Dormancy Dotaz Zobrazit nápovědu
BACKGROUND: A water-impermeable testa acts as a barrier to a seed's imbibition, thereby imposing dormancy. The physical and functional properties of the macrosclereids are thought to be critical determinants of dormancy; however, the mechanisms underlying the maintenance of and release from dormancy in pea are not well understood. METHODS: Seeds of six pea accessions of contrasting dormancy type were tested for their ability to imbibe and the permeability of their testa was evaluated. Release from dormancy was monitored following temperature oscillation, lipid removal and drying. Histochemical and microscopic approaches were used to characterize the structure of the testa. KEY RESULTS: The strophiole was identified as representing the major site for the entry of water into non-dormant seeds, while water entry into dormant seeds was distributed rather than localized. The major barrier for water uptake in dormant seeds was the upper section of the macrosclereids, referred to as the 'light line'. Dormancy could be released by thermocycling, dehydration or chloroform treatment. Assays based on either periodic acid or ruthenium red were used to visualize penetration through the testa. Lipids were detected within a subcuticular waxy layer in both dormant and non-dormant seeds. The waxy layer and the light line both formed at the same time as the establishment of secondary cell walls at the tip of the macrosclereids. CONCLUSIONS: The light line was identified as the major barrier to water penetration in dormant seeds. Its outer border abuts a waxy subcuticular layer, which is consistent with the suggestion that the light line represents the interface between two distinct environments - the waxy subcuticular layer and the cellulose-rich secondary cell wall. The mechanistic basis of dormancy break includes changes in the testa's lipid layer, along with the mechanical disruption induced by oscillation in temperature and by a decreased moisture content of the embryo.
- MeSH
- hrách setý * MeSH
- klíčení * MeSH
- semena rostlinná MeSH
- teplota MeSH
- vegetační klid MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Seed coats of six pea genotypes contrasting in dormancy were studied by laser desorption/ionization mass spectrometry (LDI-MS). Multivariate statistical analysis discriminated dormant and non-dormant seeds in mature dry state. Separation between dormant and non-dormant types was observed despite important markers of particular dormant genotypes differ from each other. Normalized signals of long-chain hydroxylated fatty acids (HLFA) in dormant JI64 genotype seed coats were significantly higher than in other genotypes. These compounds seem to be important markers likely influencing JI64 seed imbibition and germination. HLFA importance was supported by study of recombinant inbred lines (JI64xJI92) contrasting in dormancy but similar in other seed properties. Furthemore HLFA distribution in seed coat was studied by mass spectrometry imaging. HLFA contents in strophiole and hilum are significantly lower compared to other parts indicating their role in water uptake. Results from LDI-MS experiments are useful in understanding (physical) dormancy (first phases of germination) mechanism and properties related to food processing technologies (e.g., seed treatment by cooking).
Seed germination is an important life-cycle transition because it determines subsequent plant survival and reproductive success. To detect optimal spatiotemporal conditions for germination, seeds act as sophisticated environmental sensors integrating information such as ambient temperature. Here we show that the delay of germination 1 (DOG1) gene, known for providing dormancy adaptation to distinct environments, determines the optimal temperature for seed germination. By reciprocal gene-swapping experiments between Brassicaceae species we show that the DOG1-mediated dormancy mechanism is conserved. Biomechanical analyses show that this mechanism regulates the material properties of the endosperm, a seed tissue layer acting as germination barrier to control coat dormancy. We found that DOG1 inhibits the expression of gibberellin (GA)-regulated genes encoding cell-wall remodeling proteins in a temperature-dependent manner. Furthermore we demonstrate that DOG1 causes temperature-dependent alterations in the seed GA metabolism. These alterations in hormone metabolism are brought about by the temperature-dependent differential expression of genes encoding key enzymes of the GA biosynthetic pathway. These effects of DOG1 lead to a temperature-dependent control of endosperm weakening and determine the optimal temperature for germination. The conserved DOG1-mediated coat-dormancy mechanism provides a highly adaptable temperature-sensing mechanism to control the timing of germination.
- MeSH
- Arabidopsis genetika růst a vývoj fyziologie MeSH
- biomechanika MeSH
- diploidie MeSH
- geneticky modifikované rostliny MeSH
- gibereliny metabolismus MeSH
- klíčení genetika fyziologie MeSH
- konzervovaná sekvence MeSH
- Lepidium sativum genetika růst a vývoj fyziologie MeSH
- molekulární sekvence - údaje MeSH
- mutace MeSH
- proteiny huseníčku genetika MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- semena rostlinná růst a vývoj MeSH
- teplota MeSH
- vegetační klid genetika fyziologie MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The precocious germination of cereal grains before harvest, also known as pre-harvest sprouting, is an important source of yield and quality loss in cereal production. Pre-harvest sprouting is a complex grain defect and is becoming an increasing challenge due to changing climate patterns. Resistance to sprouting is multi-genic, although a significant proportion of the sprouting variation in modern wheat cultivars is controlled by a few major quantitative trait loci, including Phs-A1 in chromosome arm 4AL. Despite its importance, little is known about the physiological basis and the gene(s) underlying this important locus. In this study, we characterized Phs-A1 and show that it confers resistance to sprouting damage by affecting the rate of dormancy loss during dry seed after-ripening. We show Phs-A1 to be effective even when seeds develop at low temperature (13 °C). Comparative analysis of syntenic Phs-A1 intervals in wheat and Brachypodium uncovered ten orthologous genes, including the Plasma Membrane 19 genes (PM19-A1 and PM19-A2) previously proposed as the main candidates for this locus. However, high-resolution fine-mapping in two bi-parental UK mapping populations delimited Phs-A1 to an interval 0.3 cM distal to the PM19 genes. This study suggests the possibility that more than one causal gene underlies this major pre-harvest sprouting locus. The information and resources reported in this study will help test this hypothesis across a wider set of germplasm and will be of importance for breeding more sprouting resilient wheat varieties.
- MeSH
- chromozomy rostlin genetika fyziologie MeSH
- genotypizační techniky MeSH
- jednonukleotidový polymorfismus genetika MeSH
- klíčení genetika fyziologie MeSH
- lokus kvantitativního znaku genetika fyziologie MeSH
- mapování chromozomů MeSH
- pšenice genetika růst a vývoj MeSH
- rostlinné geny genetika fyziologie MeSH
- vegetační klid genetika fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Vegetative dormancy, that is the temporary absence of aboveground growth for ≥ 1 year, is paradoxical, because plants cannot photosynthesise or flower during dormant periods. We test ecological and evolutionary hypotheses for its widespread persistence. We show that dormancy has evolved numerous times. Most species displaying dormancy exhibit life-history costs of sprouting, and of dormancy. Short-lived and mycoheterotrophic species have higher proportions of dormant plants than long-lived species and species with other nutritional modes. Foliage loss is associated with higher future dormancy levels, suggesting that carbon limitation promotes dormancy. Maximum dormancy duration is shorter under higher precipitation and at higher latitudes, the latter suggesting an important role for competition or herbivory. Study length affects estimates of some demographic parameters. Our results identify life historical and environmental drivers of dormancy. We also highlight the evolutionary importance of the little understood costs of sprouting and growth, latitudinal stress gradients and mixed nutritional modes.
Medical intelligence unit
196 s. : grafy, tab. ; 25 cm
- MeSH
- nádorová transformace buněk MeSH
- nádorové buňky kultivované MeSH
- prekancerózy MeSH
- staging nádorů MeSH
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- onkologie
Většina patologických stavů mozkové tkáně je pravděpodobně spojena s protektivním útlumem neuronální aktivity, tzv. neurodormancí. Smyslem tohoto přepnutí na úsporný režim je ochrana nervových buněk před hrozící destrukcí. Útlum neuronální aktivity však vede k tomu, že klinický projev vzniklé poruchy je výraznější, než by odpovídalo samotnému rozsahu strukturální léze. Po skončení akutní fáze se proto neurodormance stává nadbytečnou až nežádoucí. K jejímu odstranění se experimentálně používá řada farmakologických i nefarmakologických metod. Jednou z účinných látek používaných k léčbě neurodormance je zolpidem.
Most of the various types of brain injuriy are supposed to be connected with neuroprotective supression of brain activity, so-called brain dormancy. The reason for this suppressed neuronal activity is protection of brain tissue from damage. However reduction in neuronal energy metabolism and function makes the clinical symptoms more serious. Later after brain injury inception, brain dormancy and suppression offer no benefit. Currently many experimental advances, pharmacological and non-pharmacological, are being made to achieve brain dormancy switch-off. One of drugs frequently used to restore brain function is zolpidem.
- Klíčová slova
- poškození mozkové tkáně, vegetativní stav,
- MeSH
- centrální nervový systém patofyziologie účinky léků MeSH
- GABA agonisté * farmakologie terapeutické užití MeSH
- GABA fyziologie MeSH
- kóma po poranění hlavy farmakoterapie MeSH
- lidé MeSH
- neurony fyziologie metabolismus účinky léků MeSH
- perzistentní vegetativní stav farmakoterapie patofyziologie MeSH
- poranění mozku * farmakoterapie komplikace MeSH
- pyridiny * farmakologie terapeutické užití MeSH
- receptory GABA účinky léků MeSH
- zolpidem MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
BACKGROUND: In models extensively used in studies of aging and extended lifespan, such as C. elegans and Drosophila, adult senescence is regulated by gene networks that are likely to be similar to ones that underlie lifespan extension during dormancy. These include the evolutionarily conserved insulin/IGF, TOR and germ line-signaling pathways. Dormancy, also known as dauer stage in the larval worm or adult diapause in the fly, is triggered by adverse environmental conditions, and results in drastically extended lifespan with negligible senescence. It is furthermore characterized by increased stress resistance and somatic maintenance, developmental arrest and reallocated energy resources. In the fly Drosophila melanogaster adult reproductive diapause is additionally manifested in arrested ovary development, improved immune defense and altered metabolism. However, the molecular mechanisms behind this adaptive lifespan extension are not well understood. RESULTS: A genome wide analysis of transcript changes in diapausing D. melanogaster revealed a differential regulation of more than 4600 genes. Gene ontology (GO) and KEGG pathway analysis reveal that many of these genes are part of signaling pathways that regulate metabolism, stress responses, detoxification, immunity, protein synthesis and processes during aging. More specifically, gene readouts and detailed mapping of the pathways indicate downregulation of insulin-IGF (IIS), target of rapamycin (TOR) and MAP kinase signaling, whereas Toll-dependent immune signaling, Jun-N-terminal kinase (JNK) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways are upregulated during diapause. Furthermore, we detected transcriptional regulation of a large number of genes specifically associated with aging and longevity. CONCLUSIONS: We find that many affected genes and signal pathways are shared between dormancy, aging and lifespan extension, including IIS, TOR, JAK/STAT and JNK. A substantial fraction of the genes affected by diapause have also been found to alter their expression in response to starvation and cold exposure in D. melanogaster, and the pathways overlap those reported in GO analysis of other invertebrates in dormancy or even hibernating mammals. Our study, thus, shows that D. melanogaster is a genetically tractable model for dormancy in other organisms and effects of dormancy on aging and lifespan.
- MeSH
- dlouhověkost genetika MeSH
- Drosophila melanogaster genetika fyziologie MeSH
- genom hmyzu MeSH
- genová ontologie MeSH
- inzulin genetika MeSH
- regulace genové exprese * MeSH
- rozmnožování genetika MeSH
- signální transdukce MeSH
- stárnutí genetika fyziologie MeSH
- transkriptom genetika MeSH
- zárodečné buňky metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
