulence, disappeared on the third germination day. As to nitrogen extraction, a greater percentage was obtained using distilled water as solvent, both for the raw and cooked seeds, than when using NaOH and NaCl. The trypsin inhibitors content increased on the first day of germination and then decreased. Ungerminated, autoclaved seeds, showed no trypsin inhibitors activity, whereas in the germinated cooked seeds, it increased slightly as germination days went by. Regarding protein efficiency ratio (PER), seeds with 0, 1 and 3 germination days presented no significant differences among them, the cooked seeds exhibiting higher values than the raw seeds. Apparent digestibility increased as the germination period advanced, having obtained better values when they were autoclaved. In the soybean milk acceptability test, no significant differences were observed between milk from ungerminated soybean seeds, and milk from the 3-day germinated seeds.

Animals↗
PubMed1996

A new method for the identification and isolation of genes essential for Arabidopsis thaliana seed germination.

Seed viability, dormancy and germination efficiency are very important aspects of the life cycle of plants and their potential to survive and spread in the environment. To characterize the genes controlling these processes, we have devised a technique for the selection of mutants impaired in seed germination. Selection for such a trait is complicated by physiological factors that interact with these processes and affect seed germination efficiency. The distinction between low seed germination potential due to physiological factors that interfere with seed maturation or germination and germination deficiency due to genetic factors was based on screening for tagged mutations. Arabidopsis thaliana T-DNA primary transformants obtained by an in planta transformation technique are all heterozygotes. We screened for lack of germination of 1/4 of the seeds in the progeny of independent transformants, and simultaneously for the abnormal segregation (2:1 instead of 3:1) of a kanamycin resistance marker carried by the T-DNA inserted into the genome of these primary transformants in the plants that germinate. This yielded several mutants affected in the germination processes. One of the mutants, designated ABC33, was further characterized. Once the viable embryos from non-germinating seeds were removed from their testa, they grew and displayed a dwarf phenotype which could be complemented by providing gibberellic acid. A genetic and molecular analysis, based on the characterization of the flanking genomic sequences of the T-DNA insert, showed that ABC33 is a new loss-of-function allele at the GA1 locus.

Arabidopsis↗
PubMed2004

Thiamine binding and metabolism in germinating seeds of selected cereals and legumes.

The basic characteristics of thiamine metabolism in germinating seeds of maize (Zea mays), oat (Avena sativa), faba bean (Vicia faba) and garden pea (Pisum sativum) are presented with a special emphasis of a possible thiamine storage function of seed thiamine-binding proteins (TBPs). Seeds were germinated for 6 d in the dark. Thiamine-binding activity in seeds decreased during germination by 50% in cereals and by 30% in legumes. The degradation of TBPs was also detected by polyacrylamide gel electrophoresis. The total thiamine content decreased rapidly to 20-40% of the initial value in cereal seeds during first 3 d of germination while in legume seeds thiamine content started changing from the fourth day and dropped by 50% at the sixth day. A composite pattern was found for the changes in thiamine pyrophosphate (TPP) contribution to total thiamine during seed germination. A peak of the coenzyme percentage was usually detected at the second day of germination. Another gain of TPP was often seen toward the sixth day of germination. The activity of thiamine pyrophosphokinase (EC 2.7.6.2) was high in resting legume seeds and did not significantly change during germination. In contrast, the low activity of this thiamine-activating enzyme in cereal seeds progressively increased during germination. Thiamine phosphate synthase (EC 2.5.1.3) was also detected in seeds and was shown to contribute significantly to the balance of thiamine compounds during seed germination.

Avena↗
PubMed2006

Genetic and QTL analysis for low-temperature vigor of germination in rice.

The quantitative trait loci (QTLs) for low-temperature vigor of germination (LVG) with a germination period of 7 d, 11 d, 14 d, and 17 d at 14 degrees C was identified using F(2:3) population, which included 200 individuals and lines derived from a cross of indica and japonica "Milyang 23/Jileng 1" with microsatellite markers. The correlation coefficient between LVG and other cold tolerance traits was analyzed. LVG and the cold response index for vigor of germination (CIVG) detected when the germination period was 7 d showed a continuous distribution, which was partial to lower LVG and lower CIVG in F(3) lines. LVG and CIVG detected when the germination periods were 11 d, 14 d, and 17 d showed a continuous distribution near normal, which were quantitative traits controlled by multiple genes. LVG detected when the germination period was 14 d was more correlated with other cold tolerance traits than LVG detected when the germination periods were 7 d, 11 d, and 17 d, which was significantly associated with cold tolerance during the bud bursting period, the seedling stage, the booting stage, and the growing ability under cold conditions. qLVG2 located in RM29-RM262 on chromosome 2, qLVG7-2 and qCIVG7-2 located in RM336-RM118 on chromosome 7 were detected when the germination periods were 11 d, 14 d, and 17 d. qCIVG2 located in RM29-RM262 on chromosome 2 was detected when the germination periods were 11 d and 14 d. The variation is due to the observed phenotypic variation by the above QTLs, which was increased following the germination. The variation of qLVG2 related to LVG was increased from 6.9% to 14.2%. The variation of qLVG7-2 associated with LVG was increased from 9.9% to 11.2%. The variation of qCIVG2 correlated with CIVG was increased from 6.3% to 9.0%. The variation of qCIVG7-2 associated with CIVG was increased from 8.3% to 12.9%. These QTL alleles were obtained from the tolerant parent Jileng 1, and the gene action was most likely to be partially dominant.

Breeding↗
PubMed2005

Effect of canopy position on germination and seedling survival of epiphytic bromeliads in a Mexican humid montane forest.

BACKGROUND AND AIMS: Seeds of epiphytes must land on branches with suitable substrates and microclimates to germinate and for the resulting seedlings to survive. It is important to understand the fate of seeds and seedlings in order to model populations, but this is often neglected when only established plants are included in analyses. METHODS: The seeds of five bromeliad species were exposed to different canopy positions in a Mexican montane forest, and germination and early seedling survival were recorded. Additionally, the survival of naturally dispersed seedlings was monitored in a census over 2.5 years. Survival analysis, a procedure rarely used in plant ecology, was used to study the influence of branch characteristics and light on germination and seedling survival in natural and experimental populations. KEY RESULTS: Experimental germination percentages ranged from 7.2 % in Tillandsia deppeana to 33.7 % in T. juncea, but the seeds of T. multicaulis largely failed to germinate. Twenty months after exposure between 3.5 and 9.4 % of the seedlings were still alive. There was no evidence that canopy position affected the probability of germination, but time to germination was shorter in less exposed canopy positions indicating that higher humidity accelerates germination. More experimental seedlings survived when canopy openness was high, whereas survival in census-seedlings was influenced by moss cover. While mortality decreased steadily with age in juveniles of the atmospheric Tillandsia, in the more mesomorphic Catopsis sessiliflora mortality increased dramatically in the dry season. CONCLUSIONS: Seedling mortality, rather than the failure to germinate, accounts for the differential distribution of epiphytes within the canopy studied. With few safe sites to germinate and high seedling mortality, changes of local climate may affect epiphyte populations primarily through their seedling stage.

Environment↗