Note: This page contains sample records for the topic root 3ag due from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

CORRIGENDUM: Thermal switching of the electrical conductivity of Si(111)(?3 × ?3)Ag due to a surface phase transition  

NASA Astrophysics Data System (ADS)

Our recent paper on the surface conductivity of Si(111)(?3 × ?3)Ag [1] contains an error in the numerical simulation of the space charge layer conductance presented in figure 2(b) of the paper. A new version of the figure is presented here as figure 1. The incorrect version of this figure suggested that the space charge layer conductivity of Si(111)(?3 × ?3)Ag is very similar to that of the clean Si(111)(7 × 7) surface but actually this is not the case. The space charge layer for Si(111)(7 × 7) becomes strongly insulating at low temperatures whereas it is rather conductive over the whole temperature range for Si(111)(?3 × ?3)Ag. Figure 1 Figure 1. Experimental results (broken lines and markers) together with simulations (solid lines) of the conductance. The simulation in (b) has now been corrected, but the figure is otherwise the same as figure 2 from [1]. The model calculation shows the expected conductance of the bulk and space charge layer in (a) and (b) and for the expected conductance of a 3 ML Ag film with bulk properties in (c). The error in the calculation of the space charge layer conductivity has an impact on the interpretation of the low temperature measurements. Based on the incorrect calculation, it was concluded that the measurements are always surface sensitive, but this is not the case. In fact, the measured conductance in the low temperature regime is now quite similar to the conductance one could expect for the bulk and space charge layer.The interpretation of the data as a switching due to the surface phase transition is still consistent with results, especially since the transition in conductivity is much steeper than one would expect for a mechanism involving the freezing of carriers in the space charge region. However, we would also like to mention an alternative interpretation at this point. The free-electron like surface state on Si(111)(?3 × ?3)Ag is unoccupied at zero temperature because the bottom of the band coincides with the Fermi energy [2]. At finite temperature, thermally excited carriers are present in the surface state band. It is therefore conceivable that the strong change in surface conductivity is caused by the thermal emptying of the surface state band as the temperature is lowered. At low temperature, the surface state band is devoid of carriers and only transport through the bulk and space charge layer can be observed. References [1] Wells J W, Kallehauge J F and Hofmann Ph 2007 J. Phys.: Condens. Matter 19 176008 [2] Crain J N, Gallagher M C, McChesney J L, Bissen M and Himpsel F J 2005 Phys. Rev. B 72 045312

Wells, J. W.; Kallehauge, J. F.; Hofmann, Ph

2008-04-01

2

STM images apparently corresponding to a stable structure: considerable fluctuation of a phase boundary of the Si(111)-(square root of (3) x square root of (3))-Ag surface.  

PubMed

We study scanning tunneling microscopy (STM) images near a phase boundary of the Si(111)- (square root of (3) x square root of (3))-Ag surface by using Monte Carlo simulations based on results of first-principles calculations. The boundary is found to fluctuate from snapshot to snapshot, and the feature of the simulated STM images differs distinctly from the observed one with a straightly extending honeycomb pattern of bright spots. Remarkably, statistical averages of the simulated images reproduce the observed feature. This study gives a warning of our tendency to relate STM images revealing clear arrangement of bright spots with some stable structure. PMID:11580712

Nakamura, Y; Kondo, Y; Nakamura, J; Watanabe, S

2001-09-19

3

Effect of Aggregates Compaction in Soil Hydraulic Properties, due to Root Growth  

NASA Astrophysics Data System (ADS)

The rhizosphere is critical for soil-root interactions, however, physical processes within the soil around roots and implications of these processes, such as plant water and nutrient uptake, continue to raise questions. Soil compaction, due to root growth, results in favorable physical conditions in the rhizosphere to foster plant growth by providing aeration under wet conditions and improving water storage and flow toward the roots under dry conditions. In unsaturated conditions, the air transfer occurs through the macropores, while the water transfer occurs through the aggregates; providing the plant with these two vital elements, continuously. At the aggregate-scale, compaction gives connectivity within the aggregates. As the contact area between the aggregates increases, more water may be transfer to the plant. As result, the hydraulic conductivity of the rhizosphere may be higher than that at initial conditions (i.e., before compaction). This idea is important, as usually compaction is associated with decreasing water conductivity. This study focuses on understanding the role of roots to modify the soil, and in particular, their impact on rhizosphere hydraulic properties at the aggregate-scale. Using HYDRUS 3D, an aggregate system was modeled. It was found that the saturated hydraulic conductivity of the system increased following an S-shape as contact area increased due to compaction. This result differs from previous studies that assumed a quadratic relation. In addition, it was found that the compaction of big pores within the aggregates will be more beneficial for water extraction purposes, than the change in pore-size distribution within the aggregates due to compaction.

Aravena, J. E.; Tyler, S. W.; Berli, M.

2009-12-01

4

Stochastic modeling of salt accumulation in the root zone due to capillary flux from brackish groundwater  

Microsoft Academic Search

Root zone salinity depends on the mean fluxes (P,U,L,ET)Root zone salinity increases almost linear with groundwater salinityIf U>L root zone concentration becomes larger than in groundwater and vice versa

S. H. H. Shah; R. W. Vervoort; S. Suweis; A. J. Guswa; A. Rinaldo; S. E. A. T. M. van der Zee

2011-01-01

5

Alterations in soybean root development due to cultural practices: A review  

Microsoft Academic Search

The heterogeneous nature of the soil of the root zone will produce wide variations in soybean (Glycine max (L.) Merrill) root development. The effects of management practices on root development are not as well understood as are the effects of cultural practices on shoot development. General descriptions of soybean root system production are presented in the literature. Evidence has also

F. J. Coale; J. H. Grove

1986-01-01

6

Reduced filament coupling in Bi(2223)/BaZrO3/Ag composite tapes  

NASA Astrophysics Data System (ADS)

Multifilamentary Bi(2223)/Ag tapes often exhibit AC loss levels comparable to those measured in monofilamentary samples, which is partly due to the large coupling currents induced in the low resistive sheath material. Surrounding the individual filaments by electrically insulating barrier layers suppresses these currents and strongly reduces the coupling. We demonstrate this effect with various types of magnetic and self-field AC loss measurements on a series of Bi(2223)/BaZrO3/Ag tapes. We also discuss the influence of barrier thickness, twist pitch length and filament arrangement on the measured losses in these composite conductors.

Dhallé, M.; Polcari, A.; Marti, F.; Witz, G.; Huang, Y. B.; Flükiger, R.; Clerc, S.; Kwasnitza, K.

1998-12-01

7

Stochastic modeling of salt accumulation in the root zone due to capillary flux from brackish groundwater  

NASA Astrophysics Data System (ADS)

Groundwater can be a source of both water and salts in semiarid areas, and therefore, capillary pressure-induced upward water flow may cause root zone salinization. To identify which conditions result in hazardous salt concentrations in the root zone, we combined the mass balance equations for salt and water, further assuming a Poisson-distributed daily rainfall and brackish groundwater quality. For the water fluxes (leaching, capillary upflow, and evapotranspiration), we account for osmotic effects of the dissolved salt mass using Van`t Hoff's law. Root zone salinity depends on salt transport via capillary flux and on evapotranspiration, which concentrates salt in the root zone. Both a wet climate and shallow groundwater lead to wetter root zone conditions, which in combination with periodic rainfall enhances salt removal by leaching. For wet climates, root zone salinity (concentrations) increases as groundwater is more shallow (larger groundwater influence). For dry climates, salinity increases as groundwater is deeper because of a drier root zone and less leaching. For intermediate climates, opposing effects can push the salt balance either way. Root zone salinity increases almost linearly with groundwater salinity. With a simple analytical approximation, maximum concentrations can be related to the mean capillary flow rate, leaching rate, water saturation, and groundwater salinity for different soils, climates, and groundwater depths.

Shah, S. H. H.; Vervoort, R. W.; Suweis, S.; Guswa, A. J.; Rinaldo, A.; van der Zee, S. E. A. T. M.

2011-09-01

8

[Sciatica due to unusual causes: Tarlov cysts and nerve roots anomalies].  

PubMed

Tarlov cysts and nerve roots anomalies usually involve lumbosacral roots and are often asymptomatic. MRI has enabled recognition of many conditions that used to be missed by CT or myelography investigations performed for back and leg pain. However, even without additional compressive impingement (disc hernia, spondylolisthesis or lumbar canal stenosis) these anomalies can be responsible for sciatica, motor deficit and bladder sphincter dysfunction. Tarlov cysts are perinervous dilatations of the dorsal root ganglion. CT and especially MRI can reveal these cysts and their precise relations with the neighboring structures. Delayed filling of the cysts can be visualized on the myelogram. MRI is more sensitive than CT myelography for a positive diagnosis of nerve root anomalies, a differential diagnosis with disc hernia and classification of these anomalies. Surgical treatment is indicated for symptomatic Tarlov cysts and nerve root anomalies resistant to conservative treatment. Better outcome is observed in patients with an additional compressive impingement component. We report two cases of sciatica: one caused by Tarlov cysts diagnosed by MRI and the other by nerve root anomalies diagnosed by CT myelography. In both cases, conservative treatment was undertaken. The clinical, radiological and therapeutic aspects of these disorders are discussed. PMID:18809189

Younes, M; Korbaa, W; Zrour, S; Bejia, I; Touzi, M; Bergaoui, N

2008-09-21

9

Plant growth promotion may compensate for losses due to moderate Aphanomyces root rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

A two-year study was conducted to investigate the use of chemically-induced resistance and biocontrol bacteria for reducing sugar beet root rot disease caused by the oomycete organism Aphanomyces cochlioides. Stand establishment, yield, and quality analysis of sugarbeets from replicated field plots...

10

Localized application of soil organic matter shifts distribution of cluster roots of white lupin in the soil profile due to localized release of phosphorus  

PubMed Central

Background and Aims Phosphorus (P) is a major factor controlling cluster-root formation. Cluster-root proliferation tends to concentrate in organic matter (OM)-rich surface-soil layers, but the nature of this response of cluster-root formation to OM is not clear. Cluster-root proliferation in response to localized application of OM was characterized in Lupinus albus (white lupin) grown in stratified soil columns to test if the stimulating effect of OM on cluster-root formation was due to (a) P release from breakdown of OM; (b) a decrease in soil density; or (c) effects of micro-organisms other than releasing P from OM. Methods Lupin plants were grown in three-layer stratified soil columns where P was applied at 0 or 330 mg P kg?1 to create a P-deficient or P-sufficient background, and OM, phytate mixed with OM, or perlite was applied to the top or middle layers with or without sterilization. Key Results Non-sterile OM stimulated cluster-root proliferation and root length, and this effect became greater when phytate was supplied in the presence of OM. Both sterile OM and perlite significantly decreased cluster-root formation in the localized layers. The OM position did not change the proportion of total cluster roots to total roots in dry biomass among no-P treatments, but more cluster roots were concentrated in the OM layers with a decreased proportion in other places. Conclusions Localized application of non-sterile OM or phytate plus OM stimulated cluster-root proliferation of L. albus in the localized layers. This effect is predominantly accounted for by P release from breakdown of OM or phytate, but not due to a change in soil density associated with OM. No evidence was found for effects of micro-organisms in OM other than those responsible for P release.

Li, Hai-Gang; Shen, Jian-Bo; Zhang, Fu-Suo; Lambers, Hans

2010-01-01

11

Plasmon-Enhanced Upconversion Fluorescence in Er3+:Ag Phosphate Glass: the Effect of Heat Treatment  

NASA Astrophysics Data System (ADS)

The melt quenching method is used to prepare erbium-doped silver nanoparticle (NP) embedded phosphate glass. The effect of annealing on the glass on the formation of silver NPs produced by the reduction of silver (Ag+ ?Ag°) is studied. The glass samples are characterized by x-ray diffraction, UV-vis-NIR absorption, photoluminescence spectroscopy and transmission electron microscopy (TEM) imaging. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs located around ~442 nm. The TEM imaging shows the homogeneous distribution of silver NPs of almost spherical shape with an average diameter of ~5 nm. Upconversion luminescence spectra show two major emissions at 550 and 638 nm, originating from the 4S3/2 and 4F9/2 energy levels of the Er3+ ions, respectively. The enhancement in the luminescence intensity of both the green and red bands is found to be due to the effective local field of the silver NPs as well as the energy transfer from the nanoclusters, comprised of centers with silver ions bound to silver atoms in dimers or trimers to Er3+ ions, whereas quenching occurred due to the energy transfer from erbium ions to silver NPs (Er3+ ?Ag°).

Raja, J. Amjad; R. Sahar, M.; K. Ghoshal, S.; R. Dousti, M.; Riaz, S.; R. Samavati, A.; N. A Jamaludin, M.; Naseem, S.

2013-02-01

12

Multiple scattering effects on X-ray photoelectron diffraction from Si(111) ?3 × ?3Ag and Sb surfaces  

Microsoft Academic Search

The effects of multiple scattering (MS) on X-ray photoelectron diffraction (XPD) from Si(111)?3 × ?3-Ag and -Sb (referred to as ?3-Ag and -Sb) surfaces have been studied using a MS concentric-shell algorithm for sufficiently large clusters. Significant MS effects that cannot be reconciled by a kinematical treatment have been seen for the ?3-Ag surface, but not for the ?3-Sb surface.

X. Chen; T. Abukawa; S. Kono

1996-01-01

13

AN ALKALINE HYDROLYSIS TISSUE DIGESTION SYSTEM FOR A BSL-3-AG CONTAINMENT FACILITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

An alkaline hydrolysis tissue digestion system was installed at the Arthropod-borne Animal Diseases Research Laboratory (ABADRL) Biosafety Level (BSL) 3-AG containment facility in 2000 to replace the antiquated pathologic waste incinerator because of significant costs for upgrading this incinerator ...

14

C-C bond coupling between the organometallic cations CH3Ag2+, CH3Cu2+ and CH3AgCu+ and allyliodide.  

PubMed

Electrospray ionisation on a mixture of AgNO(3) (in MeOH/H(2)O/acetic acid), (CH(3)CO(2))(2)Cu (in MeOH) and acetic acid (in MeOH) yields the metal carboxylate cations CH(3)CO(2)Ag(2)(+), CH(3)CO(2)AgCu(+) and CH(3)CO(2)Cu(2)(+). Collision induced dissociation of these carboxylate cations yields the organometallic cations CH(3)Ag(2)(+), CH(3)AgCu(+) and CH(3)Cu(2)(+). The ion-molecule reactions of these organometallic cations with allyliodide were studied in a quadrupole ion trap mass spectrometer. C-C bond coupling occurred to yield the ionic products Ag(2)I(+), AgCuI(+) and Cu(2)I(+). DFT calculations were carried out on these C-C bond coupling reactions. In all cases, the reactions are highly exothermic and involve initial coordination of the allyliodide to both metal atoms, with the iodine coordinating to one atom and the alkene moiety coordinating to the other. The overall mechanism of C-C bond coupling involves oxidative addition of the allyliodide followed by reductive elimination of 1-butene. PMID:19333507

Khairallah, George N; Waters, Tom; O'Hair, Richard A J

2009-02-20

15

Multiple scattering study of X-ray photoelectron diffraction from Si(111)- 3 × 3 - Ag surface  

Microsoft Academic Search

X-ray photoelectron diffraction (XPD) from Si(111)-3 × 3-Ag surface has been studied by an efficient multiple scattering cluster (MSC) scheme with sufficiently large clusters. It is found that there is a strong multiple scattering effect on the surface, and thus a failure of kinematical theory for XPD is seen for this surface. With a reliability factor (R-factor) analysis, we have

X. Chen; T. Abukawa; J. Tani; S. Kono

1996-01-01

16

Doping of a surface band on Si (111) &surd;(3)×&surd;(3)Ag  

Microsoft Academic Search

A semiconducting surface-state band on Si (111) &surd;(3)×&surd;(3)-Ag is doped by adsorption of additional Ag and Au atoms. Very high levels of doping can be achieved (0.0015 0.086 electrons per 1×1 unit cell), such that the silicon surface degenerates into a metal. The doping alters the band structure of the surface state and causes the rigid-band model to break down.

J. N. Crain; M. C. Gallagher; J. L. McChesney; M. Bissen; F. J. Himpsel

2005-01-01

17

Dim C60 fullerenes on Si(111) 3×3-Ag surface  

NASA Astrophysics Data System (ADS)

Scanning tunneling microscopy (STM) observations of the close-packed C60 fullerene arrays on Si(111) 3×3-Ag surface have revealed the presence of dim C60 molecules which constitute 9-12% of all fullerenes. The dim C60 fullerenes reside ~ 1.6 Å lower than the bright ("normal") C60. While the bright C60 are in continuous rotation, the dim C60 are fixed in one of the single orientations, indicating a more tight bonding to the surface. At room temperature (RT), the dynamic switching from bright to dim C60 and vice versa has been detected. Switching slows down with decreasing temperature and becomes completely frozen at 110 K, which implies that the switching is a thermally driven process. RT deposition of ~ 0.1 monolayer of Ag onto C60 array eliminates completely the dim C60 molecules. Experimental results can be understood if one assumes that formation of the dim C60 is associated with disintegration of Ag trimer on Si(111) 3×3-Ag surface under a given C60 fullerene.

Gruznev, D. V.; Matetskiy, A. V.; Bondarenko, L. V.; Zotov, A. V.; Saranin, A. A.; Chou, J. P.; Wei, C. M.; Wang, Y. L.

2013-06-01

18

DRY MATTER ALLOCATION AND ROOT MORPHOLOGY OF SUGARCANE, SAWGRASS, AND ST. AUGUSTINEGRASS DUE TO WATER-TABLE DEPTH  

Technology Transfer Automated Retrieval System (TEKTRAN)

Peat soils in the Everglades Agricultural Area of south Florida are subsiding and releasing nutrients in waterways due to decomposition by aerobic microorganisms. Restoring Everglades peat involves adding organic matter back to the soil as did the native sawgrass in predrainage time and removing nut...

19

Electroforming and Ohmic contacts in Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown process that changes the diode from its initial high resistance state (HRS) to a low resistance state (LRS). After electroforming, resistance switching memories (RSMs) use voltages to switch from HRS to LRS and back. Many MIM combinations are proposed for use in RSMs. In many cases conduction in the LRS is nearly temperature independent at low temperatures; an Ohmic contact with a barrier to electron injection of ~0 eV results from electroforming. Electroforming of Al-Al2O3-Ag diodes with amorphous anodic Al2O3 thicknesses between 12 and 41 nm has been studied. Two anodizing electrolytes have been used; 0.1 M ammonium pentaborate (bor-H2O) and a solution of 0.1 M of ammonium pentaborate per liter of ethylene glycol (bor-gly). Polarization of Al2O3 and negative charge in Al2O3 are much larger when Al2O3 is formed in bor-H2O solution than when Al is anodized in bor-gly solution. Electroforming of Al-Al2O3-Ag diodes results in an Ohmic contact at the Al-Al2O3 interface, voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) from filamentary conducting channels. Two distinct modes of electroforming occur for Al-Al2O3-Ag diodes. ?-forming occurs for 2.5 V <~ VS <~ 5 V, where VS is the applied voltage. It is characterized by an abrupt current jump with the simultaneous appearance of EL and EM. ?-forming occurs for VS >~ 7 V. I-V curves, EL, and EM develop gradually and are smaller than for ?-forming. Electroforming occurs more readily for diodes with Al2O3 formed in bor-H2O that have greater defect densities. Fully developed I-V curves have similar VCNR, EL, and EM after ?-forming or ?-forming. A model is proposed in which excited states of F-centers, oxygen vacancies in amorphous anodic Al2O3, form defect conduction bands. Electroforming that results in an Ohmic contact requires injection of positive charge at the Al-Al2O3 interface. ?-forming is the result of ionization of F-center recombination centers with energies that are close to the Al Fermi level. Hole injection by high-field ionization of valence band states of Al2O3 causes ?-forming.

Hickmott, T. W.

2012-03-01

20

Electromigration of Sn37Pb and Sn3Ag1.5Cu\\/Sn3Ag0.5Cu composite flip-chip solder bumps with Ti\\/Ni(V)\\/Cu under bump metallurgy  

Microsoft Academic Search

We examine electromigration fatigue reliability and morphological patterns of Sn–37Pb and Sn–3Ag–1.5Cu\\/Sn–3Ag–0.5Cu composite solder bumps in a flip–chip package assembly with Ti\\/Ni(V)\\/Cu UBM. The flip–chip test vehicle was subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4A\\/150°C, 0.5A\\/150°C, 0.6A\\/125°C, 0.6A\\/135°C, and 0.6A\\/150°C. The electrothermal coupling analysis was employed to investigate the current crowding

Yi-Shao Lai; Kuo-Ming Chen; Chin-Li Kao; Chiu-Wen Lee; Ying-Ta Chiu

2007-01-01

21

Electromigration reliability of Sn37Pb and Sn3Ag1.5Cu\\/Sn3Ag0.5Cu composite flip-chip solder bumps with Ti\\/Ni(V)\\/Cu under bump metallurgy  

Microsoft Academic Search

We examine electromigration fatigue reliability and morphological patterns of Sn-37Pb and Sn-3Ag-1.5Cu\\/Sn-3Ag-0.5Cu composite solder bumps in a flip-chip package assembly. The test vehicle is subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4 A\\/150 degC, 0.5 A\\/150 degC, 0.6 A\\/125 degC, 0.6 A\\/135 degC, and 0.6 A\\/150 degC. An electrothermal coupling analysis is

Yi-Shao Lai; Kuo-Ming Chen; Chiu-Wen Lee; Chin-Li Kao; Yu-Hsiu Shao

2005-01-01

22

Visualization of Thermally Fluctuating Surface Structure in Noncontact Atomic-Force Microscopy and Tip Effects on Fluctuation: Theoretical Study of Si(111)-( &surd;3 ×&surd;3)Ag Surface  

Microsoft Academic Search

We investigated noncontact atomic-force microscopy (NC-AFM) images of a thermally fluctuating surface structure together with tip effects based on the first-principles electronic state calculation. As an example the Si(111)-( (3)×(3))-Ag ( (3)-Ag) surface is studied. We have succeeded in theoretically visualizing the thermal fluctuation of the (3)-Ag surface at room temperature, and in reproducing the observed NC-AFM image for the

Naruo Sasaki; Satoshi Watanabe; Masaru Tsukada

2002-01-01

23

A First Principles Study on Dissociation and Adsorption Processes of H2 on Pd3Ag(111) Surface  

NASA Astrophysics Data System (ADS)

We investigated dissociative adsorption of H2 molecule on Pd3Ag(111) surface based on the constructed potential energy surfaces (PESs) from the results of first principles calculations. This study is performed to understand H2 dissociative adsorption mechanism on Pd3Ag(111) surface which acts as permeable film for H2 which is a product of biomass gasification. The PES results indicate that when the H2 molecule approaches the Ag atom of the 1st atomic layer, the activation barriers for dissociation start to increase. The dissociation of H2 on the surface has negligible activation barrier when the H2 center of mass (CM) is directly above the bridge site of Pd atoms while the hydrogen atoms are directed towards the hcp and fcc hollow sites. The average local density of states (LDOS) of the d-orbital of surface Pd atoms show peak in the region around the Fermi level which is not observed from the LDOS of the Ag atom in Pd3Ag(111) surface. This strongly supports the results of the constructed PES for H2 dissociative adsorption mechanism towards Pd3Ag(111) surface. This study will be significant for the design of hydrogen-permeable films which has applications on biomass-operated fuel cells.

Dipojono, Hermawan Kresno; Padama, Allan Abraham B.; Ozawa, Nobuki; Nakanishi, Hiroshi; Kasai, Hideaki

2010-11-01

24

Neutron diffraction and 119Sn Mössbauer study of Sm3Ag4Sn4  

NASA Astrophysics Data System (ADS)

The magnetic properties of Sm3Ag4Sn4 have been investigated using bulk magnetization, 119Sn Mössbauer spectroscopy and neutron diffraction. We find that the Néel temperature (TN) is 26.0(5) K, well above the value of ~9 K previously determined using magnetic susceptibility measurements. Neutron diffraction data indicate that the Sm moments most likely adopt either the IPmm'm or IPmmm' magnetic space groups, neither of which allows order at the 2d site, in marked contrast to the vast majority of other compounds in the R3T4X4 family. Transferred hyperfine field models suggest that the IPmmm' is the only group that is consistent with the 119Sn Mössbauer results. We derive a samarium moment of 0.47 ± 0.10 ?B on the Sm 4e site at 3 K. 119Sn Mössbauer spectroscopy shows that the system undergoes a spin reorientation transition at 8.3(3) K, where the moments rotate towards the a-axis.

Voyer, C. J.; Ryan, D. H.; Cadogan, J. M.; Cranswick, L. M. D.; Napoletano, M.; Riani, P.; Canepa, F.

2007-10-01

25

Contrasting diurnal variations in soil organic carbon decomposition and root respiration due to a hysteresis effect with soil temperature in a Gossypium s. (cotton) plantation  

Microsoft Academic Search

To understand the characteristics of the diurnal variation in soil respiration and its response to temperature, we used root\\u000a exclusion plots, and buried CO2 sensors in situ during the late growing season in northwestern China. Soil organic carbon (SOC) decomposition and root respiration\\u000a dynamics were quantified. In our study, we found that the diurnal variations in root respiration and soil

Zhiguo Li; Xiujun Wang; Runhua Zhang; Juan Zhang; Changyan Tian

2011-01-01

26

Striga seed-germination activity of root exudates and compounds present in stems of Striga host and nonhost (trap crop) plants is reduced due to root colonization by arbuscular mycorrhizal fungi.  

PubMed

Root colonization by arbuscular mycorrhizal (AM) fungi reduces stimulation of seed germination of the plant parasite Striga (Orobanchaceae). This reduction can affect not only host plants for Striga, resulting in a lower parasite incidence, but also false hosts or trap crops, which induce suicidal Striga seed germination, thereby diminishing their effectiveness. In order to better understand these AM-induced effects, we tested the influence of root colonization by different AM fungi on the seed-germination activity of root exudates of the Striga hermonthica nonhost plants cowpea and cotton on S. hermonthica. We also tested the effect of AM fungi on the seed-germination activity of the Striga gesnerioides host plant cowpea on S. gesnerioides. Moreover, we studied whether mycorrhization affects the transport of seed-germination activity to above-ground plant parts. Mycorrhization not only resulted in a lower seed germination of S. gesnerioides in the presence of root exudates of the S. gesnerioides host cowpea but also seed germination of S. hermonthica was also lower in the presence of root exudates of the S. hermonthica nonhosts cowpea and cotton. Downregulation of the Striga seed-germination activity occurs not only in root exudates upon root colonization by different AM fungi but also in the compounds produced by stems. The lowered seed-germination activity does not appear to depend on the presence of seed germination inhibitors in the root exudates of mycorrhizal plants. The implication for Striga control in the field is discussed. PMID:19238457

Lendzemo, V; Kuyper, T W; Vierheilig, H

2009-02-24

27

Intermetallic Compounds Formed in In-3Ag Solder BGA Packages with ENIG and ImAg Surface Finishes  

NASA Astrophysics Data System (ADS)

During the reflow process of In-3Ag solder ball grid array (BGA) packages with electroless nickel immersion gold (ENIG) and immersion silver (ImAg) surface finishes, continuous (Au0.9Ni0.1)In2 and scallop-shaped (Ag0.9Cu0.1)In2 intermetallic layers form at the interfaces of In-3Ag solder with Au/Ni/Cu and Ag/Cu pads, respectively. The (Au0.9Ni0.1)In2 layer breaks into clusters with increases in the aging time and temperature. Aging at 115 °C results in the formation of an additional continuous Ni10In27 layer on the Ni/Cu pads and the migration of (Au0.9Ni0.1)In2 intermetallic clusters into the solder matrix. In contrast, the (Ag0.9Cu0.1)In2 scallops grow into a continuous layer after aging treatment. Accompanying the interfacial reactions, AgIn2 precipitates in the interior of In-3Ag solder balls and coarsens during aging, causing the ball shear strengths of reflown ENIG (1.18 N) and ImAg (1.11 N)-surface-finished solder joints to decrease gradually. However, the migration of (Au0.9Ni0.1)In2 clusters into the solder matrix of ENIG-surface-finished In-3Ag packages leads to an increase in their ball shear strengths after aging at 115 °C over 300 h. Both the ENIG- and ImAg-surface-finished In-3Ag solder joints, after ball shear tests, have fractured across the solder balls with ductile characteristics.

Chuang, T. H.; Jain, C. C.; Wang, S. S.

2009-11-01

28

Arsenic-induced root growth inhibition in mung bean ( Phaseolus aureus Roxb.) is due to oxidative stress resulting from enhanced lipid peroxidation  

Microsoft Academic Search

Arsenic (As) toxicity and its biochemical effects have been mostly evaluated in ferns and a few higher plants. In this study,\\u000a we investigated the effect of As (10.0 and 50.0 ?M) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde\\u000a and conjugated dienes), electrolyte leakage, H2O2 content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb.). Arsenic

Harminder Pal Singh; Daizy R. Batish; Ravinder Kumar Kohli; Komal Arora

2007-01-01

29

Effect of Ni addition on the Sn0.3Ag0.7Cu solder joints  

Microsoft Academic Search

It is gradually recognized that Sn-Ag-Cu is better alloy system for application prospect in the lead-free solders. In order to cut down the cost and improve properties, researchers have always been searching for proper compositions and adding elements to improve properties actively. This paper has investigated the effect of Ni addition on Sn-0.3Ag-0.7Cu (SAC0307) low-Ag solder joint. The results of

Lingling Wang; Fenglian Sun; Yang Liu; Lifeng Wang

2009-01-01

30

The Overlayer Structure on the Si(001)-(2×3)Ag Surface Determined by X-ray Photoelectron Diffraction  

Microsoft Academic Search

X-ray photoelectron diffraction (XPD) patterns of Ag 3d electrons from a single domain Si(001)-(2×3)-Ag surface were examined. Single scattering cluster and multiple scattering cluster simulations of the Ag 3d XPD patterns indicate an overlayer that contains four Ag atoms aligned almost linearly along the threefold direction in the unit cell on the Si(001) surface. The four-Ag-atom arrangement is discussed in

M. Shimomura; T. Abukawa; M. Higa; M. Nakamura; S. M. Shivaprasad; H. W. Yeom; S. Suzuki; S. Sato; J. Tani; S. Kono

1998-01-01

31

Interfacial microstructure between Sn-3Ag-xBi alloy and Cu substrate with or without electrolytic Ni plating  

NASA Astrophysics Data System (ADS)

The microstructure of the interfacial phase of Sn-3Ag-xBi alloy on a Cu substrate with or without electrolytic Ni plating was evaluated. Bismuth additions into Sn-Ag alloys do not affect interfacial phase formations. Without plating, ?-Cu6Sn5/?-Cu3Sn interfacial phases developed as reaction products in the as-soldered condition. The ?-phase Cu6Sn5 with a hexagonal close-packed structure grows about 1-µm scallops. The ?-phase Cu3Sn with an orthorhombic structure forms with small 100-nm grains between ?-Cu6Sn5 and Cu. For Ni plating, a Ni3Sn4 layer of monoclinic structure formed as the primary reaction product, and a thin ?-Ni3Sn2 layer of hexagonal close-packed structure forms between the Ni3Sn4 and Ni layer. In the Ni layer, Ni-Sn compound particles of nanosize distribute by Sn diffusion into Ni. On the total thickness of interfacial reaction layers, Sn-3Ag-6Bi joints are thicker by about 0.9 µm for the joint without Ni plating and 0.18 µm for the joint with Ni plating than Sn-3Ag joints, respectively. The thickening of interfacial reaction layers can affect the mechanical properties of strength and fatigue resistance.

Hwang, Chi-Won; Lee, Jung-Goo; Suganuma, Katsuaki; Mori, Hirotaro

2003-02-01

32

Striga seed-germination activity of root exudates and compounds present in stems of Striga host and nonhost (trap crop) plants is reduced due to root colonization by arbuscular mycorrhizal fungi  

Microsoft Academic Search

Root colonization by arbuscular mycorrhizal (AM) fungi reduces stimulation of seed germination of the plant parasite Striga (Orobanchaceae). This reduction can affect not only host plants for Striga, resulting in a lower parasite incidence, but also false hosts or trap crops, which induce suicidal Striga seed germination, thereby diminishing their effectiveness. In order to better understand these AM-induced effects, we

V. W. Lendzemo; T. W. Kuyper; H. Vierheilig

2009-01-01

33

MRI in soils: determination of water concent changes due to root water uptake by means of a multi-slice-multi-echo sequence (MSME)  

Microsoft Academic Search

Root water uptake by ricinus communis (castor bean) in fine sand was investigated using MRI with multiecho sampling. Before starting the experiments the plants germinated and grew for 3 weeks in a cylindrical container with a diameter of 9 cm. Immediately before the MRI experiments started, the containers were water-saturated and sealed, so water content changes were only caused by

A. Pohlmeier; F. Vergeldt; E. Gerkema; As van H; Dusschoten van D; H. Vereecken

2010-01-01

34

Effects of defect size in root region on fatigue strength of fillet welded joints—root failure of non?load?carrying cruciform fillet welded joints due to toe treatment (2 report)  

Microsoft Academic Search

This paper describes an investigation of the effects of the defect size in the root region on the fatigue strength of non?load?carrying cruciform fillet welded joints by FEM analysis, fatigue tests, and hardness tests. The results may be summarised as follows. 1. Through TIG dressing of the toe region of fillet welded joints, joints have a fatigue limit of 1.4?2.5

S. Ohta; H. Kitamura

1994-01-01

35

Heterogeneity and topsoil depletion due to tillage erosion and soil co-extraction with root vegetables: a serious threat to sustainable agricultural land use in the UK  

NASA Astrophysics Data System (ADS)

The term soil erosion has become almost synonymous with water erosion and yet tillage erosion and soil loss with root crop harvest, although less visible, may be responsible for the majority of the on-site costs of soil erosion in many arable areas of the UK. The study reported here is a first attempt to model soil erosion associated with these processes in England and Wales, at the National scale. A GIS-based modelling approach in the Arc/Info environment is employed in order to meet the requirement for large-scale evaluation of erosion severity. Existing models that have been subject to independent test are used or adapted and widely available data is employed in model parameterisation. Tillage erosion is simulated using a diffusion-type model and a slope curvature index derived from coarse-scale topographic data. The curvature index is calibrated by statistical comparison to curvature values derived from a high resolution digital terrain model. Soil loss with root crop harvest is simulated using information concerning patterns of sugar beet and potato cultivation and estimation of soil moisture during the crop harvest season. Soil loss associated with root crop harvest may be as high as 1 t ha-1 year-1 if land is permanently used for root crops in a 3 year rotation. However, when the arable area of the UK is considered as a whole root crop harvest is responsible for a mean rate of soil loss of approximately 0.1 t ha-1 year-1. Tillage erosion is found to be the dominant process of soil redistribution and onsite erosion on arable land, in comparison with both soil loss through root crop harvest and with long-term water erosion rates. Mean gross rates of tillage erosion were found to be 3.7 t ha-1 year-1, representing approximately 7.4 t ha-1 year-1 erosion and the same rate of deposition. Soil redistribution at these rates is generating an heterogeneous soilscape in which continued functioning for food and fibre production may be jeopardized. These problems may be exacerbated by increased water stress in eroded soils if climate change does, as predicted, result in hotter and drier summers.

Quine, Timothy; van Oost, Kristof

2010-05-01

36

Conductivity study on GeS2-Ga2S3-AgI-Ag chalcohalide glasses  

NASA Astrophysics Data System (ADS)

A new kind of ion-conducting glasses based on GeS2-Ga2S3-AgI system is prepared. A relatively large amount of silver can be dissolved into this kind of glass system, and the obtained glasses are still transparent in the red part of the visible spectrum. Only a three times increase in the silver concentration can lead to approximately two hundred times increase in the ionic conductivity. The structural contributions to the ionic conductivity of the glasses are discussed. The present glasses show potential to be used as solid state electrolyte.

Ren, Jing; Yan, Qiqi; Wagner, Tomas; Zima, Vitezslav; Frumar, Miloslav; Frumarova, Bozena; Chen, Guorong

2013-07-01

37

RNAi mediated silencing of a wall associated kinase, OsiWAK1 in Oryza sativa results in impaired root development and sterility due to anther indehiscence: Wall Associated Kinases from Oryza sativa.  

PubMed

The Wall-Associated Kinase, one of the receptor-like kinase (RLK) gene families in plant, plays important roles in cell expansion, pathogen resistance and heavy metal stress tolerance in Arabidopsis thaliana. Here, we isolated a cDNA encoding a novel WAK from indica rice and designated as OsiWAK1 (Oryza sativa indica WAK-1). In this study, the RNAi construct with OsiWAK1 gene cloned in sense and antisense orientation separated by a functional intron under constitutive promoter, was introduced through biolistic gene gun method into the rice cultivar "IR-50" to determine the effect of OsiWAK1 transcript silencing on rice plant development. Examination of the transgenic plants reveals that OsiWAK1 transcript silencing in rice results in dwarf plants because of the reduction in the size of leaves, flag-leaves, internodes and panicle. The development of root primordia during germination, root hairs and lateral rooting was also effected. Microscopic analysis revealed that the decrease in size is due to reduction in the cell size but not the number of cells. In addition, the transgenic plants also exhibited sterile phenotype due to anther indehiscence and 40 % reduction in pollen viability. These data suggest that OsiWAK1 may play an important role in rice plant growth and development. PMID:23572996

Kanneganti, Vydehi; Gupta, Aditya Kumar

2011-01-21

38

Root systems  

NSDL National Science Digital Library

One purpose that roots serve is that of anchoring the plant in the ground. Roots also take up water and nutrients for the plant. Plants all have different root system types to fit their individual needs and locations.

N/A N/A (U.S. Government;)

2004-10-30

39

Transparent organic thin film transistors with WO3/Ag/WO3 source-drain electrodes fabricated by thermal evaporation  

NASA Astrophysics Data System (ADS)

High-performance transparent organic thin film transistors using a WO3/Ag/WO3 (WAW) multilayer as the source and drain electrodes have been developed without breaking the vacuum. The WAW electrodes were deposited by thermal evaporation at room temperature, leading to little damage to organic film. The optimized WAW electrode shows high transmittance (86.57%), low sheet resistance (11 ?/sq), and a high work function (5.0 eV). Consequently, we obtained high performance devices with mobility of 8.44 × 10-2 cm2/V . s, an on/off ratio of approximately 1.2 × 106, and an average visible range transmittance of 81.5%.

Zhang, Nan; Hu, Yongsheng; Liu, Xingyuan

2013-07-01

40

Adsorbate-Induced Segregation in a PdAg Membrane Model System: Pd3Ag(1 1 1)  

SciTech Connect

Thin PdAg alloy membranes with 20–25% Ag are being developed for hydrogen separation technology. Despite many investigations on such membranes as well as representative experimental and theoretical model systems, unresolved issues remain concerning the effect of the alloy surface structure and composition on adsorption and vice versa. Therefore, the interaction between hydrogen, carbon monoxide or oxygen with the surface of a PdAg model alloy was studied using periodic self-consistent density functional theory (DFT-GGA) calculations. In particular, the adsorption structure, coverage dependence and possible adsorption-induced segregation phenomena were addressed using Pd3Ag(1 1 1) model surfaces with varying degrees of surface segregation. In agreement with previous experimental and theoretical investigations, we predict Ag surface termination to be energetically favorable in vacuum. The segregation of Ag is then reversed upon adsorption of H, CO or O. For these adsorbates, the binding is strongest on Pd three-fold hollow sites, and hence complete Pd termination is favored at high coverage of H or CO, while 25% Ag may remain under oxygen because of the lower O-saturation coverage. CO adsorption provides a somewhat stronger driving force for Pd segregation when compared to H, and this may have implications with respect to permeation properties of PdAg alloy surfaces. Our predictions for high coverage are particularly relevant in underlining the importance of segregation phenomena to the hydrogen transport properties of thin PdAg alloy membranes.

Svenum, I. H.; Herron, Jeffrey A.; Mavrikakis, Manos; Venvik, H. J.

2012-10-15

41

Descendant root volume varies as a function of root type: estimation of root biomass lost during uprooting in Pinus pinaster  

PubMed Central

Root systems of woody plants generally display a strong relationship between the cross-sectional area or cross-sectional diameter (CSD) of a root and the dry weight of biomass (DWd) or root volume (Vd) that has grown (i.e., is descendent) from a point. Specification of this relationship allows one to quantify root architectural patterns and estimate the amount of material lost when root systems are extracted from the soil. However, specifications of this relationship generally do not account for the fact that root systems are comprised of multiple types of roots. We assessed whether the relationship between CSD and Vd varies as a function of root type. Additionally, we sought to identify a more accurate and time-efficient method for estimating missing root volume than is currently available. We used a database that described the 3D root architecture of Pinus pinaster root systems (5, 12, or 19 years) from a stand in southwest France. We determined the relationship between CSD and Vd for 10,000 root segments from intact root branches. Models were specified that did and did not account for root type. The relationships were then applied to the diameters of 11,000 broken root ends to estimate the volume of missing roots. CSD was nearly linearly related to the square root of Vd, but the slope of the curve varied greatly as a function of root type. Sinkers and deep roots tapered rapidly, as they were limited by available soil depth. Distal shallow roots tapered gradually, as they were less limited spatially. We estimated that younger trees lost an average of 17% of root volume when excavated, while older trees lost 4%. Missing volumes were smallest in the central parts of root systems and largest in distal shallow roots. The slopes of the curves for each root type are synthetic parameters that account for differentiation due to genetics, soil properties, or mechanical stimuli. Accounting for this differentiation is critical to estimating root loss accurately.

Danjon, Frederic; Caplan, Joshua S.; Fortin, Mathieu; Meredieu, Celine

2013-01-01

42

Effect of indium addition on the microstructural formation and soldered interfaces of Sn-2.5Bi-1Zn-0.3Ag lead-free solder  

NASA Astrophysics Data System (ADS)

The microstructural formation and properties of Sn-2.5Bi- xIn-1Zn-0.3Ag (in wt%) alloys and the evolution of soldered interfaces on a Cu substrate were investigated. Apart from the relatively low melting point (about 195°C), which is close to that of conventional eutectic Sn-Pb solder, the investigated solder presents superior wettability, solderability, and ductility. The refined equiaxial grains enhance the mechanical properties, and the embedded bulk intermetallic compounds (IMCs) (Cu6Sn5 and Cu5Zn8) and granular Bi particles improve the joint reliability. The addition of In reduces the solubility of Zn in the ?-Sn matrix and strongly influences the separation and growth behaviors of the IMCs. The soldered interface of Sn-2.5Bi- xIn-1Zn-0.3Ag/Cu consists of Cu-Zn and Cu-Sn IMC layers.

Dong, Ming-jie; Gao, Zhi-ming; Liu, Yong-chang; Wang, Xun; Yu, Li-ming

2012-11-01

43

Relationship between root structure and root cadmium uptake in maize  

Microsoft Academic Search

A clear description of the mechanism of root cadmium absorption is required in order to understand how this toxic metal is phytoaccumulated. An experiment was carried out in order to test the hypotheses that (1) the Cd uptake is higher for maize roots grown in hydroponics than for those grown in aeroponics, (2) this difference is due to the fact

Tanegmart Redjala; Ivan Zelko; Thibault Sterckeman; Valérie Legué; Alexander Lux

2011-01-01

44

Noble and alkali adatoms on a \\mathrm {Si(111) \\sqrt {3} \\times \\sqrt {3}} -Ag surface: a first-principles study  

NASA Astrophysics Data System (ADS)

Using first-principles calculations, we present a comprehensive study on the atomic and electronic structures of metal adatoms (noble metals Ag, Au, Cu and alkali metals Li, Na, K) adsorbed on a \\mathrm {Si(111)\\sqrt {3} \\times \\sqrt {3}} -Ag (hereafter \\sqrt {3} -Ag) surface. We found that adsorption of noble and alkali adatoms can induce significant structural changes in the topmost Ag layer. The most striking and interesting results are the immersion of the noble and Li adatoms into the substrate Ag layer and the finding of the most stable configurations with three adatoms incorporating into or being adsorbed on the surface dependent on their atomic radii. We also found that the almost empty two-dimensional free-electron-like band s1 and its band folding s1* of the original surface band s1 of the \\sqrt {3} -Ag surface split into a gap at the surface Brillouin zone (SBZ) boundary with adsorption of an adatom. The two surface bands gradually move downwards and the s1 band is gradually filled with an increase of coverage. The s1 band is fully occupied with the largest band gap ~ 0.25 eV between the s1 and s1* bands at the critical coverage of 0.14 monolayers (ML) [three adatoms in a \\mathrm {Si(111)}\\sqrt {21} \\times \\sqrt {21} -Ag (hereafter \\sqrt {21} -Ag) unit cell], which corresponds to the most stable adsorption phase. Although the adsorption configurations are different, both the noble and alkali adatom adsorptions give rise to similar electronic structures at low coverages, indicating a free-electron-like character of the adsorption surfaces.

Xie, Xin; Li, J. M.; Chen, W. G.; Wang, F.; Li, S. F.; Sun, Q.; Jia, Yu

2010-03-01

45

Compression stress-strain and creep properties of the 52In48Sn and 97In3Ag low-temperature Pb-free solders  

Microsoft Academic Search

Lead (Pb)-free, low melting temperature solders are required for step-soldering processes used to assemble micro-electrical\\u000a mechanical system (MEMS) and optoelectronic (OE) devices. Stress-strain and creep studies, which provide solder mechanical\\u000a properties for unified creep-plasticity (UCP) predictive models, were performed on the Pb-free 97In-3Ag (wt.%) and 58In-42Sn\\u000a solders and counterpart Pb-bearing 80In-15Pb-5Ag and 70In-15Sn-9.6Pb-5.4Cd alloys. Stress-strain tests were performed at 4.4

Paul T. Vianco; Jerome A. Rejent; Arlo F. Fossum; Michael K. Neilsen

46

In situ observation of thermomigration of Sn atoms to the hot end of 96.5Sn-3Ag-0.5Cu flip chip solder joints  

NASA Astrophysics Data System (ADS)

In this study, we investigated the phenomenon of thermomigration in 96.5Sn-3Ag-0.5Cu flip chip solder joints at an ambient temperature of 150 °C. We observed mass protrusion on the chip side (hot end), indicating that Sn atoms moved to the hot end, and void formation on the substrate side (cold end). The diffusion markers also moved to the substrate side, in the same direction of the vacancy flux, indicating that the latter played a dominant role during the thermomigration process. The molar heat of transport (Q*) of the Sn atoms was 3.38 kJ/mol.

Ouyang, Fan-Yi; Kao, C.-L.

2011-12-01

47

Mechanical test after temperature cycling on lead-free Sn3Ag0.5Cu solder joint  

Microsoft Academic Search

The solder balls on the plastic ball grid array (PBGA) packages provide both electrical input\\/output and mechanical supports. Mechanical properties and strengths of solder balls significantly influence the PBGA package reliability. Temperature cycling test has been widely used in flip-chip technology (FCT) in order to simulate the failure mode due to fatigue and aging under repeatedly heat treatment. In this

Chung-Nan Peng; Jenq-Gong Duh

2008-01-01

48

Descendant root volume varies as a function of root type: estimation of root biomass lost during uprooting in Pinus pinaster.  

PubMed

Root systems of woody plants generally display a strong relationship between the cross-sectional area or cross-sectional diameter (CSD) of a root and the dry weight of biomass (DWd) or root volume (Vd) that has grown (i.e., is descendent) from a point. Specification of this relationship allows one to quantify root architectural patterns and estimate the amount of material lost when root systems are extracted from the soil. However, specifications of this relationship generally do not account for the fact that root systems are comprised of multiple types of roots. We assessed whether the relationship between CSD and Vd varies as a function of root type. Additionally, we sought to identify a more accurate and time-efficient method for estimating missing root volume than is currently available. We used a database that described the 3D root architecture of Pinus pinaster root systems (5, 12, or 19 years) from a stand in southwest France. We determined the relationship between CSD and Vd for 10,000 root segments from intact root branches. Models were specified that did and did not account for root type. The relationships were then applied to the diameters of 11,000 broken root ends to estimate the volume of missing roots. CSD was nearly linearly related to the square root of Vd, but the slope of the curve varied greatly as a function of root type. Sinkers and deep roots tapered rapidly, as they were limited by available soil depth. Distal shallow roots tapered gradually, as they were less limited spatially. We estimated that younger trees lost an average of 17% of root volume when excavated, while older trees lost 4%. Missing volumes were smallest in the central parts of root systems and largest in distal shallow roots. The slopes of the curves for each root type are synthetic parameters that account for differentiation due to genetics, soil properties, or mechanical stimuli. Accounting for this differentiation is critical to estimating root loss accurately. PMID:24167506

Danjon, Frédéric; Caplan, Joshua S; Fortin, Mathieu; Meredieu, Céline

2013-10-23

49

Energies and excited-state dynamics of 1Bu+, 1Bu- and 3Ag- states of carotenoids bound to LH2 antenna complexes from purple photosynthetic bacteria  

NASA Astrophysics Data System (ADS)

Time-resolved pump-probe stimulated-emission and transient-absorption spectra were recorded after excitation with ˜30 fs pulses to the 1Bu+(0) and optically-forbidden diabatic levels of carotenoids, neurosporene, spheroidene and lycopene having n = 9-11 double bonds, bound to LH2 antenna complexes from Rhodobacter sphaeroides G1C, 2.4.1 and Rhodospirillum molischianum. The low-energy shift of stimulated emission from the covalent 1Bu-(0) and 3Ag-(0) levels slightly larger than that from the ionic 1Bu+(0) state suggests the polarization, whereas more efficient triplet generation suggests the twisting of the conjugated chain in Cars bound to the LH2 complexes, when compared to Cars free in solution.

Christiana, Rebecca; Miki, Takeshi; Kakitani, Yoshinori; Aoyagi, Shiho; Koyama, Yasushi; Limantara, Leenawaty

2009-10-01

50

Image analysis from root system pictures  

NASA Astrophysics Data System (ADS)

Root research has been hampered by a lack of good methods and by the amount of time involved in making measurements. In general the studies from root system are made with either monolith or minirhizotron method which is used as a quantitative tool but requires comparison with conventional destructive methods. This work aimed to analyze roots systems images, obtained from a root atlas book, to different crops in order to find the root length and root length density and correlate them with the literature. Five crops images from Zea mays, Secale cereale, Triticum aestivum, Medicago sativa and Panicum miliaceum were divided in horizontal and vertical layers. Root length distribution was analyzed for horizontal as well as vertical layers. In order to obtain the root length density, a cuboidal volume was supposed to correspond to each part of the image. The results from regression analyses showed root length distributions according to horizontal or vertical layers. It was possible to find the root length distribution for single horizontal layers as a function of vertical layers, and also for single vertical layers as a function of horizontal layers. Regression analysis showed good fits when the root length distributions were grouped in horizontal layers according to the distance from the root center. When root length distributions were grouped according to soil horizons the fits worsened. The resulting root length density estimates were lower than those commonly found in literature, possibly due to (1) the fact that the crop images resulted from single plant situations, while the analyzed field experiments had more than one plant; (2) root overlapping may occur in the field; (3) root experiments, both in the field and image analyses as performed here, are subject to sampling errors; (4) the (hand drawn) images used in this study may have omitted some of the smallest roots.

Casaroli, D.; Jong van Lier, Q.; Metselaar, K.

2009-04-01

51

Fabrication of a solid state power source for ambient conditions using solid electrolyte system (SbI3)0.3-(Ag2CrO4)0.7  

NASA Astrophysics Data System (ADS)

Fast ion conducting system (SbI3)0.3 - (Ag2CrO4)0.7 containing 0.3 mole fraction SbI3 was synthesized by rapid melt-quenching method. The open circuit voltage, (OCV) measured for the solid state primary electrochemical cell fabricated using the above best conducting composition (SbI3)0.3 - (Ag2Cr04)0.7 is found to be 641 mV. Detailed discharge characteristics evaluated under different load conditions for the solid state cell have indicated certain interesting features.

Suthanthiraraj, S. Austin; Sarojini, S.

2012-06-01

52

Singlet internal conversion processes in the order of 1Bu+?3Ag-?1Bu-?2Ag-?1Ag- in all- trans-spheroidene and lycopene as revealed by subpicosecond time-resolved Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Key Raman lines ascribable to the 1Bu+, 3Ag-, 1Bu- and 2Ag- states were identified in the subpicosecond time-resolved Raman spectra of spheroidene and lycopene having 10 and 11 conjugated double bonds, respectively. The sequential rise-and-decay of the key Raman lines showed the internal conversion processes of 1Bu+?3Ag-?1Bu-?2Ag-?1Ag- (ground). The time constant in each step of internal conversion reflects the energy gap between the relevant states that had been determined by measurement of resonance - Raman excitation profiles [K. Furuichi, T. Sashima, Y. Koyama, Chem. Phys. Lett. 356 (2002) 547].

Rondonuwu, Ferdy S.; Kakitani, Yoshinori; Tamura, Hiroshi; Koyama, Yasushi

2006-09-01

53

Effects of High-Temperature Treatment on the Reaction Between Sn-3%Ag-0.5%Cu Solder and Sputtered Ni-V Film on Ferrite Substrate  

NASA Astrophysics Data System (ADS)

We have demonstrated a novel sputtering method for lead-free thin metal films on ferrite substrates for surface-mount inductor applications. In a surface-mounting process, the cladding of enameled wire needs to be burnt off at high temperature, which requires the devices to withstand a high-temperature reliability test at 420°C for 10 s. There are no reports that a sputtered film of thickness less than 6 ?m can withstand this test. In this work, we used Ag/Ni-7 wt.%V double metal layers for the metallization. The dissolution of Ni-7 wt.%V in Sn-3%Ag-0.5%Cu lead-free solder at various temperatures was studied in detail. Scanning electron microscopy with energy-dispersive x-ray spectroscopy was used to investigate the interfacial reaction between the sputtered films and the solder. The intermetallic compounds are mainly (Cu,Ni)6Sn5 at 250°C; however, (Ni,Cu)3Sn4 becomes the predominant composition at 420°C. In addition, although outdiffusion of V atoms from the Ni-V layer was observed, its effect on the intermetallic compound (IMC) was insignificant. We further confirmed that the proposed metallization is able to pass the aforementioned high-temperature reliability test.

Shen, Xiaohu; Jin, Hao; Dong, Shurong; Wong, Hei; Zhou, Jian; Guo, Zhaodi; Wang, Demiao

2012-11-01

54

Roots and Shoots  

NSDL National Science Digital Library

In this outdoor activity, learners discover that plants aren't just shoots (stem, branches, leaves, and flowers) growing above ground, but contain plenty of roots growing undergroundâmore than half the mass of a plant can be its roots. Learners dig up "mystery" plants to investigate their root structures, and match them to different types of root systems. Learners also learn about animals found near plant roots and how humans use roots.

Science, Lawrence H.

2008-01-01

55

Root responses to flooding.  

PubMed

Soil water-logging and submergence pose a severe threat to plants. Roots are most prone to flooding and the first to suffer from oxygen shortage. Roots are vital for plant function, however, and maintenance of a functional root system upon flooding is essential. Flooding-resistant plants possess a number of adaptations that help maintain oxygen supply to the root. Plants are also capable of initiating organogenesis to replace their original root system with adventitious roots if oxygen supply becomes impossible. This review summarizes current findings on root development and de novo root genesis in response to flooding. PMID:23608517

Sauter, Margret

2013-04-19

56

How the soil-root interface affects water availability to plants  

Microsoft Academic Search

Water supply to roots is essential for plant life. To sustain the root water uptake, a continuous liquid phase has to be maintained at the interface between soil and roots. Gaps between soil and roots may interrupt the liquid-phase continuity across the soil-root interface, acting as capillary barriers for the water flow. Additionally, due to the radial geometry of the

Andrea Carminati; Ahmad Moradi

2010-01-01

57

Affine root systems and dual numbers  

NASA Astrophysics Data System (ADS)

The root systems in Carroll spaces with degenerate metric are defined. It is shown that their Cartan matrices and reflection groups are affine. Due to the geometric consideration the root system structure of affine algebras is determined by a sufficiently simple algorithm.

Kostyakov, I. V.; Gromov, N. A.; Kuratov, V. V.

58

Banana root and soil health project - Australia  

Microsoft Academic Search

The banana plant forms an adventitious root system that is dependent on soil physical, chemical and biological properties to function efficiently. A pot experiment demonstrated that increasing soil compaction was able to significantly reduce the weight of banana roots and shoots. However, in the presence of Radopholus similis the effects of soil compaction were obscured, due to the significant reduction

Tony Pattison; Linda Smith; Philip Moody; John Armour; Kim Badcock; Jenny Cobon; Velupillai Rasiah; Stewart Lindsay

59

Topographic and ecologic controls on root reinforcement  

NASA Astrophysics Data System (ADS)

Shallow landslides are a significant hazard in steep, soil-mantled landscapes. During intense rainfall events, the distribution of shallow landslides is controlled by variations in landscape gradient, the frictional and cohesive properties of soil and roots, and the subsurface hydrologic response. While gradients can be estimated from digital elevation models, information on soil and root properties remains sparse. We investigated whether geomorphically controlled variations in ecology affect the spatial distribution of root cohesion by measuring the distribution and tensile strength of roots from soil pits dug downslope of 15 native trees in the southern Appalachian Mountains, North Carolina, United States. Root tensile strengths from different hardwood tree species were similar and consistently higher than the only native shrub species measured (Rhododendron maximum). Roots were stronger in trees found on noses (areas of divergent topography) relative to those in hollows (unchanneled, convergent topography) coincident with the variability in cellulose content. This cellulose variability is likely related to topographic differences in soil water potential. For all species, roots were concentrated close to the soil surface, with roots in hollows being more evenly distributed in the soil column than those on noses. Trees located on noses had higher mean root cohesion than those in hollows because of a higher root tensile force. R. maximum had the shallowest, weakest roots suggesting that recent expansion of this species due to fire suppression has likely lowered the root cohesion of some hollows. Quantification of this feedback between physiologic controls on root growth and slope hydrology has allowed us to create a curvature-based model of root cohesion that is a significant improvement on current models that assume a spatially averaged value.

Hales, T. C.; Ford, C. R.; Hwang, T.; Vose, J. M.; Band, L. E.

2009-09-01

60

Water transport across roots  

Microsoft Academic Search

Usually, roots are looked at as rather perfect osmometers with the endodermis being the ‘root membrane’ which is equivalent to the plasma membrane of cells. However, this ‘single-equivalent-membrane model’ of the root does not explain the findings of a variable hydraulic resistance of roots as well as of differences between hydraulic and osmotic water flow and of low reflection coefficients

Ernst Steudle; Lehrstuhl PflanzenOkologie

1994-01-01

61

Oxygen permeation properties of dense Bi{sub 1.5}Er{sub 0.5}O{sub 3}-Ag cermet membranes  

SciTech Connect

Oxygen permeation experiments were performed on dense mixed-conducting ceramic-metal composite membranes (thickness 0.2 to 2 mm) Bi{sub 1.5}Er{sub 0.5}O{sub 3}-Ag with 10.0, 27.8, and 40.0 volume percent (v/o) silver, respectively, in the temperature range 873 to 993 K and oxygen partial pressure range 10{sup {minus}3.5} to 1 bar O{sub 2}. The oxygen fluxes increased with increasing silver content. In the cermets with a nonpercolative silver phase (10.0 and 27.8 v/o), the increased oxygen flux relative to that of pure Bi{sub 1.5}Er{sub 0.5}O{sub 3} was attributed to faster kinetics of surface oxygen exchange in the presence of silver. Percolativity of the silver phase in the 40 v/o Ag composition enhances the ambipolar diffusion of oxygen ions and electrons. High oxygen fluxes ({approximately} 0.25 mmol/m{sup 2}s at 873 K) were observed with the latter composition, which were shown to be fully limited by the surface exchange kinetics. The activation energy for oxygen permeation in the temperature range 848 to 1,003 K is about 85 to 95 kJ/mol for the compositions without percolativity of silver and 115 kJ/mol for the composite with 40 v/o Ag, which reflects a change of the rate-limiting step upon passing the percolation threshold. Results from both permeation and isotopic exchange measurements on the composition with Ag percolativity indicated the kinetic order of the surface process in oxygen to be 1/4, indicating a process fundamentally different from that on pure Bi{sub 1.5}Er{sub 0.5}O{sub 3}.

Elshof, J.E. ten; Nguyen, N.Q.; Otter, M.W. den; Bouwmeester, H.J.M. [Univ. of Twente, Enschede (Netherlands)

1997-12-01

62

A numerical solution of whole plant nutrient uptake for soil-root systems with root hairs  

Microsoft Academic Search

Summary  Root hairs increase phosphorus, P, uptake over that due to the plant root alone. A mechanistic model using 16 parameters was\\u000a developed to describe this process. The model was verified with an experiment using six species that varied widely in root\\u000a hair length, density and radius. A sensitivity analysis was conducted and the results are included to illustrate the situations

S. Itoh; S. A. Barber

1983-01-01

63

Excited-State Dynamics of Overlapped Optically-Allowed 1Bu+ and Optically-Forbidden 1Bu? or 3Ag? Vibronic Levels of Carotenoids: Possible Roles in the Light-Harvesting Function  

PubMed Central

The unique excited-state properties of the overlapped (diabatic) optically-allowed 1Bu+ and the optically-forbidden 1Bu? or 3Ag? vibronic levels close to conical intersection (‘the diabatic pair’) are summarized: Pump-probe spectroscopy after selective excitation with ?100 fs pulses of all-trans carotenoids (Cars) in nonpolar solvent identified a symmetry selection rule in the diabatic electronic mixing and diabatic internal conversion, i.e., ‘1Bu+-to-1Bu? is allowed but 1Bu+-to-3Ag? is forbidden’. On the other hand, pump-probe spectroscopy after coherent excitation with ?30 fs of all-trans Cars in THF generated stimulated emission with quantum beat, consisting of the long-lived coherent diabatic cross term and a pair of short-lived incoherent terms.

Koyama, Yasushi; Kakitani, Yoshinori; Miki, Takeshi; Christiana, Rebecca; Nagae, Hiroyoshi

2010-01-01

64

Presence and absence of electronic mixing in shorter-chain and longer-chain carotenoids: Assignment of the symmetries of 1Bu- and 3Ag- states located just below the 1Bu+ state  

NASA Astrophysics Data System (ADS)

In spheroidene (having the number of conjugated double bonds n = 10), stimulated emission was observed from the mixed vibronic levels of 1Bu+(0)+1Bu-(2) and 1Bu+(1)+1Bu-(3), whereas in lycopene, anhydrorhodovibrin and spirilloxanthin ( n = 11-13), stimulated emission, from the pure vibronic levels of 1Bu+(0) and 1Bu+(1). Thus, the 1Bu+ state can mix with the 1Bu- state but not with the 3Ag- state, both being located just below the 1Bu+ state. The presence and absence of the mixing of the neighboring diabatic states support the symmetries of the next low-lying 1Bu- and 3Ag- states.

Sutresno, Adita; Kakitani, Yoshinori; Zuo, Ping; Li, Chunyong; Koyama, Yasushi; Nagae, Hiroyoshi

2007-10-01

65

Evaluation of diverse soybean germplasm for root growth and architecture  

Microsoft Academic Search

Root characteristics of soybean (Glycine max (L.) Merr.) improve drought avoidance by increasing water uptake from the soil profile. Screening genotypes for improved\\u000a root architecture without breaking the taproots or losing lateral roots is a challenge. Due to difficulty in separating roots\\u000a from field or potting soil, a rapid and effective screening method with a suitable growth medium to assess

Lakshmi P. Manavalan; Satish K. Guttikonda; Vinh T. Nguyen; J. Grover Shannon; Henry T. Nguyen

2010-01-01

66

Root selection methods in flood analysis  

NASA Astrophysics Data System (ADS)

In the 1970s, de Laine developed a root-matching procedure for estimating unit hydrograph ordinates from estimates of the fast component of the total runoff from multiple storms. Later, Turner produced a root selection method which required only data from one storm event and was based on recognising a pattern typical of unit hydrograph roots. Both methods required direct runoff data, i.e. prior separation of the slow response. This paper introduces a further refinement, called root separation, which allows the estimation of both the unit hydrograph ordinates and the effective precipitation from the full discharge hydrograph. It is based on recognising and separating the quicker component of the response from the much slower components due to interflow and/or baseflow. The method analyses the z-transform roots of carefully selected segments of the full hydrograph. The root patterns of these separate segments tend to be dominated by either the fast response or the slow response. This paper shows how their respective time-scales can be distinguished with an accuracy sufficient for practical purposes. As an illustration, theoretical equations are derived for a conceptual rainfall-runoff system with the input split between fast and slow reservoirs in parallel. These are solved analytically to identify the reservoir constants and the input splitting parameter. The proposed method, called "root separation", avoids the subjective selection of rainfall roots in the Turner method as well as the subjective matching of roots in the original de Laine method.

Parmentier, Benoît; Dooge, James C. I.; Bruen, Michael

67

Seeking roots and tracing lineages: constructing a framework of reference for roots and genealogical tourism  

Microsoft Academic Search

Travel for the purpose of seeking roots, or roots tourism, is understood to be focused on the descendants of a diaspora living in contemporary multicultural societies and travelling to ancestral homelands in search of identity and belongingness. It is an almost negligible niche segment of heritage tourism due to an obscure amalgam of contextual concepts. The primary purpose of this

Gregory Higginbotham

2012-01-01

68

Developmental Changes in Peanut Root Structure during Root Growth and Root-structure Modification by Nodulation  

Microsoft Academic Search

† Background and Aims Basic information about the root and root nodule structure of leguminous crop plants is incomplete, with many aspects remaining unresolved. Peanut (Arachis hypogaea) forms root nodules in a unique process. Structures of various peanut root types were studied with emphasis on insufficiently characterized lateral roots, changes in roots during their ontogenesis and root modification by nodule

RYOSUKE TAJIMA; JUN ABE; O NEW LEE; SHIGENORI MORITA; ALEXANDER LUX

2008-01-01

69

The Root Pressure Phenomenon  

ERIC Educational Resources Information Center

Describes experiments demonstrating that root pressure in plants is probably controlled by a circadian rhythm (biological clock). Root pressure phenomenon plays significant part in water transport in contradiction with prevalent belief. (PS)

Marsh, A. R.

1972-01-01

70

The Root Pressure Phenomenon  

ERIC Educational Resources Information Center

|Describes experiments demonstrating that root pressure in plants is probably controlled by a circadian rhythm (biological clock). Root pressure phenomenon plays significant part in water transport in contradiction with prevalent belief. (PS)|

Marsh, A. R.

1972-01-01

71

WHY ROOTING FAILS.  

SciTech Connect

I explore the origins of the unphysical predictions from rooted staggered fermion algorithms. Before rooting, the exact chiral symmetry of staggered fermions is a flavored symmetry among the four 'tastes.' The rooting procedure averages over tastes of different chiralities. This averaging forbids the appearance of the correct 't Hooft vertex for the target theory.

CREUTZ,M.

2007-07-30

72

Corky root rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

Corky root rot (corchosis) was first reported in Argentina in 1985, but the disease was presumably present long before that. The disease occurs in most alfalfa-growing areas of Argentina but is more common in older stands. In space-planted alfalfa trials scored for root problems, corky root rot was ...

73

Drought-induced changes in soil contact and hydraulic conductivity for roots of Opuntia ficus-indica with and without rhizosheaths  

Microsoft Academic Search

Water movement between roots and soil can be limited by incomplete root–soil contact, such as that caused by air gaps due to root shrinkage, and can also be influenced by rhizosheaths, composed of soil particles bound together by root exudates and root hairs. The possible occurrence of air gaps between the roots and the soil and their consequences for the

Gretchen B. North; Park S. Nobel

1997-01-01

74

Quantitative trait loci for root-penetration ability and root thickness in rice: comparison of genetic backgrounds.  

PubMed

Drought is the major abiotic stress limiting rice (Oryza sativa) production and yield stability in rainfed lowland and upland ecosystems. Root systems play an important role in drought resistance. Incorporation of root selection criteria in drought resistance improvement is difficult due to lack of reliable and efficient screening techniques. Using a wax-petrolatum layer system simulated to compacted soil layers, root traits were evaluated in a doubled haploid (DH) population derived from the cross between 'IR64' and 'Azucena'. Twelve putative QTLs (quantitative trait loci) were detected by interval mapping comprising four QTLs for root-penetration ability, four QTLs for root thickness, two QTLs for penetrated root number, and two QTLs for total root number. These QTLs individually explained 8.4% to 16.4% of the phenotypic variation. No QTL was detected for maximum penetrated root length by interval mapping. One QTL located between RG104 and RG348 was found to influence both root-penetration ability and root thickness. QTLs for root-penetration ability and root thickness were compared across two populations, 'IR64'-'Azucena' and 'CO39'-'Moroberekan', and different testing conditions. The identified consistent QTLs could be used for marker-assisted selection for deep and thick roots with high root-penetration ability in rice. PMID:10701113

Zheng, H G; Babu, R C; Pathan, M S; Ali, L; Huang, N; Courtois, B; Nguyen, H T

2000-02-01

75

Lateral Root Initiation or the Birth of a New Meristem  

Microsoft Academic Search

Root branching happens through the formation of new meristems out of a limited number of pericycle cells inside the parent\\u000a root. As opposed to shoot branching, the study of lateral root formation has been complicated due to its internal nature,\\u000a and a lot of questions remain unanswered. However, due to the availability of new molecular tools and more complete genomic

Ive De Smet; Steffen Vanneste; Dirk Inzé; Tom Beeckman

2006-01-01

76

Non-destructive estimation of lateral root distribution in an aridland perennial  

Microsoft Academic Search

Estimation of root distributions in natural systems remains challenging due to the difficulties in excavation and easy breakage of fine roots. Identifying lateral fine root distribution is necessary to determine the potential exploitation of spatially and temporally variable nutrient supplies that characterize most arid ecosystems. We estimated this potential by taking field measurements of lateral root distribution of the small

Michael S. Peek; Irwin N. Forseth

2005-01-01

77

The roots of trees  

NASA Astrophysics Data System (ADS)

The root of a tree develops the twofold function of absorbing water mixed with mineral salts, and anchoring the plant to the substrate. The former activity is the more important in determining the spreading of a root. If, however, the root is regarded only as a bundle of stiffeners implanted in a semi-infinite elastic medium and we want to optimize its shape, then the problem can be reduced to an optimization problem in elasticity.

Villaggio, Piero

78

The problem of banana root deterioration and its impact on production: Latin America's experience  

Microsoft Academic Search

The deterioration of the banana root system and its effect on production is due to climatic, edaphic (physical and chemical) and biological factors. There are two kinds of root deterioration processes: 1) a fast one with accelerated collapse of the root system (days to months) due to site specific characteristics such as limited effective depth of soil, very high sand,

Carlos A. Gauggel; Francisco Sierra; Gloria Arévalo

79

Spatio-temporal analysis of development of basal roots of common bean (Phaseolus vulgaris L.)  

PubMed Central

Temporal development of roots is key to the understanding of root system architecture of plants which influences nutrient uptake, anchorage and plant competition. Using time lapse imaging we analyzed developmental patterns of length, growth angle, depth and curvature of Phaseolus basal roots from emergence till 48 h in two genotypes, B98311 and TLP19 with contrasting growth angles. In both genotypes all basal roots appeared almost simultaneously, but their growth rates varied which accounted for differences in root length. The growth angles of the basal roots fluctuated rapidly during initial development due to oscillatory root growth causing local bends. Beyond 24 h, as the root curvature stabilized, so did the growth angle. Therefore growth angle of basal roots is not a very reliable quantity for characterizing root architecture, especially during early seedling development. Comparatively, tip depth is a more robust measure of vertical distribution of the basal roots even during early seedling development.

2011-01-01

80

Spatio-temporal analysis of development of basal roots of common bean (Phaseolus vulgaris L.).  

PubMed

Temporal development of roots is key to the understanding of root system architecture of plants which influences nutrient uptake, anchorage and plant competition. Using time lapse imaging we analyzed developmental patterns of length, growth angle, depth and curvature of Phaseolus basal roots from emergence till 48 h in two genotypes, B98311 and TLP19 with contrasting growth angles. In both genotypes all basal roots appeared almost simultaneously, but their growth rates varied which accounted for differences in root length. The growth angles of the basal roots fluctuated rapidly during initial development due to oscillatory root growth causing local bends. Beyond 24 h, as the root curvature stabilized, so did the growth angle. Therefore growth angle of basal roots is not a very reliable quantity for characterizing root architecture, especially during early seedling development. Comparatively, tip depth is a more robust measure of vertical distribution of the basal roots even during early seedling development. PMID:21701251

Basu, Paramita; Pal, Anupam

2011-07-01

81

Regulation of Arabidopsis root development by small signaling peptides  

PubMed Central

Plant root systems arise de novo from a single embryonic root. Complex and highly coordinated developmental networks are required to ensure the formation of lateral organs maximizes plant fitness. The Arabidopsis root is well-suited to dissection of regulatory and developmental networks due to its highly ordered, predictable structure. A myriad of regulatory signaling networks control the development of plant roots, from the classical hormones such as auxin and cytokinin to short-range positional signaling molecules that relay information between neighboring cells. Small signaling peptides are a growing class of regulatory molecules involved in many aspects of root development including meristem maintenance, the gravitropic response, lateral root development, and vascular formation. Here, recent findings on the roles of regulatory peptides in these aspects of root development are discussed.

Delay, Christina; Imin, Nijat; Djordjevic, Michael A.

2013-01-01

82

Meniscus root repair.  

PubMed

Root tears are a subset of meniscal injuries that result in significant knee joint pathology. Occurring on either the medial or lateral side, root tears are defined as radial tears or avulsions of the posterior horn attachment to bone. After a root tear, there is a significant increase in tibio-femoral contact pressure concomitant with altered knee joint kinematics. Previous cadaver studies from our institution have shown that root repair of the medial meniscus is successful in restoring joint biomechanics to within normal limits. Indications for operative management of meniscal root tears include (1) a symptomatic medial meniscus root tear with minimal arthritis and having failed non-operative treatment, and (2) a lateral root tear in associated with an ACL tear. In this review, we describe diagnosis, imaging, patient selection, and arthroscopic surgical technique of medial and lateral meniscus root injuries. In addition we highlight the pearls of repair technique, associated complications, post-operative rehabilitation regimen, and expected outcomes. PMID:22555205

Vyas, Dharmesh; Harner, Christopher D

2012-06-01

83

Seeds: Roots and Shoots  

NSDL National Science Digital Library

In this indepth hands-on activity, learners build a structure that allows them to observe the growth of roots and the correlation between root growth and stem extension. Because no dirt is used in this arrangement, a guiding question can be posed: What does the plant need to grow? The PDF includes activity rationale, procedure, background and follow-up discussion suggestions.

Education Development Center, Inc.

2010-01-01

84

ROOTING GUATEMALAN AVOCADO CUTTINGS  

Microsoft Academic Search

SUMMARY A method is described which, although not considered commercially practical, proved to be very successful in rooting cuttings of Guatemalan avocado varieties. Essentially it consists of obtaining cuttings from stems, the bases of which have at no time been exposed to light or low humidity. In certain experimental work with the avocado, own rooted trees, that is trees propagated

E. F. Frolich

85

Aortic root replacement  

Microsoft Academic Search

Between September 1976 and September 1993, 270 patients underwent aortic root replacement at our institution. Two hundred fifty-two patients underwent a Bentall composite graft repair and 18 patients received a cryopreserved homograft aortic root. One hundred eighty-seven patients had a Marfan aneurysm of the ascending aorta (41 with dissection) and 53 patients had an aneurysm resulting from nonspecific medial degeneration

Vincent L. Gott; A. Marc Gillinov; Reed E. Pyeritz; Duke E. Cameron; Bruce A. Reitz; Peter S. Greene; Christopher D. Stone; Robert L. Ferris; Diane E. Alejo; Victor A. McKusick

1995-01-01

86

Developmental anatomy and branching of roots of four Zeylanidium species (podostemaceae), with implications for evolution of foliose roots.  

PubMed

Podostemaceae have markedly specialized and diverse roots that are adapted to extreme habitats, such as seasonally submerged or exposed rocks in waterfalls and rapids. This paper describes the developmental anatomy of roots of four species of Zeylanidium, with emphasis on the unusual association between root branching and root-borne adventitious shoots. In Z. subulatum and Z. lichenoides with subcylindrical or ribbon-like roots, the apical meristem distal (exterior) to a shoot that is initiated within the meristem area reduces and loses meristematic activity. This results in a splitting into two meristems that separate the parental root and lateral root (anisotomous dichotomy). In Z. olivaceum with lobed foliose roots, shoots are initiated in the innermost zone of the marginal meristem, and similar, but delayed, meristem reduction usually occurs, producing a parenchyma exterior to shoots located between root lobes. In some extreme cases, due to meristem recovery, root lobing does not occur, so the margin is entire. In Z. maheshwarii with foliose roots, shoots are initiated proximal to the marginal meristem and there is no shoot-root lobe association. Results suggest that during evolution from subcylindrical or ribbon-like roots to foliose roots, reduction of meristem exterior to a shoot was delayed and then arrested as a result of inward shifting of the sites of shoot initiation. The evolutionary reappearance of a protective tissue or root cap in Z. olivaceum and Z. maheshwarii in the Zeylanidium clade is implied, taking into account the reported molecular phylogeny and root-cap development in Hydrobryum. PMID:12451029

Hiyama, Y; Tsukamoto, I; Imaichi, R; Kato, M

2002-12-01

87

A new Approach for Quantifying Root-Reinforcement of Streambanks: the RipRoot Model  

NASA Astrophysics Data System (ADS)

Riparian vegetation plays an important role in controlling geotechnical and fluvial processes acting along and within streambanks through the binding effects of roots. Quantification of this mechanical effect is therefore essential to accurately model streambank stability. Until now, most attempts to include the effects of root reinforcement by riparian vegetation have used root-cohesion values estimated using the Wu et al. (1979) equation, requiring the tensile strengths and diameters of the roots crossing the potential shear-plane. However, the Wu et al. equation is a static model that assumes that all roots break, and that they all break simultaneously. Field observations and laboratory experiments have shown that in reality the roots do not all break simultaneously, and that the breaking of roots during mass failure is in fact a dynamic process. Static models such as the Wu et al. equation are therefore likely to produce overestimations of cohesion due to roots. As a response to this concern, a dynamic root reinforcement model (RipRoot) was developed, based on the concepts of fiber bundle models (FBM's) used in materials science. Within the model the root-soil system is loaded incrementally resulting in progressive root breaking and redistribution of stresses from the broken roots to the remaining intact roots in the soil matrix. The redistribution and loading process continues until either all of the roots have broken, or equilibrium is reached where the root network supports the driving force imposed on the bank. The increase in bank cohesion using the static Wu et al. equation are 18% to 38% higher than RipRoot for riparian tree species, including Black Willow, Sandbar Willow, Cottonwood, River Birch and Eastern Sycamore, and 49% higher for Switch Grass. These variations in cohesion values can have a significant impact on streambank Factor of Safety (Fs) values calculated using the Simon et al. (2000) bank-stability model. For example, a 3m high silt streambank had a Fs of 0.98 without vegetation, indicating instability. With the addition of cohesion from 200 River Birch roots this value increased to 1.22 using the RipRoot value (Conditionally Stable) and 1.37 using the Wu et al. equation (Stable). In this example both of the root models produced cohesion values that were large enough to make the bank more stable, but the more conservative value from RipRoot suggests the bank may only be conditionally stable. Results to date indicate that the dynamic nature of RipRoot removes some of the overestimation from the static equation of Wu et al. (1979), therefore producing more realistic values for root reinforcement, which are particularly useful and important in the context of river management and restoration.

Pollen, N. L.; Simon, A.

2003-12-01

88

Root hydrotropism: an update.  

PubMed

While water shortage remains the single-most important factor influencing world agriculture, there are very few studies on how plants grow in response to water potential, i.e., hydrotropism. Terrestrial plant roots dwell in the soil, and their ability to grow and explore underground requires many sensors for stimuli such as gravity, humidity gradients, light, mechanical stimulations, temperature, and oxygen. To date, extremely limited information is available on the components of such sensors; however, all of these stimuli are sensed in the root cap. Directional growth of roots is controlled by gravity, which is fixed in direction and intensity. However, other environmental factors, such as water potential gradients, which fluctuate in time, space, direction, and intensity, can act as a signal for modifying the direction of root growth accordingly. Hydrotropism may help roots to obtain water from the soil and at the same time may participate in the establishment of the root system. Current genetic analysis of hydrotropism in Arabidopsis has offered new players, mainly AHR1, NHR1, MIZ1, and MIZ2, which seem to modulate how root caps sense and choose to respond hydrotropically as opposed to other tropic responses. Here we review the mechanism(s) by which these genes and the plant hormones abscisic acid and cytokinins coordinate hydrotropism to counteract the tropic responses to gravitational field, light or touch stimuli. The biological consequence of hydrotropism is also discussed in relation to water stress avoidance. PMID:23258371

Cassab, Gladys I; Eapen, Delfeena; Campos, María Eugenia

2012-12-20

89

Seasonal Populations of Pratylenchus penetrans and Meloidogyne hapla in Strawberry Roots  

PubMed Central

Strawberry roots were sampled through the year to determine the populations and distribution of Pratylenchus penetrans and Meloidogyne hapla. Three strawberry root types were sampled—structural roots; feeder roots without secondary tissues; and suberized, black perennial roots. Both lesion and root-knot nematodes primarily infected feeder roots from structural roots or healthy perennial roots. Few nematodes were recovered from soil, diseased roots, or suberized roots. Lesion nematode recovery was correlated with healthy roots. In both 1997 and 1998, P. penetrans populations peaked about day 150 (end of May) and then declined. The decline in numbers corresponded to changes in total strawberry root weight and root type distribution. The loss of nematode habitat resulted from loss of roots due to disease and the transition from structural to suberized perennial roots. Meloidogyne hapla juvenile recovery peaked around 170 days (mid June) in 1997 and at 85, 147, 229, and 308 days (late March, late May, mid August, and early November, respectively) in 1998. There appear to be at least four generations per year of M. hapla in Connecticut. Diagnostic samples from an established strawberry bed may be most reliable and useful when they include feeder roots taken in late May.

Lamindia, J. A.

2002-01-01

90

Roles of Morphology, Anatomy, and Aquaporins in Determining Contrasting Hydraulic Behavior of Roots1[OA  

PubMed Central

The contrasting hydraulic properties of wheat (Triticum aestivum), narrow-leafed lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus) roots were identified by integrating measurements of water flow across different structural levels of organization with anatomy and modeling. Anatomy played a major role in root hydraulics, influencing axial conductance (Lax) and the distribution of water uptake along the root, with a more localized role for aquaporins (AQPs). Lupin roots had greater Lax than wheat roots, due to greater xylem development. Lax and root hydraulic conductance (Lr) were related to each other, such that both variables increased with distance from the root tip in lupin roots. Lax and Lr were constant with distance from the tip in wheat roots. Despite these contrasting behaviors, the hydraulic conductivity of root cells (Lpc) was similar for all species and increased from the root surface toward the endodermis. Lpc was largely controlled by AQPs, as demonstrated by dramatic reductions in Lpc by the AQP blocker mercury. Modeling the root as a series of concentric, cylindrical membranes, and the inhibition of AQP activity at the root level, indicated that water flow in lupin roots occurred primarily through the apoplast, without crossing membranes and without the involvement of AQPs. In contrast, water flow across wheat roots crossed mercury-sensitive AQPs in the endodermis, which significantly influenced Lr. This study demonstrates the importance of examining root morphology and anatomy in assessing the role of AQPs in root hydraulics.

Bramley, Helen; Turner, Neil C.; Turner, David W.; Tyerman, Stephen D.

2009-01-01

91

Seasonal Populations of Pratylenchus penetrans and Meloidogyne hapla in Strawberry Roots.  

PubMed

Strawberry roots were sampled through the year to determine the populations and distribution of Pratylenchus penetrans and Meloidogyne hapla. Three strawberry root types were sampled-structural roots; feeder roots without secondary tissues; and suberized, black perennial roots. Both lesion and root-knot nematodes primarily infected feeder roots from structural roots or healthy perennial roots. Few nematodes were recovered from soil, diseased roots, or suberized roots. Lesion nematode recovery was correlated with healthy roots. In both 1997 and 1998, P. penetrans populations peaked about day 150 (end of May) and then declined. The decline in numbers corresponded to changes in total strawberry root weight and root type distribution. The loss of nematode habitat resulted from loss of roots due to disease and the transition from structural to suberized perennial roots. Meloidogyne hapla juvenile recovery peaked around 170 days (mid June) in 1997 and at 85, 147, 229, and 308 days (late March, late May, mid August, and early November, respectively) in 1998. There appear to be at least four generations per year of M. hapla in Connecticut. Diagnostic samples from an established strawberry bed may be most reliable and useful when they include feeder roots taken in late May. PMID:19265965

Lamindia, J A

2002-12-01

92

Surgical Treatment of Ascending Aorta and Aortic Root Aneurysms  

Microsoft Academic Search

Aneurysms of the aortic root and ascending aorta are often due to degenerative disease of media. Aneurysm of the aortic root often affects patients in their second to fourth decades of life, whereas aneurysm of the ascending aorta occurs mostly in the fifth to seventh decades of life. These aneurysms can cause aortic insufficiency, dissection, and\\/or rupture. Current guidelines recommend

Tirone E. David

2010-01-01

93

Development of a heat exchanger root-cause analysis methodology  

Microsoft Academic Search

The objective of this work is to determine a generic methodology for approaching the accurate identification of the root cause of component failure. Root-cause determinations are an everyday challenge to plant personnel, but they are handled with widely differing degrees of success due to the approaches, levels of diagnostic expertise, and documentation. The criterion for success is simple: If the

D. B. Jarrell; R. C. Stratton

1989-01-01

94

Root-end Filling Materials Alter Fibroblast Differentiation  

Microsoft Academic Search

Root-end filling materials are commonly used following endodontic surgical procedures; however, their effect on adjacent soft tissues is poorly understood. We predict that, due to the differences in their chemical composition, these materials will have profoundly different effects on the survival and differentiation of fibroblasts. Many of the root-end filling materials examined were initially cytotoxic to both PDL and gingival

S. Bonson; B. G. Jeansonne; T. E. Lallier

2004-01-01

95

Roots of Terror.  

National Technical Information Service (NTIS)

The Women in International Studies (WIIS), Georgetown University, in cooperation with the Strategic Studies Institute (SSI), U.S. Army War College, conducted a colloquium, 'The Roots of Terror: Understanding the Evolving Threat of Global Terrorism,' on Fe...

C. Johnson

2007-01-01

96

Corn root gravitropism  

NSDL National Science Digital Library

Gravitropism is the turning or growing in a different direction of a plant in response to gravity. This corn plant's root grows downward and exhibits positive gravitropism because it is growing toward gravity's pull.

Roger P. Hangarter (Indiana University;Department of Biology)

2000-01-01

97

The RootChip: An Integrated Microfluidic Chip for Plant Science[W][OA  

PubMed Central

Studying development and physiology of growing roots is challenging due to limitations regarding cellular and subcellular analysis under controlled environmental conditions. We describe a microfluidic chip platform, called RootChip, that integrates live-cell imaging of growth and metabolism of Arabidopsis thaliana roots with rapid modulation of environmental conditions. The RootChip has separate chambers for individual regulation of the microenvironment of multiple roots from multiple seedlings in parallel. We demonstrate the utility of The RootChip by monitoring time-resolved growth and cytosolic sugar levels at subcellular resolution in plants by a genetically encoded fluorescence sensor for glucose and galactose. The RootChip can be modified for use with roots from other plant species by adapting the chamber geometry and facilitates the systematic analysis of root growth and metabolism from multiple seedlings, paving the way for large-scale phenotyping of root metabolism and signaling.

Grossmann, Guido; Guo, Woei-Jiun; Ehrhardt, David W.; Frommer, Wolf B.; Sit, Rene V.; Quake, Stephen R.; Meier, Matthias

2011-01-01

98

Modelling increased soil cohesion by plant roots with EUROSEM  

NASA Astrophysics Data System (ADS)

Soil cohesion is an important variable to model soil detachment by runoff (Morgan et al., 1998a). As soil particles are not loose, soil detachment by runoff will be limited by the cohesion of the soil material. It is generally recognized that plant roots contribute to the overall cohesion of the soil. Determination of this increased cohesion and soil roughness however is complicated and measurements of shear strength and soil reinforcement by plant roots are very time- and labour consuming. A model approach offers an alternative for the assessment of soil cohesion provided by plant roots However, few erosion models account for the effects of the below-ground biomass in their calculation of erosion rates. Therefore, the main objectives of this study is to develop an approach to improve an existing soil erosion model (EUROSEM) accounting for the erosion-reducing effects of roots. The approach for incorporating the root effects into this model is based on a comparison of measured soil detachment rates for bare and for root-permeated topsoil samples with predicted erosion rates under the same flow conditions using the erosion equation of EUROSEM. Through backwards calculation, transport capacity efficiencies and corresponding soil cohesion values can be assessed for bare and root-permeated topsoils respectively. The results are promising and show that grass roots provide a larger increase in soil cohesion as compared with tap-rooted species and that the increase in soil cohesion is not significantly different under wet and dry soil conditions, either for fibrous root systems or for tap root systems. Relationships are established between measured root density values and the corresponding calculated soil cohesion values, reflecting the effects of roots on the resistance of the topsoil to concentrated flow incision. These relationships enable one to incorporate the root effect into the soil erosion model EUROSEM, through adapting the soil cohesion input value. A scenario analysis performed with EUROSEM for different vegetation treatments, indicates that runoff and soil loss on root-permeated topsoils are slightly higher as compared to fully covered grass fields or harvested grass fields with some plant residue left, but much smaller as compared to bare topsoils. Moreover, when re-vegetating bare soils, roots are responsible for a large part of the reduction in soil loss and runoff by concentrated flow. Hence, this analysis shows that the contribution of roots to soil cohesion is very important for preventing soil loss and reducing runoff volume. The increase in soil shear strength due to the binding effect of roots on soil particles is two orders of magnitude lower as compared with soil reinforcement achieved when roots mobilize their tensile strength during soil shearing and root breakage.

de Baets, S.; Poesen, J.; Torri, D.; Salvador, M. P.

2009-04-01

99

Gravisensitivity of cress roots  

NASA Astrophysics Data System (ADS)

The minimum dose (stimulus x time [gs]) eliciting a visible gravitropic response, has been determined using continuous and intermittent stimulation and two different accelerations at 1g and 0.1g. The minimum dose of 20 - 30 gs estimated for microgravity roots and of 50 - 60 gs for roots grown on a 1g-centrifuge indicated a higher sensitivity of microgravity roots. Applying intermittent stimuli to microgravity-grown roots, gravitropic responses were observed after two stimuli of 13.5 gs separated by a stimulus free interval of 118 s. The curvature of microgravity-grown roots to lateral stimulation by 0.1 g was remarkably smaller than by 1g in spite of the same doses which were applied to the seedlings. Microscopic investigations corresponding to stimulations in the range of the threshold values, demonstrated small displacement (< 2 ?m) of statoliths in root statocytes. Accepting the statolith theory, one can conclude that stimulus transformation has to occur in the cytoplasm in close vicinity to the statoliths and that this transformation system was affected during seedling cultivation in microgravity.

Volkmann, Dieter; Tewinkel, Martin

100

Root architecture impacts on root decomposition rates in switchgrass  

NASA Astrophysics Data System (ADS)

Roots strongly contribute to soil organic carbon accrual, but the rate of soil carbon input via root litter decomposition is still uncertain. Root systems are built up of roots with a variety of different diameter size classes, ranging from very fine to very coarse roots. Since fine roots have low C:N ratios and coarse roots have high C:N ratios, root systems are heterogeneous in quality, spanning a range of different C:N ratios. Litter decomposition rates are generally well predicted by litter C:N ratios, thus decomposition of roots may be controlled by the relative abundance of fine versus coarse roots. With this study we asked how root architecture (i.e. the relative abundance of fine versus coarse roots) affects the decomposition of roots systems in the biofuels crop switchgrass (Panicum virgatum L.). To understand how root architecture affects root decomposition rates, we collected roots from eight switchgrass cultivars (Alamo, Kanlow, Carthage, Cave-in-Rock, Forestburg, Southlow, Sunburst, Blackwell), grown at FermiLab (IL), by taking 4.8-cm diameter soil cores from on top of the crown and directly next to the crown of individual plants. Roots were carefully excised from the cores by washing and analyzed for root diameter size class distribution using WinRhizo. Subsequently, root systems of each of the plants (4 replicates per cultivar) were separated in 'fine' (0-0.5 mm), 'medium' (0.5-1 mm) and 'coarse' roots (1-2.5 mm), dried, cut into 0.5 cm (medium and coarse roots) and 2 mm pieces (fine roots), and incubated for 90 days. For each of the cultivars we established five root-treatments: 20g of soil was amended with 0.2g of (1) fine roots, (2) medium roots, (3) coarse roots, (4) a 1:1:1 mixture of fine, medium and coarse roots, and (5) a mixture combining fine, medium and coarse roots in realistic proportions. We measured CO2 respiration at days 1, 3, 7, 15, 30, 60 and 90 during the experiment. The 13C signature of the soil was -26‰, and the 13C signature of plants was -12‰, enabling us to differentiate between root-derived C and native SOM-C respiration. We found that the relative abundance of fine, medium and coarse roots were significantly different among cultivars. Root systems of Alamo, Kanlow and Cave-in-Rock were characterized by a large abundance of coarse-, relative to fine roots, whereas Carthage, Forestburg and Blackwell had a large abundance of fine, relative to coarse roots. Fine roots had a 28% lower C:N ratio than medium and coarse roots. These differences led to different root decomposition rates. We conclude that root architecture should be taken into account when predicting root decomposition rates; enhanced understanding of the mechanisms of root decomposition will improve model predictions of C input to soil organic matter.

de Graaff, M.; Schadt, C.; Garten, C. T.; Jastrow, J. D.; Phillips, J.; Wullschleger, S. D.

2010-12-01

101

The "Green" Root Beer Laboratory  

ERIC Educational Resources Information Center

|No, your students will not be drinking green root beer for St. Patrick's Day--this "green" root beer laboratory promotes environmental awareness in the science classroom, and provides a venue for some very sound science content! While many science classrooms incorporate root beer-brewing activities, the root beer lab presented in this article has…

Clary, Renee; Wandersee, James

2010-01-01

102

Hydraulic conductivity of rice roots  

Microsoft Academic Search

A pressure chamber and a root pressure probe technique have been used to measure hydraulic conductivities of rice roots (root Lpr per m 2 of root surface area). Young plants of two rice (Oryza sativa L.) varieties (an upland variety, cv. Azucena and a lowland variety, cv. IR64) were grown for 31-40 d in 12 h days with 500 mmol

Naoko Miyamoto; Ernst Steudle; Tadashi Hirasawa; Renee Lafitte

2001-01-01

103

Arabidopsis Alcohol Dehydrogenase Expression in Both Shoots and Roots Is Conditioned by Root Growth Environment1  

PubMed Central

It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. ?-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.

Chung, Hwa-Jee; Ferl, Robert J.

1999-01-01

104

Phosphate starvation of maize inhibits lateral root formation and alters gene expression in the lateral root primordium zone  

PubMed Central

Background Phosphorus (P) is an essential macronutrient for all living organisms. Maize (Zea mays) is an important human food, animal feed and energy crop throughout the world, and enormous quantities of phosphate fertilizer are required for maize cultivation. Thus, it is important to improve the efficiency of the use of phosphate fertilizer for maize. Results In this study, we analyzed the maize root response to phosphate starvation and performed a transcriptomic analysis of the 1.0-1.5?cm lateral root primordium zone. In the growth of plants, the root-to-shoot ratio (R/L) was reduced in both low-phosphate (LP) and sufficient-phosphate (SP) solutions, but the ratio (R/L) exhibited by the plants in the LP solution was higher than that of the SP plants. The growth of primary roots was slightly promoted after 6?days of phosphate starvation, whereas the numbers of lateral roots and lateral root primordia were significantly reduced, and these differences were increased when associated with the stress caused by phosphate starvation. Among the results of a transcriptomic analysis of the maize lateral root primordium zone, there were two highlights: 1) auxin signaling participated in the response and the modification of root morphology under low-phosphate conditions, which may occur via local concentration changes due to the biosynthesis and transport of auxin, and LOB domain proteins may be an intermediary between auxin signaling and root morphology; and 2) the observed retardation of lateral root development was the result of co-regulation of DNA replication, transcription, protein synthesis and degradation and cell growth. Conclusions These results indicated that maize roots show a different growth pattern than Arabidopsis under low-phosphate conditions, as the latter species has been observed to halt primary root growth when the root tip comes into contact with low-phosphate media. Moreover, our findings enrich our understanding of plant responses to phosphate deficits and of root morphogenesis in maize.

2012-01-01

105

Root communication among desert shrubs.  

PubMed Central

Descriptive and experimental studies of desert shrub distributions have revealed important questions about the mechanisms by which plants interact. For example, do roots interact by mechanisms other than simple competition for limiting resources? We investigated this question using the desert shrubs Ambrosia dumosa and Larrea tridentata grown in chambers that allowed observation of roots during intraplant and intra- and interspecific interplant encounters. Two types of root "communication" were revealed. Ambrosia root systems appear to be capable of detecting and avoiding other Ambrosia root systems, whereas Larrea roots inhibit Larrea and Ambrosia roots in their vicinity. Images

Mahall, B E; Callaway, R M

1991-01-01

106

The Roots of Carnivorous Plants  

Microsoft Academic Search

Carnivorous plants may benefit from animal-derived nutrients to supplement minerals from the soil. Therefore, the role and importance of their roots is a matter of debate. Aquatic carnivorous species lack roots completely, and many hygrophytic and epiphytic carnivorous species only have a weakly devel-oped root system. In xerophytes, however, large, extended and\\/or deep-reaching roots and sub-soil shoots develop. Roots develop

Wolfram Adlassnig; Marianne Peroutka; Hans Lambers; Irene K. Lichtscheidl

2005-01-01

107

Understanding the Impact of Root Morphology on Overturning Mechanisms: A Modelling Approach  

PubMed Central

Background and Aims The Finite Element Method (FEM) has been used in recent years to simulate overturning processes in trees. This study aimed at using FEM to determine the role of individual roots in tree anchorage with regard to different rooting patterns, and to estimate stress distribution in the soil and roots during overturning. Methods The FEM was used to carry out 2-D simulations of tree uprooting in saturated soft clay and loamy sand-like soil. The anchorage model consisted of a root system embedded in a soil block. Two root patterns were used and individual roots removed to determine their contribution to anchorage. Key Results In clay-like soil the size of the root–soil plate formed during overturning was defined by the longest roots. Consequently, all other roots localized within this plate had no influence on anchorage strength. In sand-like soil, removing individual root elements altered anchorage resistance. This result was due to a modification of the shape and size of the root–soil plate, as well as the location of the rotation axis. The tap root and deeper roots had more influence on overturning resistance in sand-like soil compared with clay-like soil. Mechanical stresses were higher in the most superficial roots and also in leeward roots in sand-like soil. The relative difference in stresses between the upper and lower sides of lateral roots was sensitive to root insertion angle. Assuming that root eccentricity is a response to mechanical stresses, these results explain why eccentricity differs depending on root architecture. Conclusions A simple 2-D Finite Element model was developed to better understand the mechanisms involved during tree overturning. It has been shown how root system morphology and soil mechanical properties can modify the shape of the root plate slip surface as well as the position of the rotation axis, which are major components of tree anchorage.

Fourcaud, Thierry; Ji, Jin-Nan; Zhang, Zhi-Qiang; Stokes, Alexia

2008-01-01

108

Global Patterns of Vertical Root Distributions and Maximum Rooting Depths  

NASA Astrophysics Data System (ADS)

Plant roots are important pathways in global biogeochemical cycles. Roots transport water from the soil to the atmosphere and carbon from the atmosphere into the soil, redistribute nutrients and water in the soil profile, and contribute to the weathering of soil minerals. Data on the vertical distribution and maximum depths of roots in the soil profile are needed to quantify these and other processes. The global coverage of such root data is uneven, which makes it desirable to estimate global root distributions and maximum rooting depths from measurements of aboveground vegetation structure, soil parameters, and climatic variables. We analyzed root two databases compiled from the literature to determine the biotic and abiotic factors that influence vertical root distributions in global ecosystems and maximum rooting depths of individual plants. The first database included 520 vertical root profiles from 286 geographic locations. The second database included 1350 rooting depths for individual plants species from water-limited systems globally. Vertical root distributions were characterized by interpolated 50% and 95% rooting depths (the depths above which 50% or 95% of all roots are located). The 95% rooting depths increased with decreasing latitude from 80\\deg to 30\\deg, but showed no clear trend in the tropics. Mean annual evapotranspiration, precipitation, and length of the warm season were all positively correlated with rooting depths. Globally, more than 90% of all profiles had at least 50% of all roots in the upper 0.3 m of the soil profile (incl. organic horizons) and 95% of all roots in the upper 2 m. Deeper 50% and 95% rooting depths were mainly found in water-limited ecosystems. Median rooting depths of individual plants in water-limited ecosystems increased with increasing precipitation from less than 1 m in deserts with <50 mm of mean annual precipitation to about 2 m in climates with 650 to 750 mm mean annual precipitation. Maximum rooting depths were largely independent of climate and ranged between 2 and 4 m for herbaceous plants and between 4 and 6 m for woody plants. The on average deepest roots were found in trees, followed by shrubs, semi-shrubs, perennial herbaceous plants, annuals, and stem succulents. Root distributions and maximum rooting depths are highly variable, but significant proportions of the variability can be explained by empirical relationships with aboveground vegetation structure, climate, and soil characteristics. Such relationships could potentially be used to improve the parameterization of roots in models of land-atmosphere interactions.

Schenk, H. J.; Jackson, R. B.

2001-05-01

109

Root water extraction under combined water and osmotic stress  

NASA Astrophysics Data System (ADS)

Many crop and water management issues pertain to the entire plant-root system and may include both water and osmotic stress. The challenge is to find a concise set of soil physical and plant physiological parameters which characterize this system and enable us to quantify root water uptake and stomatal conditions. Among the soil physical parameters, the matric potential function appears to be very useful to determine the onset of drought stress and the decline of root water uptake thereafter. We may use this concept at root level, but also at plant level. In the latter case the concept allows for soil physical and root density heterogeneity, soil water fluxes within the root zone, and compensation of root water uptake when certain parts of the root zone contain more water than other parts. The input parameters are often already used in vadose zone models: potential transpiration rate, root length density, minimum root surface pressure head and soil hydraulic functions. Recently the authors extended their water uptake concept at root level to include osmotic stress due to salinity. In literature various concepts for combined water and salt stress are used. All these concepts include calibration parameters to accommodate the different root water uptake response to soil water pressure head and osmotic head. When using the matric flux potential, we may get rid of these calibration parameters. We employ the fact that osmotic head in the soil water due to salts counteracts the osmotic head in the roots. We will show simulated results of this concept and compare them to other common approaches. The developed concept shows the large influence of root density and soil hydraulic functions, factors which are usually not explicitly accounted for. Also we hypothesize how the presented concept can be used in one- or multi-dimensional agrohydrological models with non-uniform root zones. No additional empirical input parameters are required. An important feature is automatic compensation of drought and salinity stress in particular parts of the root zone by extra root water extraction in less dry and/or saline parts.

van Dam, J. C.; de Jong van Lier, Q.; Metselaar, K.

2009-04-01

110

Neutron tomography of the root-soil interface: water distribution around different parts of the root structure  

NASA Astrophysics Data System (ADS)

Although the importance of the root-soil interface in water uptake by plant roots has been acknowledged in many studies, there is a gap of knowledge on how water enters the roots. The main reason for this gap is the technical difficulties in resolving soil moisture dynamics in the vicinity of roots. Spatially and temporally resolved data on water flow across soil-root interface is needed to improve our understanding of mechanisms controlling water uptake by roots. We used neutron tomography to image soil water distribution around roots in-situ. We grew chick peas and lupines in sand-filled cylinders for 10 days at a water potential of -20 hPa. The samples were tomographed for 4 days over day and night and during a drying period and after rewetting. We observed that water content near the root surface was higher than in the bulk soil during the whole course of measurement for all the samples. Our hypothesis is that this increase of water content next to roots was due to the distinct water retention curve of the soil next to roots, the rhizosphere. Our hypothesis is that the rhizosphere water retention curve is caused by mucilage exuded by roots. Mucilage contains more than 90% water even at low water potentials, consequently increasing the water holding capacity of the rhizosphere. In another words, the roots modify the physical and chemical properties of their rhizosphere. The thickness of the area of increasing water, rhizosphere, varied along the root length. It ranged from slightly less than 1.5 mm in the distal part of the roots to more than 3 mm around the root tip. Also, it was slightly thicker around the main root compared to the lateral roots. As the soil water was being consumed by the roots, the extent of the rhizosphere decreased slightly, and then increased again after rewetting. We expect that the high water-holding capacity of the rhizosphere favors root water uptake, especially in dry soils. Most of the present modeling approaches neglect this effect.

Moradi, A. B.; Carminati, A.

2009-12-01

111

Resprouting from roots in four Brazilian tree species.  

PubMed

Previous studies pointed out that species richness and high density values within the Leguminosae in Brazilian forest fragments affected by fire could be due, at least partially, to the high incidence of root sprouting in this family. However, there are few studies of the factors that induce root sprouting in woody plants after disturbance. We investigated the bud formation on root cuttings, and considered a man-made disturbance that isolates the root from the shoot apical dominance of three Leguminosae (Bauhinia forficata Link., Centrolobium tomentosum Guill. ex Benth, and Inga laurina (Sw.) Willd) and one Rutaceae (Esenbeckia febrifuga (St. Hil.) Juss. ex Mart.). All these species resprout frequently after fire. We also attempted to induce bud formation on root systems by removing the main trunk, girdling or sectioning the shallow lateral roots from forest tree species Esenbeckia febrifuga and Hymenaea courbaril L. We identified the origin of shoot primordia and their early development by fixing the samples in Karnovsky solution, dehydrating in ethyl alcohol series and embedding in plastic resin. Serial sections were cut on a rotary microtome and stained with toluidine blue O. Permanent slides were mounted in synthetic resin. We observed different modes of bud origin on root cuttings: close to the vascular cambium (C. tomentosum), from the callus (B. forficata and E. febrifuga) and from the phloematic parenchyma proliferation (I. laurina). Fragments of B. forficata root bark were also capable of forming reparative buds from healing phellogen formed in callus in the bark's inner side. In the attempt of bud induction on root systems, Hymenaea courbaril did not respond to any of the induction tests, probably because of plant age. However, Esenbeckia febrifuga roots formed suckers when the main trunk was removed or their roots were sectioned and isolated from the original plant. We experimentally demonstrated the ability of four tree species to resprout from roots after disturbance. Our results suggest that the release of apical dominance enables root resprouting in the studied species. PMID:19928472

Hayashi, Adriana Hissae; Appezzato-da-Glória, Beatriz

2009-09-01

112

Cytosolic pH regulates root water transport during anoxic stress through gating of aquaporins  

Microsoft Academic Search

Flooding of soils results in acute oxygen deprivation (anoxia) of plant roots during winter in temperate latitudes, or after irrigation, and is a major problem for agriculture. One early response of plants to anoxia and other environmental stresses is downregulation of water uptake due to inhibition of the water permeability (hydraulic conductivity) of roots (Lpr). Root water uptake is mediated

Colette Tournaire-Roux; Moira Sutka; Hélène Javot; Elisabeth Gout; Patricia Gerbeau; Doan-Trung Luu; Richard Bligny; Christophe Maurel

2003-01-01

113

Mechanisms Coordinating Wheat Seedling Growth Response as Affected by Shoot\\/Root Ratio  

Microsoft Academic Search

Excision of four out of five roots in 7-day-old wheat seedlings (Triticum durum Desf.) rapidly suppressed shoot growth promoted biomass accumulation by the remained root largely due to its expanded branching. Next, the rate of shoot growth increased although was not completely recovered. After the reduction of the root system, the rate of photosynthesis in the leaves of seedlings did

L. B. Vysotskaya

2005-01-01

114

Rapid Effects of Indoleacetic Acid and Ethylene on the Growth of Intact Pea Roots 1  

PubMed Central

Root auxanometers were used to determine the growth rates of individual intact primary roots accurately and quickly. The growth of pea (Pisum sativum L.) roots was inhibited by both indoleacetic acid and ethylene within 20 minutes. A supramaximal concentration of ethylene inhibited root growth less than did 5 to 20 ?m indoleacetic acid, indicating that inhibition of root growth by auxin was not due only to indoleacetic acid-induced ethylene production. Inhibition of root growth was largely relieved within 60 minutes of removal of both growth regulators.

Rauser, Wilfried E.; Horton, Roger F.

1975-01-01

115

Cointegration and Unit Roots  

Microsoft Academic Search

This paper provides an updated survey of a burgeoning literature in testing, estimation and model specification in the presence of integrated variables. Integrated variables are a specific class of non-stationary variables which seem to characterize faithfully the properties of many macroeconomic tie seris. The analysis of cointegration develops out of the esxistence of unit roots and offers a generic route

Juan José Dolado; Tim Jenkinson; Simon Sosvilla-Rivero

1990-01-01

116

Diageotropism in Vanilla Roots.  

PubMed

Diageotropic growth in the dark and geotropic growth in the light occurred in the roots of cuttings of three Vanilla species. The diageotropic response also occurred in far-red, red, orange, and green light, while positive geotropism resulted only if blue light was present. PMID:17834304

Irvine, J E; Freyre, R H

1961-07-01

117

Great Plains Roots.  

ERIC Educational Resources Information Center

|Sandy White Hawk, Sicangu Lakota, was adopted by white missionaries as an infant and suffered child abuse. After 33 years, she found her birth family and formed First Nations Orphans Association, which uses songs and ceremonies to help adoptees return to their roots. Until the 1970s, federal agencies and welfare organizations facilitated removal…

Frey, Jennifer

2001-01-01

118

Great Plains Roots.  

ERIC Educational Resources Information Center

Sandy White Hawk, Sicangu Lakota, was adopted by white missionaries as an infant and suffered child abuse. After 33 years, she found her birth family and formed First Nations Orphans Association, which uses songs and ceremonies to help adoptees return to their roots. Until the 1970s, federal agencies and welfare organizations facilitated removal…

Frey, Jennifer

2001-01-01

119

Root hair sweet growth  

PubMed Central

Root hairs are single cells specialized in the absorption of water and nutrients from the soil. Growing root hairs require intensive cell-wall changes to accommodate cell expansion at the apical end by a process known as tip or polarized growth. We have recently shown that cell wall glycoproteins such as extensins (EXTs) are essential components of the cell wall during polarized growth. Proline hydroxylation, an early posttranslational modification of cell wall EXTs that is catalyzed by prolyl 4-hydroxylases (P4Hs), defines the subsequent O-glycosylation sites in EXTs. Biochemical inhibition or genetic disruption of specific P4Hs resulted in the blockage of polarized growth in root hairs. Our results demonstrate that correct hydroxylation and also further O-glycosylation on EXTs are essential for cell-wall self-assembly and, hence, root hair elongation. The changes that O-glycosylated cell-wall proteins like EXTs undergo during cell growth represent a starting point to unravel the entire biochemical pathway involved in plant development.

Velasquez, Silvia M; Iusem, Norberto D

2011-01-01

120

Roots of Empathy.  

ERIC Educational Resources Information Center

Describes the "Roots of Empathy" program for elementary school students in some Toronto schools, designed to teach about parenting, human development, and emotional literacy, and to nurture the growth of empathy. Focuses on development of a culture of caring, the role of perspective taking for conflict resolution, the positive neuroscience message…

Gordon, Mary

2001-01-01

121

Unit Root Testing  

Microsoft Academic Search

A frequent criticism of unit root tests concerns the poor power and size properties that many such tests exhibit. However, during the past decade or so intensive research has been conducted to alleviate these problems and great advances have been made. The present paper provides a selective survey of recent contributions to improve upon both the size and power of

Niels Haldrup; Michael Jansson

122

"Roots": Medium and Message.  

ERIC Educational Resources Information Center

A national telephone survey indicated that audiences rated the television production of "Roots" positively in terms of the following: realistic portrayal of the people and the times; relevance for contemporary race relations; perceived emotional effect; and increased understanding of the psychology of black people. However, a comparison of the…

Kinnamon, Keneth

123

Accounting carbon storage in decaying root systems of harvested forests.  

PubMed

Decaying root systems of harvested trees can be a significant component of belowground carbon storage, especially in intensively managed forests where harvest occurs repeatedly in relatively short rotations. Based on destructive sampling of root systems of harvested loblolly pine trees, we estimated that root systems contained about 32% (17.2 Mg ha(-1)) at the time of harvest, and about 13% (6.1 Mg ha(-1)) of the soil organic carbon 10 years later. Based on the published roundwood output data, we estimated belowground biomass at the time of harvest for loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina. We then calculated C that remained in the decomposing root systems in 2005 using the decay function developed for loblolly pine. Our calculations indicate that the amount of C stored in decaying roots of loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina was 7.1 Tg. Using a simple extrapolation method, we estimated 331.8 Tg C stored in the decomposing roots due to timber harvest from 1995 to 2005 in the conterminous USA. To fully account for the C stored in the decomposing roots of the US forests, future studies need (1) to quantify decay rates of coarse roots for major tree species in different regions, and (2) to develop a methodology that can determine C stock in decomposing roots resulting from natural mortality. PMID:22535427

Wang, G Geoff; Van Lear, David H; Hu, Huifeng; Kapeluck, Peter R

2011-07-01

124

Evaluating Ecohydrological Theories of Woody Root Distribution in the Kalahari  

PubMed Central

The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1) the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis), and (2) the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis). Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity.

Bhattachan, Abinash; Tatlhego, Mokganedi; Dintwe, Kebonye; O'Donnell, Frances; Caylor, Kelly K.; Okin, Gregory S.; Perrot, Danielle O.; Ringrose, Susan; D'Odorico, Paolo

2012-01-01

125

Distribution and speciation of Mn in hydrated roots of cowpea at levels inhibiting root growth.  

PubMed

The phytotoxicity of Mn is important globally due to its increased solubility in acid or waterlogged soils. Short-term (?24 h) solution culture studies with 150 µM Mn were conducted to investigate the in situ distribution and speciation of Mn in apical tissues of hydrated roots of cowpea [Vigna unguiculata (L.) Walp. cv. Red Caloona] using synchrotron-based techniques. Accumulation of Mn was rapid; exposure to 150 µM Mn for only 5 min resulting in substantial Mn accumulation in the root cap and associated mucigel. The highest tissue concentrations of Mn were in the root cap, with linear combination fitting of the data suggesting that??80% of this Mn(II) was associated with citrate. Interestingly, although the primary site of Mn toxicity is typically the shoots, concentrations of Mn in the stele of the root were not noticeably higher than in the surrounding cortical tissues in the short-term (?24 h). The data provided here from the in situ analyses of hydrated roots exposed to excess Mn are, to our knowledge, the first of this type to be reported for Mn and provide important information regarding plant responses to high Mn in the rooting environment. PMID:22892034

Kopittke, Peter M; Lombi, Enzo; McKenna, Brigid A; Wang, Peng; Donner, Erica; Webb, Richard I; Blamey, F Pax C; de Jonge, Martin D; Paterson, David; Howard, Daryl L; Menzies, Neal W

2012-09-13

126

Root canal medicaments.  

PubMed

The ultimate goals of endodontic treatment are complete removal of bacteria, their byproducts and pulpal remnants from infected root canals and the complete seal of disinfected root canals. Intracanal medicaments have been thought an essential step in killing the bacteria in root canals; however, in modern endodontics, shaping and cleaning may be assuming greater importance than intracanal medicaments as a means of disinfecting root canals. Until recently, formocresol and its relatives were frequently used as intracanal medicaments, but it was pointed out that such bactericidal chemicals dressed in the canal distributed to the whole body from the root apex and so might induce various harmful effects including allergies. Furthermore, as these medicaments are potent carcinogenic agents, there is no indication for these chemicals in modern endodontic treatment. Today, biocompatibility and stability are essential properties for intracanal medicaments. The more modern meaning of intracanal dressing is for a blockade against coronal leakage from the gap between filling materials and cavity wall. Calcium hydroxide has been determined as suitable for use as an intracanal medicament as it is stable for long periods, harmless to the body, and bactericidal in a limited area. It also induces hard tissue formation and is effective for stopping inflammatory exudates. Single-visit endodontics, where intracanal medicaments are not used, is generally not now contraindicated and various reports have shown that the clinical outcomes between single- and multiple- visit endodontics are similar. There is no reason to counsel against single-visit endodontics: however, if multiple-visit endodontics is chosen, calcium hydroxide is recommended to be used as an intracanal medicament. PMID:19323305

Kawashima, Nobuyuki; Wadachi, Reiko; Suda, Hideaki; Yeng, Thai; Parashos, Peter

2009-02-01

127

Roles of phosphatidylinositol 3-kinase in root hair growth.  

PubMed

The root hair is a model system for understanding plant cell tip growth. As phosphatidylinositol 3-phosphate [PtdIns(3)P] has been shown in other plant cell types to regulate factors that affect root hair growth, including reactive oxygen species (ROS) levels, cytoskeleton, and endosomal movement, we hypothesized that PtdIns(3)P is also important for root hair elongation. The enzyme that generates PtdIns(3)P, phosphatidylinositol 3-kinase (PI3K), was expressed in root hair cells of transgenic plants containing the PI3K promoter:beta-glucuronidase reporter construct. To obtain genetic evidence for the role of PtdIns(3)P in root hair elongation, we attempted to isolate Arabidopsis (Arabidopsis thaliana) mutant plants that did not express the gene VPS34 encoding the PI3K enzyme. However, the homozygous mutant was lethal due to gametophytic defects, and heterozygous plants were not discernibly different from wild-type plants. Alternatively, we made transgenic plants expressing the PtdIns(3)P-binding FYVE domain in the root hair cell to block signal transduction downstream of PtdIns(3)P. These transgenic plants had shorter root hairs and a reduced hair growth rate compared with wild-type plants. In addition, LY294002, a PI3K-specific inhibitor, inhibited root hair elongation but not initiation. In LY294002-treated root hair cells, endocytosis at the stage of final fusion of the late endosomes to the tonoplast was inhibited and ROS level decreased in a dose-dependent manner. Surprisingly, the LY294002 effects on ROS and root hair elongation were similar in rhd2 mutant plants, suggesting that RHD2 was not the major ROS generator in the PtdIns(3)P-mediated root hair elongation process. Collectively, these results suggest that PtdIns(3)P is required for maintenance of the processes essential for root hair cell elongation. PMID:18408046

Lee, Yuree; Bak, Gwangbae; Choi, Yunjung; Chuang, Wen-I; Cho, Hyung-Taeg; Lee, Youngsook

2008-04-11

128

Invertase Activity in Root Growth  

NSDL National Science Digital Library

This resource is a manual for instructing a laboratory exercise in plant biology and enzyme kinetics. Students microscopically observe corn root sections and determine by enzymatic assays, the intergrase enzyme activity in selected regions of the root.

Chris J. Perumalla (University of Toronto;); Johan A. Hellebust (University of Toronto;); Corey A. Goldman (University of Toronto;)

1994-01-01

129

Water transport in barley roots  

Microsoft Academic Search

Radial transport of water in excised barley (Hordeum distichon, cv. Villa) roots was measured using a new method based on the pressure-probe technique. After attaching excised roots to the probe, root pressures of 0.9 to 2.9 bar were developed. They could be altered either by changing the root pressure artificially (with the aid of the probe) or by changing the

E. Steudle; W. D. Jeschke

1983-01-01

130

Characterization of mechanical properties of transgenic tobacco roots expressing a recombinant monoclonal antibody against tooth decay.  

PubMed

In this article, we describe a new approach that allows the determination of the magnitude of force required to break single plant roots. Roots were taken from transgenic tobacco plants, expressing a secreted monoclonal antibody. They were divided into four key developmental stages. A novel micromanipulation technique was used to pull to breakage, single tobacco roots in buffer in order to determine their breaking force. A characteristic uniform step-wise increase in the force up to a peak force for breakage was observed. The mean breaking force and mean work done were 101mN and 97microJ per root respectively. However, there was a significant increase in breaking force from the youngest white roots to the oldest, dark red-brown roots. We speculate that this was due to increasing lignin deposition with root stage of development (shown by phloroglucinol staining). No significant differences between fresh root mass, original root length, or mean root diameter for any of the root categories were found, displaying their uniformity, which would be beneficial for bioprocessing. In addition, no significant difference in antibody yield from the different root categories was found. These data show that it is possible to characterise the force requirements for root breakage and should assist in the optimisation of recombinant protein extraction from these roots. PMID:18496877

Hassan, Sally; Liu, Wei; Ma, Julian K-C; Thomas, Colin R; Keshavarz-Moore, Eli

2008-07-01

131

Lesson 24: Roots and Radicals  

NSDL National Science Digital Library

Exponential notation for Nth roots and radicals is introduced. A short discussion about Nth roots and irrational numbers follows before symbolic manipulation of fractional exponents and solving equations is presented. Power functions and solving radical equations are presented before the lesson concludes with roots of negative numbers.

2011-01-01

132

Formation of AgFeO2, ?-FeOOH, and Ag2O from mixed Fe(NO3)3-AgNO3 solutions at high pH  

NASA Astrophysics Data System (ADS)

Precipitation of ternary oxide silver ferrite (AgFeO2), iron oxyhydroxide goethite (?-FeOOH) and silver(I) oxide (Ag2O) from mixed Fe(NO3)3-AgNO3 solutions in a whole [Ag+]:[Fe3+] concentration ratio range at high pH was investigated using X-ray powder diffraction (XRD), 57Fe Mössbauer, FT-IR and UV-Vis-NIR spectroscopies and field emission scanning electron microscopy (FE-SEM). Strong alkalis organic tetramethylammonium hydroxide (TMAH) or inorganic NaOH were used as precipitating agents. Monodispersed lath-like ?-FeOOH particles were formed from a pure Fe(NO3)3 solution. The presence of Ag+ ions influenced the formation of the delafossite-type ternary oxide AgFeO2 beside ?-FeOOH. The positions of XRD and Mössbauer lines did not suggest any significant incorporation of Ag+ ions into the ?-FeOOH structure. AgFeO2 was formed in the precipitation system with the equimolar initial [Ag+]:[Fe3+] concentration ratio. The size and shape of AgFeO2 particles, as well as their structural polytype (2H or 3R), were dependent on reaction temperature, aging time and alkali used. In systems with an excess of Ag+ ions mixtures of AgFeO2 and Ag2O were formed. Single phase Ag2O precipitated from a pure AgNO3 solution.

Krehula, Stjepko; Musi?, Svetozar

2013-07-01

133

Control of Arabidopsis Root Development  

PubMed Central

The Arabidopsis root has been the subject of intense research over the past decades. This research has led to significantly improved understanding of the molecular mechanisms underlying root development. Key insights into the specification of individual cell types, cell patterning, growth and differentiation, branching of the primary root, and responses of the root to the environment have been achieved. Transcription factors and plant hormones play key regulatory roles. Recently, mechanisms involving protein movement and the oscillation of gene expression have also been uncovered. Root gene regulatory networks controlling root development have been reconstructed from genome-wide profiling experiments, revealing novel molecular connections and models. Future refinement of these models will lead to a more complete description of the complex molecular interactions that give rise to a simple growing root.

Petricka, Jalean J.; Winter, Cara M.; Benfey, Philip N.

2013-01-01

134

Arabidopsis thaliana root growth kinetics and lunisolar tidal acceleration.  

PubMed

• All living organisms on Earth are continually exposed to diurnal variations in the gravitational tidal force due to the Sun and Moon. • Elongation of primary roots of Arabidopsis thaliana seedlings maintained at a constant temperature was monitored for periods of up to 14 d using high temporal- and spatial-resolution video imaging. The time-course of the half-hourly elongation rates exhibited an oscillation which was maintained when the roots were placed in the free-running condition of continuous illumination. • Correlation between the root growth kinetics collected from seedlings initially raised under several light protocols but whose roots were subsequently in the free-running condition and the lunisolar tidal profiles enabled us to identify that the latter is the probable exogenous determinant of the rhythmic variation in root elongation rate. Similar observations and correlations using roots of Arabidopsis starch mutants suggest a central function of starch metabolism in the response to the lunisolar tide. The periodicity of the lunisolar tidal signal and the concomitant adjustments in root growth rate indicate that an exogenous timer exists for the modulation of root growth and development. • We propose that, in addition to the sensitivity to Earthly 1G gravity, which is inherent to all animals and plants, there is another type of responsiveness which is attuned to the natural diurnal variations of the lunisolar tidal force. PMID:22583121

Fisahn, Joachim; Yazdanbakhsh, Nima; Klingele, Emile; Barlow, Peter

2012-05-14

135

Hydraulic conductivity of rice roots.  

PubMed

A pressure chamber and a root pressure probe technique have been used to measure hydraulic conductivities of rice roots (root Lp(r) per m(2) of root surface area). Young plants of two rice (Oryza sativa L.) varieties (an upland variety, cv. Azucena and a lowland variety, cv. IR64) were grown for 31-40 d in 12 h days with 500 micromol m(-2) s(-1) PAR and day/night temperatures of 27 degrees C and 22 degrees C. Root Lp(r) was measured under conditions of steady-state and transient water flow. Different growth conditions (hydroponic and aeroponic culture) did not cause visible differences in root anatomy in either variety. Values of root Lp(r) obtained from hydraulic (hydrostatic) and osmotic water flow were of the order of 10(-8) m s(-1) MPa(-1) and were similar when using the different techniques. In comparison with other herbaceous species, rice roots tended to have a higher hydraulic resistance of the roots per unit root surface area. The data suggest that the low overall hydraulic conductivity of rice roots is caused by the existence of apoplastic barriers in the outer root parts (exodermis and sclerenchymatous (fibre) tissue) and by a strongly developed endodermis rather than by the existence of aerenchyma. According to the composite transport model of the root, the ability to adapt to higher transpirational demands from the shoot should be limited for rice because there were minimal changes in root Lp(r) depending on whether hydrostatic or osmotic forces were acting. It is concluded that this may be one of the reasons why rice suffers from water shortage in the shoot even in flooded fields. PMID:11520872

Miyamoto, N; Steudle, E; Hirasawa, T; Lafitte, R

2001-09-01

136

Geoperception in primary and lateral roots of Phaseolus vulgaris (Fabaceae). I. Structure of columella cells.  

PubMed

Primary roots of Phaseolus vulgaris (Fabaceae) are positively geotropic, while lateral roots are not responsive to gravity In order to elucidate the structural basis for this differential georesponse, we have performed a qualitative and quantitative analysis of the ultrastructure of columella cells of primary and lateral roots of P. vulgaris. Root systems were fixed in situ so as not to disturb the ultrastructure of the columella cells. The columellas of primary roots are more extensive than those of lateral roots. The volumes of columella cells of primary roots are approximately twice those of columella cells of lateral roots. However, columella cells of primary roots contain greater absolute volumes and numbers of all cellular components examined than do columella cells of lateral roots. Also, the relative volumes of cellular components in columella cells of primary and lateral roots are statistically indistinguishable. The endoplasmic reticulum is sparse and distributed randomly in both types of columella cells. Both types of columella cells contain numerous sedimented amyloplasts, none of which contact the cell wall or form complexes with other cellular organelles. Therefore, positive geotropism by roots must be due to a factor(s) other than the presence of sedimented amyloplasts alone. Furthermore, it is unlikely that amyloplasts and plasmodesmata form a multi-valve system that controls the movement of growth regulating substances through the root cap. PMID:11541079

Ransom, J S; Moore, R

1983-08-01

137

Role of NINJA in root jasmonate signaling.  

PubMed

Wound responses in plants have to be coordinated between organs so that locally reduced growth in a wounded tissue is balanced by appropriate growth elsewhere in the body. We used a JASMONATE ZIM DOMAIN 10 (JAZ10) reporter to screen for mutants affected in the organ-specific activation of jasmonate (JA) signaling in Arabidopsis thaliana seedlings. Wounding one cotyledon activated the reporter in both aerial and root tissues, and this was either disrupted or restricted to certain organs in mutant alleles of core components of the JA pathway including COI1, OPR3, and JAR1. In contrast, three other mutants showed constitutive activation of the reporter in the roots and hypocotyls of unwounded seedlings. All three lines harbored mutations in Novel Interactor of JAZ (NINJA), which encodes part of a repressor complex that negatively regulates JA signaling. These ninja mutants displayed shorter roots mimicking JA-mediated growth inhibition, and this was due to reduced cell elongation. Remarkably, this phenotype and the constitutive JAZ10 expression were still observed in backgrounds lacking the ability to synthesize JA or the key transcriptional activator MYC2. Therefore, JA-like responses can be recapitulated in specific tissues without changing a plant's ability to make or perceive JA, and MYC2 either has no role or is not the only derepressed transcription factor in ninja mutants. Our results show that the role of NINJA in the root is to repress JA signaling and allow normal cell elongation. Furthermore, the regulation of the JA pathway differs between roots and aerial tissues at all levels, from JA biosynthesis to transcriptional activation. PMID:24003128

Acosta, Iván F; Gasperini, Debora; Chételat, Aurore; Stolz, Stéphanie; Santuari, Luca; Farmer, Edward E

2013-09-03

138

Density of the continental roots: Compositional and thermal contributions  

USGS Publications Warehouse

The origin and evolution of cratonic roots has been debated for many years. Precambrian cratons are underlain by cold lithospheric roots that are chemically depleted. Thermal and petrologic data indicate that Archean roots are colder and more chemically depleted than Proterozoic roots. This observation has led to the hypothesis that the degree of depletion in a lithospheric root depends mostly on its age. Here we test this hypothesis using gravity, thermal, petrologic, and seismic data to quantify differences in the density of cratonic roots globally. In the first step in our analysis we use a global crustal model to remove the crustal contribution to the observed gravity. The result is the mantle gravity anomaly field, which varies over cratonic areas from -100 to +100 mGal. Positive mantle gravity anomalies are observed for cratons in the northern hemisphere: the Baltic shield, East European Platform, and the Siberian Platform. Negative anomalies are observed over cratons in the southern hemisphere: Western Australia, South America, the Indian shield, and Southern Africa. This indicates that there are significant differences in the density of cratonic roots, even for those of similar age. Root density depends on temperature and chemical depletion. In order to separate these effects we apply a lithospheric temperature correction using thermal estimates from a combination of geothermal modeling and global seismic tomography models. Gravity anomalies induced by temperature variations in the uppermost mantle range from -200 to +300 mGal, with the strongest negative anomalies associated with mid-ocean ridges and the strongest positive anomalies associated with cratons. After correcting for thermal effects, we obtain a map of density variations due to lithospheric compositional variations. These maps indicate that the average density decrease due to the chemical depletion within cratonic roots varies from 1.1% to 1.5%, assuming the chemical boundary layer has the same thickness as the thermal boundary layer. The maximal values of the density drop are in the range 1.7-2.5%, and correspond to the Archean portion of each craton. Temperatures within cratonic roots vary strongly, and our analysis indicates that density variations in the roots due to temperature are larger than the variations due to chemical differences. ?? 2003 Elsevier Science B.V. All rights reserved.

Kaban, M. K.; Schwintzer, P.; Artemieva, I. M.; Mooney, W. D.

2003-01-01

139

The distribution and strength of riparian tree roots in relation to riverbank reinforcement  

NASA Astrophysics Data System (ADS)

The main influences of plants on the mass stability of riverbanks are those that affect the strength of bank sediments. Plants enhance bank strength by reducing pore-water pressures and by directly reinforcing bank material with their roots. In this paper we do not consider bank hydrology but focus on quantifying increases in sediment strength due to root reinforcement. Root reinforcement is a function of root strength, interface friction between the roots and the soil, and the distribution of roots within the soil. Field and laboratory studies of Australian riparian trees, river red gum (Eucalyptus camaldulensis) and swamp paperbark (Melaleuca ericifolia), indicate that bank reinforcement, due to the roots of these species, decreases exponentially with depth below the soil surface and distance away from the trees. Differences in the spatial distribution of root reinforcement are illustrated by a comparison of the apparent cohesion due to roots (cr) with the effective cohesion of the saturated bank material (15 kPa). Directly below the river red gum, root reinforcement is equal to effective cohesion at 1·7 m depth. At the dripline (17 m from the trunk), root reinforcement is equal to material strength at 0·4 m depth. For the swamp paperbark, cr=15 kPa at 1·1 m depth beneath surface, at the trunks, and at 0·4 m depth at the dripline (2·5 m from the trunk). A description of the spatial distribution of root reinforcement is important in the riverbank context. We find that interspecies differences in the strength of living roots have less significance for bank reinforcement than interspecies differences in root distribution.

Abernethy, Bruce; Rutherfurd, Ian D.

2001-01-01

140

Photophobic behavior of maize roots.  

PubMed

Primary roots of young maize seedlings showed peculiar growth behavior when challenged by placing them on a slope, or if whole seedlings were turned upside down. Importantly, this behavior was dependent on the light conditions. If roots were placed on slopes in the dark, they performed "crawling" behavior and advanced rapidly up the slope. However, as soon as these roots were illuminated, their crawling movements along their horizontal paths slowed down, and instead tried to grow downwards along the gravity vector. A similar light-induced switch in the root behavior was observed when roots were inverted, by placing them in thin glass capillaries. As long as they were kept in the darkness, they showed rapid growth against the gravity vector. If illuminated, these inverted roots rapidly accomplished U-turns and grew down along the gravity vector, eventually escaping from the capillaries upon reaching their open ends. De-capped roots, although growing vigorously, did not display these light-induced photophobic growth responses. We can conclude that intact root cap is essential for the photophobic root behavior in maize. PMID:22751294

Burbach, Christian; Markus, Katharina; Zhang, Yin; Schlicht, Markus; Baluška, František

2012-07-01

141

Maximum-rank root subsystems of hyperbolic root systems  

NASA Astrophysics Data System (ADS)

A Kac-Moody algebra is said to be hyperbolic if it corresponds to a generalized Cartan matrix of hyperbolic type. Root subsystems of root systems of algebras of this kind are studied. The main result of the paper is the classification of the maximum-rank regular hyperbolic subalgebras of hyperbolic Kac-Moody algebras.

Tumarkin, P. V.

2004-02-01

142

Root canals in two-rooted maxillary second molars.  

PubMed

The aim of this study was to register the root canal number, root canal position, and root canal cross-section in human two-rooted, permanent maxillary second molars. One hundred and fifty-nine such teeth extracted in Denmark were cross-sectioned at the mid-root level and apically in accordance with precise guidelines. The observations were made in a stereomicroscope, corresponding to the above-mentioned section levels. At mid-root there were two canals present in 11% of the teeth examined; the canals were located mesially and distofacially, mesiofacially and distally, or facially and lingually. Three canals positioned mesiofacially, distofacially, and lingually were observed in 89% of the teeth. At the same level 62% of the canal cross-sections were noncircular, some being, for instance, C-shaped, whereas 38% of the cross-sections were circular. Apically, two canals were found, representing 19% of the teeth, with the canal position as at mid-root; 81% of the teeth were three-canaled with the same canal position as at mid-root. At the apical level 60% of the canal cross-sections were noncircular, whereas 40% of the cross-sections were circular. PMID:9477024

Carlsen, O; Alexandersen, V

1997-12-01

143

Glutamate Oxaloacetate Transaminase in Pea Root Nodules 1  

PubMed Central

Glutamate oxaloacetate transaminase (l-glutamate: oxaloacetate aminotransferase, EC 2.6.1.1 [GOT]), a key enzyme in the flow of carbon between the organic acid and amino acid pools in pea (Pisum sativum L.) root nodules, was studied. By ion exchange chromatography, the presence of two forms of GOT in the cytoplasm of pea root nodule cells was established. The major root nodule form was present in only a small quantity in the cytoplasm of root cells. Fractionation of root nodule cell extracts demonstrated that the increase in the GOT activity during nodule development was due to the increase of the activity in the cytoplasm of the plant cells, and not to an increase in activity in the plastids or in the mitochondria. The kinetic properties of the different cytoplasmic forms of GOT were studied. Some of the Km values differed, but calculations indicated that not the kinetic properties but a high concentration of the major root nodule form caused the observed increase in GOT activity in the pea root nodules. It was found that the reactions of the malate/aspartate shuttle are catalyzed by intact bacteroids, and that these reactions can support nitrogen fixation. It is proposed that the main function of the nodule-stimulated cytoplasmic form of GOT is participation in this shuttle.

Appels, Michiel A.; Haaker, Huub

1991-01-01

144

Role of CIPK6 in root growth and auxin transport  

PubMed Central

In our recent publication,1 we have shown that a T-DNA insertion in Arabidopsis CIPK6 gene encoding a CBL-interacting protein kinase caused reduction in expression of the gene and emergence of lateral roots. The change in phenotype in the mutant line was likely due to reduction in shoot-to-root acropetal and the root tip basipetal auxin transport. Here we report identification of a homozygous knockout line of AtCIPK6 (atcipk6) with no detectable expression of the gene in normal growth condition. The knockout line exhibited considerable decrease in growth rate of the taproot as well as in emergence of lateral roots. The mutant line also showed reduction in the root tip basipetal and shoot-to-root acropetal auxin transport. Relative rate of auxin transport and the root phenotype of the atcipk6 closely matched with those of pgp4-1, an Arabidopsis line mutated in PGP4. This gene encodes an ABC integral membrane transporter, which functions in polar auxin transport. These observations strengthen our earlier proposal that CIPK6 is probably involved in polar auxin transport and indicate that it may function through the PGP4 auxin transporter.

Tripathi, Vineeta; Syed, Nazia; Laxmi, Ashverya

2009-01-01

145

Contribution of relative growth rate to root foraging by annual and perennial grasses from California oak woodlands  

Microsoft Academic Search

Plants forage for nutrients by increasing their root length density (RLD) in nutrient-rich soil microsites through root morphological changes resulting in increased root biomass density (RBD), specific root length (SRL), or branching frequency (BF). It is commonly accepted that fast-growing species will forage more than slow-growing species. However, foraging responses may be due solely to differences in relative growth rates

Zachary T. Aanderud; Caroline S. Bledsoe; James H. Richards

2003-01-01

146

Live cell imaging of Arabidopsis root hairs.  

PubMed

Root hairs are tubular extensions from the root surface that expand by tip growth. This highly focused type of cell expansion, combined with position of root hairs on the surface of the root, makes them ideal cells for microscopic observation. This chapter describes the method that is routinely used in our laboratory for live cell imaging of Arabidopsis root hairs. PMID:24132430

Ketelaar, Tijs

2014-01-01

147

Nahm's equations and root systems  

NASA Astrophysics Data System (ADS)

A method of deriving solutions to Nahm''s equations based on root structure of simple Lie algebras is given. As an illustration of this method the recently found solutions to Nahm''s equations with tetrahedral and octahedral symmetries are shown to correspond to A 2 and A 3 root systems.

Brzezi?ski, Tomasz; Merabet, Houari

1997-11-01

148

Root canals in one-rooted maxillary second molars.  

PubMed

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists. PMID:1411268

Carlsen, O; Alexandersen, V; Heitmann, T; Jakobsen, P

1992-10-01

149

Procedural Due Process.  

ERIC Educational Resources Information Center

A central issue in litigation arising from adverse employment decisions affecting school personnel is the adequacy of due process procedures. Due process is required only if a teacher is able to establish a protected property or liberty interest. The first section of this chapter accordingly discusses the circumstances under which due process is…

Cambron-McCabe, Nelda H.

150

Evaluation of root fungicides as root dips for the control of root rot in storage, 2009  

Technology Transfer Automated Retrieval System (TEKTRAN)

Root rot in storage can lead to considerable sucrose losses in storage and adversely affect factory processing as well. The use of fungicide treatments applied to the root surface prior to storage were investigated to determine if they could reduce storage rots caused by Botrytis sp., Penicillium s...

151

Adaptive significance of root grafting in trees.  

National Technical Information Service (NTIS)

Root grafting has long been observed in forest trees but the adaptive significance of this trait has not been fully explained. Various authors have proposed that root grafting between trees contributes to mechanical support by linking adjacent root system...

C. Loehle R. Jones

1988-01-01

152

Auxin Induced Lateral Root Formation in Chicory  

Microsoft Academic Search

The supply of auxins [2,4-dichlorophenoxy acetic acid (2,4D), indole-3 acetic acid (1AA) and ?-naphthaleneacetic acid (NAA)] to excised chicory roots induced the formation of lateral root meristems mainly located close to the pre-existing apical root meristem. Lateral root growth induced in non-excised roots required higher auxin concentrations. Inhibition of root elongation and concomittant enlargement of the apices was also observed.

CHRISTOPHE VUYLSTEKER; ERIC DEWAELE; SERGE RAMBOUR

1998-01-01

153

Root complex and root canal system: a correlation analysis using one-rooted mandibular second molars.  

PubMed

The principal aim of this investigation was to verify an expected, probable correlation between certain variables, which are initially represented in the macrostructure of the root complex corresponding to the cemento-dentin junction, and certain variables that subsequently manifest themselves in the root canal system. A material consisting of 76 one-rooted, permanent mandibular second molars (M2 inf) was used. The specimens were cut at the mid-root level and all observations were made on the coronal root segment using a stereomicroscope. Relevant variables of the root complex were observed. The total macromorphologic variation of the root complex could be subdivided and classified in well-defined, distinguishable types. In accordance with the single root complex type an expected, logically deduced configuration of the root canal system was established. The relevant variables of the canal system were then recorded. Finally, the root complex morphology, as well as the expected and actually observed canal configuration, were compared type by type. In 76.3% of the teeth a good concordance could be shown between the expected and the actual canal configuration, whereas in 23.7% of the specimens there was a divergence. In 42.1% of the investigated teeth, 1 centrally localized main canal with varying cross section images, among them a C-shaped image, was found. In 30.3%, 2 main canals were found, which were often localized mesially and distally. In 23.7%, 3 main canals were observed: 1 mesiofacial, 1 mesiolingual and 1 distal. In the remaining 3.9%, 1 non-independent supernumerary canal was seen in a distolingual position. PMID:2399422

Carlsen, O

1990-08-01

154

Role of Cytokinin and Auxin in Shaping Root Architecture: Regulating Vascular Differentiation, Lateral Root Initiation, Root Apical Dominance and Root Gravitropism  

PubMed Central

• Background and Aims Development and architecture of plant roots are regulated by phytohormones. Cytokinin (CK), synthesized in the root cap, promotes cytokinesis, vascular cambium sensitivity, vascular differentiation and root apical dominance. Auxin (indole-3-acetic acid, IAA), produced in young shoot organs, promotes root development and induces vascular differentiation. Both IAA and CK regulate root gravitropism. The aims of this study were to analyse the hormonal mechanisms that induce the root's primary vascular system, explain how differentiating-protoxylem vessels promote lateral root initiation, propose the concept of CK-dependent root apical dominance, and visualize the CK and IAA regulation of root gravitropiosm. • Key Issues The hormonal analysis and proposed mechanisms yield new insights and extend previous concepts: how the radial pattern of the root protoxylem vs. protophloem strands is induced by alternating polar streams of high IAA vs. low IAA concentrations, respectively; how differentiating-protoxylem vessel elements stimulate lateral root initiation by auxin–ethylene–auxin signalling; and how root apical dominance is regulated by the root-cap-synthesized CK, which gives priority to the primary root in competition with its own lateral roots. • Conclusions CK and IAA are key hormones that regulate root development, its vascular differentiation and root gravitropism; these two hormones, together with ethylene, regulate lateral root initiation.

ALONI, R.; ALONI, E.; LANGHANS, M.; ULLRICH, C. I.

2006-01-01

155

IAA transport in corn roots includes the root cap  

SciTech Connect

In earlier reports we concluded that auxin is the growth regulator that controls gravicurvature in roots and that the redistribution of auxin occurs within the root cap. Since other reports did not detect auxin in the root cap, we attempted to confirm the IAA does move through the cap. Agar blocks containing {sup 3}H-IAA were applied to the cut surface of 5 mm long apical segments of primary roots of corn (mo17xB73). After 30 to 120 min radioactivity (RA) of the cap and root tissue was determined. While segments suspended in water-saturated air accumulated very little RA in the cap, application of 0.5 {mu}1 of dist. water to the cap (=controls) increased RA of the cap dramatically. Application to the cap of 0.5 {mu}1 of sorbitol or the Ca{sup 2+} chelator EGTA reduced cap RA to 46% and 70% respectively compared to water, without affecting uptake. Control root segments gravireacted faster than non-treated or osmoticum or EGTA treated segments. The data indicate that both the degree of hydration and calcium control the amount of auxin moving through the cap.

Hasenstein, K.H. (Univ. of SW Louisiana, Lafayette (USA))

1989-04-01

156

Is root growth under phosphorus deficiency affected by source or sink limitations?  

Microsoft Academic Search

Reduced net photosynthesis (Pn) and decreasing shoot and root biomass are typical effects of phos- phorus deficiency in plants. Lower biomass accumu- lation could be the result of reduced Pn (source limitation), but may also be due to direct negative effects of low P availability on growth (sink limitation). Because of the principal importance of root growth for P uptake,

Matthias Wissuwa; Gloria Gamat; Abdelbagi M. Ismail

2005-01-01

157

Stem and root carbohydrate dynamics in modern vs obsolete cotton cultivars  

Technology Transfer Automated Retrieval System (TEKTRAN)

The lower stem and root starch reserve is a necessary source of photoassimilates for completion of reproductive development in cotton. The objectives of this research was to determine if carbohydrate levels in the lower stem and roots have been altered due to over 100 years of breeding efforts. In ...

158

COUPLING FINE ROOT DYNAMICS WITH ECOSYSTEM CARBON CYCLING IN BLACK SPRUCE FORESTS OF INTERIOR ALASKA  

Microsoft Academic Search

Fine root processes play a prominent role in the carbon and nutrient cycling of boreal ecosystems due to the high proportion of biomass allocated belowground and the rapid decomposition of fine roots relative to aboveground tissues. To examine these issues in detail, major components of ecosystem carbon flux were studied in three mature black spruce forests in interior Alaska, where

Roger W. Ruess; Ronald L. Hendrick; Andrew J. Burton; Kurt S. Pregitzer; Bjartmar Sveinbjornssön; Michael F. Allen; Gregory E. Maurer

2003-01-01

159

Tree roots and damages in the Jewish catacombs of Villa Torlonia (Roma)  

Microsoft Academic Search

Damages to hypogeal archaeological monuments, caused by the growth of tree roots, are frequently reported in the city of Rome. Problems of compatibility between trees and underground structures may become complex in the case of historical gardens. The Jewish catacombs of Villa Torlonia show relevant conservation problems, some of them arising from damages due to root growth, and consolidating interventions

G. Caneva; G. Galotta; L. Cancellieri; V. Savo

2009-01-01

160

RESPONSE OF SOYBEAN ISOLINES DIFFERING IN PHYTOPHTHORA ROOT ROT RESISTANCE TO FIELD FLOODING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Phytophthora root rot (PRR) and flooding in soybeans is often a problem on heavy clays or poorly drained soils. Phytophthora root rot (PRR) resistance could decrease losses due to flooding? Alleles for PRR resistance in soybean have been found at eight loci with some loci having more than one all...

161

Effect of living roots on soil organic matter decomposition  

Microsoft Academic Search

Contradictory data exist in the literature about the effects of living roots on soil organic matter decom- position. Decomposition of labelled plant material is markedly lowered in the presence of cultivated plant cover or in natural grasslands, when compared to bare soil controls due to the difference of the physical environment between the plant covered soil and the fallow soil

WEIXIN CHENG; D COLEMAN

1990-01-01

162

Piriformospora indica, a Cultivable Plant-Growth-Promoting Root Endophyte  

PubMed Central

Piriformospora indica (Hymenomycetes, Basidiomycota) is a newly described cultivable endophyte that colonizes roots. Inoculation with the fungus and application of fungal culture filtrate promotes plant growth and biomass production. Due to its ease of culture, this fungus provides a model organism for the study of beneficial plant-microbe interactions and a new tool for improving plant production systems.

Varma, Ajit; Savita Verma; Sudha; Sahay, Nirmal; Butehorn, Britta; Franken, Philipp

1999-01-01

163

SPRIT: Identifying horizontal gene transfer in rooted phylogenetic trees  

Microsoft Academic Search

BACKGROUND: Phylogenetic trees based on sequences from a set of taxa can be incongruent due to horizontal gene transfer (HGT). By identifying the HGT events, we can reconcile the gene trees and derive a taxon tree that adequately represents the species' evolutionary history. One HGT can be represented by a rooted Subtree Prune and Regraft (RSPR) operation and the number

Tobias Hill; Karl JV Nordström; Mikael Thollesson; Tommy M Säfström; Andreas KE Vernersson; Robert Fredriksson; Helgi B Schiöth

2010-01-01

164

Piriformospora indica, a cultivable plant-growth-promoting root endophyte  

PubMed

Piriformospora indica (Hymenomycetes, Basidiomycota) is a newly described cultivable endophyte that colonizes roots. Inoculation with the fungus and application of fungal culture filtrate promotes plant growth and biomass production. Due to its ease of culture, this fungus provides a model organism for the study of beneficial plant-microbe interactions and a new tool for improving plant production systems. PMID:10347070

Varma; Savita; Sudha; Sahay; Butehorn; Franken

1999-06-01

165

Swarming Behavior in Plant Roots  

PubMed Central

Interactions between individuals that are guided by simple rules can generate swarming behavior. Swarming behavior has been observed in many groups of organisms, including humans, and recent research has revealed that plants also demonstrate social behavior based on mutual interaction with other individuals. However, this behavior has not previously been analyzed in the context of swarming. Here, we show that roots can be influenced by their neighbors to induce a tendency to align the directions of their growth. In the apparently noisy patterns formed by growing roots, episodic alignments are observed as the roots grow close to each other. These events are incompatible with the statistics of purely random growth. We present experimental results and a theoretical model that describes the growth of maize roots in terms of swarming.

Ciszak, Marzena; Comparini, Diego; Mazzolai, Barbara; Baluska, Frantisek; Arecchi, F. Tito; Vicsek, Tamas; Mancuso, Stefano

2012-01-01

166

Power and Roots by Recursion.  

ERIC Educational Resources Information Center

|This article illustrates how questions from elementary finance can serve as motivation for studying high order powers, roots, and exponential functions using Logo procedures. A second discussion addresses a relatively unknown algorithm for the trigonometric exponential and hyperbolic functions. (PK)|

Aieta, Joseph F.

1987-01-01

167

Modelling root soil-water extraction of two different root systems in 3D  

NASA Astrophysics Data System (ADS)

Modelling plant root systems’ extraction of soil water is essential for understanding both the effect of plants on subsurface water and water-mediated plant competition. This study compares two types of root systems with respect to their water-extraction characteristics. Three-dimensional representations of a deep-branching taproot system and a sinker-root pectinate system are constructed using original code in the MATLAB language. The two systems occupy the same volume (implying similar carbon costs to the plants) but differ widely in their geometry and topology. COMSOL software is used to model flow of water in the soil with the Richards equation in 3D and the flow within each root system towards the root collar. Two sets of boundary conditions are explored: a no-flow boundary all around the domain as well as a constant water potential in the bottom boundary. Extraction by the two systems is modeled in separate domains as well as in competition. Quantitative and qualitative differences between water extraction patterns of the two systems will emerge in this ongoing research. We expect the topology of the pectinate system to prove more efficient at transporting abundant water in the constant water potential scenario, while the taproot system can be expected to extract more scarce water under the no-flow boundary condition due to its geometry. We aim to quantify such differences that emerge from the modeling study, as part of an effort to understand plant competitive dynamics and the impact of plant communities on the hydrological cycle.

Bouda, M.; Saiers, J. E.

2010-12-01

168

Roots: Its Impact and Implications  

PubMed Central

What is contained in Roots, the 587-page narrative that captured an entire world population? The answer is not simple, nor is it overly complex, but rather an admixture of significant psychological, sociological, and timing factors that served to ignite the fuse of human fascination for the unknown, the hidden truths, the obscure, and the forbidden. This paper analyzes the impact and implications of Roots on many facets of American society.

Jefferson, Roland S.

1979-01-01

169

Nerve and Nerve Root Biomechanics  

Microsoft Academic Search

\\u000a Together, the relationship between the mechanical response of neural tissues and the related mechanisms of injury provide\\u000a a foundation for defining relevant thresholds for injury. The nerves and nerve roots are biologic structures with specific\\u000a and important functions, and whose response to mechanical loading can have immediate, long-lasting and widespread consequences.\\u000a In particular, when nerves or nerve roots are mechanically

Kristen J. Nicholson; Beth A. Winkelstein

170

Abscisic acid biosynthesis in roots  

Microsoft Academic Search

The pathway of water-stress-induced abscisic acid (ABA) biosynthesis in etiolated and light-grown leaves has been elucidated (see A.D. Parry and R. Horgan, 1991, Physiol. Plant. 82, 320–326). Roots also have the ability to synthesise ABA in response to stress and it was therefore of interest to examine root extracts for the presence of carotenoids, including those known to be ABA

Andrew D. Parry; Roger Horgan

1992-01-01

171

Characterization of Root-Knot Nematode Resistance in Medicago truncatula  

PubMed Central

Root knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes infect all important crop species, and the annual economic loss due to these pathogens exceeds $90 billion. We screened the worldwide accession collection with the root-knot nematodes Meloidogyne incognita, M. arenaria and M. hapla, soybean cyst nematode (SCN-Heterodera glycines), sugar beet cyst nematode (SBCN-Heterodera schachtii) and clover cyst nematode (CLCN-Heterodera trifolii), revealing resistant and susceptible accessions. In the over 100 accessions evaluated, we observed a range of responses to the root-knot nematode species, and a non-host response was observed for SCN and SBCN infection. However, variation was observed with respect to infection by CLCN. While many cultivars including Jemalong A17 were resistant to H. trifolii, cultivar Paraggio was highly susceptible. Identification of M. truncatula as a host for root-knot nematodes and H. trifolii and the differential host response to both RKN and CLCN provide the opportunity to genetically and molecularly characterize genes involved in plant-nematode interaction. Accession DZA045, obtained from an Algerian population, was resistant to all three root-knot nematode species and was used for further studies. The mechanism of resistance in DZA045 appears different from Mi-mediated root-knot nematode resistance in tomato. Temporal analysis of nematode infection showed that there is no difference in nematode penetration between the resistant and susceptible accessions, and no hypersensitive response was observed in the resistant accession even several days after infection. However, less than 5% of the nematode population completed the life cycle as females in the resistant accession. The remainder emigrated from the roots, developed as males, or died inside the roots as undeveloped larvae. Genetic analyses carried out by crossing DZA045 with a susceptible French accession, F83005, suggest that one gene controls resistance in DZA045.

Dhandaydham, Murali; Charles, Lauren; Zhu, Hongyan; Starr, James L.; Huguet, Thierry; Cook, Douglas R.; Prosperi, Jean-Marie; Opperman, Charles

2008-01-01

172

Substantive due process after Gonzales v. Carhart.  

PubMed

This Article begins in Part I with a doctrinal evaluation of the status of Washington v. Glucksberg ten years after that decision was handed down. Discussion begins with consideration of the Roberts Court's recent decision in Gonzales v. Carhart and then turns to the subject of Justice Kennedy's views in particular on substantive due process. In Part II, the Article goes on to consider whether the Glucksberg test for substantive due process decision making is correct in light of the original meaning of the Fourteenth Amendment. The Article concludes in Parts II and III that Glucksberg is right to confine substantive due process rights recognition to recognition only of those rights that are deeply rooted in history and tradition. PMID:18595213

Calabresi, Steven G

2008-06-01

173

Adaptable Due Process  

Microsoft Academic Search

The requirements of procedural due process must adapt to our constantly changing world. Over thirty years have passed since the Supreme Court in Goldberg v. Kelly and Mathews v. Eldridge adopted what appears to be a dynamic, fact-intensive approach to determining the procedures required by the Due Process Clause. Federal, state, and local government agencies responded by establishing new procedural

Jason Parkin

2012-01-01

174

Root nodulation of Sesbania rostrata.  

PubMed

The tropical legume Sesbania rostrata can be nodulated by Azorhizobium caulinodans on both its stem and its root system. Here we investigate in detail the process of root nodulation and show that nodules develop exclusively at the base of secondary roots. Intercellular infection leads to the formation of infection pockets, which then give rise to infection threads. Concomitantly with infection, cortical cells of the secondary roots dedifferentiate, forming a meristem which has an "open-basket" configuration and which surrounds the initial infection site. Bacteria are released from the tips of infection threads into plant cells via "infection droplets," each containing several bacteria. Initially, nodule differentiation is comparable to that of indeterminate nodules, with the youngest meristematic cells being located at the periphery and the nitrogen-fixing cells being located at the nodule center. Because of the peculiar form of the meristem, Sesbania root nodules develop uniformly around a central axis. Nitrogen fixation is detected as early as 3 days following inoculation, while the nodule meristem is still active. Two weeks after inoculation, meristematic activity ceases, and nodules then show the typical histology of determinate nodules. Thus, root nodule organogenesis in S. rostrata appears to be intermediate between indeterminate and determinate types. PMID:8106317

Ndoye, I; de Billy, F; Vasse, J; Dreyfus, B; Truchet, G

1994-02-01

175

The bHLH transcription factor SPATULA regulates root growth by controlling the size of the root meristem  

PubMed Central

Background The Arabidopsis thaliana gene SPATULA (SPT), encoding a bHLH transcription factor, was originally identified for its role in pistil development. SPT is necessary for the growth and development of all carpel margin tissues including the style, stigma, septum and transmitting tract. Since then, it has been shown to have pleiotropic roles during development, including restricting the meristematic region of the leaf primordia and cotyledon expansion. Although SPT is expressed in roots, its role in this organ has not been investigated. Results An analysis of embryo and root development showed that loss of SPT function causes an increase in quiescent center size in both the embryonic and postembryonic stem cell niches. In addition, root meristem size is larger due to increased division, which leads to a longer primary root. spt mutants exhibit other pleiotropic developmental phenotypes, including more flowers, shorter internodes and an extended flowering period. Genetic and molecular analysis suggests that SPT regulates cell proliferation in parallel to gibberellic acid as well as affecting auxin accumulation or transport. Conclusions Our data suggest that SPT functions in growth control throughout sporophytic growth of Arabidopsis, but is not necessary for cell fate decisions except during carpel development. SPT functions independently of gibberellic acid during root development, but may play a role in regulating auxin transport or accumulation. Our data suggests that SPT plays a role in control of root growth, similar to its roles in above ground tissues.

2013-01-01

176

A study of the role of root morphological traits in growth of barley in zinc-deficient soil.  

PubMed

Zinc (Zn) deficiency reduces crop yields globally. This study investigated the importance of root morphological traits, especially root hairs, in plant growth and Zn uptake. Wild-type barley (Hordeum vulgare) Pallas and its root-hairless mutant brb were grown in soil and solution culture at different levels of Zn supply for 16 d. Root morphological traits (root length, diameter, and surface area) were measured using the WinRHIZOPro Image Analysis system. In soil culture, Pallas had greater shoot dry matter, shoot Zn concentration, shoot Zn content, and Zn uptake per cm(2) root surface area than brb, primarily under zinc deficiency. Both Pallas and brb developed longer roots under Zn deficiency. Development of root hairs was not affected by plant Zn status. In solution culture, there were no significant genotypic differences in any of the parameters measured, indicating that mutation in brb does not affect growth and Zn uptake. However, both Pallas and brb developed longer and thinner roots, and root hair growth was less than in soil culture, and was not affected by plant Zn status. The better growth and greater Zn uptake of Pallas compared with brb in Zn-deficient soil can be attributed primarily to greater root surface area due to root hairs in Pallas rather than other root morphological differences. PMID:17609531

Genc, Y; Huang, C Y; Langridge, P

2007-07-03

177

Ammonium Triggers Lateral Root Branching in Arabidopsis in an AMMONIUM TRANSPORTER1;3-Dependent Manner[W  

PubMed Central

Root development is strongly affected by the plant’s nutritional status and the external availability of nutrients. Employing split-root systems, we show here that local ammonium supply to Arabidopsis thaliana plants increases lateral root initiation and higher-order lateral root branching, whereas the elongation of lateral roots is stimulated mainly by nitrate. Ammonium-stimulated lateral root number or density decreased after ammonium or Gln supply to a separate root fraction and did not correlate with cumulative uptake of 15N-labeled ammonium, suggesting that lateral root branching was not purely due to a nutritional effect but most likely is a response to a sensing event. Ammonium-induced lateral root branching was almost absent in a quadruple AMMONIUM TRANSPORTER (qko, the amt1;1 amt1;2 amt1;3 amt2;1 mutant) insertion line and significantly lower in the amt1;3-1 mutant than in the wild type. Reconstitution of AMT1;3 expression in the amt1;3-1 or in the qko background restored higher-order lateral root development. By contrast, AMT1;1, which shares similar transport properties with AMT1;3, did not confer significant higher-order lateral root proliferation. These results show that ammonium is complementary to nitrate in shaping lateral root development and that stimulation of lateral root branching by ammonium occurs in an AMT1;3-dependent manner.

Lima, Joni E.; Kojima, Soichi; Takahashi, Hideki; von Wiren, Nicolaus

2010-01-01

178

Community composition of root-associated fungi in a Quercus-dominated temperate forest: "codominance" of mycorrhizal and root-endophytic fungi.  

PubMed

In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak-dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic units (OTUs) of fungi were found from 159 terminal-root samples from 12 plant species occurring in the forest. Due to the dominance of an oak species (Quercus serrata), diverse ectomycorrhizal clades such as Russula, Lactarius, Cortinarius, Tomentella, Amanita, Boletus, and Cenococcum were observed. Unexpectedly, the root-associated fungal community was dominated by root-endophytic ascomycetes in Helotiales, Chaetothyriales, and Rhytismatales. Overall, 55.3% of root samples were colonized by both the commonly observed ascomycetes and ectomycorrhizal fungi; 75.0% of the root samples of the dominant Q. serrata were so cocolonized. Overall, this study revealed that root-associated fungal communities of oak-dominated temperate forests were dominated not only by ectomycorrhizal fungi but also by diverse root endophytes and that potential ecological interactions between the two ecotypes may be important to understand the complex assembly processes of belowground fungal communities. PMID:23762515

Toju, Hirokazu; Yamamoto, Satoshi; Sato, Hirotoshi; Tanabe, Akifumi S; Gilbert, Gregory S; Kadowaki, Kohmei

2013-04-05

179

Effects of root diameter and root nitrogen concentration on in situ root respiration among different seasons and tree species  

Microsoft Academic Search

Knowledge of root respiration is a prerequisite for a better understanding of ecosystem carbon budget and carbon allocation.\\u000a However, there are not many relevant data in the literature on direct measurements of in situ root respiration by root chamber\\u000a method. Furthermore, few studies have been focused on the effects of root diameter (D\\u000a r) and root nitrogen concentration (N\\u000a r)

Dima Chen; Lixia Zhou; Xingquan Rao; Yongbiao Lin; Shenglei Fu

2010-01-01

180

Root penetration through sealing layers at mine deposit sites.  

PubMed

To prevent acid mine drainage arising from oxygen and water penetration of sulphide-rich mine tailings, the tailings are covered with layers of dry sealing material. Plant roots have a great ability to penetrate dense materials, and if the roots are able to penetrate the sealing layer of a tailings deposit, its oxygen-shielding properties could be reduced. The objective of this study was to evaluate whether plant roots are able to penetrate sealing layers covering mine tailings deposits. Root penetration into layers of various sealing materials, such as clayey moraine (clay, 8-10%; silt, 22-37%; sand, 37-55%; gravel, 15-18%), moraine (unspecified), 6-mm bentonite (kaolin clay) fabric, lime and clay, Cefyll (mixture of pulverized coal fly ash, cement and water) and a mixture containing biosludge (30-35%) and bioashes (65-70%), was investigated. In the field, roots were studied by digging trenches alongside vegetation growing in 3- and 10-year-old mine sites. In the greenhouse root growth of Betula pendula, Pinus sylvestris, Poa pratensis and Salix viminalis were studied in compartments where the plants had been growing for 22 months. The results from the field experiment indicated that roots are able to penetrate both deep down in the cover layer (1.7 m) and also into the sealing layers of various materials, and even to penetrate hard Cefyll. The addition of nutrients in the top cover reduced deep root growth and thereby also penetration through the sealing layer. Low hydraulic conductivity of the sealing layer or a thick cover layer had less effect on root penetration. In the greenhouse experiment roots did not penetrate the thin bentonite fabric, due to low pH (2.1-2.7) that was created from the underlying weathered mine tailings. The clayey moraine was penetrated by all species used in the greenhouse experiment; Pinus sylvestris had the greatest ability to penetrate. To prevent root penetration of the other sealing layer, a suitable condition for the plants should be created in the upper part of the cover layer, namely a sufficient amount of plant nutrients. However, to define such a condition is difficult since different plant species have different requirements. PMID:17253002

Stoltz, Eva; Greger, Maria

2006-12-01

181

Biotechnological Induction of Rooting in Arbutus menziesii  

Microsoft Academic Search

This work tests the ability of the bacterium hairy-root (Agrobacterium rhizogenes) to induce the formation of adventitious roots on Pacific mad- rone (Arbutus menziesii) stems and cuttings. Madrone stems 6, 9, 12 and 18 months of age are innoculated at different seasons of the year and tested for the production of adventitious roots. Successful rooting of stems with endogenously produced

Barbara Selemon; Toby Bradshaw

182

Aortic root dilation after the Ross procedure  

Microsoft Academic Search

This study evaluated changes in neoaortic root geometry in patients who underwent the Ross procedure. Serial postoperative echocardiographic measurements of the neoaortic root indexed to the square root of body surface area (centimeters divided by meters) were obtained from 30 patients (age range 3.1 to 31.4 years) and compared with paired preoperative and immediate postoperative values. Normal aortic root diameter

M. Victoria T Tantengco; Richard A Humes; Sandra K Clapp; Kevin W Lobdell; Henry L Walters; Mehdi Hakimi; Michael L Epstein

1999-01-01

183

Transcript profiling of early lateral root initiation  

Microsoft Academic Search

At the onset of lateral root initiation in Arabidopsis thaliana, the phytohormone auxin activates xylem pole pericycle cells for asymmetric cell division. However, the molecular events leading from auxin to lateral root initiation are poorly understood, in part because the few responsive cells in the process are embedded in the root and are thus difficult to access. A lateral root

Kristiina Himanen; Marnik Vuylsteke; Steffen Vanneste; Steven Vercruysse; Elodie Boucheron; Philippe Alard; Dominique Chriqui; Marc van Montagu; Dirk Inzé; Tom Beeckman

2004-01-01

184

Free-living amoebae isolated from water-hyacinth root (Eichhornia crassipes).  

PubMed

Free-living amoebae are widely distributed in aquatic environments and their hygienic, medical and ecological relationships to man are increasingly important. The purpose of this study was to isolate free-living amoebae from water-hyacinth root (Eichhornia crassipes) and the water of an urban lake in Mexico City. Five grams of wet root were seeded on non-nutritive agar with Enterobacter aerogenes (NNE). Water samples were concentrated by centrifugation at 1200g for 15min and the pellet was seeded on NNE. Of the 16 isolated genera, 10 were detected in both habitats. The most frequent were Vannella in root and Acanthamoeba and Naegleria in water. The total number of isolates and genera isolated from root was higher than that isolated from water. The differences between root and water are probably due to the morphological characteristics of water-hyacinth root, which provides a large habitat and refuge area for many organisms. PMID:20117108

Ramirez, Elizabeth; Robles, Esperanza; Martinez, Blanca

2010-02-01

185

Enzymes hydrolyzing structural components and ferrous ion cause rusty-root symptom on ginseng (Panax ginseng).  

PubMed

Microbial induction of rusty-root was proved in this study. The enzymes hydrolyzing plant structural materials, including pectinase, pectolyase, ligninase, and cellulase, caused the rusty-root in ginseng. Pectinase and pectolyase produced the highest rusty-color formation. Ferrous ion (Fe+++) caused the synergistic effect on rusty-root formation in ginseng when it was used with pectinase. The effect of ferric ion (Fe++) on rusty-root formation was slow, compared with Fe+++, probably due to gradual oxidation to Fe+++. Other metal ions including the ferric ion (Fe++) did not affect rusty-root formation. The endophytic bacteria Agrobacterium tumefaciens, Lysobacter gummosus, Pseudomonas veronii, Pseudomonas marginalis, Rhodococcus erythropolis, and Rhodococcus globerulus, and the rotten-root forming phytophathogenic fungus Cylindrocarpon destructans, caused rusty-root. The polyphenol formation (rusty color) was not significantly different between microorganisms. The rotten-root-forming C. destructans produced large quantities of external cellulase activity (about 2.3 U[micronM/min/mg protein]), which indicated the pathogenecity of the fungus, whereas the bacteria produced 0.1-0.7 U. The fungal external pectinase activities (0.05 U) and rusty-root formation activity were similar to those of the bacteria. In this report, we proved that microbial hydrolyzing enzymes caused rusty-root (Hue value 15 degrees) of ginseng, and ferrous ion worsened the symptom. PMID:21364303

Lee, Chanyong; Kim, Kwang Yup; Lee, Jo-Eun; Kim, Sunghan; Ryu, Dongkul; Choi, Jae-Eul; An, Gilhwan

2011-02-01

186

Adventitious root mass distribution in progeny of four perennial ryegrass (Lolium perenne L.) groups selected for root shape  

Microsoft Academic Search

The effects of one cycle of selection for adventitious root system shape (i.e. percentage of total root mass in successive depth increments) were investigated in progeny of four perennial ryegrass pools with contrasting rooting patterns: (1) low surface (0–10 cm) root mass and roots to 1 m; (2) high surface root mass and roots to 1 m; (3) high root

JR Crush; SN Nichols; L. Ouyang

2010-01-01

187

A METHOD TO SEPARATE PLANT ROOTS FROM SOIL AND ANALYZE ROOT SURFACE AREA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Analysis of the effects of soil management practices on crop production requires a knowledge of these effects on plant roots. Much time is required to wash plant roots from soil and separate the living plant roots from organic debris and previous years' roots. We developed a root washer that can acc...

188

Hypoxic acclimation to anoxia in Avena roots  

Microsoft Academic Search

Hypoxic pretreatment (H-PT; incubated in 5% O2 atmospherefor 24 h) greatly improved subsequent tolerance of anoxia in theprimary roots of Avena sativa. Survival of H-PT roots inanoxia increased by 6.4-fold compared to that of non-pretreated (N-PT) roots ofthe seedlings. ATP concentration in the H-PT roots was 4.8-fold greater thanthat in the N-PT roots at 12 h after onset of anoxia.

Hisashi Kato-Noguchi

2002-01-01

189

Genomics of Root–Microbe Interactions  

Microsoft Academic Search

\\u000a Roots are exposed to a multitude of soil organisms and often form intimate associations with bacteria, fungi, and nematodes.\\u000a Microbes influence roots by producing signals, toxins, altering nutrient cycling, and by invading roots as endosymbionts or\\u000a endoparasites. Genomic tools have helped to elucidate the molecular changes induced in roots by microbes. Two mutualistic\\u000a symbioses of roots, those with nitrogen-fixing rhizobia

Ulrike Mathesius; Giel E. van Noorden

190

Ephemeral root modules in Fraxinus mandshurica.  

PubMed

Historically, ephemeral roots have been equated with 'fine roots' (i.e. all roots of less than an arbitrary diameter, such as 2 mm), but evidence shows that 'fine roots' in woody species are complex branching systems with both rapid-cycling and slow-cycling components. A precise definition of ephemeral roots is therefore needed. Using a branch-order classification, a rhizotron method and sequential sampling of a root cohort, we tested the hypothesis that ephemeral root modules exist within the branching Fraxinus mandshurica (Manchurian ash) root system as distal nonwoody lateral branches, which show anatomical, nutritional and physiological patterns distinct from their woody mother roots. Our results showed that in F. mandshurica, distal nonwoody root branch orders die rapidly as intact lateral branches (or modules). These nonwoody branch orders exhibited highly synchronous changes in tissue nitrogen concentrations and respiration, dominated root turnover, nutrient flux and root respiration, and never underwent secondary development. The ephemeral root modules proposed here may provide a functional basis for differentiating and sampling short-lived absorptive roots in woody plants, and represent a conceptual leap over the traditional coarse-fine root dichotomies based on arbitrary size classes. PMID:21058949

Xia, Mengxue; Guo, Dali; Pregitzer, Kurt S

2010-09-07

191

Reliability and Failure Mechanism of Current-Stressed 99.3Sn0.7Cu\\/96.5Sn3Ag0.5Cu Composite Flip-Chip Solder Joints with Cu or Au\\/Ni\\/Cu Substrate Pad Metallization  

Microsoft Academic Search

Electromigration and thermomigration in the flip chip package are apparent in the reliability test. The 99.3Sn-0.7Cu\\/96.5Sn-3Ag-0.5Cu composite flip-chip solder joints with Ti\\/Ni(V)\\/Cu under bump metallurgy and different surface finishes are investigated when applied current density of 10 kA\\/cm2 and 15 kA\\/cm2 at 150degC and 125degC, respectively. Experimental results show the solder migrates to the Al trace in the chip when

Ying-Ta Chiu; Yu-Hsiu Shao; Yi-Shao Lai

2008-01-01

192

Root status and future developments  

SciTech Connect

In this talk the authors review the major additions and improvements made to the ROOT system in the last 18 months and present their plans for future developments. The additions and improvements range from modifications to the I/O sub-system to allow users to save and restore objects of classes that have not been instrumented by special ROOT macros, to the addition of a geometry package designed for building, browsing, tracking and visualizing detector geometries. Other improvements include enhancements to the quick analysis sub-system (TTree::Draw()), the addition of classes that allow inter-file object references (TRef, TRefArray), better support for templates and STL classes, amelioration of the Automatic Script Compiler and the incorporation of new fitting and mathematical tools. Efforts have also been made to increase the modularity of the ROOT system with the introduction of more abstract interfaces and the development of a plug-in manager. In the near future, they intend to continue the development of PROOF and its interfacing with GRID environments. They plan on providing an interface between Geant3, Geant4 and Fluka and the new geometry package. The ROOT-GUI classes will finally be available on Windows and they plan to release a GUI inspector and builder. In the last year, ROOT has drawn the endorsement of additional experiments and institutions. It is now officially supported by CERN and used as key I/O component by the LCG project.

Rene Brun et al.

2003-10-01

193

Electrotropism of Maize Roots 1  

PubMed Central

We examined the kinetics of electrotropic curvature in solutions of low electrolyte concentration using primary roots of maize (Zea mays L., variety Merit). When submerged in oxygenated solution across which an electric field was applied, the roots curved rapidly and strongly toward the positive electrode (anode). The strength of the electrotropic response increased and the latent period decreased with increasing field strength. At a field strength of 7.5 volts per centimeter the latent period was 6.6 minutes and curvature reached 60 degrees in about 1 hour. For electric fields greater than 10 volts per centimeter the latent period was less than 1 minute. There was no response to electric fields less than 2.8 volts per centimeter. Both electrotropism and growth were inhibited when indoleacetic acid (10 micromolar) was included in the medium. The auxin transport inhibitor pyrenoylbenzoic acid strongly inhibited electrotropism without inhibiting growth. Electrotropism was enhanced by treatments that interfere with gravitropism, e.g. decapping the roots or pretreating them with ethyleneglycol-bis-[?-ethylether]-N,N,N?,N?-tetraacetic acid. Similarly, roots of agravitropic pea (Pisum sativum, variety Ageotropum) seedlings were more responsive to electrotropic stimulation than roots of normal (variety Alaska) seedlings. The data indicate that the early steps of gravitropism and electrotropism occur by independent mechanisms. However, the motor mechanisms of the two responses may have features in common since auxin and auxin transport inhibitors reduced both gravitropism and electrotropism.

Ishikawa, Hideo; Evans, Michael L.

1990-01-01

194

Resonance dependence of gravitropicreactionof cress roots in weak combined magnetic fields.  

NASA Astrophysics Data System (ADS)

The gravitropic reaction of cress was studied in combined magnetic fields, that is the static magnetic field of the order of Earth's one and parallel to it alternating magnetic field. The frequency region for alternating magnetic field was varied in wide diapason ( from 1 Hz up to 45 Hz). The magnitude of alternating magnetic field was equal to 6 microT. The magnetic field conditions were well reproducible. For this purpose the external magnetic field was shielded in the work volume and artificial magnetic field was created in the volume. Both ferromagnetic metal shield and superconductive one with warm volume for work were used. The magnetic noises inside both of ferromagnetic metal and superconductive shields were measured to provide the well reproducible characteristics of artificial field created in the work volume. The objects of investigation were the roots of cress after 2-3-days germination. They were located in the closed humid room, that was located inside the shield in the artificially created magnetic field. All roots were in the darkness. For control we used the analogous roots located in the analogous volume but only in the static magnetic field of the Earth. We measured the divergence angle of the root from its primary direction of growing. We obtained the following results. The curve of dependence of measured angles on the frequency of alternating component of magnetic field had series of sharp peaks. These peaks were well reproducible and their location depended on the magnitude of the static component of magnetic field. The frequency of peak location is in direct proportion with its magnitude. The analysis showed that the location of peaks coincided very well with the cyclotron frequencies of the following ions: Ca+2, Cu+1 , K+1: Fe+3: Ag+1: and with the cyclotron frequencies of ions of phytohormons such as ions of indolile-acetic acid, abscise acid and gibberellins. Some quantitive analogies between the gravitropic process and the effect of combined magnetic field are discussed at the molecular level. In particularly it was shown that in the gravity field the pressure difference between the upper and down parts of the root was of the order of the pressure difference created by the Lorenz force. The displacement of the point where the pressure approached the maximum value on membrane surface could lead to the changes in the ion transport direction and so to the changes of the gravitropic reaction direction. The possibilities of the method for the studying the gravitropic reaction were discussed.

Bogatina, N. I.; Sheykina, N. V.; Kordyum, E. L.

195

Root gravitropism and root hair development constitute coupled developmental responses regulated by auxin homeostasis in the Arabidopsis root apex.  

PubMed

Active polar transport establishes directional auxin flow and the generation of local auxin gradients implicated in plant responses and development. Auxin modulates gravitropism at the root tip and root hair morphogenesis at the differentiation zone. Genetic and biochemical analyses provide evidence for defective basipetal auxin transport in trh1 roots. The trh1, pin2, axr2 and aux1 mutants, and transgenic plants overexpressing PIN1, all showing impaired gravity response and root hair development, revealed ectopic PIN1 localization. The auxin antagonist hypaphorine blocked root hair elongation and caused moderate agravitropic root growth, also leading to PIN1 mislocalization. These results suggest that auxin imbalance leads to proximal and distal developmental defects in Arabidopsis root apex, associated with agravitropic root growth and root hair phenotype, respectively, providing evidence that these two auxin-regulated processes are coupled. Cell-specific subcellular localization of TRH1-YFP in stele and epidermis supports TRH1 engagement in auxin transport, and hence impaired function in trh1 causes dual defects of auxin imbalance. The interplay between intrinsic cues determining root epidermal cell fate through the TTG/GL2 pathway and environmental cues including abiotic stresses modulates root hair morphogenesis. As a consequence of auxin imbalance in Arabidopsis root apex, ectopic PIN1 mislocalization could be a risk aversion mechanism to trigger root developmental responses ensuring root growth plasticity. PMID:23252740

Rigas, Stamatis; Ditengou, Franck Anicet; Ljung, Karin; Daras, Gerasimos; Tietz, Olaf; Palme, Klaus; Hatzopoulos, Polydefkis

2012-12-18

196

Due process traditionalism.  

PubMed

In important cases, the Supreme Court has limited the scope of "substantive due process" by reference to tradition, but it has yet to explain why it has done so. Due process traditionalism might be defended in several distinctive ways. The most ambitious defense draws on a set of ideas associated with Edmund Burke and Friedrich Hayek, who suggested that traditions have special credentials by virtue of their acceptance by many minds. But this defense runs into three problems. Those who have participated in a tradition may not have accepted any relevant proposition; they might suffer from a systematic bias; and they might have joined a cascade. An alternative defense sees due process traditionalism as a second-best substitute for two preferable alternatives: a purely procedural approach to the Due Process Clause, and an approach that gives legislatures the benefit of every reasonable doubt. But it is not clear that in these domains, the first-best approaches are especially attractive; and even if they are, the second-best may be an unacceptably crude substitute. The most plausible defense of due process traditionalism operates on rule-consequentialist grounds, with the suggestion that even if traditions are not great, they are often good, and judges do best if they defer to traditions rather than attempting to specify the content of "liberty" on their own. But the rule-consequentialist defense depends on controversial and probably false assumptions about the likely goodness of traditions and the institutional incapacities of judges. PMID:18595214

Sunstein, Cass R

2008-06-01

197

Stimulation of in vitro root and shoot growth of potato by increasing sucrose concentration in the presence of fluridone, an inhibitor of abscisic acid synthesis  

Microsoft Academic Search

Fluridone, an inhibitor of abscisic acid (ABA) biosynthesis, strongly stimulated rooting of nodal stem segments of potato (Solanum tuberosum L.) cultivar Arran Banner cultured in darkness on tuberisation medium. Inclusion of 10-6 M ABA in the culture medium prevented this rooting response, indicating that root proliferation in the presence of fluridone could be due to inhibition of ABA synthesis. The

B. M. R. Harvey; G. Bowden; C. Reavey; C. Selby

1994-01-01

198

Surgical treatment of ascending aorta and aortic root aneurysms.  

PubMed

Aneurysms of the aortic root and ascending aorta are often due to degenerative disease of media. Aneurysm of the aortic root often affects patients in their second to fourth decades of life, whereas aneurysm of the ascending aorta occurs mostly in the fifth to seventh decades of life. These aneurysms can cause aortic insufficiency, dissection, and/or rupture. Current guidelines recommend surgical treatment when the diameter of the aneurysm exceeds 50 mm. In patients with family history of aortic dissection or with Loyes-Dietz syndrome (a more severe form of Marfan syndrome), surgery should be considered when they are even smaller. Composite replacement of the aortic valve and ascending aorta used to be the standard treatment for patients with aortic root aneurysms. During the past 2 decades, a conservative procedure whereby the aneurysm is replaced with Dacron graft and the aortic valve is preserved has gained widespread use, and the results have been excellent in experienced hands. PMID:20226961

David, Tirone E

199

Root branching: mechanisms, robustness, and plasticity.  

PubMed

Plants are sessile organisms that must efficiently exploit their habitat for water and nutrients. The degree of root branching impacts the efficiency of water uptake, acquisition of nutrients, and anchorage. The root system of plants is a dynamic structure whose architecture is determined by modulation of primary root growth and root branching. This plasticity relies on the continuous integration of environmental inputs and endogenous developmental programs controlling root branching. This review focuses on the cellular and molecular mechanisms involved in the regulation of lateral root distribution, initiation, and organogenesis with the main focus on the root system of Arabidopsis thaliana. We also examine the mechanisms linking environmental changes to the developmental pathways controlling root branching. Recent progress that emphasizes the parallels to the formation of root branches in other species is discussed. PMID:23801487

Dastidar, Mouli Ghosh; Jouannet, Virginie; Maizel, Alexis

2011-12-08

200

Root perforations following endodontics: a case for surgical management.  

PubMed

Despite technological advancements in dental instrumentation and techniques, endodontic mishaps remain commonplace. Perforations during access preparation, canal instrumentation, root filling, or preparation of post space are not unusual and instruments may fracture during filing or reaming or when attempting to bypass fractured instruments in the root canal. Many of these complications are hard to avoid due to extreme variations in root canal anatomy, root shapes, curvatures, and canal calcification. Procedural errors impede proper endodontic therapy and increase the risk of treatment failure; as a result, the prognosis is compromised, especially in nonvital teeth or teeth with periradicular lesions. Perforations may lead to short-term or long-term complications (that is, infection, periapical cyst, or granuloma formation); in addition, restorative material may be extruded through the perforation. Clinicians often have difficulty diagnosing and treating root perforations, particularly in posterior teeth (specifically in the area of the mandibular bifurcation); however, such complications do not mean that the tooth must be extracted. This article discusses treatment of perforations near the bifurcation of a mandibular first molar and an apical perforation in a premolar. Both teeth were salvaged via surgery without the use of additional biomaterials. PMID:17333960

Motamedi, Mohammad Hosein Kalantar

201

Root system architecture from coupling cell shape to auxin transport.  

PubMed

Lateral organ position along roots and shoots largely determines plant architecture, and depends on auxin distribution patterns. Determination of the underlying patterning mechanisms has hitherto been complicated because they operate during growth and division. Here, we show by experiments and computational modeling that curvature of the Arabidopsis root influences cell sizes, which, together with tissue properties that determine auxin transport, induces higher auxin levels in the pericycle cells on the outside of the curve. The abundance and position of the auxin transporters restricts this response to the zone competent for lateral root formation. The auxin import facilitator, AUX1, is up-regulated by auxin, resulting in additional local auxin import, thus creating a new auxin maximum that triggers organ formation. Longitudinal spacing of lateral roots is modulated by PIN proteins that promote auxin efflux, and pin2,3,7 triple mutants show impaired lateral inhibition. Thus, lateral root patterning combines a trigger, such as cell size difference due to bending, with a self-organizing system that mediates alterations in auxin transport. PMID:19090618

Laskowski, Marta; Grieneisen, Verônica A; Hofhuis, Hugo; Hove, Colette A Ten; Hogeweg, Paulien; Marée, Athanasius F M; Scheres, Ben

2008-12-16

202

Technological Due Process  

Microsoft Academic Search

Distinct and complementary procedures for adjudication and rulemaking lie at the heart of twentieth-century administrative law. Due process requires agencies to provide individuals notice and an opportunity to be heard. Through public rulemaking, agencies can foreclose policy issues that individuals might otherwise raise in adjudication. One system allows for focused advocacy; the other features broad participation. Each procedural regime compensates

Danielle Keats Citron

2008-01-01

203

Technological Due Process  

Microsoft Academic Search

Distinct and complementary procedures for adjudications and rulemaking lie at the heart of twentieth-century administrative law. Due process required agencies to provide individuals notice and an opportunity to be heard. Agencies could foreclose policy issues that individuals might otherwise raise in adjudications through public rulemaking. One system allowed focused advocacy; the other featured broad participation. Each procedural regime compensated for

Danielle Keats Citron

2008-01-01

204

Root system stabilization of sugarcane fertigated by subsurface drip using a minirhizotron  

NASA Astrophysics Data System (ADS)

To improve the efficiency of water use in irrigation practices and to provide information for modeling the knowledge of plants root system becomes necessary. The use of subsurface drip irrigation (SDI) in sugarcane cultivation is an interesting cultural practice to improve production and allow cultivation in marginal lands due to water deficits conditions. The SDI provides better water use efficiency, due to the water and nutrients application in root zone plants. However, despite of the agronomic importance, few studies about the root system of sugarcane were performed. The use of root scanner is an alternative to the evaluation of the root system, which enables the continuous study of the roots throughout the cycle and for many years, but data about the use of this method for sugarcane are still scarce. The aim of this study was to determine the time required for stabilization of the root system growth of sugarcane cultivar IACSP-5000 around the access tube in which images were captured. The field experiment was carried out in Campinas, São Paulo State, Brazil. The fertigation was applied by a subsurface drip system.. The soil moisture was monitored by capacitance probes. The pH and electrical conductivity of the soil solution were monitored through solution extractor. Two access tubes with 1.05 m length were used, with 7 days difference between installations. The images were captured at 110, 128, 136, 143 and 151 days after harvest cane-plant, in the second cycle (1st cane ratoon), with the Root Scanner CI-600 ™ and were analyzed the number of roots and root length in each layer in different depths in the soil profile by software RootSnap! ™. The results show that the highest rates of increase in the number and length of roots were observed in the first 27 days. Absolute growth rates of up to 81 mm day-1 and 38 mm day-1 were presented in 0-20 and 20-40 cm layer respectively. The number of roots stabilized from 27 days after installation of the tube, while the length of the root system stabilized between 30 and 40 days. Root growth was more intense in the first two layers (0 to 0.4 m depth) of soil profile, which presented more than 80% of the total root length after the stabilization.

Yukitaka Pessinatti Ohashi, Augusto; Célia de Matos Pires, Regina; Barros de Oliveira Silva, Andre Luiz; Vasconcelos Ribeiro, Rafael

2013-04-01

205

Strigolactones fine-tune the root system.  

PubMed

Strigolactones were originally discovered to be involved in parasitic weed germination, in mycorrhizal association and in the control of shoot architecture. Despite their clear role in rhizosphere signaling, comparatively less attention has been given to the belowground function of strigolactones on plant development. However, research has revealed that strigolactones play a key role in the regulation of the root system including adventitious roots, primary root length, lateral roots, root hairs and nodulation. Here, we review the recent progress regarding strigolactone regulation of the root system and the antagonism and interplay with other hormones. PMID:23801297

Rasmussen, Amanda; Depuydt, Stephen; Goormachtig, Sofie; Geelen, Danny

2013-06-26

206

Adsorption and absorption of polycyclic aromatic hydrocarbons to rice roots  

Microsoft Academic Search

Rice roots and surrounding air, soil and water samples were collected for polycyclic aromatic hydrocarbon (PAH) analysis. The rice roots were separated into lateral roots and nodal roots, and the PAH concentration in the former was found to be higher than that in the latter. In addition, root physiological characteristics including root biotic mass, root lipid content and specific surface

X. C. Jiao; F. L. Xu; R. Dawson; S. H. Chen; S. Tao

2007-01-01

207

Fractal geometry of root systems: Field observations of contrasting genotypes of common bean ( Phaseolus vulgaris L.) grown under different phosphorus regimes  

Microsoft Academic Search

Root growth and architecture are important for phosphorus acquisition due to the relative immobility of P in the soil. Fractal\\u000a geometry is a potential new approach to the analysis of root architecture. Substantial genetic variation in root growth and\\u000a architecture has been observed in common bean. Common bean (Phaseolus vulgaris L.) genotypes with contrasting root architecture\\u000a were grown under moderate

Kai L. Nielsen; Carter R. Miller; Douglas Beck; Jonathan P. Lynch

1999-01-01

208

Do increased summer precipitation and N deposition alter fine root dynamics in a Mojave Desert ecosystem?  

PubMed

Climate change is expected to impact the amount and distribution of precipitation in the arid southwestern United States. In addition, nitrogen (N) deposition is increasing in these regions due to increased urbanization. Responses of belowground plant activity to increases in soil water content and N have shown inconsistent patterns between biomes. In arid lands, plant productivity is limited by water and N availability so it is expected that changes in these factors will affect fine root dynamics. The objectives of this study were to quantify the effects of increased summer precipitation and N deposition on fine root dynamics in a Mojave Desert ecosystem during a 2-year field experiment using minirhizotron measurements. Root length density, production, and mortality were measured in field plots in the Mojave Desert receiving three 25 mm summer rain events and/or 40 kg N ha(-1)  yr(-1) . Increased summer precipitation and N additions did not have an overall significant effect on any of the measured root parameters. However, differences in winter precipitation resulting from interannual variability in rainfall appeared to affect root parameters with root production and turnover increasing following a wet winter most likely due to stimulation of annual grasses. In addition, roots were distributed more deeply in the soil following the wet winter. Root length density was initially higher under canopies compared to canopy interspaces, but converged toward the end of the study. In addition, roots tended to be distributed more deeply into the soil in canopy interspace areas. Results from this study indicated that increased summer precipitation and N deposition in response to climate change and urbanization are not likely to affect fine root dynamics in these Mojave Desert ecosystems, despite studies showing aboveground plant physiological responses to these environmental perturbations. However, changes in the amount and possibly distribution of winter precipitation may affect fine root dynamics. PMID:23504850

Verburg, Paul S J; Young, Andrew C; Stevenson, Bryan A; Glanzmann, Isabelle; Arnone, John A; Marion, Giles M; Holmes, Christopher; Nowak, Robert S

2012-12-21

209

The FairRoot framework  

NASA Astrophysics Data System (ADS)

The FairRoot framework is an object oriented simulation, reconstruction and data analysis framework based on ROOT. It includes core services for detector simulation and offline analysis. The framework delivers base classes which enable the users to easily construct their experimental setup in a fast and convenient way. By using the Virtual Monte Carlo concept it is possible to perform the simulations using either Geant3 or Geant4 without changing the user code or the geometry description. Using and extending the task mechanism of ROOT it is possible to implement complex analysis tasks in a convenient way. Moreover, using the FairCuda interface of the framework it is possible to run some of these tasks also on GPU. Data IO, as well as parameter handling and data base connections are also handled by the framework. Since some of the experiments will not have an experimental setup with a conventional trigger system, the framework can handle also free flowing input streams of detector data. For this mode of operation the framework provides classes to create the needed time sorted input streams of detector data out of the event based simulation data. There are also tools to do radiation studies and to visualize the simulated data. A CMake-CDash based building and monitoring system is also part of the FairRoot services which helps to build and test the framework on many different platforms in an automatic way, including also Continuous Integration.

Al-Turany, M.; Bertini, D.; Karabowicz, R.; Kresan, D.; Malzacher, P.; Stockmanns, T.; Uhlig, F.

2012-12-01

210

Lesson 10: Extraction of Roots  

NSDL National Science Digital Library

This lesson introduces quadratic equations and graphs. Equations of the form ax^2 + c = 0 are solved via extraction of roots. Later application problems involving volume and surface area and compound interest (problems of the form a(x - p)^2 = q ) are presented.

2011-01-01

211

Excising the Root from STEM  

ERIC Educational Resources Information Center

There are a number of well-intentioned STEM initiatives, some designed to improve the recruitment and retention of science teachers. Sometimes it appears that the initiators are remote from direct contact with the "grass roots" issues that feed the "stem" on which the blossoms of young enthusiastic recruits to the science teaching profession are…

Lock, Roger

2009-01-01

212

Magnetophoretic Induction of Root Curvature.  

National Technical Information Service (NTIS)

The last year of the grant period concerned the consolidation of previous experiments to ascertain that the theoretical premise apply not just to root but also to shoots. In addition, we verified that high gradient magnetic fields do not interfere with re...

K. H. Hasenstein

1997-01-01

213

Cutting the Roots of Violence.  

ERIC Educational Resources Information Center

|Violence is rooted in obedience to authority and in comparisons--foundations of our institutions of parenting and schooling. Obedience brings reward and punishment, comparison perpetuates a cycle of competition and conflict. Television violence is especially harmful because children easily understand visual images. The Reality Research approach…

Koziey, Paul W.

1996-01-01

214

Arrested root formation of 4 second premolars: report of a patient.  

PubMed

The shape and size of tooth roots are genetically and phylogenetically predetermined. Clinical defects in root formation can manifest in the form of shortened roots caused by either root agenesis or root resorption. We report on a patient who came at age 7 years for space management. In the 2-year period after the initial visit, maxillary arch expansion was performed, followed by serial extractions of all 4 first premolars. A radiograph taken about 18 months after the serial extraction showed that although the crowns of all 4 second premolars had erupted fully into the arch, the roots were only about half of their normal length. With a family history of 1 sibling with a missing second premolar and the symmetrical distribution and pattern of the teeth in the 4 dental quadrants, we speculated that the arrested root development was due most likely to a genetic predisposition. Arrested root development is difficult to predict, but a potential warning sign is a family history of malformed or missing teeth. Proper, adequate, and accurate records continue to remain critical for both medical and legal purposes in the treatment of patients with potential problems in root agenesis. PMID:22554759

Pinzon, Maria L; Gong, Siew-Ging

2012-05-01

215

Cell biology and genetics of root hair formation in Arabidopsis thaliana.  

PubMed

In this review we integrate the information available on the cell biology of root hair formation with recent findings from the analysis of root hair mutants of Arabidopsis thaliana. The mature Arabidopsis root epidermis consists of root-hair-producing cells and non-root-hair-producing cells. Root hair growth begins with a swelling of the outer epidermal wall. It has been postulated that this is due to a pH-mediated localised cell wall loosening. From the bulge a single root hair emerges which grows by tip growth. The root hair tip consists of a vesicle-rich zone and an organelle-rich subapical zone. The vesicles supply new plasma membrane and cell wall material for elongation. The cytoskeleton and its associated regulatory proteins such as profilin and spectrin are proposed to be involved in the targeting of vesicles. Ca2+ influxes and gradients are present in hair tips, but their function is still unclear. Mutants have been isolated with lesions in various parts of the root hair developmental pathway from bulge identity and initiation to control of tip diameter and extent and polarity of elongation. PMID:11732053

Ryan, E; Steer, M; Dolan, L

2001-01-01

216

Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution  

USGS Publications Warehouse

This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

Sorrell, B. K.; Mendelssohn, I. A.; McKee, K. L.; Woods, R. A.

2000-01-01

217

A global analysis of fine root production as affected by soil nitrogen and phosphorus  

PubMed Central

Fine root production is the largest component of belowground production and plays substantial roles in the biogeochemical cycles of terrestrial ecosystems. The increasing availability of nitrogen (N) and phosphorus (P) due to human activities is expected to increase aboveground net primary production (ANNP), but the response of fine root production to N and P remains unclear. If roots respond to nutrients as ANNP, fine root production is anticipated to increase with increasing soil N and P. Here, by synthesizing data along the nutrient gradient from 410 natural habitats and from 469 N and/or P addition experiments, we showed that fine root production increased in terrestrial ecosystems with an average increase along the natural N gradient of up to 0.5 per cent with increasing soil N. Fine root production also increased with soil P in natural conditions, particularly at P < 300 mg kg?1. With N, P and combined N + P addition, fine root production increased by a global average of 27, 21 and 40 per cent, respectively. However, its responses differed among ecosystems and soil types. The global average increases in fine root production are lower than those of ANNP, indicating that above- and belowground counterparts are coupled, but production allocation shifts more to aboveground with higher soil nutrients. Our results suggest that the increasing fertilizer use and combined N deposition at present and in the future will stimulate fine root production, together with ANPP, probably providing a significant influence on atmospheric CO2 emissions.

Yuan, Z. Y.; Chen, Han Y. H.

2012-01-01

218

Silicon alleviates cadmium toxicity in Avicennia marina (Forsk.) Vierh. seedlings in relation to root anatomy and radial oxygen loss.  

PubMed

The effects of Si on growth, the anatomy of the roots, radial oxygen loss (ROL) and Fe/Mn plaque on the root surface were investigated in Avicennia marina (Forsk.) Vierh. seedlings under Cd stress. Si prompted the growth of seedlings and reduced the Cd concentration in the root, stem and leaf of A. marina. Si prompted the development of the apoplastic barrier in the roots, which may be related to the reduction of Cd uptake. The higher amount of ROL and Mn plaque on the root surface due to Si were also related to the promotion of Cd tolerance in A. marina seedlings. Therefore, it is concluded that the alteration of the anatomy of the roots, the increase of ROL and Mn plaque of A. marina seedlings play an important role in alleviation of Cd toxicity due to Si. PMID:24095049

Zhang, Qiong; Yan, Chongling; Liu, Jingchun; Lu, Haoliang; Wang, Wenyun; Du, Jingna; Duan, Hanhui

2013-10-04

219

The evolutionary root of flowering plants.  

PubMed

Correct rooting of the angiosperm radiation is both challenging and necessary for understanding the origins and evolution of physiological and phenotypic traits in flowering plants. The problem is known to be difficult due to the large genetic distance separating flowering plants from other seed plants and the sparse taxon sampling among basal angiosperms. Here, we provide further evidence for concern over substitution model misspecification in analyses of chloroplast DNA sequences. We show that support for Amborella as the sole representative of the most basal angiosperm lineage is founded on sequence site patterns poorly described by time-reversible substitution models. Improving the fit between sequence data and substitution model identifies Trithuria, Nymphaeaceae, and Amborella as surviving relatives of the most basal lineage of flowering plants. This finding indicates that aquatic and herbaceous species dominate the earliest extant lineage of flowering plants. [; ; ; ; ; .]. PMID:22851550

Goremykin, Vadim V; Nikiforova, Svetlana V; Biggs, Patrick J; Zhong, Bojian; Delange, Peter; Martin, William; Woetzel, Stefan; Atherton, Robin A; McLenachan, Patricia A; Lockhart, Peter J

2012-07-31

220

Coarse root distribution of a semi-arid oak savanna estimated with ground penetrating radar  

NASA Astrophysics Data System (ADS)

The binary nature of Northern California's ecohydrology, in which water is either abundantly available or scarce, should be reflected in the root architecture of the native blue oak. Our objective was to quantify carbon storage and understand how the form of the root system facilitates ecosystem functioning despite the asynchrony between winter water availability, spring leaf growth, and dry-summer canopy maintenance. To do this, we surveyed coarse root distribution with a ground penetrating radar (GPR), due to its advantages in covering large areas rapidly and non-destructively. We calibrated root biomass detected by GPR against roots excavated from a number of small pits. Based on a survey of six tree configurations (varying in age, size, and clumping), we found that coarse roots occupy the full soil profile and that coarse root biomass of old large trees reached a peak directly above the bedrock. As opposed to other semi-arid regions, where trees often develop extensive shallow lateral coarse roots to exploit the entire wet-soil medium, we found that root density decreased with distance from the bole, and dropped sharply beyond a distance of 2 m. We upscaled tree root biomass to stand scale (2.8 ± 0.4 kg m-2) based on lidar analysis of the relative abundance of each tree configuration. We argue that this deep and narrow root structure reflects the ecohydrology of oaks in this ecosystem. An extensive lateral root system would not be beneficial during the growing season, when water is sufficiently abundant, nor during summer, when soil water is highly limited.

Raz-Yaseef, Naama; Koteen, Laura; Baldocchi, Dennis D.

2013-03-01

221

Evaluation of variation of root shape of Japanese radish (Raphanus sativus L.) based on image analysis using elliptic Fourier descriptors  

Microsoft Academic Search

Variation was of root shape in Japanese radish, due to genotypes, soil types and growth stages, were quantitatively evaluated\\u000a by principal components scores based on elliptic Fourier descriptors. Photographic images of sampled roots on 35mm color reversal\\u000a films were converted into digital images. After image processing, the contour of each root was expressed as chain-code and\\u000a then described by 77

Hiroyoshi Iwata; Satoshi Niikura; Seiji Matsuura; Yasushi Takano; Yasuo Ukai

1998-01-01

222

Modelling Root Systems Using Oriented Density Distributions  

NASA Astrophysics Data System (ADS)

Root architectural models are essential tools to understand how plants access and utilize soil resources during their development. However, root architectural models use complex geometrical descriptions of the root system and this has limitations to model interactions with the soil. This paper presents the development of continuous models based on the concept of oriented density distribution function. The growth of the root system is built as a hierarchical system of partial differential equations (PDEs) that incorporate single root growth parameters such as elongation rate, gravitropism and branching rate which appear explicitly as coefficients of the PDE. Acquisition and transport of nutrients are then modelled by extending Darcy's law to oriented density distribution functions. This framework was applied to build a model of the growth and water uptake of barley root system. This study shows that simplified and computer effective continuous models of the root system development can be constructed. Such models will allow application of root growth models at field scale.

Dupuy, Lionel X.

2011-09-01

223

Inhibition of strigolactones promotes adventitious root formation  

PubMed Central

Roots that form from non-root tissues (adventitious roots) are crucial for cutting propagation in the forestry and horticulture industries. Strigolactone has been demonstrated to be an important regulator of these roots in both Arabidopsis and pea using strigolactone deficient mutants and exogenous hormone applications. Strigolactones are produced from a carotenoid precursor which can be blocked using the widely available but broad terpenoid biosynthesis blocker, fluridone. We demonstrate here that fluridone can be used to promote adventitious rooting in the model species Pisum sativum (pea). In addition, in the garden species Plumbago auriculata and Jasminium polyanthum fluridone was equally as successful at promoting roots as a commercial rooting compound containing NAA and IBA. Our findings demonstrate that inhibition of strigolactone signaling has the potential to be used to improve adventitious rooting in commercially relevant species.

Beveridge, Christine A.; Geelen, Danny

2012-01-01

224

Controls on Ecosystem and Root Respiration in an Alaskan Peatland  

NASA Astrophysics Data System (ADS)

Boreal ecosystems cover 14% of the vegetated surface on earth and account for 25-30% of the world’s soil carbon (C), mainly due to large carbon stocks in deep peat and frozen soil layers. While peatlands have served as historical sinks of carbon, global climate change may trigger re-release of C to the atmosphere and may turn these ecosystems into net C sources. Rates of C release from a peatland are determined by regional climate and local biotic and abiotic factors such as vegetation cover, thaw depth, and peat thickness. Soil CO2 fluxes are driven by both autotrophic (plant) respiration and heterotrophic (microbial) respiration. Thus, changes in plant and microbial activity in the soil will impact CO2 emissions from peatlands. In this study, we explored environmental and vegetation controls on ecosystem respiration and root respiration in a variety of wetland sites. The study was conducted at the Alaskan Peatland Experiment (APEX; www.uoguelph.ca/APEX) sites in the Bonanza Creek Experimental Forest located 35 km southwest of Fairbanks Alaska. We measured ecosystem respiration, root respiration, and monitored a suite of environmental variables along a vegetation and soil moisture gradient including a black spruce stand with permafrost, a shrubby site with permafrost, a tussock grass site, and a herbaceous open rich fen. Within the rich fen, we have been conducting water table manipulations including a control, lowered, and raised water table treatment. In each of our sites, we measured total ecosystem respiration using static chambers and root respiration by harvesting roots from the uppermost 20 cm and placing them in a root cuvette to obtain a root flux. Ecosystem respiration (ER) on a ?mol/m2/sec basis varied across sites. Water table was a significant predictor of ER at the lowered manipulation site and temperature was a strong predictor at the control site in the rich fen. Water table and temperature were both significant predictors of ER at the raised manipulation site. Root respiration fluxes on a ppm CO2/sec/g dry mass basis were highest for herbaceous species, which dominated the open rich fen sites. Root respiration flux was significantly lower in tree-dominated black spruce sites. It appears that the variation in root respiration explains the variation in ER between herbaceous and tree-dominated systems. Therefore an important next step is to partition ER into heterotrophic and autotrophic components across these ecosystems. This in turn will provide a better assessment of peatland C responses to global climate change.

McConnell, N. A.; McGuire, A. D.; Harden, J. W.; Kane, E. S.; Turetsky, M. R.

2010-12-01

225

The Compact Root Architecture1 Gene Regulates Lignification, Flavonoid Production, and Polar Auxin Transport in Medicago truncatula1[W  

PubMed Central

The root system architecture is crucial to adapt plant growth to changing soil environmental conditions and consequently to maintain crop yield. In addition to root branching through lateral roots, legumes can develop another organ, the nitrogen-fixing nodule, upon a symbiotic bacterial interaction. A mutant, cra1, showing compact root architecture was identified in the model legume Medicago truncatula. cra1 roots were short and thick due to defects in cell elongation, whereas densities of lateral roots and symbiotic nodules were similar to the wild type. Grafting experiments showed that a lengthened life cycle in cra1 was due to the smaller root system and not to the pleiotropic shoot phenotypes observed in the mutant. Analysis of the cra1 transcriptome at a similar early developmental stage revealed few significant changes, mainly related to cell wall metabolism. The most down-regulated gene in the cra1 mutant encodes a Caffeic Acid O-Methyl Transferase, an enzyme involved in lignin biosynthesis; accordingly, whole lignin content was decreased in cra1 roots. This correlated with differential accumulation of specific flavonoids and decreased polar auxin transport in cra1 mutants. Exogenous application of the isoflavone formononetin to wild-type plants mimicked the cra1 root phenotype, whereas decreasing flavonoid content through silencing chalcone synthases restored the polar auxin transport capacity of the cra1 mutant. The CRA1 gene, therefore, may control legume root growth through the regulation of lignin and flavonoid profiles, leading to changes in polar auxin transport.

Laffont, Carole; Blanchet, Sandrine; Lapierre, Catherine; Brocard, Lysiane; Ratet, Pascal; Crespi, Martin; Mathesius, Ulrike; Frugier, Florian

2010-01-01

226

Root induction by Agrobacterium rhizogenes in walnut  

Microsoft Academic Search

Agrobacterium rhizogenes (wild-type, strain 1855), when applied to the basal part of microcuttings of walnut (J. regia L.), produced numerous adventitious roots in vitro: 58.6% of rooting was induced in microcuttings in hormone free medium and 62.9% and abundant callus formation in the presence of IBA. A. rhizogenes did not induce rooting when IAA was present in the rooting medium.

Emilia Caboni; Paola Lauri; Mariagrazia Tonelli; Giuseppina Falasca; Carmine Damiano

1996-01-01

227

Development of ROOT Services for Grid  

NASA Astrophysics Data System (ADS)

ROOT is a platform-independent, object-oriented framework used for facing the challenges in the high-energy physics data analysis. Physical experiments as NA48, CMS, ALICE and ATLAS use for data storage and analysis G-Lite Grid infrastructure and ROOT framework for interactive manipulation of the analyzed data. It is strategically important ROOT to be used in Grid middleware. The aim of this paper is to present methodology for exposing legacy ROOT functionalities as services.

Goranova, R.

2010-11-01

228

Root Cap and the Perception of Gravity  

Microsoft Academic Search

DURING investigations into the fine structure of apical meristems under the electron microscope, one of us (S. G.) discovered that it was possible, in maize and barley, to detach the intact root cap cleanly from the rest of the root tip. This is shown in Fig. 1. The roots of grasses are characterized by having a discrete cap meristem and,

B. E. Juniper; Suzanne Groves; BRURIA LANDAU-SCHACHAR; L. J. AUDUS

1966-01-01

229

Auxin Transport Promotes Arabidopsis Lateral Root Initiation  

Microsoft Academic Search

Lateral root development in Arabidopsis provides a model for the study of hormonal signals that regulate postembry- onic organogenesis in higher plants. Lateral roots originate from pairs of pericycle cells, in several cell files positioned opposite the xylem pole, that initiate a series of asymmetric, transverse divisions. The auxin transport inhibitor N -1-naph- thylphthalamic acid (NPA) arrests lateral root development

Ilda Casimiro; Alan Marchant; Rishikesh P. Bhalerao; Tom Beeckman; Sandra Dhooge; Ranjan Swarup; Neil Graham; Dirk Inzé; Goran Sandberg; Pedro J. Casero; Malcolm Bennett

2001-01-01

230

EFFECTS OF OZONE ON ROOT PROCESSES  

EPA Science Inventory

Ozone alters root growth and root processes by first reducing photosynthesis and altering foliar metabolic pathways. The alteration in foliar metabolism is reflected in lowered carbohydrate levels in the roots. This can reduce key metabolic processes such as mineral uptake and sy...

231

Involvement of polyamines in root development  

Microsoft Academic Search

Root development is under the control of hormonal, metabolic, and environmental cues that can act on genetically-controlled developmental programmes and thus affect the plasticity of root architecture. These processes involve not only the five `classical' plant hormones, but also other growth regulators, such as polyamines. The present review emphasises the importance of polyamines in the different aspects of root development:

Ivan Couée; Irène Hummel; Cécile Sulmon; Gwenola Gouesbet; Abdelhak El Amrani

2004-01-01

232

Celebrex Offers a Small Protection From Root  

Microsoft Academic Search

A B S T R A C T Tooth movement results from alveolar bone resorption\\/deposition following application of orthodontic forces, and root resorption can be an undesirable complication associated with this process. No treatment for external root resorption is available to date. Objective: To determine if COX-2 inhibitors like Celebrex are effec- tive in protecting root resorption associated with orthodontic

John Jerome; Timothy Brunson; Gerald Takeoka; Chad Foster; Hong B. Moon; Enrique Grageda; Maggie Zeichner-David

2005-01-01

233

Application of glutathione to roots selectively inhibits cadmium transport from roots to shoots in oilseed rape.  

PubMed

Glutathione is a tripeptide involved in various aspects of plant metabolism. This study investigated the effects of the reduced form of glutathione (GSH) applied to specific organs (source leaves, sink leaves, and roots) on cadmium (Cd) distribution and behaviour in the roots of oilseed rape plants (Brassica napus) cultured hydroponically. The translocation ratio of Cd from roots to shoots was significantly lower in plants that had root treatment of GSH than in control plants. GSH applied to roots reduced the Cd concentration in the symplast sap of root cells and inhibited root-to-shoot Cd translocation via xylem vessels significantly. GSH applied to roots also activated Cd efflux from root cells to the hydroponic solution. Inhibition of root-to-shoot translocation of Cd was visualized, and the activation of Cd efflux from root cells was also shown by using a positron-emitting tracer imaging system (PETIS). This study investigated a similar inhibitory effect on root-to-shoot translocation of Cd by the oxidized form of glutathione, GSSG. Inhibition of Cd accumulation by GSH was abolished by a low-temperature treatment. Root cells of plants exposed to GSH in the root zone had less Cd available for xylem loading by actively excluding Cd from the roots. Consequently, root-to-shoot translocation of Cd was suppressed and Cd accumulation in the shoot decreased. PMID:23364937

Nakamura, Shin-ichi; Suzui, Nobuo; Nagasaka, Toshinori; Komatsu, Fumiya; Ishioka, Noriko S; Ito-Tanabata, Sayuri; Kawachi, Naoki; Rai, Hiroki; Hattori, Hiroyuki; Chino, Mitsuo; Fujimaki, Shu

2013-01-29

234

Root-soil mechanical interactions during pullout and failure of root bundles  

Microsoft Academic Search

Roots play a major role in reinforcing and stabilizing steep hillslopes. Most studies in slope stability implement root reinforcement as an apparent cohesion by upscaling the behavior of static individual roots. Recent studies, however, have shown that much better predictions of slope stability can be made if the progressive failure of bundles of roots are considered. The characteristics of progressive

M. Schwarz; D. Cohen; D. Or

2010-01-01

235

Assessing root traits associated with root rot resistance in common bean  

Microsoft Academic Search

Detecting differences in root architecture and growth patterns among common bean (Phaseolus vulgaris L.) genotypes may provide unique selection criteria for genetic resistance to Fusarium root rot. Genetic variation in root system architecture was quantified for 10 contrasting bean genotypes that represent four common bean classes (kidney, cranberry, black, and snap bean) under greenhouse conditions and under root rot disease

B Román-Avilés; S. S Snapp; J. D Kelly

2004-01-01

236

Root induction in three species of bamboo with different rooting abilities  

Microsoft Academic Search

Rooting of in vitro axillary shoots from adult field culms of Bambusa atra, Dendrocalamus giganteus and D. hookeri and of juvenile seedling shoots of D. giganteus were investigated. B. atra rooted spontaneously without exogenous auxin during axillary shoot proliferation, while both Dendrocalamus species rooted only on transfer to rooting media with indole-3-butyric acid (IBA). D. giganteus required coumarin, an auxin

S. M. S. D. Ramanayake; K. M. M. N. Maddegoda; M. C. Vitharana; G. D. G. Chaturani

2008-01-01

237

Indirect Methods Produce Higher Estimates of Fine Root Production and Turnover Rates than Direct Methods  

PubMed Central

The production and turnover of fine roots play substantial roles in the biogeochemical cycles of terrestrial ecosystems. However, the disparity among the estimates of both production and turnover, particularly due to technical limitations, has been debated for several decades. Here, we conducted a meta-analysis to compare published estimates of fine root production and turnover rates derived from different methods at the same sites and at the same sampling time. On average, the estimates of fine root production and turnover rates were 87% and 124% higher, respectively, by indirect methods than by direct methods. The substantially higher fine root production and turnover estimated by indirect methods, on which most global carbon models are based, indicate the necessity of re-assessing the global carbon model predictions for atmospheric carbon sequestration in soils as a result of the production and turnover of fine roots.

Yuan, Z. Y.; Chen, Han Y. H.

2012-01-01

238

Iron plaque formation and morphoanatomy of roots from species of restinga subjected to excess iron.  

PubMed

The restingas, a sandy coastal plain ecosystem of Brazil, have received an additional amount of iron due to the activity of mining industries. The present study aims to characterize morphoanatomically and histochemically the iron plaque formation on roots of Ipomoea pes-caprae L. and Canavalia rosea DC, cultivated in hydroponic solution with and without excess iron. The iron plaque formation as well as changes in the external morphology of the lateral roots of both species were observed after the subjection to excess iron. Changes in the nutrient uptake, and in the organization and form of the pericycle and cortex cells were observed for both species. Scanning electron microscopy showed evident iron plaques on the whole surface of the root. The iron was histolocalized in all root tissues of both species. The species of restinga studied here formed iron plaque in their roots when exposed to excess of this element, which may compromise their development in environments polluted by particulated iron. PMID:22169228

Siqueira-Silva, Advanio Inácio; da Silva, Luzimar Campos; Azevedo, Aristéa Alves; Oliva, Marco Antonio

2011-12-09

239

Exploring mechanisms of root erosion by flood in laboratory experiments  

NASA Astrophysics Data System (ADS)

Riparian vegetation developing on the bare alluvial sediment may strongly contribute to the local stabilization of river bedforms and, in turn to the resulting river morphodynamics. Both seedlings from germinated seeds or woody debris deposits that start taking roots in the gravel sediment eventually develop into vegetation patches depending on the frequency and magnitude of floods. Ultimately, the interaction between river hydrology and vegetation growth time scales depends on the anchoring mechanism of certain root type and age within the non-cohesive alluvial soil. Recently, we started to explore the mechanisms of flow erosion in the presence of vegetation roots at the laboratory scale, in order to help explaining some observations that have been made at the laboratory scale (Perucca et al., this Session) and in the field, that is a restored river reach (Pasquale et al., this Session). In this paper, we propose a conceptual mechanism showing that root erosion by floods depends on root architecture (age and structure), and that uprooting is essentially of two types. The first type is relevant to young vegetation and is mainly due to a balance between flow drag force and resistance to uprooting. The second type concerns more mature vegetation and implies that considerable localized erosion additionally takes place in order to produce uprooting. Such two processes occur at completely different time scales, being quite instantaneous the first, and rather delayed the second. Although made at laboratory scale, the results of our preliminary experiments seem to support the idea ursued by the conceptual model. Future test will aim at better unravel the details of the root erosion dynamics and at formulating a modelling theory therof, the implications of which range from ecohydrology to river restoration practice.

Edmaier, Katharina; Perona, Paolo

2010-05-01

240

A sustainability root cause analysis methodology and its application  

Microsoft Academic Search

In the design of chemical\\/energy production systems, a major challenge is to identify the bottleneck issues and improve its sustainability effectively. Due to the multi-dimensional feature of sustainability, how to account for the impacts of various design factors and the cause-and-effect relationships can be very difficult. This paper will present a sustainability root cause analysis method based on the combination

Abhishek Jayswal; Xiang Li; Anand Zanwar; Helen H. Lou; Yinlun Huang

2011-01-01

241

Effects of marigold (Tagetes sp.) roots on soil microorganisms  

Microsoft Academic Search

Marigolds (genus Tagetes) suppress populations of soil endopathogenic nematodes such as Pratylenchus penetrans and Meloidogyne species. Nematode suppression by marigolds is thought to be due to thiophenes, heterocyclic sulfur-containing molecules abundant\\u000a in this plant. When activated, thiophenes such as ?-terthienyl produce oxygen radicals. If marigold roots release such a powerful\\u000a biocidal agent and it is activated in soil, microbial populations

E. Topp; S. Millar; H. Bork; M. Welsh

1998-01-01

242

The rhizosphere revisited: root microbiomics  

PubMed Central

The rhizosphere was defined over 100 years ago as the zone around the root where microorganisms and processes important for plant growth and health are located. Recent studies show that the diversity of microorganisms associated with the root system is enormous. This rhizosphere microbiome extends the functional repertoire of the plant beyond imagination. The rhizosphere microbiome of Arabidopsis thaliana is currently being studied for the obvious reason that it allows the use of the extensive toolbox that comes with this model plant. Deciphering plant traits that drive selection and activities of the microbiome is now a major challenge in which Arabidopsis will undoubtedly be a major research object. Here we review recent microbiome studies and discuss future research directions and applicability of the generated knowledge.

Bakker, Peter A. H. M.; Berendsen, Roeland L.; Doornbos, Rogier F.; Wintermans, Paul C. A.; Pieterse, Corne M. J.

2013-01-01

243

A New Anatomically Based Nomenclature for the Roots and Root Canals--Part 1: Maxillary Molars  

PubMed Central

Numerous terminologies have been employed in the dental literature to describe the roots and root canal systems of maxillary molars. This multiplicity in naming of roots and canals makes the reader susceptible to misinterpretation and confusion. No consensus thus far has been arrived at for defining the names of roots and root canals in maxillary molars, including their various morphological aberrations. The anatomical relation of roots and their root canals were identified and were subsequently named based on definite sets of criteria. A new method for identification and naming of roots and root canal anatomy in maxillary molars, based on their root and canal relationship, was formulated and is presented in this paper. The nomenclature makes certain essential modifications to the traditional approach to accommodate naming of the various aberrations presented in the maxillary molars. A simple, yet extensive, nomenclature system has been proposed that appropriately names the internal and external morphology of maxillary molars.

Kottoor, Jojo; Albuquerque, Denzil Valerian; Velmurugan, Natanasabapathy

2012-01-01

244

Sustainability: characteristics and scientific roots  

Microsoft Academic Search

Literature about sustainable development is abundant and expanding, and syntheses are therefore increasingly necessary. This\\u000a paper represents an effort to characterize the main principles behind the concept of sustainability and to identify and describe\\u000a the scientific approaches at the root of each of those principles. From a scientific point of view, the identification of\\u000a sustainability principles is possibly more interesting

Nuno QuentalJulia; Júlia M. Lourenço; Fernando Nunes da Silva

2011-01-01

245

Calcium in Root Hair Growth  

Microsoft Academic Search

\\u000a The growth of cells as diverse as fungal hyphae, pollen tubes, algal rhizoids, and root hairs is characterized by a highly\\u000a localized control of cell expansion confined to the growing tip. The cellular regulators that have been shown to maintain\\u000a this spatial localization of growth range from monomeric G-proteins and the actin cytoskeleton to protein kinases and phospholipid-modulating\\u000a enzymes. A

T. Bibikova; S. Gilroy

246

The Biblical Roots of Democracy  

Microsoft Academic Search

While democracy is usually perceived as a Greco-European development, it is note-worthy that some of its roots can be found in the Bible. The Covenant between God and the tribes of Israel at Mount Sinai is based on the people’s consent. God is seen as the King of Israel: theocracy means the rule of God literally, and not the rule

Mordecai Roshwald

2006-01-01

247

Root systems of chaparral shrubs  

Microsoft Academic Search

Root systems of chaparral shrubs were excavated from a 70 m2 plot of a mixed chaparral stand located on a north-facing slope in San Diego County (32°54' N; 900 m above sea level). The main shrub species present were Adenostoma fasciculatum, Arctostaphylos pungens, Ceanothus greggii, Erigonum fasciculatum, and Haplopappus pinifolius. Shrubs were wired into their positions, and the soil was

Jochen Kummerow; David Krause; William Jow

1977-01-01

248

Root functioning modifies seasonal climate  

PubMed Central

Hydraulic redistribution (HR), the nocturnal vertical transfer of soil water from moister to drier regions in the soil profile by roots, has now been observed in Amazonian trees. We have incorporated HR into an atmospheric general circulation model (the National Center for Atmospheric Research Community Atmospheric Model Version 2) to estimate its impact on climate over the Amazon and other parts of the globe where plants displaying HR occur. Model results show that photosynthesis and evapotranspiration increase significantly in the Amazon during the dry season when plants are allowed to redistribute soil water. Plants draw water up and deposit it into the surface layers, and this water subsidy sustains transpiration at rates that deep roots alone cannot accomplish. The water used for dry season transpiration is from the deep storage layers in the soil, recharged during the previous wet season. We estimate that HR increases dry season (July to November) transpiration by ?40% over the Amazon. Our model also indicates that such an increase in transpiration over the Amazon and other drought-stressed regions affects the seasonal cycles of temperature through changes in latent heat, thereby establishing a direct link between plant root functioning and climate.

Lee, Jung-Eun; Oliveira, Rafael S.; Dawson, Todd E.; Fung, Inez

2005-01-01

249

Shoot regeneration capacity from roots and transgenic hairy roots of tomato cultivars and wild related species  

Microsoft Academic Search

The organogenetic competence of roots and Agrobacterium rhizogenes-induced hairy roots of twelve Lycopersicon genotypes was investigated. Both roots and hairy roots of L. peruvianum, L. chilense, L. hirsutum and two L. peruvianum-derived genotypes regenerated shoots after 2–4 weeks of incubation on zeatin-contained medium. Anatomical analysis showed\\u000a that shoot regeneration in roots could be direct or indirect, depending on the genotype

Lázaro E. P. Peres; Patrícia G. Morgante; Cláudia Vecchi; Jane E. Kraus; Marie-Anne van Sluys

2001-01-01

250

Linking root morphology, longevity and function to root branch order: a case study in three shrubs  

Microsoft Academic Search

Root branching order supports a powerful approach to understanding complex root systems; however, how the pattern of root\\u000a morphological characteristics, tissue carbon (C) and nitrogen (N) concentrations, and root lifespan are related to anatomical\\u000a features of variable root orders for mature shrubs (?19 years old) in sandy habitats is still unclear. In this study, these\\u000a relationships were investigated for three typical

Gang Huang; Xue-yong Zhao; Ha-lin Zhao; Ying-xin Huang; Xiao-an Zuo

2010-01-01

251

Non-invasive imaging of the aortic root : towards optimal evaluation and sizing of stented (tissue engineered) heart valves  

Microsoft Academic Search

In Part I of this thesis the application of multidetector-row computed tomography (MDCT) (Chapter 2) and magnetic resonance imaging (MRI) (Chapter 3) in the imaging of the aortic root has been investigated. Imaging of the stenotic aortic root by echocardiography, MDCT or MRI is relevant for TAVI. Due to the non-invasiveness of this implantation technique, direct visual assessment by the

L. M. de Heer

2012-01-01

252

Lateral root organogenesis - from cell to organ.  

PubMed

Unlike locomotive organisms capable of actively approaching essential resources, sessile plants must efficiently exploit their habitat for water and nutrients. This involves root-mediated underground interactions allowing plants to adapt to soils of diverse qualities. The root system of plants is a dynamic structure that modulates primary root growth and root branching by continuous integration of environmental inputs, such as nutrition availability, soil aeration, humidity, or salinity. Root branching is an extremely flexible means to rapidly adjust the overall surface of the root system and plants have evolved efficient control mechanisms, including, firstly initiation, when and where to start lateral root formation; secondly lateral root primordia organogenesis, during which the development of primordia can be arrested for a certain time; and thirdly lateral root emergence. Our review will focus on the most recent advances in understanding the molecular mechanisms involved in the regulation of lateral root initiation and organogenesis with the main focus on root system of the model plant Arabidopsis thaliana. PMID:20934368

Benková, Eva; Bielach, Agnieszka

2010-10-08

253

The biomechanics of Pachycereus pringlei root systems.  

PubMed

We report on the root system of the large columnar cactus species Pachycereus pringlei to explore the hypothesis that increasing plant size decreases the ability to resist wind-throw but increases the capacity to absorb and store nutrients in roots (i.e., plant size limits the performance of these functions and may shift the performance of one function in favor of another as size increases). Based on 18 plants differing in size, the root system is characterized by a broad and deep bayonet-like root central to a shallow and extensive lateral system of root elements bearing sinker roots near the stem base. All root types have a living secondary cortex and contain wood with a large volume fraction of ray tissues that increases toward the stem base. Wood stiffness and tensile strength are correlated negatively with the ray tissue volume fraction and thus decrease toward the stem base in lateral and bayonet roots. Calculations show that the ability of the bayonet and proximal lateral root elements to resist wind-throw decreases with increasing plant size, whereas the nutrient absorption/storage capacity of the total root system increases with plant size (i.e., a size-dependent shift between these two root functions occurs). PMID:21669707

Niklas, Karl J; Molina-Freaner, Francisco; Tinoco-Ojanguren, Clara; Paolillo, Dominick J

2002-01-01

254

Light Sheet Tomography (LST) for in situ imaging of plant roots.  

PubMed

The production of crops capable of efficient nutrient use is essential for addressing the problem of global food security. The ability of a plant's root system to interact with the soil micro-environment determines how effectively it can extract water and nutrients. In order to assess this ability and develop the fast and cost effective phenotyping techniques which are needed to establish efficient root systems, in situ imaging in soil is required. To date this has not been possible due to the high density of scatterers and absorbers in soil or because other growth substrates do not sufficiently model the heterogeneity of a soil's microenvironment. We present here a new form of light sheet imaging with novel transparent soil containing refractive index matched particles. This imaging method does not rely on fluorescence, but relies solely on scattering from root material. We term this form of imaging Light Sheet Tomography (LST). We have tested LST on a range of materials and plant roots in transparent soil and gel. Due to the low density of root structures, i.e. relatively large spaces between adjacent roots, long-term monitoring of lettuce root development in situ with subsequent quantitative analysis was achieved. PMID:23938474

Yang, Zhengyi; Downie, Helen; Rozbicki, Emil; Dupuy, Lionel X; Macdonald, Michael P

2013-07-15

255

X-ray photoelectron spectroscopy surface analysis of aluminum ion stress in barley roots. [Hordeum vulgare  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) has been used to analyze root surface changes when Dayton barley (Hordeum vulgare) (Al tolerant) and Kearney barley (Al sensitive) seedlings were grown in nutrient solution in the presence and absence of 37.0 micromolar Al. The electron spectra from root surfaces contained strong lines in order of decreasing intensity from organic forms of carbon, oxygen, and nitrogen and weak lines due to inorganic elements in the form of anions and cations on the surface. The surface composition of root tips from Kearney was C, 65.6%; 0, 26.8%; N, 4.4% and tips from Dayton was C, 72.7%; O, 23.6%; N, 1.9%, grown in the absence of aluminum. Electron lines characteristic of nitrate, potassium, chloride, phosphate were also present in the spectra from those roots. Dayton roots grown in the presence of 37.0 micromolar aluminum contained 2.1% aluminum while Kearney contained 1.3% aluminum. The ratio of aluminum to phosphate was close to 1.0. Dayton roots usually contained twice as much aluminum phosphate in the surface region as Kearney. Dayton may be less susceptible to Al toxic effects by accumulation of aluminum phosphate on the root surface which then acts as a barrier to the transport of aluminum into the interior of the roots.

Millard, M.M.; Foy, C.D.; Coradetti, C.A.; Reinsel, M.D. (Department of Agriculture, Beltsville, MD (USA))

1990-06-01

256

A plausible mechanism for auxin patterning along the developing root  

Microsoft Academic Search

BACKGROUND: In plant roots, auxin is critical for patterning and morphogenesis. It regulates cell elongation and division, the development and maintenance of root apical meristems, and other processes. In Arabidopsis, auxin distribution along the central root axis has several maxima: in the root tip, in the basal meristem and at the shoot\\/root junction. The distal maximum in the root tip

Victoria V Mironova; Nadezda A Omelyanchuk; Guy Yosiphon; Stanislav I Fadeev; Nikolai A Kolchanov; Eric Mjolsness; Vitaly A Likhoshvai

2010-01-01

257

Plant responsiveness to root-root communication of stress cues  

PubMed Central

Background and Aims Phenotypic plasticity is based on the organism's ability to perceive, integrate and respond to multiple signals and cues informative of environmental opportunities and perils. A growing body of evidence demonstrates that plants are able to adapt to imminent threats by perceiving cues emitted from their damaged neighbours. Here, the hypothesis was tested that unstressed plants are able to perceive and respond to stress cues emitted from their drought- and osmotically stressed neighbours and to induce stress responses in additional unstressed plants. Methods Split-root Pisum sativum, Cynodon dactylon, Digitaria sanguinalis and Stenotaphrum secundatum plants were subjected to osmotic stress or drought while sharing one of their rooting volumes with an unstressed neighbour, which in turn shared its other rooting volume with additional unstressed neighbours. Following the kinetics of stomatal aperture allowed testing for stress responses in both the stressed plants and their unstressed neighbours. Key Results In both P. sativum plants and the three wild clonal grasses, infliction of osmotic stress or drought caused stomatal closure in both the stressed plants and in their unstressed neighbours. While both continuous osmotic stress and drought induced prolonged stomatal closure and limited acclimation in stressed plants, their unstressed neighbours habituated to the stress cues and opened their stomata 3–24 h after the beginning of stress induction. Conclusions The results demonstrate a novel type of plant communication, by which plants might be able to increase their readiness to probable future osmotic and drought stresses. Further work is underway to decipher the identity and mode of operation of the involved communication vectors and to assess the potential ecological costs and benefits of emitting and perceiving drought and osmotic stress cues under various ecological scenarios.

Falik, Omer; Mordoch, Yonat; Ben-Natan, Daniel; Vanunu, Miriam; Goldstein, Oron; Novoplansky, Ariel

2012-01-01

258

Ammonium Uptake by Rice Roots (III. Electrophysiology).  

PubMed Central

The transmembrane electrical potential differences ([delta][psi]) were measured in epidermal and cortical cells of intact roots of 3-week-old rice (Oryza sativa L. cv M202) seedlings grown in 2 or 100 [mu]M NH4+ (G2 or G100 plants, respectively). In modified Johnson's nutrient solution containing no nitrogen, [delta][psi] was in the range of -120 to -140 mV. Introducing NH4+ to the bathing medium caused a rapid depolarization. At the steady state, average [delta][psi] of G2 and G100 plants were -116 and -89 mV, respectively. This depolarization exhibited a biphasic response to external NH4+ concentration similar to that reported for 13NH4+ influx isotherms (M.Y. Wang, M.Y. Siddiqi, T.J. Ruth, A.D.M. Glass [1993] Plant Physiol 103: 1259-1267). Plots of membrane depolarization versus 13NH4+ influx were also biphasic, indicating distinct coupling processes for the two transport systems, with a breakpoint between two concentration ranges around 1 mM NH4+. The extent of depolarization was also influenced by nitrogen status, which was larger for G2 plants than for G100 plants. Depolarization of [delta][psi] due to NH4+ uptake was eliminated by a protonophore (carboxylcyanide-m-chlorophenylhydrazone), inhibitors of ATP synthesis (sodium cyanide plus salicylhydroxamic acid), or an ATPase inhibitor (diethylstilbestrol). The results of these observations are discussed in the context of the mechanisms of NH4+ uptake by high- and low-affinity transport systems operating across the plasma membranes of root cells.

Wang, M. Y.; Glass, ADM.; Shaff, J. E.; Kochian, L. V.

1994-01-01

259

Hydrogenase in actinorhizal root nodules and root nodule homogenates.  

PubMed Central

Hydrogenases were measured in intact actinorhizal root nodules and from disrupted nodules of Alnus glutinosa, Alnus rhombifolia, Alnus rubra, and Myrica pensylvanica. Whole nodules took up H2 in an O2-dependent reaction. Endophyte preparations oxidized H2 through the oxyhydrogen reaction, but rates were enhanced when hydrogen uptake was coupled to artificial electron acceptors. Oxygen inhibited artifical acceptor-dependent H2 uptake. The hydrogenase system from M. pensylvanica had a different pattern of coupling to various electron acceptors than the hydrogenase systems from the alders; only the bayberry system evolved H2 from reduced viologen dyes.

Benson, D R; Arp, D J; Burris, R H

1980-01-01

260

Synthesis and structure of the cluster cation (Pt/sub 3/(/mu//sub 3/-S)(AuPPh/sub 3/)(/mu//sub 3/-AgCl)(/mu/-Ph/sub 2/PCH/sub 2/PPh/sub 2/)/sub 3/)/sup +/, containing both PtAu and PtAg bonds  

SciTech Connect

Interest in Pt-Au and Pt-Ag compounds is growing because the gold or silver incorporation causes significant changes in the activity and selectivity of platinum catalysts. The reaction of (Pt/sub 3/H(/mu//sub 3/-S)(/mu/-dppm)/sub 3/)/sup +/ (dppm = Ph/sub 2/PCH/sub 2/PPh/sub 2/) with Ph/sub 3/PAu/sup +/ was carried out with the aim of substituting the hydride ligand by the Ph/sub 3/PAu/sup +/ ligand. This aim was not achieved; however, the compound (Pt/sub 3/(/mu//sub 3/-S)(AuPPh/sub 3/)(/mu//sub 3/-AgCl)(/mu/-Ph/sub 2/PCH/sub 2/PPh/sub 2/)/sub 3/)/sup +/ containing the Pt/sub 3/AuAg core was isolated. The synthesis, structure, and spectroscopic properties of this complex are reported. 23 refs., 1 fig., 3 tabs.

Douglas, G.; Jennings, M.C.; Manojlovic-Muir, L.; Puddephatt, R.J.

1988-11-30

261

Root Water Uptake and Tracer Transport in a Lupin Root System: Integration of Magnetic Resonance Images and the Numerical Model RSWMS  

NASA Astrophysics Data System (ADS)

Combination of experimental studies with detailed deterministic models help understand root water uptake processes. Recently, Javaux et al. developed the RSWMS model by integration of Doussa?s root model into the well established SWMS code[1], which simulates water and solute transport in unsaturated soil [2, 3]. In order to confront RSWMS modeling results to experimental data, we used Magnetic Resonance Imaging (MRI) technique to monitor root water uptake in situ. Non-invasive 3-D imaging of root system architecture, water content distributions and tracer transport by MR were performed and compared with numerical model calculations. Two MRI experiments were performed and modeled: i) water uptake during drought stress and ii) transport of a locally injected tracer (Gd-DTPA) to the soil-root system driven by root water uptake. Firstly, the high resolution MRI image (0.23x0.23x0.5mm) of the root system was transferred into a continuous root system skeleton by a combination of thresholding, region-growing filtering and final manual 3D redrawing of the root strands. Secondly, the two experimental scenarios were simulated by RSWMS with a resolution of about 3mm. For scenario i) the numerical simulations could reproduce the general trend that is the strong water depletion from the top layer of the soil. However, the creation of depletion zones in the vicinity of the roots could not be simulated, due to a poor initial evaluation of the soil hydraulic properties, which equilibrates instantaneously larger differences in water content. The determination of unsaturated conductivities at low water content was needed to improve the model calculations. For scenario ii) simulations confirmed the solute transport towards the roots by advection. 1. Simunek, J., T. Vogel, and M.T. van Genuchten, The SWMS_2D Code for Simulating Water Flow and Solute Transport in Two-Dimensional Variably Saturated Media. Version 1.21. 1994, U.S. Salinity Laboratory, USDA, ARS: Riverside, California. 2. Javaux, M., et al., Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake. Vadose Zone J., 2008. 7(3): p. 1079-1088. 3. Schröder, T., et al., Effect of Local Soil Hydraulic Conductivity Drop Using a Three Dimensional Root Water Uptake Model. Vadose Zone J., 2008. 7(3): p. 1089-1098.

Pohlmeier, Andreas; Vanderborght, Jan; Haber-Pohlmeier, Sabina; Wienke, Sandra; Vereecken, Harry; Javaux, Mathieu

2010-05-01

262

PATTERNS IN SOIL FERTILITY AND ROOT HERBIVORY INTERACT TO INFLUENCE FINE-ROOT DYNAMICS.  

SciTech Connect

Fine-scale soil nutrient enrichment typically stimulates root growth, but it may also increase root herbivory, resulting in trade-offs for plant species and potentially influencing carbon cycling patterns. We used root ingrowth cores to investigate the effects of microsite fertility and root herbivory on root biomass in an aggrading upland forest in the coastal plain of South Carolina, USA. Treatments were randomly assigned to cores from a factorial combination of fertilizer and insecticide. Soil, soil fauna, and roots were removed from the cores at the end of the experiment (8–9 mo), and roots were separated at harvest into three diameter classes. Each diameter class responded differently to fertilizer and insecticide treatments. The finest roots (,1.0 mm diameter), which comprised well over half of all root biomass, were the only ones to respond significantly to both treatments, increasing when fertilizer and when insecticide were added (each P , 0.0001), with maximum biomass found where the treatments were combined (interaction term significant, P , 0.001). These results suggest that root-feeding insects have a strong influence on root standing crop with stronger herbivore impacts on finer roots and within more fertile microsites. Thus, increased vulnerability to root herbivory is a potentially significant cost of root foraging in nutrient-rich patches.

Stevens, Glen, N.; Jones, Robert, H.

2006-03-01

263

Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton  

PubMed Central

A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100?mM) or non-uniform NaCl concentrations (0/200 and 50/150?mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na+ concentrations in leaves. The [Na+] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na+] in the ‘0’ side roots was possibly due to transportation of foliar Na+ to roots through phloem. Plants under non-uniform salinity extruded more Na+ from the root than those under uniform salinity. Root Na+ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na+ efflux and H+ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na+ extrusion was probably due to active Na+/H+ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na+ concentration, transport of excessive foliar Na+ to the low salinity side, and enhanced Na+ efflux from the low salinity root.

Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A. Egrinya

2012-01-01

264

The role of root system architecture and root hairs in promoting anchorage against uprooting forces in Allium cepa and root mutants of Arabidopsis thaliana  

Microsoft Academic Search

The role played by lateral roots and root hairs in promoting plant anchorage, and specifically resist- ance to vertical uprooting forces has been deter- mined experimentally. Two species were studied, Allium cepa (onion) which has a particularly simple root system and two mutants of Arabidopsis thaliana, one without root hairs (rhd 2-1) and another with reduced lateral root branching (axr

Peter H. J. Bailey; J. D. Currey; A. H. Fitter

2002-01-01

265

Root exudates mediate kin recognition in plants  

PubMed Central

Though recent work has demonstrated that plants can recognize species, kin versus strangers, and self/non-self roots, no mechanism for identity recognition in plants has yet been found. Here we examined the role of soluble chemicals in signaling among roots. Utilizing Arabidopsis thaliana, we exposed young seedlings to liquid media containing exudates from siblings, strangers (non-siblings), or only their own exudates. In one experiment, root secretions were inhibited by sodium orthovanadate and root length and number of lateral roots were measured. In a second experiment, responses to siblings, strangers, and their own exudates were measured for several accessions (genotypes), and the traits of length of the longest lateral root and hypocotyl length were also measured. The exposure of plants to the root exudates of strangers induced greater lateral root formation than exposure of plants to sibling exudates. Stranger recognition was abolished upon treatment with the secretion inhibitor. In one experiment, plants exposed to sibling or stranger exudates have shorter roots than plants only exposed to their own exudates. This self/non-self recognition response was not affected by the secretion inhibitor. The results demonstrate that that kin recognition and self/non-self are two separate identity recognition systems involving soluble chemicals. Kin recognition requires active secretion by roots.

Biedrzycki, Meredith L; Jilany, Tafari A

2010-01-01

266

The Source of Carbon for Root Respiration  

NASA Astrophysics Data System (ADS)

In the Enriched Background Isotope Study (EBIS) that took advantage of a whole-ecosystem radiocarbon label that occurred in the temperate forest near Oak Ridge, Tennessee, we measured the radiocarbon signature of total soil respiration, heterotrophic respiration and root respiration, at different times during the last 3 growing seasons (2002-2004). By applying a mass balance approach, the relative and absolute contributions of heterotrophic and root respiration to total soil respiration were estimated. In contrast to heterotrophic respiration, root respiration seemed to be less affected by changes in soil moisture and temperature but rather showed a link to photosynthetic activity with a very similar pattern during the growing season as that of leaf area index. The radiocarbon signature of root respiration was very dynamic with low values in spring compared to the summer. The sources of variation can include changes in the local atmospheric signature and/or changes in the source of C being respired. Two different sites with different values and patterns of local atmospheric radiocarbon signature showed the same pattern in radiocarbon signatures of root respiration indicating that the source of variation was phenological. Low values during the spring could indicate the use of stored carbohydrates switching to more recent photosynthetic products as the summer progresses. As a first attempt to elucidate the source of C respired by roots, we will compare the radiocarbon content of starch, cellulose and soluble sugars in roots to that of bulk root material and root respired CO2. These radiocarbon signatures can help us identify the pool of C that is most likely being respired by roots during the growing season. A better understanding of the source of C for root respiration has implications for understanding the role of root respiration in C cycling in temperate forests, specifically the timescale over which carbon is fixed through photosynthesis and returned to the atmosphere by root respiration.

Cisneros-Dozal, L.; Trumbore, S.; Zheng, S.

2004-12-01

267

Random roots and lineage sorting.  

PubMed

Lineage sorting has been suggested as a major force in generating incongruent phylogenetic signal when multiple gene partitions are examined. The degree of lineage sorting can be estimated using the coalescent process and simulation studies have also pointed to a major role for incomplete lineage sorting as a factor in phylogenetic inference. Some recent empirical studies point to an extreme role for this phenomenon with up to 50-60% of all informative genes showing incongruence as a result of lineage sorting. Here, we examine seven large multi-partition genome level data sets over a large range of taxonomic representation. We took the approach of examining outgroup choice and its impact on tree topology, by swapping outgroups into analyses with successively larger genetics distances to the ingroup. Our results indicate a linear relationship of outgroup distance with incongruence in the data sets we examined suggesting a strong random rooting effect. In addition, we attempted to estimate the degree of lineage sorting in several large genome level data sets by examining triads of very closely related taxa. This exercise resulted in much lower estimates of incongruent genes that could be the result of lineage sorting, with an overall estimate of around 10% of the total number of genes in a genome showing incongruence as a result of true lineage sorting. Finally we examined the behavior of likelihood and parsimony approaches on the random rooting phenomenon. Likelihood tends to stabilize incongruence as outgroups get further and further away from the ingroup. In one extreme case, likelihood overcompensates for sequence divergence but increases random rooting causing long branch repulsion. PMID:22445448

Rosenfeld, Jeffrey A; Payne, Ansel; DeSalle, Rob

2012-03-14

268

The variability of root cohesion as an influence on shallow landslide susceptibility in the Oregon Coast Range  

USGS Publications Warehouse

Decades of quantitative measurement indicate that roots can mechanically reinforce shallow soils in forested landscapes. Forests, however, have variations in vegetation species and age which can dominate the local stability of landslide-initiation sites. To assess the influence of this variability on root cohesion we examined scarps of landslides triggered during large storms in February and November of 1996 in the Oregon Coast Range and hand-dug soil pits on stable ground. At 41 sites we estimated the cohesive reinforcement to soil due to roots by determining the tensile strength, species, depth, orientation, relative health, and the density of roots ???1 mm in diameter within a measured soil area. We found that median lateral root cohesion ranges from 6.8-23.2 kPa in industrial forests with significant understory and deciduous vegetation to 25.6-94.3 kPa in natural forests dominated by coniferous vegetation. Lateral root cohesion in clearcuts is uniformly ???10 kPa. Some 100-year-old industrial forests have species compositions, lateral root cohesion, and root diameters that more closely resemble 10-year-old clearcuts than natural forests. As such, the influence of root cohesion variability on landslide susceptibility cannot be determined solely from broad age classifications or extrapolated from the presence of one species of vegetation. Furthermore, the anthropogenic disturbance legacy modifies root cohesion for at least a century and should be considered when comparing contemporary landslide rates from industrial forests with geologic background rates.

Schmidt, K. M.; Roering, J. J.; Stock, J. D.; Dietrich, W. E.; Montgomery, D. R.; Schaub, T.

2001-01-01

269

Anatomical evaluation of the root canal diameter and root thickness on the apical third of mesial roots of molars  

Microsoft Academic Search

The purpose was to determine the diameter of the main root canal and wall thickness in the apical dentin in mesial roots of\\u000a maxillary and mandibular molars. Forty mesiobuccal and mesial root specimens were sectioned horizontally at 1, 2 and 3 mm\\u000a from the apex, and measured at each top surface by using optical microscopy to an accuracy of ×20 magnification.

Josué Martos; Gustavo Henrique Tatsch; Augusto César Tatsch; Luiz Fernando Machado Silveira; Carmen María Ferrer-Luque

270

General complex polynomial root solver  

NASA Astrophysics Data System (ADS)

This general complex polynomial root solver, implemented in Fortran and further optimized for binary microlenses, uses a new algorithm to solve polynomial equations and is 1.6-3 times faster than the ZROOTS subroutine that is commercially available from Numerical Recipes, depending on application. The largest improvement, when compared to naive solvers, comes from a fail-safe procedure that permits skipping the majority of the calculations in the great majority of cases, without risking catastrophic failure in the few cases that these are actually required.

Skowron, J.; Gould, A.

2012-12-01

271

Long term adjustment of canopy root depth and strength: Implications catchment hydrology and slope stability  

NASA Astrophysics Data System (ADS)

The species composition of southern Appalachian forests is changing rapidly due to fire suppression, residential expansion and introduced parasites, such as the woody adelgid. Changes in the distribution and age of tree and understory species cause changes in rooting characteristics and therefore the stability of slopes. Roots increase soil cohesive strength and fail in tension during debris flows. The amount of root reinforcement to the soil mass is dependent on the number, size and tensile strength of the roots. We have characterized how changes in the composition of southern Appalachian forests, particularly the expansion of Rhododenron maximum due to fire suppression, may affect the potential for slope failure. We measured the vertical distribution and tensile strength of roots for fifteen individual trees and two mixed species locations in the Coweeta Hydrological Laboratory, North Carolina. The individual pits were chosen to capture variations in species (10 species total), topographic position (nose, side slope, hollow), and age (a range of DBH between 5 cm and 60 cm). Root tensile strengths from different hardwood species were very similar, while rhododendron, a woody shrub, has considerably weaker roots. Roots are concentrated close to the soil surface (at least 70% of biomass occurs within 50 cm of the surface) and variations in this pattern occur primarily as a function of age. R. maximum roots are shallower and weaker than tree roots, which when coupled with low transpiration rates, lowers the total cohesive strength and makes them susceptible to high pore pressure events. We have investigated the potential for mapping R. maximum based on the ratio of near-infrared to red within leaf-off color infrared images. When we combine the remotely-sensed distribution of R. maximum with the root cohesion data from individual pits, we can produce a realistic spatial distribution of root cohesion for southern Appalachian forests. The spatial distribution of root cohesion can be coupled with an eco-hydrological model (we use the Regional Hydro-Ecologic Simulation System (RHESSys)) to understand how coupled changes between hydrology and ecology affect the slope stability of southern Appalachian forests.

Hales, T. C.; Taehee, H.; Band, L.; Vose, J.

2007-12-01

272

[Effects nutrients on the seedlings root hair development and root growth of Poncirus trifoliata under hydroponics condition].  

PubMed

Ahydroponics experiment was conducted to study the effects of nutrients (N, P, K, Ca, Mg, Fe, and Mn) deficiency on the length of primary root, the number of lateral roots, and the root hair density, length, and diameter on the primary root and lateral roots of Poncirus trifoliata seedlings. Under the deficiency of each test nutrient, root hair could generate, but was mainly concentrated on the root base and fewer on the root tip. The root hair density on lateral roots was significantly larger than that on primary root, but the root hair length was in adverse. The deficiency of each test nutrient had greater effects on the growth and development of root hairs, with the root hair density on primary root varied from 55.0 to 174.3 mm(-2). As compared with the control, Ca deficiency induced the significant increase of root hair density and length on primary root, P deficiency promoted the root hair density and length on the base and middle part of primary root and on the lateral roots significantly, Fe deficiency increased the root hair density but decreased the root hair length on the tip of primary root significantly, K deficiency significantly decreased the root hair density, length, and diameter on primary root and lateral roots, whereas Mg deficiency increased the root hair length of primary root significantly. In all treatments of nutrient deficiency, the primary root had the similar growth rate, but, with the exceptions of N and Mg deficiency, the lateral roots exhibited shedding and regeneration. PMID:24066535

Cao, Xiu; Xia, Ren-Xue; Zhang, De-Jian; Shu, Bo

2013-06-01

273

Genotypic recognition and spatial responses by rice roots  

PubMed Central

Root system growth and development is highly plastic and is influenced by the surrounding environment. Roots frequently grow in heterogeneous environments that include interactions from neighboring plants and physical impediments in the rhizosphere. To investigate how planting density and physical objects affect root system growth, we grew rice in a transparent gel system in close proximity with another plant or a physical object. Root systems were imaged and reconstructed in three dimensions. Root–root interaction strength was calculated using quantitative metrics that characterize the extent to which the reconstructed root systems overlap each other. Surprisingly, we found the overlap of root systems of the same genotype was significantly higher than that of root systems of different genotypes. Root systems of the same genotype tended to grow toward each other but those of different genotypes appeared to avoid each other. Shoot separation experiments excluded the possibility of aerial interactions, suggesting root communication. Staggered plantings indicated that interactions likely occur at root tips in close proximity. Recognition of obstacles also occurred through root tips, but through physical contact in a size-dependent manner. These results indicate that root systems use two different forms of communication to recognize objects and alter root architecture: root-root recognition, possibly mediated through root exudates, and root-object recognition mediated by physical contact at the root tips. This finding suggests that root tips act as local sensors that integrate rhizosphere information into global root architectural changes.

Fang, Suqin; Clark, Randy T.; Zheng, Ying; Iyer-Pascuzzi, Anjali S.; Weitz, Joshua S.; Kochian, Leon V.; Edelsbrunner, Herbert; Liao, Hong; Benfey, Philip N.

2013-01-01

274

Analysis of root meristem size development.  

PubMed

Plant post-embryonic development takes place in the meristems. In the root of the model plant Arabidopsis thaliana, stem cells organized in a stem-cell niche in the apex of the root meristem generate transit-amplifying cells, which undergo additional division in the proximal meristem and differentiate in the elongation/differentiation zone. For meristem maintenance, and therefore continuous root growth, the rate of cell differentiation must equal the rate of generation of new cells: how this balance is achieved is a central question in plant development. We have shown that maintenance of the Arabidopsis root meristem size is established by a balance between the antagonistic effects of cytokinin, which promotes cell differentiation, and auxin, which promotes cell division. Cytokinin antagonizes auxin in a specific developmental domain (the vascular tissue transition zone) from where it controls the differentiation rate of all the other root tissues. Here, we describe protocols to analyze development of root meristems. PMID:20734261

Perilli, Serena; Sabatini, Sabrina

2010-01-01

275

Environmental effects on the maturation of the endodermis and multiseriate exodermis of Iris germanica roots  

PubMed Central

Background and Aims Most studies of exodermal structure and function have involved species with a uniseriate exodermis. To extend this work, the development and apoplastic permeability of Iris germanica roots with a multiseriate exodermis (MEX) were investigated. The effects of different growth conditions on MEX maturation were also tested. In addition, the exodermises of eight Iris species were observed to determine if their mature anatomy correlated with habitat. Methods Plants were grown in soil, hydroponics (with and without a humid air gap) or aeroponics. Roots were sectioned and stained with various dyes to detect MEX development from the root apical meristem, Casparian bands, suberin lamellae and tertiary wall thickenings. Apoplastic permeability was tested using dye (berberine) and ionic (ferric) tracers. Key Results The root apical meristem was open and MEX development non-uniform. In soil-grown roots, the exodermis started maturing (i.e. Casparian bands and suberin lamellae were deposited) 10 mm from the tip, and two layers had matured by 70 mm. In both hydro- and aeroponically grown roots, exodermal maturation was delayed. However, in areas of roots exposed to an air gap in the hydroponic system, MEX maturation was accelerated. In contrast, maturation of the endodermis was not influenced by the growth conditions. The mature MEX had an atypical Casparian band that was continuous around the root circumference. The MEX prevented the influx and efflux of berberine, but had variable resistance to ferric ions due to their toxic effects. Iris species living in well-drained soils developed a MEX, but species in water-saturated substrates had a uniseriate exodermis and aerenchyma. Conclusions MEX maturation was influenced by the roots' growth medium. The MEX matures very close to the root tip in soil, but much further from the tip in hydro- and aeroponic culture. The air gap accelerated maturation of the second exodermal layer. In Iris, the type of exodermis was correlated with natural habitat suggesting that a MEX may be advantageous for drought tolerance.

Meyer, Chris J.; Seago, James L.; Peterson, Carol A.

2009-01-01

276

Mean age of carbon in fine roots from temperate forests and grasslands with different management  

NASA Astrophysics Data System (ADS)

Fine roots are the most dynamic portion of a plant's root system and a major source of soil organic matter. By altering plant species diversity and composition, soil conditions and nutrient availability, and consequently belowground allocations and dynamics of root carbon (C) inputs, land-use and management changes may influence organic C storage in terrestrial ecosystems. In three German regions we measured fine root radiocarbon (14C) content to estimate the mean time since C in root tissues was fixed from the atmosphere in 54 grassland and forest plots with different management and soil conditions. The mean age of C in fine roots in forest environments averaged 11.3±1.8 years (mean ± SE, n=27) and was significantly older and more variable compared to grassland environments (1.7±0.4 years, n=27). We further found that management affects the mean age of fine root C in temperate grasslands mediated by changes in plant species diversity and composition. Fine root mean C age is positively correlated to plant diversity (r=0.65) and to the number of perennial species (r=0.77). In temperate grasslands the mean age of fine root C is also influenced by the study region mainly due to differences in soil characteristics and climate, with averages of 0.7±0.1 years (n=9) on mostly organic sandy soils and of 1.8±0.3 years (n=9) and 2.6±0.3 (n=9) in more silty and clayey soils respectively. Our results indicate an internal redistribution of C in perennial species and suggest linkages between fine root C age and management in grasslands. These findings improve our ability to predict and model belowground C fluxes across broader spatial scales.

Solly, Emily; Schrumpf, Marion; Schöning, Ingo; Boch, Steffen; Trumbore, Susan

2013-04-01

277

Truffles regulate plant root morphogenesis via the production of auxin and ethylene.  

PubMed

Truffles are symbiotic fungi that form ectomycorrhizas with plant roots. Here we present evidence that at an early stage of the interaction, i.e. prior to physical contact, mycelia of the white truffle Tuber borchii and the black truffle Tuber melanopsorum induce alterations in root morphology of the host Cistus incanus and the nonhost Arabidopsis (Arabidopsis thaliana; i.e. primary root shortening, lateral root formation, root hair stimulation). This was most likely due to the production of indole-3-acetic acid (IAA) and ethylene by the mycelium. Application of a mixture of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and IAA fully mimicked the root morphology induced by the mycelium for both host and nonhost plants. Application of the single hormones only partially mimicked it. Furthermore, primary root growth was not inhibited in the Arabidopsis auxin transport mutant aux1-7 by truffle metabolites while root branching was less effected in the ethylene-insensitive mutant ein2-LH. The double mutant aux1-7;ein2-LH displayed reduced sensitivity to fungus-induced primary root shortening and branching. In agreement with the signaling nature of truffle metabolites, increased expression of the auxin response reporter DR5GFP in Arabidopsis root meristems subjected to the mycelium could be observed, confirming that truffles modify the endogenous hormonal balance of plants. Last, we demonstrate that truffles synthesize ethylene from l-methionine probably through the alpha-keto-gamma-(methylthio)butyric acid pathway. Taken together, these results establish the central role of IAA and ethylene as signal molecules in truffle/plant interactions. PMID:19535471

Splivallo, Richard; Fischer, Urs; Göbel, Cornelia; Feussner, Ivo; Karlovsky, Petr

2009-06-17

278

Root and root canal morphology of the human permanent maxillary first molar: a literature review.  

PubMed

The objective of this study was to review the literature with respect to the root and canal systems in the maxillary first molar. Root anatomy studies were divided into laboratory studies (in vitro), clinical root canal system anatomy studies (in vivo) and clinical case reports of anomalies. Over 95% (95.9%) of maxillary first molars had three roots and 3.9% had two roots. The incidence of fusion of any two or three roots was approximately 5.2%. Conical and C-shaped roots and canals were rarely found (0.12%). This review contained the most data on the canal morphology of the mesiobuccal root with a total of 8399 teeth from 34 studies. The incidence of two canals in the mesiobuccal root was 56.8% and of one canal was 43.1% in a weighted average of all reported studies. The incidence of two canals in the mesiobuccal root was higher in laboratory studies (60.5%) compared to clinical studies (54.7%). Less variation was found in the distobuccal and palatal roots and the results were reported from fourteen studies consisting of 2576 teeth. One canal was found in the distobuccal root in 98.3% of teeth whereas the palatal root had one canal in over 99% of the teeth studied. PMID:16934622

Cleghorn, Blaine M; Christie, William H; Dong, Cecilia C S

2006-06-30

279

Root-to-Root Travel of the Beneficial Bacterium Azospirillum brasilense†  

PubMed Central

The root-to-root travel of the beneficial bacterium Azospirillum brasilense on wheat and soybean roots in agar, sand, and light-textured soil was monitored. We used a motile wild-type (Mot+) strain and a motility-deficient (Mot-) strain which was derived from the wild-type strain. The colonization levels of inoculated roots were similar for the two strains. Mot+ cells moved from inoculated roots (either natural or artificial roots in agar, sand, or light-textured soil) to noninoculated roots, where they formed a band-type colonization composed of bacterial aggregates encircling a limited part of the root, regardless of the plant species. The Mot- strain did not move toward noninoculated roots of either plant species and usually stayed at the inoculation site and root tips. The effect of attractants and repellents was the primary factor governing the motility of Mot+ cells in the presence of adequate water. We propose that interroot travel of A. brasilense is an essential preliminary step in the root-bacterium recognition mechanism. Bacterial motility might have a general role in getting Azospirillum cells to the site where firmer attachment favors colonization of the root system. Azospirillum travel toward plants is a nonspecific active process which is not directly dependent on nutrient deficiency but is a consequence of a nonspecific bacterial chemotaxis, influenced by the balance between attractants and possibly repellents leaked by the root.

Bashan, Yoav; Holguin, Gina

1994-01-01

280

A Rooted Net of Life  

PubMed Central

Abstract Phylogenetic reconstruction using DNA and protein sequences has allowed the reconstruction of evolutionary histories encompassing all life. We present and discuss a means to incorporate much of this rich narrative into a single model that acknowledges the discrete evolutionary units that constitute the organism. Briefly, this Rooted Net of Life genome phylogeny is constructed around an initial, well resolved and rooted tree scaffold inferred from a supermatrix of combined ribosomal genes. Extant sampled ribosomes form the leaves of the tree scaffold. These leaves, but not necessarily the deeper parts of the scaffold, can be considered to represent a genome or pan-genome, and to be associated with members of other gene families within that sequenced (pan)genome. Unrooted phylogenies of gene families containing four or more members are reconstructed and superimposed over the scaffold. Initially, reticulations are formed where incongruities between topologies exist. Given sufficient evidence, edges may then be differentiated as those representing vertical lines of inheritance within lineages and those representing horizontal genetic transfers or endosymbioses between lineages. Reviewers W. Ford Doolittle, Eric Bapteste and Robert Beiko.

2011-01-01

281

DNS measurements at a root server  

Microsoft Academic Search

The Domain Name System (DNS) prescribes domain names to be used in network transactions (email, web requests, etc.) instead of IP addresses. The root of the DNS distributed database is managed by 13 root nameservers. We passively measure the performance of one of them: F.root-servers.net. These measurements show an astounding number of bogus queries: from 60-85% of observed queries were

Nevil Brownlee; K. C. Claffy; E. Nemeth

2001-01-01

282

Nodulation of rooted leaves in leguminous plants  

Microsoft Academic Search

Summary  Root formation was obtained on the petioles of detached leaves of several leguminous plants, particularly on the primary leaves\\u000a of bean. Root formation is easily obtained in artificial light at a temperature of 22 to 24°C. In the greenhouse it is optimal\\u000a in early spring and late autumn. During hot summer seasons no roots but callus was formed on the

T. A. Lie

1971-01-01

283

Cluster Roots: A Curiosity in Context  

Microsoft Academic Search

Cluster roots are an adaptation for nutrient acquisition from nutrient-poor soils. They develop on root systems of a range\\u000a of species belonging to a number of different families (e.g., Proteaceae, Casuarinaceae, Fabaceae and Myricaceae) and are\\u000a also found on root systems of some crop species (e.g., albus, Macadamia integrifoliaandCucurbita pepo). Their morphology is variable but typically, large numbers of determinate

Michael W. Shane; Hans Lambers

2005-01-01

284

Riparian roots through time, space and disturbance  

Microsoft Academic Search

Riparian zones are landscape features adjacent to streams and are widely recognized as important in reducing erosion and filtering\\u000a groundwater. Few studies directly investigate rooting dynamics of riparian areas, and little information exists concerning\\u000a riparian root densities, biomass, depth profiles, changes through time, or vulnerability to disturbance. This study examined\\u000a spatial and temporal patterns in root systems in streamsides influenced

Darby K. Kiley; Rebecca L. Schneider

2005-01-01

285

Mechanized instrumentation of root canals oscillating systems.  

PubMed

Cleaning and shaping are important steps in the root canal treatment. Despite the technological advances in endodontics, K and Hedstroen files are still widely used. In an attempt to be more effective in preparing the root canals, faster and more cutting efficient kinematic, alloys and design alternatives utilizing mechanically oscillating or rotary files are proposed. Even with all these technological innovating alternatives, the preparation of root canals remains a challenge. PMID:23579914

Leonardo, Renato de Toledo; Puente, Carlos Garcia; Jaime, Alejandro; Jent, Carol

2013-01-01

286

A Consistent Test for a Unit Root  

Microsoft Academic Search

This article investigates several U.S. macroeconomic time series for the presence of a unit root using a newly developed test. This test has stationarity as its null hypothesis, and the alternative is a unit-root process. The test is shown to be consistent, and its asymptotic null distribution is determined. Our findings contrast sharply with those obtained via the standard unit-root

S. J. Leybourne; B. P. M. McCabe

1994-01-01

287

Cardiac tamponade due to left ventricular pseudoaneurysm after aortic valve replacement.  

PubMed

Left ventricular outflow tract pseudoaneurysm is a rare but a potentially lethal complication, mainly after aortic root endocarditis or surgery. Usually, it originates from a dehiscence in the mitral-aortic intervalvular fibrosa and arises posteriorly to the aortic root. We report a rare case of a patient with cardiac tamponade due to left ventricular pseudoaneurysm after aortic valve replacement. The subsequent surgical resection was performed successfully. PMID:23439359

Baydar, Onur; Co?kun, Ugur; Balaban, Betul; Cetin, Gurkan; Firatli, Inci; Ersanli, Murat Kazim; Kucukoglu, Mehmet Serdar

2013-02-01

288

The Course of Due Process.  

ERIC Educational Resources Information Center

Discussion of due process rights for children with disabilities considers common issues leading to due process requests, due process procedures, hearing officers, procedural violations, effects of due process meetings, and areas for improvement (i.e., accountability, paperwork). Tables list categories of procedural violations with examples and…

Getty, Laura A.; Summy, Sarah E.

2004-01-01

289

Cling - The New Interactive Interpreter for ROOT 6  

NASA Astrophysics Data System (ADS)

Cling is an interactive C++ interpreter, built on top of Clang and LLVM compiler infrastructure. Like its predecessor Cint, Cling realizes the read-print-evaluate-loop concept, in order to leverage rapid application development. Implemented as a small extension to LLVM and Clang, the interpreter reuses their strengths such as the praised concise and expressive compiler diagnostics. We show how to match the interpreter concept to the compiler library and generalize common set of requirements for building up an interactive interpreter. We reason the design and implementation decisions as solution to the challenge of implementing interpreter behaviour as an extension of the compiler library. We present the new features, e.g. how C++11 will come to Cling and how Cint-specific extensions are being adopted. We clarify the state of integration in the ROOT framework and the induced change set. We explain how ROOT dictionaries are simplified due to the new interpreter.

Vasilev, V.; Canal, Ph; Naumann, A.; Russo, P.

2012-12-01

290

Root canal configuration of the mandibular first premolar.  

PubMed

One hundred six human mandibular left and right first premolars, previously extracted due to nonrestorable caries, periodontal disease, or orthodontic reasons, were sectioned perpendicular to the long axis of the root starting at the cementoenamel junction. Three-millimeter sections were made with an ultrathin separating disc to the level of the anatomical apex. After 1 day in 5.25% NaOCl, each section was rinsed in phosphate-buffered saline, evaluated with a stereomicroscope, and photographed. The slides were projected and the shape of the canal, incidence of multiple canals, level of bifurcation, and any other variant anatomy were recorded. Seventy-six percent of the premolars demonstrated Type I canals and 24% contained Type IV. The shape of the canals was predominantly oval or round. An interesting finding was the number of C-shaped canals which were associated predominantly with Type IV canal systems. This occurred in 14% of the roots. PMID:1289476

Baisden, M K; Kulild, J C; Weller, R N

1992-10-01

291

Biological effects due to weak magnetic fields on plants  

NASA Astrophysics Data System (ADS)

In the evolution process, living organisms have experienced the action of the Earth's magnetic field (MF) that is a natural component of our environment. It is known that a galactic MF induction does not exceed 0.1 nT, since investigations of weak magnetic field (WMF) effects on biological systems have attracted attention of biologists due to planning long-term space flights to other planets where the magnetizing force is near 10-5 Oe. However, the role of WMF and its influence on organisms' functioning are still insufficiently investigated. A large number of experiments with seedlings of different plant species placed in WMF has found that the growth of their primary roots is inhibited during the early terms of germination in comparison with control. The proliferation activity and cell reproduction are reduced in meristem of plant roots under WMF application. The prolongation of total cell reproductive cycle is registered due to the expansion of G phase in1 different plant species as well as of G phase in flax and lentil roots along with2 relative stability of time parameters of other phases of cell cycle. In plant cells exposed to WMF, the decrease in functional activity of genome at early prereplicate period is shown. WMF causes the intensification in the processes of proteins' synthesis and break-up in plant roots. Qualitative and quantitative changes in protein spectrum in growing and differentiated cells of plant roots exposed to WMF are revealed. At ultrastructural level, there are observed such ultrastructural peculiarities as changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells of pea roots exposed to WMF. Mitochondria are the most sensitive organelle to WMF application: their size and relative volume in cells increase, matrix is electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to WMF show the Ca2 + oversaturation both in all organelles and in a hyaloplasm of the cells unlike the control ones. The data presented suggest that prolonged plant exposures to WMF may cause different biological effects at the cellular, tissue and organ level. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca 2 + homeostasis. The understanding of the fundamental mechanisms and sites of interactions between WMF and biological systems are complex and still deserve strong efforts, particular addressed to basic principles of coupling between field energy and biomolecules.

Belyavskaya, N.

292

Maxillary first molar with two root canals.  

PubMed

Knowledge regarding the anatomic morphology of maxillary molars is absolutely essential for the success of endodontic treatment. The morphology of the permanent maxillary first molar has been reviewed extensively; however, the presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. This case report presents a patient with a maxillary first molar with two roots and two root canals, who was referred to the Department of Endodontics, Tabriz University of Medical Sciences, Iran. PMID:23862051

Rahimi, Saeed; Ghasemi, Negin

2013-05-09

293

OZONE DECREASES SPRING ROOT GROWTH AND ROOT CARBOHYDRATE CONTENT IN PONDEROSA PINE THE YEAR FOLLOWING EXPOSURE  

EPA Science Inventory

Storage carbohydrates are extremely important for new shoot and root development following dormancy or during periods of high stress. he hypothesis that ozone decreases carbohydrate storage and decreases new root growth during the year following exposure was investigated. eedling...

294

Essential oils from hairy root cultures and from plant roots of Achillea millefolium  

Microsoft Academic Search

The essential oils isolated from roots of two Achillea millefolium populations (BGL and CGA) and from two hairy root cultures (A4 and LBA) derived from one of these were analysed by GC and GC–mass spectrometry. The essential oils from the plant roots were obtained in a yield of 0.10% (BGL) and 0.05% (CGA) (v\\/w), whereas that of both hairy root

P. M. L Lourenço; A. C Figueiredo; J. G Barroso; L. G Pedro; M. M Oliveira; S. G Deans; J. J. C Scheffer

1999-01-01

295

Root tip-dependent, active riboflavin secretion by Hyoscyamus albus hairy roots under iron deficiency  

Microsoft Academic Search

Hyoscyamus albus hairy roots with\\/without an exogenous gene (11 clones) were established by inoculation of Agrobacterium rhizogenes. All clones cultured under iron-deficient condition secreted riboflavin from the root tips into the culture medium and the productivity depended on the number and size of root tips among the clones. A decline of pH was observed before riboflavin production and root development.

Ataru Higa; Erika Miyamoto; Laiq ur Rahman; Yoshie Kitamura

2008-01-01

296

Piriformospora indica root colonization triggers local and systemic root responses and inhibits secondary colonization of distal roots.  

PubMed

Piriformosporaindica is a basidiomycete fungus colonizing roots of a wide range of higher plants, including crop plants and the model plant Arabidopsis thaliana. Previous studies have shown that P. indica improves growth, and enhances systemic pathogen resistance in leaves of host plants. To investigate systemic effects within the root system, we established a hydroponic split-root cultivation system for Arabidopsis. Using quantitative real-time PCR, we show that initial P. indica colonization triggers a local, transient response of several defense-related transcripts, of which some were also induced in shoots and in distal, non-colonized roots of the same plant. Systemic effects on distal roots included the inhibition of secondary P. indica colonization. Faster and stronger induction of defense-related transcripts during secondary inoculation revealed that a P. indica pretreatment triggers root-wide priming of defense responses, which could cause the observed reduction of secondary colonization levels. Secondary P. indica colonization also induced defense responses in distant, already colonized parts of the root. Endophytic fungi therefore trigger a spatially specific response in directly colonized and in systemic root tissues of host plants. PMID:23922705

Pedrotti, Lorenzo; Mueller, Martin J; Waller, Frank

2013-07-26

297

Root water uptake model based on water potential gradient with water redistribution via roots: application to coniferous forest site  

NASA Astrophysics Data System (ADS)

A simple macroscopic vertically distributed plant root water uptake (RWU) model based on traditional water-potential-gradient formulation (Vogel et al., 2013), in which the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow, was tested. This RWU modeling approach was implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation and used to simulate soil water distribution changes during a vegetation season at a forest site located in a temperate humid climate of central Europe. The main objectives were to test the ability of the presented RWU model to simulate the observed soil-plant-atmosphere interactions, and to examine the differences between empirical and more physically-based RWU modeling approaches (accommodated in the same soil water flow model). The tested RWU model was capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers was compensated for by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. Comparison of the model results with the sap flow observed reveals some limitations related to the quasi-steady-state assumption for the plant xylem and zero transpiration rates prescribed during nights and precipitation. This stated, the model seems to simulate adequately both the regular nightly hydraulic redistribution, due to reduced night transpiration, and the episodic daytime hydraulic redistribution during wet canopy events. The model results were compared to simulations produced using the semi-empirical RWU model of Feddes. Based on both an improved agreement between the observed and simulated soil water pressure responses to daily variations of transpiration, and a more realistic seasonal distribution of the transpiration rate reduction, we concluded that the physically based root water uptake model with negative RWU rates enabled substantially better approximation of the soil water extraction by spruce trees under moderate water scarcity. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, accepted.

Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir; Tesar, Miroslav

2013-04-01

298

In situ speciation and distribution of toxic selenium in hydrated roots of cowpea.  

PubMed

The speciation and spatial distribution of selenium (Se) in hydrated plant tissues is not well understood. Using synchrotron-based x-ray absorption spectroscopy and x-ray fluorescence microscopy (two-dimensional scanning [and associated mathematical model] and computed tomography), the speciation and distribution of toxic Se were examined within hydrated roots of cowpea (Vigna unguiculata) exposed to either 20 µm selenite or selenate. Based upon bulk solution concentrations, selenate was 9-fold more toxic to the roots than selenite, most likely due to increased accumulation of organoselenium (e.g. selenomethionine) in selenate-treated roots. Specifically, uptake of selenate (probably by sulfate transporters) occurred at a much higher rate than for selenite (apparently by both passive diffusion and phosphate transporters), with bulk root tissue Se concentrations approximately 18-fold higher in the selenate treatment. Although the proportion of Se converted to organic forms was higher for selenite (100%) than for selenate (26%), the absolute concentration of organoselenium was actually approximately 5-fold higher for selenate-treated roots. In addition, the longitudinal and radial distribution of Se in roots differed markedly: the highest tissue concentrations were in the endodermis and cortex approximately 4 mm or more behind the apex when exposed to selenate but in the meristem (approximately 1 mm from the apex) when exposed to selenite. The examination of the distribution and speciation of Se in hydrated roots provides valuable data in understanding Se uptake, transport, and toxicity. PMID:23835408

Wang, Peng; Menzies, Neal W; Lombi, Enzo; McKenna, Brigid A; de Jonge, Martin D; Paterson, David J; Howard, Daryl L; Glover, Chris J; James, Simon; Kappen, Peter; Johannessen, Bernt; Kopittke, Peter M

2013-07-08

299

Phenotypic plasticity of fine root growth increases plant productivity in pine seedlings  

PubMed Central

Background The plastic response of fine roots to a changing environment is suggested to affect the growth and form of a plant. Here we show that the plasticity of fine root growth may increase plant productivity based on an experiment using young seedlings (14-week old) of loblolly pine. We use two contrasting pine ecotypes, "mesic" and "xeric", to investigate the adaptive significance of such a plastic response. Results The partitioning of biomass to fine roots is observed to reduce with increased nutrient availability. For the "mesic" ecotype, increased stem biomass as a consequence of more nutrients may be primarily due to reduced fine-root biomass partitioning. For the "xeric" ecotype, the favorable influence of the plasticity of fine root growth on stem growth results from increased allocation of biomass to foliage and decreased allocation to fine roots. An evolutionary genetic analysis indicates that the plasticity of fine root growth is inducible, whereas the plasticity of foliage is constitutive. Conclusions Results promise to enhance a fundamental understanding of evolutionary changes of tree architecture under domestication and to design sound silvicultural and breeding measures for improving plant productivity.

Wu, Rongling; Grissom, James E; McKeand, Steven E; O'Malley, David M

2004-01-01

300

Control of root size and root environment of fruit trees for optimal fruit production  

Microsoft Academic Search

Recent development in technologies of irrigation and fertilization enable us to control root size and environment under field conditions. Low volume irrigation and fertilization affects root size and rate of rootlets production and consequently vegetative and reproductive processes of whole plants. The mechanisms involved seem to include growth regulators production at the root apexes and their translocation to the shoots.

Ben Ami Bravdo; I. Levin; R. Assaf

1992-01-01

301

The Root Cap Determines Ethylene-Dependent Growth and Development in Maize Roots  

Microsoft Academic Search

Besides providing protection against mechanical damage to the root tip, the root cap is involved in the per- ception and processing of diverse external and internal stimuli resulting in altered growth and development. The trans- duction of these stimuli includes hormonal signaling pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential

Achim Hahn; Roman Zimmermann; D. Wanke; K. Harter; Hans G. Edelmann

2008-01-01

302

Root Growth and Yield of Differing Alfalfa Rooting Populations under Increasing Salinity and Zero Leaching  

Microsoft Academic Search

stand of alfalfa under irrigation extended to 2.5 m (Dud- ley et al., 1994). It may be advantageous for deep-rooted Accumulation of salinity in the root zone can be detrimental to crops such as alfalfa to exploit the lower average salinity sustained crop production. Irrigation, even with moderately saline water, pushes accumulated salts deeper into the root zone, allowing of

Laura V. Vaughan; Jennifer W. MacAdam; Steven E. Smith; Lynn M. Dudley

2002-01-01

303

Root diversity in alpine plants: root length, tensile strength and plant age  

NASA Astrophysics Data System (ADS)

A high diversity of plant species and functional groups is hypothesised to increase the diversity of root types and their subsequent effects for soil stability. However, even basic data on root characteristics of alpine plants are very scarce. Therefore, we determined important root characteristics of 13 plant species from different functional groups, i.e. grasses, herbs and shrubs. We excavated the whole root systems of 62 plants from a machine-graded ski slope at 2625 m a.s.l. and analysed the rooting depth, the horizontal root extension, root length and diameter. Single roots of plant species were tested for tensile strength. The age of herbs and shrubs was determined by growth-ring analysis. Root characteristics varied considerably between both plant species and functional groups. The rooting depth of different species ranged from 7.2 ± 0.97 cm to 20.5 ± 2.33 cm, but was significantly larger in the herb Geum reptans (70.8 ± 10.75 cm). The woody species Salix breviserrata reached the highest horizontal root extensions (96.8 ± 25.5 cm). Most plants had their longest roots in fine diameter classes (0.5

Pohl, M.; Stroude, R.; Körner, C.; Buttler, A.; Rixen, C.

2009-04-01

304

Water distribution at the root-soil interface: is there more water next to roots?  

Microsoft Academic Search

Plants are big water movers and have a significant impact on soil water dynamics as well as on the global water cycle. Despite the relevance of root water uptake in terrestrial ecology, the movement of water from soil to roots still presents important open questions, e.g the following two. Which are the properties of the soil near the roots? And

A. Carminati; A. Moradi; S. Oswald; D. Vetterlein; U. Weller; H.-J. Vogel

2009-01-01

305

Relations between Roots and Coefficients of Cubic Equations with One Root Negative the Reciprocal of Another  

ERIC Educational Resources Information Center

|Under predetermined conditions on the roots and coefficients, necessary and sufficient conditions relating the coefficients of a given cubic equation x[cubed] + ax[squared] + bx + c = 0 can be established so that the roots possess desired properties. In this note, the condition for one root of a cubic equation to be "the negative reciprocal of…

Asiru, M. A.

2007-01-01

306

Root susceptibility and inoculum production from roots of Eastern United States oak species to Phytophthora ramorum  

Technology Transfer Automated Retrieval System (TEKTRAN)

Little is known about root susceptibility of eastern U.S. tree species to Phytophthora ramorum. In this study, we examined root susceptibility and inoculum production from roots. Sprouted acorns of Q. rubra, Q. palustrus, Q. coccinia, Q. alba, Q. michauxii and Q. prinus were exposed to motile zoos...

307

Root isotropy and an evaluation of a method for measuring root distribution in soil trenches  

Microsoft Academic Search

The measurement of root length density (LV) with soil depth is tedious and laborious. Yet the information is necessary in order to model root nutrient uptake. Measuring the number of roots exiting the face of a soil trench is less laborious and has previously been shown to be five times faster than the soil core-break method. Based on geometric theory,

Isabel Lopez-Zamora; Newton Falcão; N. B. Comerford; N. F. Barros

2002-01-01

308

Dehydrocostus lactone is exuded from sunflower roots and stimulates germination of the root parasite Orobanche cumana  

Microsoft Academic Search

The germination of the obligate root parasites of the Orobanchaceae depends on the perception of chemical stimuli from host roots. Several compounds, collectively termed strigolactones, stimulate the germination of the various Orobanche species, but do not significantly elicit germination of Orobanche cumana, a specific parasite of sunflower.Phosphate starvation markedly decreased the stimulatory activity of sunflower root exudates toward O. cumana,

Daniel M. Joel; Swapan K. Chaudhuri; Dina Plakhine; Hammam Ziadna; John C. Steffens

2011-01-01

309

Simple method for C?labelling root material for use in root decomposition studies  

Microsoft Academic Search

A method was devised in which plant roots can be easily and uniformly radiolabelled with C for use in soil decomposition studies. The roots were labelled from an exogenous sugar solution for a total period of 48 hours after which root decomposition studies could be performed. The method offers distinct advantages over the existing constant C?CO2 atmosphere labelling method.

D. L. Jones; P. R. Darrah

1994-01-01

310

Identification of rice root associated nitrate, sulfate and ferric iron reducing bacteria during root decomposition  

Microsoft Academic Search

Leakage of O2 from roots of aquatic plants supports the oxidation of ammonia to nitrate and of sulfide to sulfate in the rhizosphere, so that these electron acceptors may become available to the root microbial communities and affect their activity. We studied the composition of the bacterial community active in anoxically incubated rice roots by analysis of terminal restriction fragment

Daniel Scheid; Stephan Stubner; Ralf Conrad

2004-01-01

311

Inhibition of Auxin Movement from the Shoot into the Root Inhibits Lateral Root Development in Arabidopsis  

Microsoft Academic Search

In roots two distinct polar movements of auxin have been re- ported that may control different developmental and growth events. To test the hypothesis that auxin derived from the shoot and trans- ported toward the root controls lateral root development, the two polarities of auxin transport were uncoupled in Arabidopsis. Local application of the auxin-transport inhibitor naphthylphthalamic acid (NPA) at

Robyn C. Reed; Shari R. Brady; Gloria K. Muda

1998-01-01

312

Density-dependent root morphology and root distribution in the submerged plant Vallisneria natans  

Microsoft Academic Search

Root morphology, root distribution and biomass allocation in relation to plant nutrient concentration were investigated in the submerged macrophyte Vallisneria natans, growing on two types of sediment (clay and a mixture of sandy loam and clay) with three kinds of initial density (290, 650 and 1300plantsm?2). Both initial density and sediment type had significant impacts on biomass accumulation, root morphology,

Yonghong Xie; Shuqing An; Bofeng Wu; Wenwen Wang

2006-01-01

313

A new Approach for Quantifying Root-Reinforcement of Streambanks: the RipRoot Model  

Microsoft Academic Search

Riparian vegetation plays an important role in controlling geotechnical and fluvial processes acting along and within streambanks through the binding effects of roots. Quantification of this mechanical effect is therefore essential to accurately model streambank stability. Until now, most attempts to include the effects of root reinforcement by riparian vegetation have used root-cohesion values estimated using the Wu et al.

N. L. Pollen; A. Simon

2003-01-01

314

Length of the apical unbranched zone of maize axile roots: Its relationship to root elongation rate  

Microsoft Academic Search

The length of the apical unbranched zone was studied in maize axile roots. Plants were grown in an aeroponic growth chamber allowing direct measurements on individual axile roots. The total length of the roots and the length of the apical unbranched zone were measured regularly. A commonly accepted hypothesis, according to which laterals emerge at a constant distance behind the

Sylvain Pellerin; Florence Tabourel

1995-01-01

315

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones  

PubMed Central

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of ?18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil ?18O isotopic signature declined with depth, providing conditions for plant–soil ?18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes.

Isaac, Marney E; Anglaaere, Luke C N

2013-01-01

316

ROOT CAUSE ANALYSIS PROGRAM MANUAL  

SciTech Connect

Root Cause Analysis (RCA) identifies the cause of an adverse condition that, if corrected, will preclude recurrence or greatly reduce the probability of recurrence of the same or similar adverse conditions and thereby protect the health and safety of the public, the workers, and the environment. This procedure sets forth the requirements for management determination and the selection of RCA methods and implementation of RCAs that are a result of significant findings from Price-Anderson Amendments Act (PAAA) violations, occurrences/events, Significant Adverse Conditions, and external oversight Corrective Action Requests (CARs) generated by the Office of Enforcement (PAAA headquarters), the U.S. Environmental Protection Agency, and other oversight entities against Lawrence Berkeley National Laboratory (LBNL). Performance of an RCA may result in the identification of issues that should be reported in accordance with the Issues Management Program Manual.

Gravois, Melanie C.

2007-05-02

317

Root-growth-inhibiting sheet  

DOEpatents

In accordance with this invention, a porous sheet material is provided at intervals with bodies of a polymer which contain a 2,6-dinitroaniline. The sheet material is made porous to permit free passage of water. It may be either a perforated sheet or a woven or non-woven textile material. A particularly desirable embodiment is a non-woven fabric of non-biodegradable material. This type of material is known as a "geotextile" and is used for weed control, prevention of erosion on slopes, and other landscaping purposes. In order to obtain a root repelling property, a dinitroaniline is blended with a polymer which is attached to the geotextile or other porous material.

Burton, Frederick G. (Stansbury Park, UT); Cataldo, Dominic A. (Kennewick, WA); Cline, John F. (Prosser, WA); Skiens, W. Eugene (Wilsonville, OR); Van Voris, Peter (Richland, WA)

1993-01-01

318

Coupling root architecture and pore network modeling - an attempt towards better understanding root-soil interactions  

NASA Astrophysics Data System (ADS)

Understanding root-soil interactions is of high importance for environmental and agricultural management. Root uptake is an essential component in water and solute transport modeling. The amount of groundwater recharge and solute leaching significantly depends on the demand based plant extraction via its root system. Plant uptake however not only responds to the potential demand, but in most situations is limited by supply form the soil. The ability of the plant to access water and solutes in the soil is governed mainly by root distribution. Particularly under conditions of heterogeneous distribution of water and solutes in the soil, it is essential to capture the interaction between soil and roots. Root architecture models allow studying plant uptake from soil by describing growth and branching of root axes in the soil. Currently root architecture models are able to respond dynamically to water and nutrient distribution in the soil by directed growth (tropism), modified branching and enhanced exudation. The porous soil medium as rooting environment in these models is generally described by classical macroscopic water retention and sorption models, average over the pore scale. In our opinion this simplified description of the root growth medium implies several shortcomings for better understanding root-soil interactions: (i) It is well known that roots grow preferentially in preexisting pores, particularly in more rigid/dry soil. Thus the pore network contributes to the architectural form of the root system; (ii) roots themselves can influence the pore network by creating preferential flow paths (biopores) which are an essential element of structural porosity with strong impact on transport processes; (iii) plant uptake depend on both the spatial location of water/solutes in the pore network as well as the spatial distribution of roots. We therefore consider that for advancing our understanding in root-soil interactions, we need not only to extend our root models, but also improve the description of the rooting environment. Until now there have been no attempts to couple root architecture and pore network models. In our work we present a first attempt to join both types of models using the root architecture model of Leitner et al., (2010) and a pore network model presented by Raoof et al. (2010). The two main objectives of coupling both models are: (i) Representing the effect of root induced biopores on flow and transport processes: For this purpose a fixed root architecture created by the root model is superimposed as a secondary root induced pore network to the primary soil network, thus influencing the final pore topology in the network generation. (ii) Representing the influence of pre-existing pores on root branching: Using a given network of (rigid) pores, the root architecture model allocates its root axes into these preexisting pores as preferential growth paths with thereby shape the final root architecture. The main objective of our study is to reveal the potential of using a pore scale description of the plant growth medium for an improved representation of interaction processes at the interface of root and soil. References Raoof, A., Hassanizadeh, S.M. 2010. A New Method for Generating Pore-Network Models. Transp. Porous Med. 81, 391-407. Leitner, D, Klepsch, S., Bodner, G., Schnepf, S. 2010. A dynamic root system growth model based on L-Systems. Tropisms and coupling to nutrient uptake from soil. Plant Soil 332, 177-192.

Leitner, Daniel; Bodner, Gernot; Raoof, Amir

2013-04-01

319

Surgical intervention for treating an extensive internal resorption with unfavorable crown-to-root ratio  

PubMed Central

Internal resorption is a rare lesion in permanent teeth. Managing perforating internal resorption is a great challenge for dentists. This report presents a successful surgical treatment of a maxillary central incisor that had extensive root perforation due to internal resorption. After unsuccessful nonsurgical approach, during surgical intervention apical part of the resorption defect was removed and the coronal part was filled with mineral trioxide aggregate. Three years later the tooth was symptom free with normal mobility and pocket depth despite unfavorable crown-to-root ratio. This case report have shown that surgical intervention and using mineral trioxide aggregate as root canal filling material in a tooth with extensive internal resorption and unfavorable crown-to-root ratio can be considered as a treatment option.

Ashouri, Rezvan; Rekabi, Ali R; Parirokh, Masoud

2012-01-01

320

Hairy Root and Its Application in Plant Genetic Engineering  

Microsoft Academic Search

Agrobacterium rhizogenes Conn. causes hairy root disease in plants. Hairy root-infected A. rhizogenes is char- acterized by a high growth rate and genetic stability. Hairy root cultures have been proven to be an efficient means of producing secondary metabolites that are normally biosynthesized in roots of differentiated plants. Furthermore, a transgenic root system offers tremendous potential for introducing additional genes

Zhi-Bi Hu

321

Chloroplast development in isolated roots of Convolvulus arvensis (L.)  

Microsoft Academic Search

The fine structure of chloroplast development is described for isolated roots of Convolvulus arvensis. Stages in the transition from the leucoplast, characteristic of dark-grown roots, to the chloroplast, found in light-grown roots, are defined and related to chlorophyll content of the root tissue. The interdependence of tissue type and organellogenesis has been investigated for three tissues in the primary root:

Jane Heltne; Howard T. Bonnett

1970-01-01

322

Density of the continental roots: compositional and thermal contributions  

Microsoft Academic Search

The origin and evolution of cratonic roots has been debated for many years. Precambrian cratons are underlain by cold lithospheric roots that are chemically depleted. Thermal and petrologic data indicate that Archean roots are colder and more chemically depleted than Proterozoic roots. This observation has led to the hypothesis that the degree of depletion in a lithospheric root depends mostly

Mikhail K. Kaban; Peter Schwintzer; Irina M. Artemieva; Walter D. Mooney

2003-01-01

323

Influence of Environmental Variability on Root Dynamics in Northern Forests  

Microsoft Academic Search

Plant root systems are highly dynamic over various temporal and spatial scales, and are responsive to changes in environmental conditions. The objective of this review is to describe the dynamics of root structure and function in boreal and northern temperate forests and examine how edaphic and climatic characteristics and intra- and interspecific root competition impact root dynamics. Fine roots exhibit

Brian W. Brassard; Han Y. H. Chen; Yves Bergeron

2009-01-01

324

Simulation of root development based on the dielectric breakdown model  

Microsoft Academic Search

Knowing the root distribution in soil is essential for estimating water uptake by plant roots. It is difficult, however, to characterize and model undisturbed root systems. Root development in a two-dimensional potential field is simulated with the dielectric breakdown model (DBM), which implies a similarity between electric discharge and root distribution. A weighted potential gradient with an exponent rj was

O. HIROTA

1999-01-01

325

Simulation of root development based on the dielectric breakdown model  

Microsoft Academic Search

Knowing the root distribution in soil is essential for estimating water uptake by plant roots. It is difficult, however, to characterize and model undisturbed root systems. Root development in a two-dimensional potential field is simulated with the dielectric breakdown model (DBM), which implies a similarity between electric discharge and root distribution. A weighted potential gradient with an exponent ? was

J. CHIKUSHI; O. HIROTA

1998-01-01

326

Pitfalls and Opportunities: What Macroeconomists Should Know About Unit Roots  

Microsoft Academic Search

This paper is an introduction to unit root econometrics as applied in macroeconomics. The paper first discusses univariate time series analysis, emphasizing the following topics: alternative representations of unit root processes, unit root testing procedures, the power of unit root tests, and the interpretation of unit root econometrics in finite samples. A second part of the paper tackles similar issues

John Y. Campbell; Pierre Perron

1991-01-01

327

PARTIALLY LINEAR MODELS WITH UNIT ROOTS  

Microsoft Academic Search

This paper studies the asymptotic properties of a nonstationary partially linear regression model. In particular, we allow for covariates to enter the unit root (or near unit root) model in a nonparametric fashion, so that our model is an extension of the semiparametric model analyzed in Robinson (1988, Econometrica 56, 931 954). It is proved that the autoregressive parameter can

Ted Juhl; Zhijie Xiao

2005-01-01

328

Root and stem partitioning of Pinus taeda  

Microsoft Academic Search

We measured root and stem mass at three sites (Piedmont (P), Coastal Plain (C), and Sandhills (S)) in the southeastern United States. Stand density, soil texture and drainage, genetic makeup and environmental conditions varied with site while differences in tree size at each site were induced with fertilizer additions. Across sites, root mass was about one half of stem mass

Timothy J. Albaugh; H. Lee Allen; Lance W. Kress

2006-01-01

329

Fate of HERS during Tooth Root Development  

PubMed Central

Tooth root development begins after the completion of crown formation in mammals. Previous studies have shown that Hertwig's epithelial root sheath (HERS) plays an important role in root development, but the fate of HERS has remained unknown. In order to investigate the morphological fate and analyze the dynamic movement of HERS cells in vivo, we generated K14-Cre;R26R mice. HERS cells are detectable on the surface of the root throughout root formation and do not disappear. Most of the HERS cells are attached to the surface of the cementum, and others separate to become the epithelial rest of Malasez. HERS cells secrete extracellular matrix components onto the surface of the dentin before dental follicle cells penetrate the HERS network to contact dentin. HERS cells also participate in the cementum development and may differentiate into cementocytes. During root development, the HERS is not interrupted, and instead the HERS cells continue to communicate with each other through the network structure. Furthermore, HERS cells interact with cranial neural crest derived mesenchyme to guide root development. Taken together, the network of HERS cells is crucial for tooth root development.

Huang, Xiaofeng; Bringas, Pablo; Slavkin, Harold C.; Chai, Yang

2009-01-01

330

On affine extension of splint root systems  

NASA Astrophysics Data System (ADS)

Splint of root system of simple Lie algebra appears naturally in the study of (regular) embeddings of reductive subalgebras. It can be used to derive branching rules. Application of splint properties drastically simplifies calculations of branching coefficients. We study affine extension of splint root system of simple Lie algebra and obtain relations on theta and branching functions.

Lyakhovsky, V. D.; Nazarov, A. A.

2012-09-01

331

Promotion of root elongation by phosphorus deficiency  

Microsoft Academic Search

Decrease of culture solution pH and increase in cation\\/anion ratio in the plant were observed when horsegram (Macrotyloma uniflorum (Lam.) Verdc.) was grown in solution culture deficient in phosphorus. The effux of H+ from the roots of ?P plants was observed in bromocresol purple agar. The length of root cells was considerably increased by ?P treatment. Thus a close correlation

M. Anuradha; A. Narayanan

1991-01-01

332

2001 NORTH AMERICAN ROOT WEEVIL WORKSHOP PREFACE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The First North American Root Weevil Workshop was held at the Oregon State University North Willamette Research and Extension Center in Aurora, Oregon, November 1-2, 2001. The participants discussed a range of topics about root weevil biology, detection, and monitoring, as well as the population dy...

333

Improving safety through root cause analysis  

Microsoft Academic Search

Operations at the US Department of Energy -- Savannah River Site (SRS) include such diverse facilities as reactors, fuel fabrication, chemical processing, coal burning power houses, analytical laboratories and research facilities. To enhance the safety of operations at SRS, a Root Cause Analysis process has been developed and is discussed in this document. Root Cause Analysis is a three-step process

J. L. Gatlin; K. Taylor

1991-01-01

334

Competition for Nutrients and Optimal Root Allocation  

Microsoft Academic Search

The allocation of resources among roots and shoots represents the largest flux of resources within a plant and therefore should have been selected to maximize benefits to plants. Yet, it is unclear why some species like temperate grasses have such high root length density (RLD). Either the slow rate of diffusion of inorganic N in soils or interplant competition could

Joseph M. Craine

2006-01-01

335

Localised ABA signalling mediates root growth plasticity  

PubMed Central

Two recent reports show that cellular abscisic acid (ABA) signalling, together with other phytohormone signalling pathways, is crucial for salt-regulated root growth dynamics. Here we discuss these findings and place them in a broader framework on how cellular hormone signalling regulates root growth plasticity in response to environmental cues.

Ding, Zhaojun; De Smet, Ive

2013-01-01

336

Boron Uptake by Excised Barley Roots  

PubMed Central

At 2 C, all boron accumulated by excised barley roots (Hordeum vulgare L. cv. Herta) remains in the free space; i.e. active uptake is nil at this temperature. Three component fractions of free space B were apparent: (a) a surface contaminant film of B on blotted roots, (b) water free space B, and (c) B reversibly bound in the cell walls. A stoichiometric release of H+ from the roots in the presence of B indicated that B was bound by borate complexes with polysaccharides in the cell walls. Polysaccharide-borate complexes are much less stable than those of monosaccharides, and the bound B fraction could be readily removed by rinsing the roots in the presence of a monomeric polyol possessing the necessary cis-diol configuration. Cell wall material separated from excised barley roots had a B binding capacity 66% greater than that of intact roots. A 30-minute rinse in distilled H2O or 0.5 mm CaSO4 was required to remove all cell wall-bound B from the roots after a 30-minute uptake period. Thus, although B in the contaminant surface film and the water free space is rinsed from the roots within 10 minutes, a 30-minute rinse is essential if all reversibly accumulated B is to be removed from the free space.

Bowen, John E.; Nissen, Per

1976-01-01

337

Soil organic matter mobilization by root exudates  

Microsoft Academic Search

In order to study the different soil organic matter mobilisation by agrarian (Zeamais: cultivars Paolo and Sandek) and forest (Picea abies Karst. and Pinus sylvestris L.) root exudates, three different soils (Dystric Spodic Cambisol – S1, Haplic Luvisol – S2 and Calcaric Cambisol – S3) have been considered. Treating the soils with water (control) or plant root exudates, soil organic

S Nardi; G Concheri; D Pizzeghello; A Sturaro; R Rella; G Parvoli

2000-01-01

338

Seasonal unit root characteristics of disaggregated output  

Microsoft Academic Search

Tests for unit roots and cointegration have been extended to enable tests for seasonal units and more importantly tests for seasonal cointegration between series with common seasonals. To this end seasonal unit root tests are applied to unadjusted New Zealand GDP data and its disaggregated components. These, tests reveal that while aggregate GDP clearly exhibits a constant seasonal pattern a

R. Stuart McDougall

1996-01-01

339

Sheaths of the spinal nerve roots  

Microsoft Academic Search

The present study was carried out to investigate the permeability of normal spinal nerve root sheaths around dorsal and ventral roots in the rat. In vivo studies were performed using Evans bluealbumin and lanthanum chloride as tracers. The Evans blue-albumin complex is macromolecular in size and lanthanum ions are small and easily visible in the electron microscope. Both tracers were

C. Å. V. Pettersson

1993-01-01

340

Rooting Ability of Redberry Juniper Sprouts  

Microsoft Academic Search

Redberry juniper (Juniperus pinchotii Sudw.; Cupressaceae) sprout rooting ability was evaluated following their mechanical dislodgement from the shrub bases of a random sample of a Rolling Plains population. The objectives of the evaluation were to determine if dislodged sprouts are capable of producing adventitious roots and establishing as individual plants. Twenty-five sprouting shrubs were slashed then top removed with chain

Yvonne Warren; Carlton Britton

341

Topographic and ecologic controls on root reinforcement  

Microsoft Academic Search

Shallow landslides are a significant hazard in steep, soil-mantled landscapes. During intense rainfall events, the distribution of shallow landslides is controlled by variations in landscape gradient, the frictional and cohesive properties of soil and roots, and the subsurface hydrologic response. While gradients can be estimated from digital elevation models, information on soil and root properties remains sparse. We investigated whether

T. C. Hales; C. R. Ford; T. Hwang; J. M. Vose; L. E. Band

2009-01-01

342

Laminated Root Rot in Western North America.  

National Technical Information Service (NTIS)

Laminated root rot, caused by Phellinus weirii (Murr.) Gib., is a serious root disease affecting Douglas-fir and other commercially important species of conifers in northwestern North America. This report gives an overview of the disease as it occurs in t...

W. G. Thies R. N. Sturrock

1995-01-01

343

Root Coverage Technique with Enamel Matrix Derivative  

Microsoft Academic Search

Various periodontal plastic surgical techniques are employed in obtaining root coverage. Recently, the use of an enamel matrix derivative (EMD) has been reported in such treatment. We report 2 cases of root coverage surgery with a coronally positioned flap in combination with EMD (CPFEMD) and connective tissue graft in combination with EMD (CTGEMD). Case 1: The patient was a 25-year-old

Takafumi Moriyama; Shinya Matsumoto; Takemi Makiishi

2009-01-01

344

Localised ABA signalling mediates root growth plasticity.  

PubMed

Two recent reports show that cellular abscisic acid (ABA) signalling, together with other phytohormone signalling pathways, is crucial for salt-regulated root growth dynamics. Here we discuss these findings and place them in a broader framework on how cellular hormone signalling regulates root growth plasticity in response to environmental cues. PMID:24035235

Ding, Zhaojun; De Smet, Ive

2013-09-11

345

ADVANCING FINE ROOT RESEARCH WITH MINIRHIZOTRONS  

EPA Science Inventory

Minirhizotrons provide a nondestructive, in situ method for directly viewing and studying fine roots. Although many insights into fine roots have been gained using minirhizotrons, it is clear from the literature that there is still wide variation in how minirhizotrons and minirhi...

346

Anatomical and hydraulic properties of sorghum roots exposed to water deficit. [Sorghum bicolor  

SciTech Connect

The effects of a severe water stress in the upper 0-0.15 m rooting zone on development of the exodermis, endodermis and xylem and on radial (Lp) and axial (Ls) hydraulic conductances were studied for Sorghum bicolor. Lp and Lx were based on water flow rates obtained by applying a negative hydrostatic pressure to the proximal xylem ends of excised roots placed in aerated nutrient solution. The same roots were stained with fluorescent berberine and acid phloroglucinol to describe the development of the exodermal and endodermal cell walls from formation of the Casparian band (State I), to deposition of suberin lamellae (State II), and lignification (State III). Lp of 1.5 {times} 10{sup {minus}11} m{sup 3}s{sup {minus}1}MPa{sup {minus}1} was 80% lower in stressed roots than in unstressed controls. At 0.01 and 0.07 m from the root apex, stressed roots were in State III while control roots were in States I and II, respectively. SEM-image analysis for stressed roots indicated that in the exodermis a greater proportion of the cross sectional area was occupied by lignified walls than in the endodermis. Cellufluor, an apoplastic tracer, was blocked at the lignified exodermis even at 0.01 m from the apex in stressed roots. Uranin, a symplastic tracer, was taken up only in the apical region in stressed roots but farther from the apex in the controls. Lx of 7.1 {times} 10{sup {minus}11}m{sup 3}s{sup {minus}1}MPa{sup {minus}1} was 90% lower in stressed roots compared with the controls. Cellufluor test and image analysis showed that although the protoxylem and early metaxylem were conductive in both treatments, stress caused more than a 50% reduction in the diameter of the xylem elements. Results suggest that lignification of the exodermis and endodermis to a large extent decreased apoplastic and symplastic flows and hence Lp in stressed roots. The low Lx in stressed roots was due to a decrease in the diameters of the conductive xylem elements.

Cruz, R.T.; Jordan, W.R.; Drew, M.C. (Texas A and M Univ., College Station (United States))

1991-05-01

347

Cotton root response to free-air CO[sub 2] enrichment  

SciTech Connect

Field studies were undertaken for two years to investigate the effect of CO[sub 2] concentration (360 and 550 [mu]mol mol[sup [minus]1]) and soil water regime [wet, 100% of evapotranspiration (ET) replaced and dry, 75% (1990) and 76% (1991) of ET replaced] on cotton root growth at two growth stages (vegetative and reproductive). A new exposure method called free-air CO[sub 2] enrichment (FACE) was used to create large-scale test atmospheres in the field with minimal disturbance of plant microclimate. Soil root cores to a depth of 90 cm were collected within the crop row and interrow to evaluate vertical and horizontal rooting distribution. Root systems were excavated to describe morphological patterns. Laterals were divided into four classes based on diameter size . The effect of water stress of its interaction with CO[sub 2] were generally nonexistent with respect to root density. At the second sampling (reproductive), root weight per unit length was usually greater under water stress. At the initial sampling (vegetative), whole profile root density and root weight per unit length were usually increased under high CO[sub 2]. The positive effects of CO[sub 2] were limited to the 0.5 m position. At the first sampling, root dry weight density by depth increment were usually higher under FACE throughout the profile and at all horizontal positions, whereas increase in root length density were restricted to interrow positions. For most positions at the second sampling, enhancements in root weight per unit length and root length density occurred in the upper parts of the soil profile. At this period, FACE increased root dry weight density throughout the profile, especially at the interrow positions. Water stress had no effect on the taproot system at the initial period, but water stress at the second period resulted in reduced length, volume, and dry weight in the second year. At both samplings, most of the taproot measurements were increased due to extra CO[sub 2].

Prior, S.A.

1993-01-01

348

Nitrate Control of Root Hydraulic Properties in Plants: Translating Local Information to Whole Plant Response1[OA  

PubMed Central

The sessile lifestyle of plants constrains their ability to acquire mobile nutrients such as nitrate. Whereas proliferation of roots might help in the longer term, nitrate-rich patches can shift rapidly with mass flow of water in the soil. A mechanism that allows roots to follow and capture this source of mobile nitrogen would be highly desirable. Here, we report that variation in nitrate concentration around roots induces an immediate alteration of root hydraulic properties such that water is preferentially absorbed from the nitrate-rich patch. Further, we show that this coupling between nitrate availability and water acquisition results from changes in cell membrane hydraulic properties and is directly related to intracellular nitrate concentrations. Split-root experiments in which nitrate was applied to a portion of the root system showed that the response is both localized and reversible, resulting in rapid changes in water uptake to the portions of the roots exposed to the nitrate-rich patch. At the same time, water uptake by roots not supplied with nitrate was reduced. We believe that the increase in root hydraulic conductance in one part causes a decline of water uptake in the other part due to a collapse in the water potential gradient driving uptake. The translation of local information, in this case nitrate concentration, into a hydraulic signal that can be transmitted rapidly throughout the plant and thus coordinate responses at the whole plant level, represents an unexpected, higher level physiological interaction that precedes the level of gene expression.

Gorska, Anna; Ye, Qing; Holbrook, N. Michele; Zwieniecki, Maciej A.

2008-01-01

349

Non-destructive quantification of cereal roots in soil using high-resolution X-ray tomography.  

PubMed

One key constraint to further understanding plant root development is the inability to observe root growth in situ due to the opaque nature of soil. Of the present non-destructive techniques, computed tomography (CT) is best able to capture the complexities of the edaphic environment. This study compared the accuracy and impact of X-ray CT measurement of in situ root systems with standard technology (soil core washing and WinRhizo analysis) in the context of treatments that differed in the vertical placement of phosphorus fertilizers within the soil profile. Although root lengths quantified using WinRhizo were 8% higher than that observed in the same plants using CT, measurements of root length by the two methodologies were highly correlated. Comparison of scanned and unscanned plants revealed no effect of repeated scanning on plant growth and CT was not able to detect any changes in roots between phosphorus treatments that was observed using WinRhizo. Overall, the CT technique was found to be fast, safe, and able to detect roots at high spatial resolutions. The potential drawbacks of CT relate to the software to digitally segment roots from soil and air, which will improve significantly as automated segmentation algorithms are developed. The combination of very fast scans and automated segmentation will allow CT methodology to realize its potential as a high-throughput technique for the quantification of roots in soils. PMID:22271595

Flavel, Richard J; Guppy, Christopher N; Tighe, Matthew; Watt, Michelle; McNeill, Ann; Young, Iain M

2012-01-23

350

Clinical management of infected root canal dentin.  

PubMed

Several hundred different species of bacteria are present in the human intraoral environment. Bacterial penetration of root canal dentin occurs when bacteria invade the root canal system. These bacteria may constitute a reservoir from which root canal reinfection may occur during or after endodontic treatment. The learning objective of this article is to review endodontic microbiology, update readers on the role of bacteria in pulp and periapical disease, and discuss the principles of management of infected root canal dentin. Complete debridement, removal of microorganisms and affected dentin, and chemomechanical cleansing of the root canal are suggested as being the cornerstones of successful endodontic therapy, followed by intracanal medication to remove residual bacteria, when required. PMID:9242125

Love, R M

1996-08-01

351

Photosynthesis of root chloroplasts developed in Arabidopsis lines overexpressing GOLDEN2-LIKE transcription factors.  

PubMed

In plants, genes involved in photosynthesis are encoded separately in nuclei and plastids, and tight cooperation between these two genomes is therefore required for the development of functional chloroplasts. Golden2-like (GLK) transcription factors are involved in chloroplast development, directly targeting photosynthesis-associated nuclear genes for up-regulation. Although overexpression of GLKs leads to chloroplast development in non-photosynthetic organs, the mechanisms of coordination between the nuclear gene expression influenced by GLKs and the photosynthetic processes inside chloroplasts are largely unknown. To elucidate the impact of GLK-induced expression of photosynthesis-associated nuclear genes on the construction of photosynthetic systems, chloroplast morphology and photosynthetic characteristics in greenish roots of Arabidopsis thaliana lines overexpressing GLKs were compared with those in wild-type roots and leaves. Overexpression of GLKs caused up-regulation of not only their direct targets but also non-target nuclear and plastid genes, leading to global induction of chloroplast biogenesis in the root. Large antennae relative to reaction centers were observed in wild-type roots and were further enhanced by GLK overexpression due to the increased expression of target genes associated with peripheral light-harvesting antennae. Photochemical efficiency was lower in the root chloroplasts than in leaf chloroplasts, suggesting that the imbalance in the photosynthetic machinery decreases the efficiency of light utilization in root chloroplasts. Despite the low photochemical efficiency, root photosynthesis contributed to carbon assimilation in Arabidopsis. Moreover, GLK overexpression increased CO? fixation and promoted phototrophic performance of the root, showing the potential of root photosynthesis to improve effective carbon utilization in plants. PMID:23749810

Kobayashi, Koichi; Sasaki, Daichi; Noguchi, Ko; Fujinuma, Daiki; Komatsu, Hirohisa; Kobayashi, Masami; Sato, Mayuko; Toyooka, Kiminori; Sugimoto, Keiko; Niyogi, Krishna K; Wada, Hajime; Masuda, Tatsuru

2013-06-07

352

Establishment of a Protein Reference Map for Soybean Root Hair Cells1[W][OA  

PubMed Central

Root hairs are single tubular cells formed from the differentiation of epidermal cells on roots. They are involved in water and nutrient uptake and represent the infection site on leguminous roots by rhizobia, soil bacteria that establish a nitrogen-fixing symbiosis. Root hairs develop by polar cell expansion or tip growth, a unique mode of plant growth shared only with pollen tubes. A more complete characterization of root hair cell biology will lead to a better understanding of tip growth, the rhizobial infection process, and also lead to improvements in plant water and nutrient uptake. We analyzed the proteome of isolated soybean (Glycine max) root hair cells using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and shotgun proteomics (1D-PAGE-liquid chromatography and multidimensional protein identification technology) approaches. Soybean was selected for this study due to its agronomic importance and its root size. The resulting soybean root hair proteome reference map identified 1,492 different proteins. 2D-PAGE followed by mass spectrometry identified 527 proteins from total cell contents. A complementary shotgun analysis identified 1,134 total proteins, including 443 proteins that were specific to the microsomal fraction. Only 169 proteins were identified by the 2D-PAGE and shotgun methods, which highlights the advantage of using both methods. The proteins identified are involved not only in basic cell metabolism but also in functions more specific to the single root hair cell, including water and nutrient uptake, vesicle trafficking, and hormone and secondary metabolism. The data presented provide useful insight into the metabolic activities of a single, differentiated plant cell type.

Brechenmacher, Laurent; Lee, Joohyun; Sachdev, Sherri; Song, Zhao; Nguyen, Tran Hong Nha; Joshi, Trupti; Oehrle, Nathan; Libault, Marc; Mooney, Brian; Xu, Dong; Cooper, Bret; Stacey, Gary

2009-01-01

353

Alternative Path Mediated ATP Synthesis in Roots of Pisum sativum upon Nitrogen Supply 1  

PubMed Central

Changes in the efficiency of root respiration were examined on intact plants of Pisum sativum L. cv Rondo after addition of nitrate or ammonium to the culture solutions. Nitrate was absorbed immediately after addition and elicited a respiratory rise (O2-uptake as well as CO2-production) to 160% at most. This occurred both in roots of plants fixing N2 and in those of non-nodulated plants pregrown for 1 or 2 weeks on a nitrogen-free culture solution. In older plants, used after 2 weeks of N-free growth, the full capacity of the cytochrome path was engaged in root respiration. This was demonstrated by the absence of an effect of the uncoupler carbonylcyanide m-chlorophenylhydrazone in the presence of 25 millimolar salicylhydroxamate, an inhibitor of the alternative path. In these plants more than 90% of the nitrate-induced stimulation of root respiration was salicylhydroxamate-sensitive. In young plants, used after 1 week of N-free growth, the cytochrome path was not saturated. Its activity increased instantaneously at the expense of alternative path activity, which initially dropped to zero and subsequently increased to 160% of the control 7 hours after nitrate supply. The rate of photosynthesis rose to 120% of the control, but not before 1 hour after nitrate supply, suggesting that the stimulation of root respiration was not due to a higher rate of photosynthesis. Experiments with plants grown with a split-root system showed that respiration rate and alternative path activity only increased in the root halves exposed to nitrogen. Ammonium was equally effective as nitrate in stimulating root respiration. These results lead to the conclusion that alternative-path mediated root respiration contributes to synthesis of ATP during at least the first 24 hours following nitrogen supply. Images Fig. 5

de Visser, Ries; Brouwer, Koos Spreen; Posthumus, Freek

1986-01-01

354

FNOCT as a fluorescent probe for in vivo localization of nitric oxide distribution in tobacco roots.  

PubMed

The nitric oxide-specific fluorescent probe Fluorescent Nitric Oxide Cheletropic Trap (FNOCT) 8a was applied to intact tobacco (Nicotiana tabacum cv. Samsun) roots to detect sites of nitric oxide formation and NO distribution. Three week old tobacco seedlings were gently removed from the sand culture pots with intact roots and transferred to small Petri dishes, whose base was replaced by a thin coverslip. Intact roots were subjected to FNOCT 8a to localize NO-dependent fluorescence in these roots; controls with an exogenous NO donor confirmed the presence and distribution of the probe in the roots. To confirm the NO-dependent fluorescence, roots were incubated with the three different NO scavengers cPTIO {2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-L-oxyl-3-oxide}, methylene blue and sodium diethyl dithiocarbamate (DCC) followed by incubation with FNOCT 8a. Methylene blue and DCC were able to completely quench NO-dependent fluorescence, cPTIO quenched partially. The roots were incubated in the presence of NaNO? and NaNO?, which are substrates for nitrite:nitric oxide reductase (NI-NOR) and plasma membrane-bound nitrate reductase (PM-NR), respectively. The NO-dependent fluorescence was more or less same at the root tips upon treatment with NaNO?, while the overall fluorescence was reduced in the presence of NaNO. Fluorescence from the living roots was visualized by inverted confocal laser scanning microscope (CLSM) using UV laser (excitation 360 nm and emission 408 nm). A specialized apparatus has been devised by the authors for analysis of intact roots as described in the methods section of this paper. Intact roots were chosen for microscopic observation rather than incised roots to avoid production of NO due to stress or physical injury. PMID:22277729

Vandana, Shweta; Sustmann, Reiner; Rauen, Ursula; Stöhr, Christine

2012-01-11

355

Root hair-specific expansins modulate root hair elongation in rice.  

PubMed

Root hair growth requires intensive cell-wall modification. This study demonstrates that root hair-specific expansin?As, a sub-clade of the cell wall-loosening expansin proteins, are required for root hair elongation in rice (Oryza sativa L.). We identified a gene encoding EXPA17 (OsEXPA17) from a rice mutant with short root hairs. Promoter::reporter transgenic lines exhibited exclusive OsEXPA17 expression in root hair cells. The OsEXPA17 mutant protein (OsexpA17) contained a point mutation, causing a change in the amino acid sequence (Gly104?Arg). This amino acid alteration is predicted to disrupt a highly conserved disulfide bond in the mutant. Suppression of OsEXPA17 by RNA interference further confirmed requirement for the gene in root hair elongation. Complementation of the OsEXPA17 mutant with other root hair EXPAs (OsEXPA30 and Arabidopsis EXPA7) can restore root hair elongation, indicating functional conservation of these root hair EXPAs in monocots and dicots. These results demonstrate that members of the root hair EXPA sub-clade play a crucial role in root hair cell elongation in Graminaceae. PMID:21309868

ZhiMing, Yu; Bo, Kang; XiaoWei, He; ShaoLei, Lv; YouHuang, Bai; WoNa, Ding; Ming, Chen; Hyung-Taeg, Cho; Ping, Wu

2011-03-21

356

Effect of partial root excision on transpiration, root hydraulic conductance and leaf growth in wheat seedlings.  

PubMed

Removal of four out of five roots did not lower transpiration and stomatal conductivity of wheat (Triticum durum Desf.) seedlings. Water content of mature expanded leaf lamina remained constant at control levels. The results suggest that the only remaining root was capable to supply the shoot with water. This was evidenced by an increase in hydraulic conductivity of the root system following partial root excision measured at low subatmospheric pressures induced by vacuum. In the absence of a hydrostatic gradient, water flow from reduced root system was initially not higher than from an intact system, but increased subsequently. ABA content was increased in roots 1 h after partial root excision, which might contribute to the increase in hydraulic conductivity. PMID:15051049

Vysotskaya, Lidia B; Arkhipova, Tatyana N; Timergalina, Leila N; Dedov, Aleksandr V; Veselov, Stanislav Yu; Kudoyarova, Guzel R

2004-03-01

357

Rooting the eukaryotic tree with mitochondrial and bacterial proteins.  

PubMed

By exploiting the large body of genome data and the considerable progress in phylogenetic methodology, recent phylogenomic studies have provided new insights into the relationships among major eukaryotic groups. However, confident placement of the eukaryotic root remains a major challenge. This is due to the large evolutionary distance separating eukaryotes from their closest relatives, the Archaea, implying a weak phylogenetic signal and strong long-branch attraction artifacts. Here, we apply a new approach to the rooting of the eukaryotic tree by using a subset of genomic information with more recent evolutionary origin-mitochondrial sequences, whose closest relatives are ?-Proteobacteria. For this, we identified and assembled a data set of 42 mitochondrial proteins (mainly encoded by the nuclear genome) and performed Bayesian and maximum likelihood analyses. Taxon sampling includes the recently sequenced Thecamonas trahens, a member of the phylogenetically elusive Apusozoa. This data set confirms the relationships of several eukaryotic supergroups seen before and places the eukaryotic root between the monophyletic "unikonts" and "bikonts." We further show that T. trahens branches sister to Opisthokonta with significant statistical support and question the bikont/excavate affiliation of Malawimonas species. The mitochondrial data set developed here (to be expanded in the future) constitutes a unique alternative means in resolving deep eukaryotic relationships. PMID:22135192

Derelle, Romain; Lang, B Franz

2011-12-01

358

Characterization of a chondroitin sulfate hydrogel for nerve root regeneration  

NASA Astrophysics Data System (ADS)

Brachial plexus injury is a serious medical problem that affects many patients annually, with most cases involving damage to the nerve roots. Therefore, a chondroitin sulfate hydrogel was designed to both serve as a scaffold for regenerating root neurons and deliver neurotrophic signals. Capillary electrophoresis showed that chondroitin sulfate has a dissociation constant in the micromolar range with several common neurotrophins, and this was determined to be approximately tenfold stronger than with heparin. It was also revealed that nerve growth factor exhibits a slightly stronger affinity for hyaluronic acid than for chondroitin sulfate. However, E8 chick dorsal root ganglia cultured in the presence of nerve growth factor revealed that ganglia cultured in chondroitin sulfate scaffolds showed more robust growth than those cultured in control gels of hyaluronic acid. It is hypothesized that, despite the stronger affinity of nerve growth factor for hyaluronic acid, chondroitin sulfate serves as a better scaffold for neurite outgrowth, possibly due to inhibition of growth by hyaluronic acid chains.

Conovaloff, Aaron; Panitch, Alyssa

2011-10-01

359

Variation of the Linkage of Root Function with Root Branch Order  

PubMed Central

Mounting evidence has shown strong linkage of root function with root branch order. However, it is not known whether this linkage is consistent in different species. Here, root anatomic traits of the first five branch order were examined in five species differing in plant phylogeny and growth form in tropical and subtropical forests of south China. In Paramichelia baillonii, one tree species in Magnoliaceae, the intact cortex as well as mycorrhizal colonization existed even in the fifth-order root suggesting the preservation of absorption function in the higher-order roots. In contrast, dramatic decreases of cortex thickness and mycorrhizal colonization were observed from lower- to higher-order roots in three other tree species, Cunninghamia lanceolata, Acacia auriculiformis and Gordonia axillaries, which indicate the loss of absorption function. In a fern, Dicranopteris dichotoma, there were several cortex layers with prominently thickened cell wall and no mycorrhizal colonization in the third- and fourth-order roots, also demonstrating the loss of absorptive function in higher-order roots. Cluster analysis using these anatomic traits showed a different classification of root branch order in P. baillonii from other four species. As for the conduit diameter-density relationship in higher-order roots, the mechanism underpinning this relationship in P. baillonii was different from that in other species. In lower-order roots, different patterns of coefficient of variance for conduit diameter and density provided further evidence for the two types of linkage of root function with root branch order. These linkages corresponding to two types of ephemeral root modules have important implication in the prediction of terrestrial carbon cycling, although we caution that this study was pseudo-replicated. Future studies by sampling more species can test the generality of these two types of linkage.

Chen, Zhengxia; Zeng, Hui

2013-01-01

360

Auxin-induced inhibition of lateral root initiation contributes to root system shaping in Arabidopsis thaliana.  

PubMed

The hormone auxin is known to inhibit root elongation and to promote initiation of lateral roots. Here we report complex effects of auxin on lateral root initiation in roots showing reduced cell elongation after auxin treatment. In Arabidopsis thaliana, the promotion of lateral root initiation by indole-3-acetic acid (IAA) was reduced as the IAA concentration was increased in the nanomolar range, and IAA became inhibitory at 25 nM. Detection of this unexpected inhibitory effect required evaluation of root portions that had newly formed during treatment, separately from root portions that existed prior to treatment. Lateral root initiation was also reduced in the iaaM-OX Arabidopsis line, which has an endogenously increased IAA level. The ethylene signaling mutants ein2-5 and etr1-3, the auxin transport mutants aux1-7 and eir1/pin2, and the auxin perception/response mutant tir1-1 were resistant to the inhibitory effect of IAA on lateral root initiation, consistent with a requirement for intact ethylene signaling, auxin transport and auxin perception/response for this effect. The pericycle cell length was less dramatically reduced than cortical cell length, suggesting that a reduction in the pericycle cell number relative to the cortex could occur with the increase of the IAA level. Expression of the DR5:GUS auxin reporter was also less effectively induced, and the AXR3 auxin repressor protein was less effectively eliminated in such root portions, suggesting that decreased auxin responsiveness may accompany the inhibition. Our study highlights a connection between auxin-regulated inhibition of parent root elongation and a decrease in lateral root initiation. This may be required to regulate the spacing of lateral roots and optimize root architecture to environmental demands. PMID:21105922

Ivanchenko, Maria G; Napsucialy-Mendivil, Selene; Dubrovsky, Joseph G

2010-10-15

361

Transcriptional profile of maize roots under acid soil growth  

PubMed Central

Background Aluminum (Al) toxicity is one of the most important yield-limiting factors of many crops worldwide. The primary symptom of Al toxicity syndrome is the inhibition of root growth leading to poor water and nutrient absorption. Al tolerance has been extensively studied using hydroponic experiments. However, unlike soil conditions, this method does not address all of the components that are necessary for proper root growth and development. In the present study, we grew two maize genotypes with contrasting tolerance to Al in soil containing toxic levels of Al and then compared their transcriptomic responses. Results When grown in acid soil containing toxic levels of Al, the Al-sensitive genotype (S1587-17) showed greater root growth inhibition, more Al accumulation and more callose deposition in root tips than did the tolerant genotype (Cat100-6). Transcriptome profiling showed a higher number of genes differentially expressed in S1587-17 grown in acid soil, probably due to secondary effects of Al toxicity. Genes involved in the biosynthesis of organic acids, which are frequently associated with an Al tolerance response, were not differentially regulated in both genotypes after acid soil exposure. However, genes related to the biosynthesis of auxin, ethylene and lignin were up-regulated in the Al-sensitive genotype, indicating that these pathways might be associated with root growth inhibition. By comparing the two maize lines, we were able to discover genes up-regulated only in the Al-tolerant line that also presented higher absolute levels than those observed in the Al-sensitive line. These genes encoded a lipase hydrolase, a retinol dehydrogenase, a glycine-rich protein, a member of the WRKY transcriptional family and two unknown proteins. Conclusions This work provides the first characterization of the physiological and transcriptional responses of maize roots when grown in acid soil containing toxic levels of Al. The transcriptome profiles highlighted several pathways that are related to Al toxicity and tolerance during growth in acid soil. We found several genes that were not found in previous studies using hydroponic experiments, increasing our understanding of plant responses to acid soil. The use of two germplasms with markedly different Al tolerances allowed the identification of genes that are a valuable tool for assessing the mechanisms of Al tolerance in maize in acid soil.

2010-01-01

362

Genome Networks Root the Tree of Life between Prokaryotic Domains  

PubMed Central

Eukaryotes arose from prokaryotes, hence the root in the tree of life resides among the prokaryotic domains. The position of the root is still debated, although pinpointing it would aid our understanding of the early evolution of life. Because prokaryote evolution was long viewed as a tree-like process of lineage bifurcations, efforts to identify the most ancient microbial lineage split have traditionally focused on positioning a root on a phylogenetic tree constructed from one or several genes. Such studies have delivered widely conflicting results on the position of the root, this being mainly due to methodological problems inherent to deep gene phylogeny and the workings of lateral gene transfer among prokaryotes over evolutionary time. Here, we report the position of the root determined with whole genome data using network-based procedures that take into account both gene presence or absence and the level of sequence similarity among all individual gene families that are shared across genomes. On the basis of 562,321 protein-coding gene families distributed across 191 genomes, we find that the deepest divide in the prokaryotic world is interdomain, that is, separating the archaebacteria from the eubacteria. This result resonates with some older views but conflicts with the results of most studies over the last decade that have addressed the issue. In particular, several studies have suggested that the molecular distinctness of archaebacteria is not evidence for their antiquity relative to eubacteria but instead stems from some kind of inherently elevated rate of archaebacterial sequence change. Here, we specifically test for such a rate elevation across all prokaryotic lineages through the analysis of all possible quartets among eight genes duplicated in all prokaryotes, hence the last common ancestor thereof. The results show that neither the archaebacteria as a group nor the eubacteria as a group harbor evidence for elevated evolutionary rates in the sampled genes, either in the recent evolutionary past or in their common ancestor. The interdomain prokaryotic position of the root is thus not attributable to lineage-specific rate variation.

Dagan, Tal; Roettger, Mayo; Bryant, David; Martin, William

2010-01-01

363

An inexpensive rhizotron design for two-dimensional, horizontal root ...  

Treesearch

Title: An inexpensive rhizotron design for two-dimensional, horizontal root ... that supports two-dimensional, horizontal root growth measurements over time ... and (3) acquiring novel rooting data that can be input to a plant growth model.

364

76 FR 51430 - Roots Pharmaceuticals, Inc.; Revocation of Registration  

Federal Register 2010, 2011, 2012, 2013

...Drug Enforcement Administration Roots Pharmaceuticals, Inc.; Revocation of Registration...issued an Order to Show Cause to Roots Pharmaceuticals, Inc. (Registrant), of American...Registration BR9610571, issued to Roots Pharmaceuticals, Inc., be, and it hereby...

2011-08-18

365

Root systems and purely elastic S-matrices (II)  

NASA Astrophysics Data System (ADS)

Starting from a recently-proposed general formula, various properties of the ADE series of purely elastic S-matrices are rederived in a universal way. In particular, the relationship between the pole structure and the bootstrap equations is shown to follow from properties of root systems. The discussion leads to a formula for the signs of the three-point couplings in the simply-laced affine Toda theories, and a simple proof of a result due to Klassen and Melzer of relevance to Thermodynamic Bethe Ansatz calculations. Laboratoire de la Direction des Sciences de la Matière du Commissariat à l'Energie Atomique.

Dorey, Patrick E.

1992-05-01

366

Ecology of Root Colonizing Massilia (Oxalobacteraceae)  

PubMed Central

Background Ecologically meaningful classification of bacterial populations is essential for understanding the structure and function of bacterial communities. As in soils, the ecological strategy of the majority of root-colonizing bacteria is mostly unknown. Among those are Massilia (Oxalobacteraceae), a major group of rhizosphere and root colonizing bacteria of many plant species. Methodology/Principal Findings The ecology of Massilia was explored in cucumber root and seed, and compared to that of Agrobacterium population, using culture-independent tools, including DNA-based pyrosequencing, fluorescence in situ hybridization and quantitative real-time PCR. Seed- and root-colonizing Massilia were primarily affiliated with other members of the genus described in soil and rhizosphere. Massilia colonized and proliferated on the seed coat, radicle, roots, and also on hyphae of phytopathogenic Pythium aphanidermatum infecting seeds. High variation in Massilia abundance was found in relation to plant developmental stage, along with sensitivity to plant growth medium modification (amendment with organic matter) and potential competitors. Massilia absolute abundance and relative abundance (dominance) were positively related, and peaked (up to 85%) at early stages of succession of the root microbiome. In comparison, variation in abundance of Agrobacterium was moderate and their dominance increased at later stages of succession. Conclusions In accordance with contemporary models for microbial ecology classification, copiotrophic and competition-sensitive root colonization by Massilia is suggested. These bacteria exploit, in a transient way, a window of opportunity within the succession of communities within this niche.

Ofek, Maya; Hadar, Yitzhak; Minz, Dror

2012-01-01

367

Infection of Narcissus Roots by Aphelenchoides subtenuis  

PubMed Central

The widespread destruction of commercially grown bulbs of Narcissus tazetta papyraceus (Paper White) has been reported in Israel. This phenomenon is usually characterized by a premature yellowing of the foliage, accompanied by root rot and dark, sunken basal plates. This study confirmed thatAphelenchoides subtenuis is the main cause of the basal plate disease of Narcissus. In contrast to other Aphelenchoides species, which feed on stems or leaves, A. subtenuis penetrates Narcissus roots. In our experiments, in winter (6 to 8 weeks after penetration), nematodes laid their eggs in the root parenchymal cells without inducing obvious symptoms on foliage or roots. Toward spring, juveniles became numerous throughout the parenchymal cells of the root cortex. Consequently, the root system collapsed rapidly, at the usual peak of bulb and foliage production. Bulbs of infected plants were small and weighed less than those of uninfected plants, and foliage became necrotic prematurely. At that time, in field conditions, secondary elements like Fusarium penetrate the bulb and cause it to rot, given this syndrome the common name of basal plate disease. To our knowledge, this is the first report of an Aphelenchoides species as a root pathogen.

Mor, M.; Spiegel, Y.

1993-01-01

368

Infection of Narcissus Roots by Aphelenchoides subtenuis.  

PubMed

The widespread destruction of commercially grown bulbs of Narcissus tazetta papyraceus (Paper White) has been reported in Israel. This phenomenon is usually characterized by a premature yellowing of the foliage, accompanied by root rot and dark, sunken basal plates. This study confirmed thatAphelenchoides subtenuis is the main cause of the basal plate disease of Narcissus. In contrast to other Aphelenchoides species, which feed on stems or leaves, A. subtenuis penetrates Narcissus roots. In our experiments, in winter (6 to 8 weeks after penetration), nematodes laid their eggs in the root parenchymal cells without inducing obvious symptoms on foliage or roots. Toward spring, juveniles became numerous throughout the parenchymal cells of the root cortex. Consequently, the root system collapsed rapidly, at the usual peak of bulb and foliage production. Bulbs of infected plants were small and weighed less than those of uninfected plants, and foliage became necrotic prematurely. At that time, in field conditions, secondary elements like Fusarium penetrate the bulb and cause it to rot, given this syndrome the common name of basal plate disease. To our knowledge, this is the first report of an Aphelenchoides species as a root pathogen. PMID:19279798

Mor, M; Spiegel, Y

1993-09-01

369

Preparation and disinfection of root canals by 308-nm excimer laser light  

NASA Astrophysics Data System (ADS)

Conventional root canal treatments often fail due to insufficient removal of root canal contents and due to ineffective reduction of bacterial growth. In vitro investigations on the 308 nm excimer laser root canal preparation showed excellent results concerning the preparation quality. The aim of the present study was to investigate the influence of 308 nm excimer laserlight on the growth of bacteria. Bacterial suspensions of Staph. aureus, E. coli, and Enterococcus faec. were irradiated with various energy densities and different time duration. In order to exclude thermal side effects the temperature rise inside the suspensions was registered during irradiation. It was able to demonstrate that 308 nm excimer laserlight effects a log reduction of germ concentration at energy densities of 0.5 - 2.4 J/cm2. Laserlight effects germ reduction even without tissue removal. The effectiveness is dependent on the type of bacteria, the energy density, and the time of irradiation. The antimicrobial effect is independent from temperature.

Liesenhoff, Tim; Folwaczny, Matthias; Lehn, Norbert

1994-09-01

370

Scalable encryption using alpha rooting  

NASA Astrophysics Data System (ADS)

Full and partial encryption methods are important for subscription based content providers, such as internet and cable TV pay channels. Providers need to be able to protect their products while at the same time being able to provide demonstrations to attract new customers without giving away the full value of the content. If an algorithm were introduced which could provide any level of full or partial encryption in a fast and cost effective manner, the applications to real-time commercial implementation would be numerous. In this paper, we present a novel application of alpha rooting, using it to achieve fast and straightforward scalable encryption with a single algorithm. We further present use of the measure of enhancement, the Logarithmic AME, to select optimal parameters for the partial encryption. When parameters are selected using the measure, the output image achieves a balance between protecting the important data in the image while still containing a good overall representation of the image. We will show results for this encryption method on a number of images, using histograms to evaluate the effectiveness of the encryption.

Wharton, Eric J.; Panetta, Karen A.; Agaian, Sos S.

2008-05-01

371

Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings.  

PubMed

Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots. PMID:23726884

Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

2013-05-30

372

Adventitious root induction in Arabidopsis thaliana as a model for in vitro root organogenesis.  

PubMed

Adventitious root formation, the development of roots on non-root tissue (e.g. leaves, hypocotyls and stems) is a critical step during micropropagation. Although root induction treatments are routinely used for a large number of species micropropagated in vitro as well as for in vivo cuttings, the mechanisms controlling adventitious rooting are still poorly understood. Researchers attempt to gain better insight into the molecular aspects by studying adventitious rooting in Arabidopsis thaliana. The existing assay involves etiolation of seedlings and measurements of de novo formed roots on the elongated hypocotyl. The etiolated hypocotyls express a novel auxin-controlled signal transduction pathway in which auxin response factors (ARFs), microRNAs and environmental conditions that drive adventitious rooting are integrated. An alternative assay makes use of so-called thin cell layers (TCL), excised strips of cells from the inflorescence stem of Arabidopsis thaliana. However, both the etiolated seedling system and the TCL assay are only distantly related to industrial rooting processes in which roots are induced on adult stem tissue. Here, we describe an adventitious root induction system that uses segments of the inflorescence stems of Arabidopsis thaliana, which have a histological structure similar to cuttings or in vitro micropropagated shoots. The system allows multiple treatments with chemicals as well as the evaluation of different environmental conditions on a large number of explants. It is therefore suitable for high throughput chemical screenings and experiments that require numerous data points for statistical analysis. Using this assay, the adventitious root induction capacity of classical auxins was evaluated and a differential response to the different auxins could be demonstrated. NAA, IBA and IAA stimulated adventitious rooting on the stem segment, whereas 2,4-D and picloram did not. Light conditions profoundly influenced the root induction capacity of the auxins. Additionally to the environmental control of adventitious root formation, we also investigated the spatial and temporal aspects of stem-based adventitious root organogenesis. To determine the cells involved in de novo root initiation on the adult stems, we adopted scanning electron microscopy, which allows the visualization of the auxin responsive stem tissue. Using this technique, direct (without callus interface) and indirect (with intermediate callus phase) organogenesis was readily distinguished. The described micro-stem segment system is also suitable for other non-woody species and it is a valuable tool to perform fast evaluations of different treatments to study adventitious root induction. PMID:23299674

Verstraeten, Inge; Beeckman, Tom; Geelen, Danny

2013-01-01

373

Getting to the roots of it: Genetic and hormonal control of root architecture  

PubMed Central

Root system architecture (RSA) – the spatial configuration of a root system – is an important developmental and agronomic trait, with implications for overall plant architecture, growth rate and yield, abiotic stress resistance, nutrient uptake, and developmental plasticity in response to environmental changes. Root architecture is modulated by intrinsic, hormone-mediated pathways, intersecting with pathways that perceive and respond to external, environmental signals. The recent development of several non-invasive 2D and 3D root imaging systems has enhanced our ability to accurately observe and quantify architectural traits on complex whole-root systems. Coupled with the powerful marker-based genotyping and sequencing platforms currently available, these root phenotyping technologies lend themselves to large-scale genome-wide association studies, and can speed the identification and characterization of the genes and pathways involved in root system development. This capability provides the foundation for examining the contribution of root architectural traits to the performance of crop varieties in diverse environments. This review focuses on our current understanding of the genes and pathways involved in determining RSA in response to both intrinsic and extrinsic (environmental) response pathways, and provides a brief overview of the latest root system phenotyping technologies and their potential impact on elucidating the genetic control of root development in plants.

Jung, Janelle K. H.; McCouch, Susan

2013-01-01

374

Composite Cucurbita pepo plants with transgenic roots as a tool to study root development  

PubMed Central

Background and Aims In most plant species, initiation of lateral root primordia occurs above the elongation zone. However, in cucurbits and some other species, lateral root primordia initiation and development takes place in the apical meristem of the parental root. Composite transgenic plants obtained by Agrobacterium rhizogenes-mediated transformation are known as a suitable model to study root development. The aim of the present study was to establish this transformation technique for squash. Methods The auxin-responsive promoter DR5 was cloned into the binary vectors pKGW-RR-MGW and pMDC162-GFP. Incorporation of 5-ethynyl-2?-deoxyuridine (EdU) was used to evaluate the presence of DNA-synthesizing cells in the hypocotyl of squash seedlings to find out whether they were suitable for infection. Two A. rhizogenes strains, R1000 and MSU440, were used. Roots containing the respective constructs were selected based on DsRED1 or green fluorescent protein (GFP) fluorescence, and DR5::Egfp-gusA or DR5::gusA insertion, respectively, was verified by PCR. Distribution of the response to auxin was visualized by GFP fluorescence or ?-glucuronidase (GUS) activity staining and confirmed by immunolocalization of GFP and GUS proteins, respectively. Key Results Based on the distribution of EdU-labelled cells, it was determined that 6-day-old squash seedlings were suited for inoculation by A. rhizogenes since their root pericycle and the adjacent layers contain enough proliferating cells. Agrobacterium rhizogenes R1000 proved to be the most virulent strain on squash seedlings. Squash roots containing the respective constructs did not exhibit the hairy root phenotype and were morphologically and structurally similar to wild-type roots. Conclusions The auxin response pattern in the root apex of squash resembled that in arabidopsis roots. Composite squash plants obtained by A. rhizogenes-mediated transformation are a good tool for the investigation of root apical meristem development and root branching.

Ilina, Elena L.; Logachov, Anton A.; Laplaze, Laurent; Demchenko, Nikolay P.; Pawlowski, Katharina; Demchenko, Kirill N.

2012-01-01

375

Due process in gifted education  

Microsoft Academic Search

Twenty?eight states and the District of Columbia currently provide due process for gifted students. When parents or administrators cannot settle a dispute at the local school board level, some states by law and\\/or regulation offer aggrieved parties the right to mediation or due process. Seven states reported holding 26 due process hearings during the years 1992–1995. This article examines these

Frances A. Karnes; Debra A. Troxclair; Ronald G. Marquardt

1998-01-01

376

Estimating root respiration, microbial respiration in the rhizosphere, and root-free soil respiration in forest soils  

Microsoft Academic Search

We hypothesized that respiration measurements made using both the basal and excised-root respiration methods would allow us to quantify three important components of soil respiration: root respiration (Rroot), microbial respiration in the rhizosphere (Rrhizo), and root-free soil respiration (Rrfs). Root respiration determined by the basal method was approximately one-third greater than root respiration determined by the excised-root method (52 versus

Daniel L Kelting; James A Burger; Gerry S Edwards

1998-01-01

377

Reference gene selection for quantitative reverse transcription-polymerase chain reaction normalization during in vitro adventitious rooting in Eucalyptus globulus Labill  

Microsoft Academic Search

BACKGROUND: Eucalyptus globulus and its hybrids are very important for the cellulose and paper industry mainly due to their low lignin content and frost resistance. However, rooting of cuttings of this species is recalcitrant and exogenous auxin application is often necessary for good root development. To date one of the most accurate methods available for gene expression analysis is quantitative

Márcia R de Almeida; Carolina M Ruedell; Felipe K Ricachenevsky; Raul A Sperotto; Giancarlo Pasquali; Arthur G Fett-Neto

2010-01-01

378

Rooting cuttings of Syringa vulgaris cv. Charles Joly and Corylus avellana cv. Aurea: the influence of stock plant pruning and shoot growth  

Microsoft Academic Search

The relationship between shoot growth and rooting was examined in two, 'difficult-to root' amenity trees, Syringa vulgaris L. cv. Charles Joly and Corylus avellana L. cv. Aurea. A range of treatments reflecting severity of pruning was imposed on field-grown stock prior to bud break. To minimise variation due to the numbers of buds that developed under different treatments, bud number

Ross Cameron; Richard Harrison-Murray; Michael Fordham; Heather Judd; Yannick Ford; Tim Marks; Rodney Edmondson

2003-01-01

379

Assessing the importance of genotype x environment interaction for root traits in rice using a mapping population. I: a soil-filled box screen  

Microsoft Academic Search

Altering root system architecture is considered a method of improving crop water and soil nutrient capture. The analysis of quantitative trait loci (QTLs) for root traits has revealed inconsistency in the same population evaluated in different environments. It must be clarified if this is due to genotype × environment interaction or considerations of statistics if the value of QTLs for marker-assisted breeding

K. MacMillan; K. Emrich; H.-P. Piepho; C. E. Mullins; A. H. Price

2006-01-01

380

Seasonal changes of whole root system conductance by a drought-tolerant grape root system  

PubMed Central

The role of root systems in drought tolerance is a subject of very limited information compared with above-ground responses. Adjustments to the ability of roots to supply water relative to shoot transpiration demand is proposed as a major means for woody perennial plants to tolerate drought, and is often expressed as changes in the ratios of leaf to root area (AL:AR). Seasonal root proliferation in a directed manner could increase the water supply function of roots independent of total root area (AR) and represents a mechanism whereby water supply to demand could be increased. To address this issue, seasonal root proliferation, stomatal conductance (gs) and whole root system hydraulic conductance (kr) were investigated for a drought-tolerant grape root system (Vitis berlandieri×V. rupestris cv. 1103P) and a non-drought-tolerant root system (Vitis riparia×V. rupestris cv. 101-14Mgt), upon which had been grafted the same drought-sensitive clone of Vitis vinifera cv. Merlot. Leaf water potentials (?L) for Merlot grafted onto the 1103P root system (–0.91±0.02 MPa) were +0.15 MPa higher than Merlot on 101-14Mgt (–1.06±0.03 MPa) during spring, but dropped by approximately –0.4 MPa from spring to autumn, and were significantly lower by –0.15 MPa (–1.43±0.02 MPa) than for Merlot on 101-14Mgt (at –1.28±0.02 MPa). Surprisingly, gs of Merlot on the drought-tolerant root system (1103P) was less down-regulated and canopies maintained evaporative fluxes ranging from 35–20 mmol vine?1 s?1 during the diurnal peak from spring to autumn, respectively, three times greater than those measured for Merlot on the drought-sensitive rootstock 101-14Mgt. The drought-tolerant root system grew more roots at depth during the warm summer dry period, and the whole root system conductance (kr) increased from 0.004 to 0.009 kg MPa?1 s?1 during that same time period. The changes in kr could not be explained by xylem anatomy or conductivity changes of individual root segments. Thus, the manner in which drought tolerance was conveyed to the drought-sensitive clone appeared to arise from deep root proliferation during the hottest and driest part of the season, rather than through changes in xylem structure, xylem density or stomatal regulation. This information can be useful to growers on a site-specific basis in selecting rootstocks for grape clonal material (scions) grafted to them.

Alsina, Maria Mar; Smart, David R.; Bauerle, Taryn; de Herralde, Felicidad; Biel, Carme; Stockert, Christine; Negron, Claudia; Save, Robert

2011-01-01

381

Simplifying the decision matrix for estimating fine root production by the sequential soil coring approach  

NASA Astrophysics Data System (ADS)

Sequential soil coring is a commonly used approach to measure seasonal root biomass and necromass, from which root production can be estimated by maximum-minimum, sum of changes, compartment-flow model, and/or decision matrix methods. Among these methods, decision matrix is the most frequently used. However, the decision matrix, often underestimating fine root production, is frequently misused in research due to inadequate documentation of its underlying logic. In this paper, we reviewed the decision matrix method and provided mathematical logic for the development of the matrix, by which not only root production but also mortality and decomposition rates can be calculated. To ease its use for large datasets, we developed simplified equations to facilitate computation of root production, mortality and decomposition to be used in MS Excel or R. We also presented results from calculations by an example using empirical data from boreal forests to show proper calculations of root production, mortality and decomposition. The simplified decision matrix presented here shall promote its application in ecology, especially for large datasets.

Yuan, Z. Y.; Chen, Han Y. H.

2013-04-01

382

The role of liquid mixing and gas-phase dispersion in a submerged, sparged root reactor.  

PubMed

An Agrobacterium-transformed root culture of Solanum tuberosum was grown in a 15-1 bubble column. The specific respiration rate decreased by a factor of ten as the tissue grew over a 25-day culture period. On days 5, 8, 13, and 21, respiration was shown to be independent of aeration rate over a range of 0.05-0.4 vvm (volume of air per volume of liquid min-1). Gas dispersion measured from argon tracer residence time distributions increased fourfold due to increased stagnation and channeling of gas through the bed of growing roots; however, introduction of an antifoam surfactant on day 20 greatly reduced dispersion with no accompanying change in respiration. Taken together, the gas dispersion and respiration studies suggest that the gas-liquid interface is not the dominant resistance to oxygen mass transfer. Liquid mixing time measured with a dye tracer increased from 1.45 +/- 0.45 min with no root tissue to 40.2 +/- 1.6 min with 180 g FW l-1 of roots in the column. In addition, the oxygen uptake rate of growing tips (5.2 +/- 0.2 mm) of individual root segments of S. tuberosum measured in a stirred microcell (600 microliters) increased with the oxygen tension of the medium. Based on these results, the role of liquid mixing, gas-phase dispersion, and diffusion in the tissue in the scaleup of root culture is discussed. PMID:9090955

Tescione, L D; Ramakrishnan, D; Curtis, W R

1997-02-15

383

Modulation of root branching by a coumarin derivative  

PubMed Central

A healthy root system is crucial to plant growth and survival. To maintain efficiency of root function, plants have to dynamically modulate root system architecture through various adaptive mechanisms such as lateral root formation to respond to a changing and diversified soil environment. Exogenous application of a coumarin derivative, 4-methylumbelliferone (4-MU), in Arabidopsis thaliana inhibits seed germination by mainly reducing primary root growth. UDP-glycosyltransferases play an integral role in the biochemical mechanism of 4-MU detoxification in plant roots.1 However, 4-MU treatment also dramatically led to increased lateral root initiation, elongation and density. Moreover, marked root bending at the root-hypocotyl junction and auxin redistribution appeared to contribute to the 4-MU-mediated lateral root formation. We propose that 4-MU would serve as a useful chemical tool to study auxin-mediated root branching.

Li, Xiang; Gao, Ming-Jun

2011-01-01

384

Testing aluminum-chelate equilibria models using sorghum root growth as a bioassay for aluminum  

Microsoft Academic Search

Aluminum toxicity is an important limitation to crop yields in the acid soils of southeastern U. S. and other parts of the world due to its detrimental effects on roots. Soluble organics in soil solution ameliorate Al toxicity, a phenomenon which can be studied employing synthetic chelates. Theoretical models predict that Al will be complexed on nearly a one to

L. M. Shuman; D. O. Wilson; E. L. Ramseur

1991-01-01

385

On an Identity for the Cycle Indices of Rooted Tree Automorphism Groups  

Microsoft Academic Search

This note deals with a formula due to G. Labelle for the summed cycle indices of all rooted trees, which resembles the well-known formula for the cycle index of the symmetric group in some way. An elementary proof is provided as well as some immediate corollaries and applications, in particular a new application to the enumeration of k-decomposable trees. A

Stephan G. Wagner

2006-01-01

386

Carbohydrate Depletion in Roots and Leaves of Salt-Stressed Potted Citrus clementina L  

Microsoft Academic Search

In citrus, damage produced by salinity is mostly due to toxic ion accumulation, since this salt-sensitive crop adjusts osmotically with high efficiency. In spite of this observation, the putative role of sugars as osmolites under salinity remains unknown. In this work, we have studied carbohydrate contents (total hexoses, sucrose and starch) in leaves and roots of citrus grown under increasing

Vicent Arbona; Aurelio J. Marco; Domingo J. Iglesias; María F. López-Climent; Manuel Talon; Aurelio Gómez-Cadenas

2005-01-01

387

The impact of pH on cytotoxic effects of three root canal irrigants  

Microsoft Academic Search

AimCytotoxicity of root canal irrigants is important due to their close contact with host tissues. This study was to assess the possible impact of pH on cytotoxic effects of MTAD, 17% EDTA, and 2.6% NaOCl on the human gingival fibroblasts using MTT assay.

Mohammad Ali Saghiri; Abbas Delvarani; Payman Mehrvarzfar; Mohsen Nikoo; Mehrdad Lotfi; Kasra Karamifar; Kamal Asgar; Sahar Dadvand

2011-01-01

388

Ethylene production and ethylene effects on respiration rate of postharvest sugarbeet roots  

Microsoft Academic Search

Ethylene elevates respiration, is induced by wounding, and contributes to wound-induced respiration in most postharvest plant products. Ethylene production and its effects on respiration rate, however, have not been determined during storage of sugarbeet (Beta vulgaris L.) root, even though any elevation in respiration due to ethylene would increase storage losses and reduce postharvest quality. To determine the effect of

Karen Klotz Fugate; Jeffrey C. Suttle; Larry G. Campbell

2010-01-01

389

Root damage analysis of aircraft engine blade subject to ice impact  

Microsoft Academic Search

The blade root response due to ice impact on an engine blade is simulated using the NASA in-house code BLASIM. The ice piece is modeled as an equivalent spherical object impacting on the leading edge of the blade and has the velocity opposite to that of the aircraft with direction parallel to the engine axis. The effect of ice impact

E. S. Reddy; G. H. Abumeri; C. C. Chamis; P. L. N. Murthy

1992-01-01

390

DEVELOPMENT AND EVALUATION OF POTATO GERMPLASM RESISTANT TO COLUMBIA ROOT-KNOT NEMATODE (MELOIDOGYNE CHITWOODI)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Columbia root-knot nematode (Meloidogyne chitwoodi) (CRN) is a serious pest of potato in the Pacific Northwest of the US. Small initial populations are capable of causing crop loss due to the ability of this nematode to reproduce rapidly in the long growing season of the Columbia Basin of Washingto...

391

First report of root rot of Chicory caused by Phytophthora cryptogea in Chile  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chicory (Cichorium intybus L. var sativum Bisch.), a relatively new high value crop in Chile, was introduced for commercial production of inulin. Inulins are polysaccharides extracted from chicory tap roots that are used in processed foods due to their beneficial gastrointestinal properties. Approxi...

392

Occupational asthma due to formaldehyde  

Microsoft Academic Search

Bronchial provocation studies on 15 workers occupationally exposed to formaldehyde are described. The results show that formaldehyde exposure can cause asthmatic reactions, and suggest that these are sometimes due to hypersensitivity and sometimes to a direct irritant effect. Three workers had classical occupational asthma caused by formaldehyde fumes, which was likely to be due to hypersensitivity, with late asthmatic reactions

P S Burge; M G Harries; W K Lam; I M OBrien; P A Patchett

1985-01-01

393

Building and tracking root shapes.  

PubMed

An algorithm aiming at robust and simultaneous registrations of a sequence of 3-D shapes was recently presented by Jacq et al. [IEEE Trans. Biomed. Eng., vol. 55, no. 5, 2008]. This algorithm has to carry out an implicit representation of their common root shape (RS). A particular emphasis was put on the median consensus shape, which is a specific type of RS. Unlike this previous study, mainly focusing on the algorithm foundations while dealing with very specific applications examples, this paper attempts to show the versatility of the RS concept through a set of three problems involving a wider scope of application. The first problem copes with the design of prosthetic cortical plates for the hip joint. It shows how an explicit reconstruction of the RS, coming with its consensus map, could bring out an intermediary anatomical support from which pragmatic choices could be made, thereby performing a tradeoff between morphological, surgical, and production considerations. The second problem addresses in vivo real-time shoulder biomechanics through a miniature 3-D video camera. This new protocol implicitly operates through RS tracking of the content of virtual spotlights. It is shown that the current medical-oriented protocol, while operating within expert offices through low-cost equipments, could challenge high-end professional equipments despite some limitations of the 3-D video cameras currently available. The last problem deals with respiratory motions. This is an auxiliary measurement required by some medical imaging systems that can be handled as a basic application case of the former new protocol. PMID:19457742

Jacq, Jean-José; Schwartz, Cédric; Burdin, Valérie; Gérard, Romain; Lefèvre, Christian; Roux, Christian; Rémy-Néris, Olivier

2009-05-19

394

Root Apex Transition Zone As Oscillatory Zone  

PubMed Central

Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen, and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command center. In accordance with the early proposal of Charles and Francis Darwin, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone.

Baluska, Frantisek; Mancuso, Stefano

2013-01-01

395

Root apex transition zone as oscillatory zone.  

PubMed

Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen, and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command center. In accordance with the early proposal of Charles and Francis Darwin, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone. PMID:24106493

Baluška, František; Mancuso, Stefano

2013-10-02

396

Root Secretions and Growth of Tree Seedlings.  

National Technical Information Service (NTIS)

The effect of root secretions has been studied largely with relation to herbaceous vegetation; both negative and positive effects were pointed out. In silviculture considerable attention is being given to this problem in cultivating mixed plantations. Stu...

L. S. Saveleva T. L. Isaeva

1965-01-01

397

LCD Root Simulation and Analysis Tools.  

National Technical Information Service (NTIS)

The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system. The package consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.

M. Iwasaki

2001-01-01

398

LCD ROOT Simulation and Analysis Tools  

SciTech Connect

The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system. The package consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.

Iwasaki, Masako

2001-02-08

399

Plant Structure--Leaves, Stems, and Roots  

NSDL National Science Digital Library

Page one consists of a full color illustration of an idealized plant, showing various leaf, stem and root features. Page two illustrates various adaptations of plant flowers, leaves and stems. All illustrations are accompanied by explanations of the structures' functions.

2000-01-01

400

Hydraulic conductivity in roots of ponderosa pine infected with black-stain (Leptographium wageneri) or annosus (Heterobasidion annosum) root disease.  

PubMed

Roots from healthy and diseased mature ponderosa pine, Pinus ponderosa Laws., trees were excavated from a site near Burns, Oregon. The diseased trees were infected with black-stain root disease, Leptographium wageneri Kendrick, or annosus root disease, Heterobasidion annosum (Fr.) Bref., or both. Axial hydraulic conductivity of the roots was measured under a positive head pressure of 5 kPa, and the conducting area was stained with safranin dye to determine specific conductivity (k(s)). In diseased roots, only 8-12% of the cross-sectional xylem area conducted water. Resin-soaked xylem completely restricted water transport and accounted for 13-16% of the loss in conducting area. In roots with black-stain root disease, 17% of the loss in conducting area was associated with unstained xylem, possibly resulting from occlusions or embolisms. Based on the entire cross-sectional area of infected roots, the k(s) of roots infected with black-stain root disease was 4.6% of that for healthy roots, whereas the k(s) of roots infected with annosus root disease was 2.6% of that for healthy roots. Although these low values were partly the result of the presence of a large number of diseased roots (72%) with no conducting xylem, the k(s) of functional xylem of diseased roots was only 33% of that for healthy roots. The low k(s) values of functional xylem in diseased roots may be caused by fungus induced occlusions preceding cavitation and embolism of tracheids. The k(s) of disease-free roots from diseased trees was only 70% of that for healthy roots from healthy trees. The disease-free roots had the same mean tracheid diameter and tissue density as the healthy roots, suggesting that the lower k(s) in disease-free roots of diseased trees may also have been caused by partial xylary occlusions. PMID:12651373

Joseph, Gladwin; Kelsey, Rick G.; Thies, Walter G.

1998-05-01

401

CASIROZ: Root parameters and types of ectomycorrhiza of young beech plants exposed to different ozone and light regimes.  

PubMed

Tropospheric ozone (O(3)) triggers physiological changes in leaves that affect carbon source strength leading to decreased carbon allocation below-ground, thus affecting roots and root symbionts. The effects of O(3) depend on the maturity-related physiological state of the plant, therefore adult and young forest trees might react differently. To test the applicability of young beech plants for studying the effects of O(3) on forest trees and forest stands, beech seedlings were planted in containers and exposed for two years in the Kranzberg forest FACOS experiment (Free-Air Canopy O(3) Exposure System, http://www.casiroz.de ) to enhanced ozone concentration regime (ambient [control] and double ambient concentration, not exceeding 150 ppb) under different light conditions (sun and shade). After two growing seasons the biomass of the above- and below-ground parts, beech roots (using WinRhizo programme), anatomical and molecular (ITS-RFLP and sequencing) identification of ectomycorrhizal types and nutrient concentrations were assessed. The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants), no trends were observed in mycorrhization (%) due to ozone treatment. The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments. It was predominantly occurring in sun-exposed plants, while its majority share was replaced by Genea hispidula in shade-grown plants. Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types. In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants. Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio. Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted. PMID:17357022

Zeleznik, P; Hrenko, M; Then, C; Koch, N; Grebenc, T; Levanic, T; Kraigher, H

2007-03-01

402

Healing of root resorption: a case report.  

PubMed

External resorption is sequelae of necrotic periodontal membrane over a large area of root following an injury to the tooth. This usually occurs after severe dental injuries such as intrusion, severe luxations or exarticulation injuries complicated by a prolonged extra oral period. This case report presents a clinical and radiographic follow up (13 months) of treatment of inflammatory external root resorption on maxillary central incisor using Vitapex. Gradual healing of resorption was observed radiographically with no tenderness or pathological mobility. PMID:12739683

Bhat, Sham S; Sharan, S S; Madan, Imneet

2003-01-01

403

Mycorrhizae are present in cycad roots  

Microsoft Academic Search

We describe the occurrence of arbuscular mycorrhizae in the roots ofZamia pumila andDioon edule. Seedlings were grown on native, unsterilized soil taken from local pinelands of south Florida, whereZ. pumila occurs naturally. Arbuscules, hyphae, hyphal coils, and vesicles occur in the parenchyma cells of the root cortex, especially\\u000a the half of the cortex next to the stele. Hyphae of the

Jack B. Fisher; Andrew P. Vovides

2004-01-01

404

Biological Markers for Evaluation of Root Resorption  

PubMed Central

Background External apical root resorption is a pathologic consequence of orthodontic tooth movement. Cementum and dentin are removed from the root surface while active force is present. Objective The aim of this study was to identify and quantify extracellular matrix proteins, dentin matrix protein 1 (DMP1), dentin phosphophoryn (PP), and dentin sialoprotein (DSP) in the gingival crevicular fluid (GCF) of subjects undergoing orthodontic treatment. Methods Subjects with mild (less than 2mm) and severe (more than 2mm) root resorption during orthodontic treatment were identified by radiographs. A control group of subjects with neither signs of root loss nor undergoing orthodontic treatment was also identified. GCF was collected from the upper incisors by using filter paper strips (Periopaper). The absorbed GCF was eluted and the proteins were separated by SDS–PAGE analysis and stained. Western blot and ELISA were also performed. One Way Anova and Scheffé test were used for statistical analysis. Results SDS-PAGE analysis identified proteins at 77, 66, 55, 50 and 26 kDa. Immunoblotting did not show any differential expression pattern between control and study groups. ELISA results revealed a significant difference in the concentrations of DMP1, PP and DSP between control and root resorption groups. Concentration of PP and DSP in severe root resorption group was also statistically higher than in mild root resorption group. Conclusion DSP and PP could be suitable biological markers for monitoring root resorption during orthodontic treatment, since a significant difference in the level of these dentin specific proteins is detected in all groups.

Balducci, Laura; Ramachandran, Amsaveni; Hao, Jianjun; Narayanan, Karthikeyan; Evans, Carla; George, Anne

2007-01-01

405

Soil physical conditions affecting seedling root growth  

Microsoft Academic Search

Summary  The role of mechanical impedance, poor aeration and water availability in restricting pea (Pisum sativum L.) seedling root growth in sandy loam soil at three bulk densities and six matric potentials was studied. Mechanical impedance\\u000a increased both with bulk density and —matric potential. In certain treatments the roots were shorter and thicker as impedance\\u000a increased but in others shorter, thicker

B. W. Eavis

1972-01-01

406

Florida Sleeve Repair for Aortic Root Aneurysm  

PubMed Central

A 74-year-old man was diagnosed with aortic root aneurysm and two-vessel coronary disease. Echocardiographic assessment revealed an enlarged sinus of Valsalva 60 mm in diameter with mild aortic regurgitation. Florida sleeve repair was performed using a vascular graft combined with coronary artery bypass grafting. The postoperative course was uncomplicated and follow-up echocardiographic evaluations showed an aortic root diameter of 38 mm without aortic insufficiency up to 1 year after surgery.

Kim, Dong Hee; Kim, Kwan Sic; Kim, Joon Bum

2013-01-01

407

MDCT Evaluation of Aortic Root Surgical Complications.  

PubMed

OBJECTIVE. CT is the primary imaging modality used after aortic root repair. Distinction of normal findings from postoperative complications is imperative and requires optimization of acquisition parameters and interpretation with advanced postprocessing tools. CONCLUSION. After aortic root surgery, findings can be categorized as complications within the aorta, complications outside the aorta, and benign postoperative changes. Distinction of normal findings from postoperative complications requires proper CT technique and an understanding of CT findings that require intervention. PMID:24059362

Chu, Linda C; Johnson, Pamela T; Cameron, Duke E; Fishman, Elliot K

2013-10-01

408

Root phenomics of crops: opportunities and challenges  

Microsoft Academic Search

Reliable techniques for screening large numbers of plants for root traits are still being developed, but include aeroponic, hydroponic and agar plate systems. Coupled with digital cameras and image analysis software, these systems permittherapidmeasurementofrootnumbers,lengthanddiameterinmoderate(typically <1000)numbersofplants.Usually suchsystemsareemployedwithrelativelysmallseedlings,andinformationisrecordedin2D.RecentdevelopmentsinX-ray microtomography have facilitated 3D non-invasive measurement of small root systems grown in solid media, allowing angular distributions to beobtainedinaddition tonumbers andlength. However, because of

Peter J. GregoryA; A. Glyn BengoughA; T. B. ThomasA; Iain M. YoungB

409

Root phenomics of crops: opportunities and challenges  

Microsoft Academic Search

Abstract. Reliable techniques for screening large numbers of plants for root traits are still being developed, but include aeroponic, hydroponic and agar plate systems. Coupled with digital cameras and image analysis software, these systems permittherapidmeasurementofrootnumbers,lengthanddiameterinmoderate(typically <1000)numbersofplants.Usually suchsystemsareemployedwithrelativelysmallseedlings,andinformationisrecordedin2D.RecentdevelopmentsinX-ray microtomography have facilitated 3D non-invasive measurement of small root systems grown in solid media, allowing angular distributions to beobtainedinaddition tonumbers andlength. However, because

Peter J. Gregory; A. Glyn Bengough; Dmitri Grinev; Sonja Schmidt; W. T. B. Thomas; Tobias Wojciechowski; Iain M. Young

410

Mapping gene activity of Arabidopsis root hairs  

PubMed Central

Background Quantitative information on gene activity at single cell-type resolution is essential for the understanding of how cells work and interact. Root hairs, or trichoblasts, tubular-shaped outgrowths of specialized cells in the epidermis, represent an ideal model for cell fate acquisition and differentiation in plants. Results Here, we provide an atlas of gene and protein expression in Arabidopsis root hair cells, generated by paired-end RNA sequencing and LC/MS-MS analysis of protoplasts from plants containing a pEXP7-GFP reporter construct. In total, transcripts of 23,034 genes were detected in root hairs. High-resolution proteome analysis led to the reliable identification of 2,447 proteins, 129 of which were differentially expressed between root hairs and non-root hair tissue. Dissection of pre-mRNA splicing patterns showed that all types of alternative splicing were cell type-dependent, and less complex in EXP7-expressing cells when compared to non-root hair cells. Intron retention was repressed in several transcripts functionally related to root hair morphogenesis, indicative of a cell type-specific control of gene expression by alternative splicing of pre-mRNA. Concordance between mRNA and protein expression was generally high, but in many cases mRNA expression was not predictive for protein abundance. Conclusions The integrated analysis shows that gene activity in root hairs is dictated by orchestrated, multilayered regulatory mechanisms that allow for a cell type-specific composition of functional components.

2013-01-01

411

Cryopreservation of Panax ginseng Adventitious Roots  

Microsoft Academic Search

We tested desiccation and\\/or vitrification procedures to cryopreserve the adventitious roots of Panax ginseng, the source of commercially produced ginsenosides. When only desiccation was applied, the post-freeze survival of 3- to 4-mm\\u000a root tips was <14% regardless of the composition of the preculture medium or the explant origin. Callus formation was frequently\\u000a observed after cryopreservation. In contrast, 90% survival and

Suk Young Oh; Chun Hua Wu; Elena Popova; Eun Joo Hahn; Kee Yoeup Paek

2009-01-01

412

The Cytoskeleton and Root Growth Behavior  

Microsoft Academic Search

\\u000a The roots of many plant species develop complex growth behaviors when germinated on hard surfaces, and scientists have learned\\u000a to use this experimental set-up to study the structure and dynamics of cytoskeletal arrays. Our knowledge of the elements\\u000a that lead to anisotropic cell expansion in rapidly elongating cells has increased by finding mutants with altered root growth\\u000a behavior as well

Laura M. Vaughn; Katherine L. Baldwin; Gengxiang Jia; Julian C. Verdonk; Allison K. Strohm; Patrick H. Masson

413

Association Between Sugarbeet Root Yield and Sugarbeet Root Maggot (Diptera: Otitidae) Damage  

Microsoft Academic Search

Sugarbeet root maggot, Tetanops myopaeformis von Roder, is a major insect pest of sugarbeet throughout much of North America. Root maggot damage is routinely rated o na0( no damage) to 5 (severe damage) scale. In 42 trials, the relationship between visual damage and root yield was examined. The mean damage rating in the absence of insecticides was 3.3 6 0.4,

L. G. CAMPBELL; A. W. ANDERSON; ROBERT DREGSETH; L. J. SMITH

414

Root size and shoot\\/root ratio as influenced by light environment of the shoot  

Microsoft Academic Search

The light environment of a plant shoot can affect its root size and the shoot\\/root biomass ratio. Photoperiodic influence on shoot\\/root ratios of first?year biennial sweetclover (Melilotus alba Desr.) plants was related to phytochrome measurement of day length and its regulation of photosynthate partitioning to favor successful completion of the life cycle. Short photoperiods alternated with long, uninterrupted nights resulted

M. J. Kasperbauer; P. G. Hunt

1992-01-01

415

Mapping genes controlling root morphology and root distribution in a doubled-haploid population of rice  

Microsoft Academic Search

A deep thick root system has been demonstrated to have a positive effect on yield of upland rice under water stress conditions.\\u000a Molecular-marker-aided selection could be helpful for the improvement of root morphological traits, which are otherwise difficult\\u000a to score. We studied a doubled-haploid population of 105 lines derived from an indica?japonica cross and mapped the genes controlling root morphology

R. Yadav; B. Courtois; N. Huang; G. McLaren

1997-01-01

416

Influence of root and root channels distributions on the lateral subsurface flow of homogeneous soils  

NASA Astrophysics Data System (ADS)

Is it recognized that vegetation influences different hydrological processes at different temporal and spatial scales. In fact, there is a wide controversial discussion on the quantification of flood risk mitigation through vegetation and forest management strategies. Nearby numerous empirical and theoretical studies at the catchment/hillslope scale there are many studies at the soil profile scale that characterize the influence of vegetation on the hydrological processes. However, the link between the different scales still be difficult. Studies at the catchment/hillslope scale emphasize the importance of lateral subsurface flow in regulating the formation of floods events. Other studies formulate the hypothesis that root distribution and root turnover influence processes such as infiltration and water retention. However, no studies could show systematically the influence of root or root channels distribution on lateral subsurface flow for different soil types and slope inclinations. In this study we used a inclined box (0.25 x 0.4 x 0.4 m) in order to measure the relation between the amount of shallow lateral subsurface flow (0-0.1 m), the deeper lateral subsurface flow (0.1 - 0.4 m), and the vertical percolation in function of factors such density of roots, diameter distribution of roots, density of root channels, diameter distribution of root channels, soil type, and slope inclination. Roots were embedded in the soil at regular depth and oriented parallel to the slope surface. The sprinkling experiments were carried out with a rainfall intensity of about 80 mm/h for duration of 10 minutes. The results show that the lateral subsurface flow is strongly influenced by both root and root channels density/distribution. Further work will aim to combine physical approaches validated for the description of the here presented laboratory results with root distribution modeling at the hillslope scale in order to quantify the lateral hydrological connectivity and the runoff coefficients of forested slopes.

Schwarz, M.

2012-04-01

417

The root and root canal morphology of the human mandibular first premolar: a literature review.  

PubMed

The purpose of this study was to undertake a comprehensive literature review of the root and root canal morphology of the mandibular first premolar. Published studies citing the anatomy and morphology of mandibular premolars report data for over 6,700 teeth. These studies were divided into anatomical studies reporting number of roots, number of canals, and apical morphology. Variations because of sex and ethnic background have also been reported, along with case reports of anomalies. Approximately 98% of the teeth in these studies were single-rooted. The incidence of two roots was 1.8%. Three roots when reported were found in 0.2% of the teeth studied. Four roots were rare and were found in less than 0.1% of the teeth studied. Studies of the internal canal morphology revealed that a single canal was present in 75.8% of the teeth. Two or more canals were found in 24.2% of the teeth studied. A single apical foramen was found in 78.9% of the teeth, whereas 21.1% had two or more apical foramina. The role of genetics and racial variation may result in differences of incidence of root number and canal number in human populations. The dental literature is not unique in studying ethnicity and sex variations. Higher incidences of teeth with additional canals and roots have been reported in Chinese, Australian, and sub-Sahara African populations. Physical anthropology studies seem to show the lowest incidence in Western Eurasian, Japanese and American Arctic populations. The root and root canal morphology of this tooth can be complex and requires careful evaluation prior to root canal therapy. PMID:17437863

Cleghorn, Blaine M; Christie, William H; Dong, Cecilia C S

2007-02-27

418

Neutral Red as a Probe for Confocal Laser Scanning Microscopy Studies of Plant Roots  

PubMed Central

• Background and Aims Neutral red (NR), a lipophilic phenazine dye, has been widely used in various biological systems as a vital stain for bright-field microscopy. In its unprotonated form it penetrates the plasma membrane and tonoplast of viable plant cells, then due to protonation it becomes trapped in acidic compartments. The possible applications of NR for confocal laser scanning microscopy (CLSM) studies were examined in various aspects of plant root biology. • Methods NR was used as a fluorochrome for living roots of Phaseolus vulgaris, Allium cepa, A. porrum and Arabidopsis thaliana (wild-type and transgenic GFP-carrying lines). The tissues were visualized using CLSM. The effect of NR on the integrity of the cytoskeleton and the growth rate of arabidopsis primary roots was analysed to judge potential toxic effects of the dye. • Key Results The main advantages of the use of NR are related to the fact that NR rapidly penetrates root tissues, has affinity to suberin and lignin, and accumulates in the vacuoles. It is shown that NR is a suitable probe for visualization of proto- and metaxylem elements, Casparian bands in the endodermis, and vacuoles in cells of living roots. The actin cytoskeleton and the microtubule system of the cells, as well as the dynamics of root growth, remain unchanged after short-term application of NR, indicating a relatively low toxicity of this chemical. It was also found that NR is a useful probe for the observation of the internal structures of root nodules and of fungal hyphae in vesicular–arbuscular mycorrhizas. • Conclusions Ease, low cost and absence of tissue processing make NR a useful probe for structural, developmental and vacuole-biogenetic studies of plant roots with CLSM.

DUBROVSKY, JOSEPH G.; GUTTENBERGER, MARTIN; SARALEGUI, ANDRES; NAPSUCIALY-MENDIVIL, SELENE; VOIGT, BORIS; BALUSKA, FRANTISEK; MENZEL, DIEDRIK

2006-01-01

419

Adaptive significance of root grafting in trees  

SciTech Connect

Root grafting has long been observed in forest trees but the adaptive significance of this trait has not been fully explained. Various authors have proposed that root grafting between trees contributes to mechanical support by linking adjacent root systems. Keeley proposes that this trait would be of greatest advantage in swamps where soils provide poor mechanical support. He provides as evidence a greenhouse study of Nyssa sylvatica Marsh in which seedlings of swamp provenance formed between-individual root grafts more frequently than upland provenance seedlings. In agreement with this within-species study, Keeley observed that arid zone species rarely exhibit grafts. Keeley also demonstrated that vines graft less commonly than trees, and herbs never do. Since the need for mechanical support coincides with this trend, these data seem to support his model. In this paper, the authors explore the mechanisms and ecological significance of root grafting, leading to predictions of root grafting incidence. Some observations support and some contradict the mechanical support hypothesis.

Loehle, C.; Jones, R.

1988-12-31

420

Defining the core Arabidopsis thaliana root microbiome.  

PubMed

Land plants associate with a root microbiota distinct from the complex microbial community present in surrounding soil. The microbiota colonizing the rhizosphere (immediately surrounding the root) and the endophytic compartment (within the root) contribute to plant growth, productivity, carbon sequestration and phytoremediation. Colonization of the root occurs despite a sophisticated plant immune system, suggesting finely tuned discrimination of mutualists and commensals from pathogens. Genetic principles governing the derivation of host-specific endophyte communities from soil communities are poorly understood. Here we report the pyrosequencing of the bacterial 16S ribosomal RNA gene of more than 600 Arabidopsis thaliana plants to test the hypotheses that the root rhizosphere and endophytic compartment microbiota of plants grown under controlled conditions in natural soils are sufficiently dependent on the host to remain consistent across different soil types and developmental stages, and sufficiently dependent on host genotype to vary between inbred Arabidopsis accessions. We describe different bacterial communities in two geochemically distinct bulk soils and in rhizosphere and endophytic compartments prepared from roots grown in these soils. The communities in each compartment are strongly influenced by soil type. Endophytic compartments from both soils feature overlapping, low-complexity communities that are markedly enriched in Actinobacteria and specific families from other phyla, notably Proteobacteria. Some bacteria vary quantitatively between plants of different developmental stage and genotype. Our rigorous definition of an endophytic compartment microbiome should facilitate controlled dissection of plant-microbe interactions derived from complex soil communities. PMID:22859206

Lundberg, Derek S; Lebeis, Sarah L; Paredes, Sur Herrera; Yourstone, Scott; Gehring, Jase; Malfatti, Stephanie; Tremblay, Julien; Engelbrektson, Anna; Kunin, Victor; del Rio, Tijana Glavina; Edgar, Robert C; Eickhorst, Thilo; Ley, Ruth E; Hugenholtz, Philip; Tringe, Susannah Green; Dangl, Jeffery L

2012-08-01

421

Biological effects due to weak magnetic field on plants  

NASA Astrophysics Data System (ADS)

Throughout the evolution process, Earth’s magnetic field (MF, about 50 ?T) was a natural component of the environment for living organisms. Biological objects, flying on planned long-term interplanetary missions, would experience much weaker magnetic fields, since galactic MF is known to be 0.1 1 nT. However, the role of weak magnetic fields and their influence on functioning of biological organisms are still insufficiently understood, and is actively studied. Numerous experiments with seedlings of different plant species placed in weak magnetic field have shown that the growth of their primary roots is inhibited during early germination stages in comparison with control. The proliferative activity and cell reproduction in meristem of plant roots are reduced in weak magnetic field. Cell reproductive cycle slows down due to the expansion of G1 phase in many plant species (and of G2 phase in flax and lentil roots), while other phases of cell cycle remain relatively stabile. In plant cells exposed to weak magnetic field, the functional activity of genome at early pre-replicate period is shown to decrease. Weak magnetic field causes intensification of protein synthesis and disintegration in plant roots. At ultrastructural level, changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells were observed in pea roots exposed to weak magnetic field. Mitochondria were found to be very sensitive to weak magnetic field: their size and relative volume in cells increase, matrix becomes electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to weak magnetic field show Ca2+ over-saturation in all organelles and in cytoplasm unlike the control ones. The data presented suggest that prolonged exposures of plants to weak magnetic field may cause different biological effects at the cellular, tissue and organ levels. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca2+ homeostasis. However, our understanding of very complex fundamental mechanisms and sites of interactions between weak magnetic fields and biological systems is still incomplete and still deserve strong research efforts.

Belyavskaya, N. A.

2004-01-01

422

White lupin cluster root acclimation to phosphorus deficiency and root hair development involve unique glycerophosphodiester phosphodiesterases.  

PubMed

White lupin (Lupinus albus) is a legume that is very efficient in accessing unavailable phosphorus (Pi). It develops short, densely clustered tertiary lateral roots (cluster/proteoid roots) in response to Pi limitation. In this report, we characterize two glycerophosphodiester phosphodiesterase (GPX-PDE) genes (GPX-PDE1 and GPX-PDE2) from white lupin and propose a role for these two GPX-PDEs in root hair growth and development and in a Pi stress-induced phospholipid degradation pathway in cluster roots. Both GPX-PDE1 and GPX-PDE2 are highly expressed in Pi-deficient cluster roots, particularly in root hairs, epidermal cells, and vascular bundles. Expression of both genes is a function of both Pi availability and photosynthate. GPX-PDE1 Pi deficiency-induced expression is attenuated as photosynthate is deprived, while that of GPX-PDE2 is strikingly enhanced. Yeast complementation assays and in vitro enzyme assays revealed that GPX-PDE1 shows catalytic activity with glycerophosphocholine while GPX-PDE2 shows highest activity with glycerophosphoinositol. Cell-free protein extracts from Pi-deficient cluster roots display GPX-PDE enzyme activity for both glycerophosphocholine and glycerophosphoinositol. Knockdown of expression of GPX-PDE through RNA interference resulted in impaired root hair development and density. We propose that white lupin GPX-PDE1 and GPX-PDE2 are involved in the acclimation to Pi limitation by enhancing glycerophosphodiester degradation and mediating root hair development. PMID:21464471

Cheng, Lingyun; Bucciarelli, Bruna; Liu, Junqi; Zinn, Kelly; Miller, Susan; Patton-Vogt, Jana; Allan, Deborah; Shen, Jianbo; Vance, Carroll P

2011-04-04

423

A New Anatomically Based Nomenclature for the Roots and Root Canals--Part 2: Mandibular Molars  

PubMed Central

Several terminologies have been employed in the dental literature to describe the roots and root canal systems of mandibular molars with no consensus being arrived at, thus far. The anatomical relation of roots and their root canals were identified and a naming system was formulated. The proposed nomenclature attempts to make certain essential modifications to the traditional approach to accommodate the naming of various aberrations presented in mandibular molars. A simple, yet extensive nomenclature system has been proposed that appropriately names the internal and external morphology of mandibular molars.

Valerian Albuquerque, Denzil; Kottoor, Jojo; Velmurugan, Natanasabapathy

2012-01-01

424

The root and root canal morphology of the human mandibular second premolar: a literature review.  

PubMed

The objective was to review thoroughly the literature of the root and root canal morphology of the human mandibular second premolar and compare the results with the mandibular first premolar. Published studies cite the anatomy and morphology of the mandibular second premolar tooth for more than 7700 teeth. These studies were divided into anatomic studies reporting the number of roots, number of canals, and apical anatomy. Differences caused by gender and ethnicity have also been reported. Individual case reports of anomalies were included to demonstrate the extreme range of variation. Almost all of the teeth in the anatomic studies were single-rooted (99.6%). The incidence of 2 roots (0.3%) and 3 roots (0.1%) was extremely rare. Anatomic studies of the internal canal morphology found that a single canal was present in 91.0% of the teeth. A single apical foramen was found in 91.8% of the teeth. The incidence of more than 1 root (0.4%), more than 1 canal system (9.9%), and more than 1 foramen (8.2%) is lower than that of the mandibular first premolar tooth (2.0%, 24.2%, and 21.1%, respectively). However, the root and root canal morphology of the mandibular second premolar can be extremely complex and requires careful assessment. PMID:17931927

Cleghorn, Blaine M; Christie, William H; Dong, Cecilia C S

2007-06-05

425

Bone metastases with nerve root compression as a late complication in patient with epithelial pleural mesothelioma  

PubMed Central

Malignant pleural mesothelioma (MPM) is an aggressive tumor with dismal prognoses and poor response to treatments. The most frequent symptoms are due to local invasion. Distant metastases are not uncommon and usually appear at late stage of the disease. However, metastases in bone have rarely been well documented. Here we report the case of a MPM patient with nerve root compression due to bone metastases 18 months after the first diagnoses of MPM.

Farinas, Lorena; Stejpanovic, Neda; Martinez, Pablo; Martinez, Alex; Zamora, Esther; Montero, Maria Angeles; Felip, Enriqueta

2013-01-01