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  • root system  (4)
  • Abscisic acid  (2)
  • Springer  (6)
  • BioMed Central
  • The American Society for Microbiology (ASM)
Document type
Keywords
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  • Springer  (6)
  • BioMed Central
  • The American Society for Microbiology (ASM)
Years
  • 1
    Electronic Resource
    Electronic Resource
    Regulation of the abscisic acid-responsive gene rab28 in maize viviparous mutants (1991)
    Springer
    Molecular genetics and genomics 230 (1991), S. 394-400 
    Details
    ISSN: 1617-4623
    Keywords: Maize rab gene ; Abscisic acid ; Water-stress ; viviparous mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have isolated a new maize gene, rab 28, that responds to abscisic acid (ABA) treatment. This gene has been characterized by determining the sequence of the cDNA and corresponding genomic copy, and by mapping the start site of its transcript. The rab 28 gene encodes a protein of predicted molecular weight 27713 Da which shows strong homology with the Lea D-34 protein identified in cotton. The proximal promoter region contains the conserved ABA-response element, CACGTGG, reported in other plant genes to be responsible for ABA induction. rab 28 mRNA has been identified as ABA-inducible in embryos and young leaves. It is also induced by water-stress in leaves of wild-type plants. Regulation of the rab 28 gene was studied in maize viviparous mutants. The results obtained with the ABA-insensitive vp1 mutant show that rab 28 transcripts do not accumulate to a significant level during embryogenesis. Surprisingly, induction of rab 28 mRNA can be achieved in young embryos by exogenous ABA treatment. Moreover, water-stressed or ABA-treated seedlings of vp1 contain significant levels of rab 28 mRNA which is not detectable in well-watered seedlings. Regulation of the rab 28 gene in excised young embryos of ABA-deficient vp2 mutants, in which influences of the maternal environment are absent, closely resembles that found in non-mutant excised young embryos. The significance of these results is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280296
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  • 2
    Electronic Resource
    Electronic Resource
    Two different Em-like genes are expressed in Arabidopsis thaliana seeds during maturation (1993)
    Springer
    Molecular genetics and genomics 238 (1993), S. 409-418 
    Details
    ISSN: 1617-4623
    Keywords: Dry seed ; Em-like genes ; Arabidopsis thaliana ; Abscisic acid ; Responsive genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using a radish cDNA probe, we have isolated and characterized two genomic clones from Arabidopsis thaliana (GEA1 and GEA6) encoding two different proteins that are homologous to the “Early methionine-labelled” (Em) protein of wheat. GEA1 differs from GEA6 and Em clones of wheat in that a sequence coding for 20 amino acid residues is tandemly repeated 4 times. These two genomic clones correspond to two genes named AtEm1 and AtEm6. Sequencing of several cDNA clones showed that both genes are expressed. The transcription start site was determined for both genes by RNase mapping. The site of polyadenylation is variable and there is no obvious consensus sequence for polyadenylation at the 3′ ends of the genes. mRNA corresponding to GEA6 is present only in nearly dry and dry seeds, whereas that corresponding to GEA1 appears in immature seeds and is maximum in dry seeds. No expression of either gene could be detected in leaf, stem, or floral buds. Expression of both genes could be detected in immature seeds when the siliques were incubated with abscisic acid (ABA), demonstrating that both genes are ABA responsive. However, examination of the 5′ upstream region does not reveal any extensive homology, suggesting that regulation of the two genes differs. In situ hybridization with a GEA1 probe demonstrated that the expression of this gene is essentially located in the provascular tissues of the cotyledons and axis of the dry seed as well as in the epiderm and outer layers of the cortex in the embryo axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292000
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation in field conditions of a three-dimensional architectural model of the maize root system: Comparison of simulated and observed horizontal root maps (1996)
    Springer
    Plant and soil 178 (1996), S. 101-112 
    Details
    ISSN: 1573-5036
    Keywords: maize ; root growth model ; root mapping ; root spatial distribution ; root system ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Most existing water and nutrient uptake models are based on the assumption that roots are evenly distributed in the soil volume. This assumption is not realistic for field conditions, and significantly alters water or nutrient uptake calculations. Therefore, development of models of root system growth that account for the spatial distribution of roots is necessary. The objective of this work was to test a three dimensional architectural model of the maize root system by comparing simulated horizontal root maps with observed root maps obtained from the field. The model was built using the current knowledge on maize root system morphogenesis and parameters obtained under field conditions. Simulated root maps (0.45 × 0.75 m) of horizontal cross sections at 3 depths and 3 dates were obtained by using the model for a plant population. Actual root maps were obtained in a deep, barrier-free clay-loamy soil by digging pits, preparing selected horizontal planes and recording root contacts on plastic sheets. Results showed that both the number of cross-sections of axile roots, and their spatial distribution characterized with the R-index value of Clark and Evans (1954), were correctly accounted for by the model at all dates and depths. The number of cross-sections of laterals was also correctly predicted. However, laterals were more clustered around axile roots on simulated root maps than on observed root maps. Although slight discrepancies appeared between simulated and observed root maps in this respect, it was concluded that the model correctly accounted for the general colonization pattern of the soil volume by roots under a maize crop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011168
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  • 4
    Electronic Resource
    Electronic Resource
    Modelling minirhizotron observations to test experimental procedures (1997)
    Springer
    Plant and soil 189 (1997), S. 81-89 
    Details
    ISSN: 1573-5036
    Keywords: methodology ; minirhizotron ; model ; root system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to help design experiments with minirhizotrons or interpret data from such experiments, a modelling approach is a valuable tool to complement empirical approaches. The general principle of this modelling approach is to calculate and to study the part of a theoretical root system that is intersected by passes through a virtual minirhizotron tube (modelled here as a cylinder). Various outputs can be calculated from this part of the root system, and related to the surrounding root system which is perfectly known, since it has been simulated and stored in a data structure. Therefore, the method involves two levels of modelling that are presented and discussed: the root system architecture of a crop, and the observations that can be achieved with minirhizotron tubes. Illustrations of the method are presented to study the effect of several factors on the rooting depth curves, and to show how images may be calculated to mimic what can actually be viewed from inside the tube. These first results show that the maximum rooting depth curves, as virtually observed in the minirhizotron tube, present large variations and strongly underestimate the maximum rooting depth of the modelled root system (up to 60 cm in average). The underestimation is still more critical when the radius of the tube is lower than 3 cm, and when the tube is close to the vertical (angle lower than 0.2 rad). The use of the 0.9 quantile instead of the average value, for each of the observation dates, leads to a better estimation of the maximum rooting depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004288430467
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of parameters describing the root system architecture of field grown maize plants (Zea mays L.) (1994)
    Springer
    Plant and soil 164 (1994), S. 155-167 
    Details
    ISSN: 1573-5036
    Keywords: axile roots ; maize ; nodal roots ; root length ; root system ; seminal roots ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to study elongation curves of maize axile roots throughout their elongation period under field conditions. Relationships between their elongation rate and the extension rate of their branched region were also studied. Maize, early-maturing cultivar Dea, was grown on a deep, barrier-free clay loam (depth 1.80m). Trenches were dug during four periods until after silking and axile roots were excavated. Parameters measured were total length and the lengths of basal and apical unbranched zones. The rank of the bearing phytomer and general data about the carrying plant were also recorded. Results showed that axile roots from lower phytomers had similar elongation rates irrespective of the rank of the carrying phytomer. This elongation rate declined with root age. A monomolecular elongation model was fitted to the experimental data. Elongation was much slower in roots from upper phytomers. A rough linear relationship was found between the elongation rate of axile roots and the length of the apical unbranched zone. This result suggests that laterals appeared on a root segment a constant time after it was formed. Possible mechanisms with may account for the declining elongation rate with root age (increasing distance from aerial parts or adverse environmental conditions in deep soil layers) and variability between individual roots are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010067
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  • 6
    Electronic Resource
    Electronic Resource
    Study of differences between vertical root maps observed in a maize crop and simulated maps obtained using a model for the three-dimensional architecture of the root system (1996)
    Springer
    Plant and soil 182 (1996), S. 329-337 
    Details
    ISSN: 1573-5036
    Keywords: architecture ; model ; root map ; root profile ; root system ; soil bulk density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Differences between observed and simulated vertical root maps were studied in an attempt to evaluate the predictive ability of a simulation model of root system architecture under field conditions on mature plants, and to identify avenues for improvement. Some methodological problems associated with root mapping in the field are considered with a sensitivity analysis. Comparisons were made on a maize crop (early maturing hybrid F1 cultivar ‘Dea’) 15 days after silking. Four vertical root maps, perpendicular to the row and midway between two successive plants, were observed. Simulated root maps for different locations along the row showed essentially the same pattern, attesting of an approximately two-dimensional distribution of the roots in such a crop. Simulation of the intesection of roots with thin layers (thickness from 0 to 20 mm) instead of a perfect plane allowed us to assess effects due to the roughness of actual trench walls, and possible artefacts in the observation of root intersections. The simulated root profiles were very sensitive to this thickness, especially in the 0–5 mm range, in both average values, and overall shape. Actual data were close to the 3 mm thick simulations. This value seems plausible under our field conditions. Differences between simulated and actual root maps were shown to be mostly accounted for by the variations in soil bulk density. Thus, this environmental parameter appears as the most important one to include into the model for improving its predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029063
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