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911.
Summary We report a study of the mechanism by which the response of plants to waterlogging can be modified by soil temperature. Wheat
was grown initially in well-aerated soil in a controlled environment room before the soil was flooded with aerated, deionized
water. The soil temperature was maintained constant in the range 6–18°C while the air temperature was at 14°C. Waterlogging
damage was greater in plants at the higher soil temperatures when the plants were compared at the same chronological age.
However, when compared at the same growth stage, the response to soil temperature was little differenti.e. plants subjected to waterlogging for a long time at low soil temperatures exhibited a similar reduction in growth and other
properties as those subjected briefly at higher temperatures. The concentration of dissolved oxygen in the soil solution declined
rapidly at all temperatures, being almost zero after 36 h waterlogging. Temperature affected rates of change of the concentrations
of dissolved carbon dioxide, ethylene, nitrous oxide, nitrite, nitrate, calcium and potassium. The importance of soil-and
plant-determined properties in the waterlogging response of plants at different temperatures are discussed. 相似文献
912.
Summary Nuclear and cytoplasmic staining methods were used to study natural senescence of the root cortex and coleoptile of wheat
and barley seedlings grown in glasshouse conditions. Coleoptiles of barley senesced more slowly than those of wheat, paralleling
the known difference in rates of root cortex senescence in these cereals. The coleoptiles and root cortices of both cereals
senesced more slowly in shaded than in unshaded conditions, but infection of the shoots of barley byErysiphe graminis had little effect on root cortex senescence.
The results are discussed in relation to infection by root- and foot-rot fungi. Previous reports on the effects of illumination
on take-all infection (Gaeumannomyces graminis) are explained. It is suggested that natural senescence of the coleoptile might affect establishment of infection by the
eyespot fungus,Pseudocercosporella herpotrichoides, either directly or through the activities of competing microorganisms. 相似文献
913.
Intact chloroplasts capable of high rates of photosynthesis fail to reduce CO2 when illuminated in the absence of oxygen. While anaerobiosis limits proton gradient formation leading to ATP deficiency (Ziem-Hanck, U. and Heber, U. (1980) Biochim. Biophys. Acta 591, 266–274), light activation of fructose-1,6-bisphosphatase was also inhibited by anaerobiosis, whereas light activation of NADP-malate dehydrogenase was stimulated by anaerobiosis, indicating that reductant was still available for light activation. The chloroplast pool of NADP was largely reduced during illumination under anaerobiosis and electron transport to oxaloacetate was not inhibited by anaerobic conditions. Significant light activation of fructose-bisphosphatase was observed in anaerobic chloroplasts with 3-phosphoglycerate as substrate, but not with dihydroxyacetone phosphate (3-phosphoglycerate supports electron transport and hence proton gradient formation). In the absence of added substrates, illumination of anaerobic chloroplasts resulted in some light activation of fructose-bisphosphatase when the pH of the medium was increased. Under these conditions, light activation was stimulated by dihydroxyacetone phosphate. Dihydroxyacetone phosphate added together with oxaloacetate allowed light activation of fructose-bisphosphatase in anaerobic chloroplasts, while neither substrate added alone was effective. Formation of a transthylakoid proton gradient can therefore substitute for an alkaline suspension medium by causing an alkaline shift of the stromal pH on illumination. The data are interpreted as indicating that fructose-bisphosphatase, but not NADP-malate dehydrogenase, requires an alkaline pH and the presence of substrate for rapid reductive light activation and they bear on the interpretation of the lag observed in photosynthesis in chloroplasts and leaves on illumination after a prolonged dark period. 相似文献
914.
Teguments from spargana of Spirometra mansonoides were disrupted and removed using 0.2% Triton ×-100. Tegumental fractions were obtained by differential centrifugation and the proteins and glycoproteins of this surface layer were partially characterized in 9 to 20% linear gradient sodium dodecyl sulfate-polyacrylamide slab gels. Electrophoretic analysis of the microtriches (brush border) and vesicular fractions revealed nine polypeptides that were common to these tegumental fractions. The polypeptide composition of the microtriches and vesicular fractions differed qualitatively and with respect to the relative concentrations of certain polypeptides. Glycopeptides of the microtriches and vesicular fractions were identified by the direct application of the following fluorescein isothiocyanate-conjugated lectins to slab gels: concanavalin A, wheat germ agglutinin, Ricinus communis agglutinin-120, soybean agglutinin, and Ulex europaeus agglutinin-1. The major polypeptides associated with the tegument were found to be glycopeptides. U. europaeus agglutinin-1 failed to label any tegumental glycopeptides. Based on the different sugar specificities of the lectins tested, the oligosaccharide chains of tegumental glycoproteins of S. mansonoides may contain the following carbohydrates: d-mannose, d-glucose, N-acetyl-d-glucosamine, N-acetylneuraminic acid, d-galactose, and N-acetyl-d-galactosamine. 相似文献
915.
Differentiation of soil properties related to the spatial association of wheat roots and soil macropores 总被引:5,自引:0,他引:5
Under certain soil conditions, e.g. hardsetting clay B-horizons of South-Eastern Australia, wheat plants do not perform as
well as would be expected given measurements of bulk soil attributes. In such soils, measurement indicates that a large proportion
(80%) of roots are preferentially located in the soil within 1 mm of macropores. This paper addresses the question of whether
there are biological and soil chemical effects concomitant with this observed spatial relationship. The properties of soil
manually dissected from the 1–3 mm wide region surrounding macropores, the macropore sheath, were compared to those that are
measured in a conventional manner on the bulk soil. Field specimens of two different soil materials were dissected to examine
biological differentiation. To ascertain whether the macropore sheath soil differs from rhizosphere soil, wheat was grown
in structured and repacked cores under laboratory conditions. The macropore sheath soil contained more microbial biomass per
unit mass than both the bulk soil and the rhizosphere. The bacterial population in the macropore sheath was able to utilise
a wider range of carbon substrates and to a greater extent than the bacterial population in the corresponding bulk soil. These
differences between the macropore sheath and bulk soil were almost non-existent in the repacked cores. Evidence for larger
numbers of propagules of the broad host range fungus Pythium in the macropore sheath soil were also obtained.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
916.
Continuous monitoring of rhizosphere respiration after labelling of plant shoots with 14CO2 总被引:1,自引:1,他引:0
Nguyen Christophe Todorovic Christine Robin Christophe Christophe Angélique Guckert Armand 《Plant and Soil》1999,212(2):189-199
The present work describes an original method to follow rate of 14CO2 and total CO2 production from rhizosphere respiration after plant shoots had been pulse-labelled with 14CO2. We used a radioactivity detector equipped with a plastic cell for flow detection of beta radiation by solid scintillation
counting. The radioactivity detector was coupled with an infrared gas analyser. The flow detection of 14CO2 was compared to trapping of 14CO2 in NaOH and counting by liquid scintillation. First, we demonstrated that NaOH (1 M) trapped 95% of the CO2 of a gaseous sample. Then, we determined that the counting efficiency of the radioactivity flow cell was 41% of the activity
of gaseous samples as determined by trapping in NaOH (1 M) and by counting by static liquid scintillation. The sensitivity
of the 14CO2- flow detection was 0.08 Bq mL−1 air and the precision was 2.9% of the activity measured compared to 0.9% for NaOH trapping method. We presented two applications
which illustrate the relevance of 14CO2-flow detection to investigations using 14C to trace photoassimilates within the plant-soil system. First, we examined the
kinetics of 14CO2 production when concentrated acid is added to NaH14CO3. This method is the most commonly used to label photoassimilates with 14C. Then, we monitored 14CO2 activity in rhizosphere respiration of 5-week old maize cultivated in soil and whose shoots had been pulse-labelled with
14CO2. We conclude that alkali traps should be used for a cumulative determination of 14CO2 because they are cheap and accurate. On the other hand, we demonstrated that the flow detection of 14CO2 had a finer temporal resolution and was consequently a relevant tool to study C dynamics in the rhizosphere at a short time
scale.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
917.
This study describes the soil solution chemistry in the rhizosphere of fine roots of sessile oak ( Quercus petraea (M.) Liebl.)
grown in rhizotrons. A control was compared with soils treated with an equivalent CaCO3 of 1.4 t ha-1 CaO. Solution samples were extracted from the B-horizon using micro suction cups with a suction of ∼40 kPa. Two series of experiments were carried out: one irrigated with rain water (age of seedling 2 to 4 months) and one
irrigated with demineralized water (age of seedlings 1.5 to 2 months). Half of the sampling points were choosen close to the
roots and half in the bulk soil. In both experiments there was generally no rhizospheric gradient after liming. In contrast,
in the control, depletion in the rhizosphere occurred for most of the ions studied (Mg, Ca, Al, K, NO3
-, NH4
+, Cl-) in the demineralized water experiment, but this was different when rainwater was used. The latter effect is probably due
to the higher solution concentrations in the rainwater experiment but could also be a result of root damage due to low Ca/Al
ratios in the rhizosphere solution. It was concluded, that liming improved the chemical composition in the rhizosphere soil
solution by increasing overall solute concentration to levels enabling sufficient and easier nutrient uptake by roots.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
918.
Development of a molecular marker for the adult plant leaf rust resistance gene Lr35 in wheat 总被引:14,自引:0,他引:14
R. Seyfarth C. Feuillet G. Schachermayr M. Winzeler B. Keller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(3-4):554-560
The objective of this work was to develop a marker for the adult plant leaf rust resistance gene Lr35. The Lr35 gene was originally introgressed into chromosome 2B from Triticum speltoides, a diploid relative of wheat. A segregating population of 96 F
2
plants derived from a cross between the resistant line ThatcherLr35 and the susceptible variety Frisal was analysed. Out of 80 RFLP probes previously mapped on wheat chromosome 2B, 51 detected
a polymorphism between the parents of the cross. Three of them were completely linked with the resistance gene Lr35. The co-segregating probe BCD260 was converted into a PCR-based sequence-tagged-site (STS) marker. A set of 48 different
breeding lines derived from several European breeding programs was tested with the STS marker. None of these lines has a donor
for Lr35 in its pedigree and all of them reacted negatively with the STS marker. As no leaf rust races virulent on Lr35 have been found in different areas of the world, the STS marker for the Lr35 resistance gene is of great value to support the introgression of this gene in combination with other leaf rust (Lr) genes into breeding material by marker-assisted selection.
Received: 14 December 1998 / Accepted: 30 January 1999 相似文献
919.
X. Shan T. K. Blake L. E. Talbert 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):1072-1078
Conversion of amplified fragment length polymorphisms (AFLPs) to sequence-specific PCR primers would be useful for many genetic-linkage
applications. We examined 21 wheat nullitetrasomic stocks and five wheat-barley addition lines using 12 and 14 AFLP primer
combinations, respectively. On average, 36.8% of the scored AFLP fragments in the wheat nullitetrasomic stocks and 22.3% in
the wheat-barley addition lines could be mapped to specific chromosomes, providing approximately 461 chromosome-specific AFLP
markers in the wheat nullitetrasomic stocks and 174 in the wheat-barley addition lines. Ten AFLP fragments specific to barley
chromosomes and 16 AFLP fragments specific to wheat 3BS and 4BS chromosome arms were isolated from the polyacrylamide gels,
re-amplified, cloned and sequenced. Primer sets were designed from these sequences. Amplification of wheat and barley genomic
DNA using the barley derived primers revealed that three primer sets amplified DNA from the expected chromosome, five amplified
fragments from all barley chromosomes but not from wheat, one amplified a similar-sized fragment from multiple barley chromosomes
and from wheat, and one gave no amplification. Amplification of wheat genomic DNA using the wheat-derived primer sets revealed
that three primer sets amplified a fragment from the expected chromosome, 11 primer sets amplified a similar-sized fragment
from multiple chromosomes, and two gave no amplification. These experiments indicate that polymorphisms identified by AFLP
are often not transferable to more sequence-specific PCR applications.
Received: 30 June 1998 / Accepted: 26 October 1998 相似文献
920.
M. R. Simón 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(2):310-314
Flag-leaf angle (FLAngle), flag-leaf area (FLarea) and flag-leaf area duration (FLADuration) are important traits in determining
yield in wheat (Triticum aestivum L). Genetic studies on these traits are very few. The objective of this study was to determine the gene action controlling
those traits in four wheat crosses. Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC(F1×P1) and BC(F1×P2)). The joint scaling test described by Mather and Jinks was used to test goodness of fit to eight genetic models. Models including
additivity, dominance and interallelic interactions best fitted the data for the three traits and the four crosses. Additive
effects were most prevalent for FLAngle. They were also significant for FLArea and FLADuration. Dominance and epistatic gene
action were also found, but the degree and direction was both trait- and genotype-specific. Heritabilities values were intermediate.
Genetic progress, although slow, can be expected when selecting for these traits; however, selection would be most effective
if delayed to later generations because of dominance and epistatic effects.
Received: 20 April 1998 / Accepted: 14 July 1998 相似文献