Heteromorphic diaspores (fruits and seeds) are an adaptive bet-hedging strategy to cope with spatiotemporally variable environments, particularly fluctuations in favourable temperatures and unpredictable precipitation regimes in arid climates. We conducted comparative analyses of the biophysical and ecophysiological properties of the two distinct diaspores (mucilaginous seed (M+ ) vs indehiscent (IND) fruit) in the dimorphic annual Aethionema arabicum (Brassicaceae), linking fruit biomechanics, dispersal aerodynamics, pericarp-imposed dormancy, diaspore abscisic acid (ABA) concentration, and phenotypic plasticity of dimorphic diaspore production to its natural habitat and climate. Two very contrasting dispersal mechanisms of the A. arabicum dimorphic diaspores were revealed. Dehiscence of large fruits leads to the release of M+ seed diaspores, which adhere to substrata via seed coat mucilage, thereby preventing dispersal (antitelechory). IND fruit diaspores (containing nonmucilaginous seeds) disperse by wind or water currents, promoting dispersal (telechory) over a longer range. The pericarp properties confer enhanced dispersal ability and degree of dormancy on the IND fruit morph to support telechory, while the M+ seed morph supports antitelechory. Combined with the phenotypic plasticity to produce more IND fruit diaspores in colder temperatures, this constitutes a bet-hedging survival strategy to magnify the prevalence in response to selection pressures acting over hilly terrain.
- MeSH
- biofyzikální jevy * MeSH
- biomechanika MeSH
- Brassicaceae fyziologie MeSH
- ekosystém MeSH
- fyziologická adaptace * MeSH
- klíčení fyziologie MeSH
- ovoce fyziologie MeSH
- půda MeSH
- semena rostlinná fyziologie MeSH
- šíření semen fyziologie MeSH
- vítr MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The apical hook is a transiently formed structure that plays a protective role when the germinating seedling penetrates through the soil towards the surface. Crucial for proper bending is the local auxin maxima, which defines the concave (inner) side of the hook curvature. As no sign of asymmetric auxin distribution has been reported in embryonic hypocotyls prior to hook formation, the question of how auxin asymmetry is established in the early phases of seedling germination remains largely unanswered. Here, we analyzed the auxin distribution and expression of PIN auxin efflux carriers from early phases of germination, and show that bending of the root in response to gravity is the crucial initial cue that governs the hypocotyl bending required for apical hook formation. Importantly, polar auxin transport machinery is established gradually after germination starts as a result of tight root-hypocotyl interaction and a proper balance between abscisic acid and gibberellins.This article has an associated 'The people behind the papers' interview.
- MeSH
- Arabidopsis MeSH
- geneticky modifikované rostliny MeSH
- gibereliny metabolismus MeSH
- hypokotyl růst a vývoj MeSH
- klíčení fyziologie MeSH
- kořeny rostlin růst a vývoj MeSH
- kyselina abscisová metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- meristém růst a vývoj MeSH
- percepce tíhy fyziologie MeSH
- proteiny huseníčku metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin metabolismus MeSH
- semenáček růst a vývoj MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Biological systems manifest continuous weak autoluminescence, which is present even in the absence of external stimuli. Since this autoluminescence arises from internal metabolic and physiological processes, several works suggested that it could carry information in the time series of the detected photon counts. However, there is little experimental work which would show any difference of this signal from random Poisson noise and some works were prone to artifacts due to lacking or improper reference signals. Here we apply rigorous statistical methods and advanced reference signals to test the hypothesis whether time series of autoluminescence from germinating mung beans display any intrinsic correlations. Utilizing the fractional Brownian bridge that employs short samples of time series in the method kernel, we suggest that the detected autoluminescence signal from mung beans is not totally random, but it seems to involve a process with a negative memory. Our results contribute to the development of the rigorous methodology of signal analysis of photonic biosignals.
- MeSH
- klíčení fyziologie MeSH
- luminiscence * MeSH
- vigna růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Background: A brief review is given of Peter W. Barlows' contributions to research on gravity tide-related phenomena in plant biology, or 'selenonastic' effects as he called them, including his early research on root growth. Also, new results are presented here from long-term recordings of spontaneous ultra-weak light emission during germination, reinforcing the relationship between local lunisolar tidal acceleration and seedling growth. Scope: The main ideas and broad relevance of the work by Barlow and his collaborators about the effects of gravity on plants are reviewed, highlighting the necessity of new models to explain the apparent synchronism between root growth and microscale gravity changes 107 times lower than that exerted by the Earth's gravity. The new results, showing for the first time the germination of coffee beans in sequential tests over 2 months, confirm the co-variation between the patterns in ultra-weak light emission and the lunisolar tidal gravity curves for the initial growth phase. For young sprouts (<1 month old), the rhythm of growth as well as variation in light emission exhibit the once a day and twice a day periodic variations, frequency components that are the hallmark of local lunisolar gravimetric tides. Although present, this pattern is less pronounced in coffee beans older than 1 month. Conclusions: The apparent co-variation between ultra-weak light emission and growth pattern in coffee seedlings and the lunisolar gravity cycles corroborate those previously found in seedlings from other species. It is proposed here that such patterns may attenuate with time for older sprouts with slow development. These data suggest that new models considering both intra- and intercellular interactions are needed to explain the putative sensing and reaction of seedlings to the variations in the gravimetric tide. Here, a possible model is presented based on supracellular matrix interconnections.
- MeSH
- Coffea fyziologie MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- fyziologie rostlin * MeSH
- gravitace * MeSH
- klíčení fyziologie MeSH
- světlo * MeSH
- Check Tag
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- Publikační typ
- biografie MeSH
- časopisecké články MeSH
- historické články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Pollen germination as a crucial process in plant development strongly depends on the accessibility of carbon as energy source. Carbohydrates, however, function not only as a primary energy source, but also as important signaling components. In a comprehensive study, we analyzed various aspects of the impact of 32 different sugars on in vitro germination of Arabidopsis pollen comprising about 150 variations of individual sugars and combinations. Twenty-six structurally different mono-, di- and oligosaccharides, and sugar analogs were initially tested for their ability to support pollen germination. Whereas several di- and oligosaccharides supported pollen germination, hexoses such as glucose, fructose and mannose did not support and even considerably inhibited pollen germination when added to germination-supporting medium. Complementary experiments using glucose analogs with varying functional features, the hexokinase inhibitor mannoheptulose and the glucose-insensitive hexokinase-deficient Arabidopsis mutant gin2-1 suggested that mannose- and glucose-mediated inhibition of sucrose-supported pollen germination depends partially on hexokinase signaling. The results suggest that, in addition to their role as energy source, sugars act as signaling molecules differentially regulating the complex process of pollen germination depending on their structural properties. Thus, a sugar-dependent multilayer regulation of Arabidopsis pollen germination is supported, which makes this approach a valuable experimental system for future studies addressing sugar sensing and signaling.
- MeSH
- Arabidopsis účinky léků fyziologie MeSH
- hexosy metabolismus farmakologie MeSH
- klíčení účinky léků fyziologie MeSH
- mannosa metabolismus farmakologie MeSH
- metabolismus sacharidů * MeSH
- oligosacharidy chemie metabolismus farmakologie MeSH
- pyl metabolismus fyziologie MeSH
- sacharidy MeSH
- sacharosa metabolismus farmakologie MeSH
- Publikační typ
- časopisecké články 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
Pectin methylesterase (PME) controls the methylesterification status of pectins and thereby determines the biophysical properties of plant cell walls, which are important for tissue growth and weakening processes. We demonstrate here that tissue-specific and spatiotemporal alterations in cell wall pectin methylesterification occur during the germination of garden cress (Lepidium sativum). These cell wall changes are associated with characteristic expression patterns of PME genes and resultant enzyme activities in the key seed compartments CAP (micropylar endosperm) and RAD (radicle plus lower hypocotyl). Transcriptome and quantitative real-time reverse transcription-polymerase chain reaction analysis as well as PME enzyme activity measurements of separated seed compartments, including CAP and RAD, revealed distinct phases during germination. These were associated with hormonal and compartment-specific regulation of PME group 1, PME group 2, and PME inhibitor transcript expression and total PME activity. The regulatory patterns indicated a role for PME activity in testa rupture (TR). Consistent with a role for cell wall pectin methylesterification in TR, treatment of seeds with PME resulted in enhanced testa permeability and promoted TR. Mathematical modeling of transcript expression changes in germinating garden cress and Arabidopsis (Arabidopsis thaliana) seeds suggested that group 2 PMEs make a major contribution to the overall PME activity rather than acting as PME inhibitors. It is concluded that regulated changes in the degree of pectin methylesterification through CAP- and RAD-specific PME and PME inhibitor expression play a crucial role during Brassicaceae seed germination.
- MeSH
- endosperm enzymologie fyziologie MeSH
- hypokotyl enzymologie fyziologie MeSH
- karboxylesterhydrolasy biosyntéza genetika fyziologie MeSH
- klíčení genetika fyziologie MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- Lepidium sativum enzymologie genetika fyziologie MeSH
- regulace genové exprese u rostlin genetika fyziologie MeSH
- rostlinné proteiny genetika fyziologie MeSH
- semena rostlinná enzymologie fyziologie MeSH
- stanovení celkové genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
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
Developmental processes are closely connected to certain states of epigenetic information which, among others, rely on methylation of chromatin. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are key cofactors of enzymes catalyzing DNA and histone methylation. To study the consequences of altered SAH/SAM levels on plant development we applied 9-(S)-(2,3-dihydroxypropyl)-adenine (DHPA), an inhibitor of SAH-hydrolase, on tobacco seeds during a short phase of germination period (6 days). The transient drug treatment induced: (1) dosage-dependent global DNA hypomethylation mitotically transmitted to adult plants; (2) pleiotropic developmental defects including decreased apical dominance, altered leaf and flower symmetry, flower whorl malformations and reduced fertility; (3) dramatic upregulation of floral organ identity genes NTDEF, NTGLO and NAG1 in leaves. We conclude that temporal SAH-hydrolase inhibition deregulated floral genes expression probably via chromatin methylation changes. The data further show that plants might be particularly sensitive to accurate setting of SAH/SAM levels during critical developmental periods.
- MeSH
- adenin analogy a deriváty toxicita MeSH
- adenosylhomocysteinasa antagonisté a inhibitory metabolismus MeSH
- DNA primery genetika MeSH
- epigeneze genetická účinky léků fyziologie MeSH
- klíčení účinky léků fyziologie MeSH
- komplementární DNA genetika MeSH
- květy anatomie a histologie fyziologie MeSH
- metylace DNA MeSH
- neparametrická statistika MeSH
- pyl fyziologie MeSH
- regulace genové exprese u rostlin účinky léků genetika fyziologie MeSH
- rostlinné proteiny metabolismus MeSH
- Southernův blotting MeSH
- tabák enzymologie fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
