Strigolactones are the most recently recognized class of phytohormones, which are also known to establish plant symbiosis with arbuscular mycorhizal fungi or induce germination of parasitic plants. Their relatively complex structures and low stability urgently calls for simple derivatives with maintained biological function. We have prepared a series of triazolide strigolactone mimics and studied their ability to affect root development of Arabidopsis thaliana. The strigolactone mimics significantly induced root elongation and lateral root formation while resembling the effect of the reference compound GR24.
- MeSH
- Arabidopsis chemistry drug effects MeSH
- Germination drug effects MeSH
- Plant Roots chemistry drug effects growth & development MeSH
- Lactones chemistry pharmacology MeSH
- Molecular Structure MeSH
- Plant Growth Regulators chemistry pharmacology physiology MeSH
- Symbiosis drug effects MeSH
- Publication type
- Journal Article MeSH
Cytokinins are required for symbiotic nodule development in legumes, and cytokinin signaling responses occur locally in nodule primordia and in developing nodules. Here, we show that the Lotus japonicus Ckx3 cytokinin oxidase/dehydrogenase gene is induced by Nod factor during the early phase of nodule initiation. At the cellular level, pCkx3::YFP reporter-gene studies revealed that the Ckx3 promoter is active during the first cortical cell divisions of the nodule primordium and in growing nodules. Cytokinin measurements in ckx3 mutants confirmed that CKX3 activity negatively regulates root cytokinin levels. Particularly, tZ and DHZ type cytokinins in both inoculated and uninoculated roots were elevated in ckx3 mutants, suggesting that these are targets for degradation by the CKX3 cytokinin oxidase/dehydrogenase. The effect of CKX3 on the positive and negative roles of cytokinin in nodule development, infection and regulation was further clarified using ckx3 insertion mutants. Phenotypic analysis indicated that ckx3 mutants have reduced nodulation, infection thread formation and root growth. We also identify a role for cytokinin in regulating nodulation and nitrogen fixation in response to nitrate as ckx3 phenotypes are exaggerated at increased nitrate levels. Together, these findings show that cytokinin accumulation is tightly regulated during nodulation in order to balance the requirement for cell divisions with negative regulatory effects of cytokinin on infection events and root development.
- MeSH
- Alleles MeSH
- Cell Differentiation MeSH
- Cytokinins metabolism MeSH
- Nitrates metabolism MeSH
- Phenotype MeSH
- Nitrogen Fixation genetics MeSH
- Phylogeny MeSH
- Homeostasis * MeSH
- Root Nodules, Plant genetics growth & development MeSH
- Lotus enzymology genetics growth & development MeSH
- Meristem cytology growth & development MeSH
- Mutation genetics MeSH
- Oxidoreductases genetics metabolism MeSH
- Promoter Regions, Genetic MeSH
- Genes, Plant MeSH
- Plant Proteins genetics metabolism MeSH
- Plant Root Nodulation genetics MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
xxi, 1015 s. : il. + 8 s.obr.příl.
- MeSH
- Communicable Diseases MeSH
- Publication type
- Handbook MeSH
- Conspectus
- Patologie. Klinická medicína
- NML Fields
- infekční lékařství
Many studies indicate that instrumentation only can not sufficiently clean the radicular dentin from bacterial infection. Aproximately 1/3 of the canal wall is not in contact with instrument at all. Remaining surface is covered with smear layer. Thorough irrigation with proper irrigant combination is therefore considered elementary for successful endodontic treatment.
- MeSH
- Chlorhexidine administration & dosage therapeutic use MeSH
- Sodium Hypochlorite administration & dosage therapeutic use MeSH
- Adult MeSH
- Edetic Acid administration & dosage therapeutic use MeSH
- Endodontics methods trends MeSH
- Therapeutic Irrigation methods MeSH
- Humans MeSH
- Root Canal Preparation methods MeSH
- Root Canal Irrigants administration & dosage contraindications therapeutic use MeSH
- Ultrasonics MeSH
- Treatment Outcome MeSH
- Outcome and Process Assessment, Health Care MeSH
- Dentistry MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Female MeSH
- Publication type
- Case Reports MeSH
... The Structure of Central Synapses 400 -- III. The Electrophysiology of Synapses 404 -- IV. ...
Physiological pharmacology
3 svazky : ilustrace ; 24 cm
- MeSH
- Autonomic Nervous System drug effects MeSH
- Central Nervous System drug effects MeSH
- Cholinergic Agents MeSH
- Central Nervous System Agents MeSH
- Central Nervous System Depressants MeSH
- Pharmaceutical Preparations MeSH
- Neuromuscular Blocking Agents MeSH
- Central Nervous System Stimulants MeSH
- Conspectus
- Farmacie. Farmakologie
- NML Fields
- farmacie a farmakologie
- NML Publication type
- kolektivní monografie
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
- Plants, Genetically Modified MeSH
- Gibberellins metabolism MeSH
- Hypocotyl growth & development MeSH
- Germination physiology MeSH
- Plant Roots growth & development MeSH
- Abscisic Acid metabolism MeSH
- Indoleacetic Acids metabolism MeSH
- Meristem growth & development MeSH
- Gravity Sensing physiology MeSH
- Arabidopsis Proteins metabolism MeSH
- Gene Expression Regulation, Plant MeSH
- Plant Growth Regulators metabolism MeSH
- Seedlings growth & development MeSH
- Gene Expression Regulation, Developmental MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Bending and torsional properties of young roots and stems were measured in nine woody angiosperms. The variation in mechanical parameters was correlated to wood anatomical traits and analysed with respect to the other two competing functions of xylem (namely storage and hydraulics). Compared with stems, roots exhibited five times greater flexibility in bending and two times greater flexibility in torsion. Lower values of structural bending and structural torsional moduli (Estr and Gstr, respectively) of roots compared with stems were associated with the presence of thicker bark and a greater size of xylem cells. Across species, Estr and Gstr were correlated with wood density, which was mainly driven by the wall thickness to lumen area ratio of fibres. Higher fractions of parenchyma did not translate directly into a lower wood density and reduced mechanical stiffness in spite of parenchyma cells having thinner, and in some cases less lignified, cell walls than fibres. The presence of wide, partially non-lignified rays contributed to low values of Estr and Gstr in Clematis vitalba. Overall, our results demonstrate that higher demands for mechanical stability in self-supporting stems put a major constraint on xylem structure, whereas root xylem can be designed with a greater emphasis on both storage and hydraulic functions.
- MeSH
- Wood chemistry growth & development MeSH
- Plant Roots chemistry growth & development MeSH
- Magnoliopsida chemistry growth & development MeSH
- Plant Stems chemistry growth & development MeSH
- Xylem chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Introduced organic pollutants in all ecosystem compartments can cause stress resulting in a wide range of responses including different root development. In this study, the effects of a polycyclic aromatic hydrocarbon-fluoranthene (FLT; 0.1, 1 and 7 mg L(-1)) on the growth, morphology and anatomical structure of roots of pea and maize was evaluated. In comparison with pea, significant stimulation of root system growth of maize caused by 0.1 mg L(-1) (total length longer by 25%, number of lateral roots by 35%) and its reduction (total length by 34%) already by 1 mg L(-1) FLT is the proof of different interspecies sensitivity to low and higher environmental loading. Nevertheless in both plant species a high loading 7 mg L(-1) FLT significantly reduced both growth (total length by 95% in pea, 94% in maize) and the number of lateral roots (by 78% in pea, 94% in maize). Significantly increased thickness of root of both maize and pea was caused by 7 mg L(-1) FLT and in maize already by 0.1 mg L(-1) FLT. It may be mainly connected with an enlargement of stele area (up to 50% in pea and 25% in maize). Increased xylem area in root tip (by up to 385% in pea, 167% in maize) and zone of maturation (up to 584% in pea, 70% in maize) and its higher portion in stele area of root tip (by 9% in pea, 21% in maize), mainly in roots exposed 7 mg L(-1) FLT, are a proof of an early differentiation of vascular tissue and a shortening of root elongation zone. Moreover in both plant species exposed to this treatment, the decline of rhizodermis cells and external layers of primary cortex was found and also significant deformation of primordia of lateral roots was recorded.
- MeSH
- Fluorenes toxicity MeSH
- Stress, Physiological MeSH
- Pisum sativum anatomy & histology drug effects physiology MeSH
- Plant Roots anatomy & histology drug effects physiology MeSH
- Zea mays anatomy & histology drug effects physiology MeSH
- Soil Pollutants toxicity MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The transmission mode of shoot-associated endophytes in hyperaccumulators and their roles in root microbiome assembly and heavy metal accumulation remain unclear. Using 16S rRNA gene profiling, we investigated the vertical transmission of shoot-associated endophytes in relation to growth and Cd/Zn accumulation of Sedum alfredii ( Crassulaceae). Endophytes were transmitted from shoot cuttings to the rhizocompartment of new plants in both sterilized (γ-irradiated) and native soils. Vertical transmission was far more efficient in the sterile soil, and the transmitted endophytes have become a dominant component of the newly established root-associated microbiome. Based on 16S rRNA genes, the vertically transmitted taxa were identified as the families of Streptomycetaceae, Nocardioidaceae, Pseudonocardiaceae, and Rhizobiaceae. Abundances of Streptomycetaceae, Nocardioidaceae, and Pseudonocardiaceae were strongly correlated with increased shoot biomass and total Cd/Zn accumulation. Inoculation of S. alfredii with the synthetic bacterial community sharing the same phylogenetic relatedness with the vertically transmitted endophytes resulted in significant improvements in plant biomass, root morphology, and Cd/Zn accumulation. Our results demonstrate that successful vertical transmission of endophytes from shoots of S. alfredii to its rhizocompartments is possible, particularly in soils with attenuated microbiomes. Furthermore, the endophyte-derived microbiome plays an important role in metal hyperaccumulation.
