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1.
Cardenas-Navarro R; Adamowicz S; Gojon A; Robin P 《Journal of experimental botany》1999,50(334):625-635
The effects of light and NO3- nutrition on
15NO3- influx in roots were
investigated in young, 19-d-old, induced tomato plants grown at a constant
air and solution temperature of 20C. Nitrate
influx was measured by 15N accumulation for 5 min,
on plants exposed to a wide range of exogenous concentrations, from 10 x
10-3 to 30 mol m-3. Influx
kinetics, fitted to the data following a non-linear procedure, showed
multiphasic patterns. The best fits were obtained when three pure and
non-additive Michaelis-Menten kinetics were applied, with phase transitions
at approximately 0.8 and 4 mol m-3. In plants grown
at 3.0 mol m-3 NO3-, the
asymptotic maximum influx rate (Imax) of each phase
declined during the night until 24 h darkness. At the end of the day
period, about a 2-fold enhancement of Imax was
observed when plants were pretreated for 3 d with 0.2 instead of 3.0 mol
m-3 NO3-. The influx rates
measured at any given NO3- concentration and the
Imax for any phase showed a negative non-linear
correlation with plant nitrate concentration. Furthermore, the results
suggest the existence of a set point, approximately 66 mol
m-3 plant nitrate, for which influx is null at any
given solution nitrate concentration. A model using modified
Michaelis-Menten kinetics is proposed to predict the influx rate as a
function of both solution and plant NO3-
concentrations. 相似文献
2.
Physiological response and yield of paclobutrazol treated tomato plants (Lycopersicon esculentum Mill.) 总被引:1,自引:0,他引:1
Experiments were conducted to study the physiologicaleffect of the plant growth retardant paclobutrazol(PBZ) and its impact on the yield of tomato plants(cv. Precador). Seedlings were treated at the time of prickingout with soil and foliar applications of PBZ atconcentrations of 1.0 and 25.0 mg l-1respectively. The results established that:-- The reduced height and the increased thickness ofthe young plant stem, as well as the accelerated rootformation are a significant advantage of the PBZtreatment, contributing to the improvement of seedlingquality at planting.-- Soil treatment (1 mg l-1) and foliar treatment(25 mg l-1) with PBZ improves the photosyntheticactivity and water balance of tomato cv. Precador.-- PBZ accelerates fruit formation and increases earlyfruit yield.-- The concentrations of the retardant used and themode of its application ensure the production offruits without any residual retardant and harmless tohuman health from a phytosanitary point of view. 相似文献
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4.
Phenylalanine ammonia-lyase (PAL; EC 4.3.1.5.) induction in cotyledons from 96-h dark-grown Lycopersicon esculentum Mill. was studied in response to continuous light and hourly light pulses (blue, red, far red). The increases of PAL promoted by blue and red pulses are reversed completely by immediately following 758 nm irradiations. The response to continuous red light could be substituted for by hourly 6-min red light pulses. The effect of continuous red treatments is mainly due to a multiple induction effect of phytochrome. In contrast to red light, hourly light pulses with far red and blue, light can only partially substitute for continuous irradiation. The continuous blue response could be due to a combination of a multiple induction response and of a high irradiance response of phytochrome. The continuous far red response, could represent a high irradiance response of phytochrome. Dichromatic irradiations indicate that phytochrome is the photoreceptor controlling the light response (PAL) in tomato seedlings.Abbreviations Norflurazon
NF-4-chloro-5-(methylamino)-2-(,,,-trifluoro-m-tolyl)-3 (2H) pyridazinone
- PAL
phenylalanine ammonia-lyase
-
phytochrome photoequilibrium Pfr/Ptot
- Pfr
far-red absorbing form of phytochrome
- Pr
red absorbing form of phytochrome
- Ptot
total phytochrome: Pr+Pfr 相似文献
5.
Profilin is a G-actin monomer-binding protein which has been shown to participate in actin-based tipgrowth of animal cells. The abundance of profilin in pollen and its occurrence in several vegetable foods raises the question of the role of profilin in plants. First, its distribution throughout various parts of the plant needs to be determined. This paper describes observations on the presence of profilin in the tomato plant (Lycopersicon esculentum Mill.). The distribution of profilin in flower buds, stems, leaves, roots, and fruits of tomato was determined by immunoblotting and by tissue printing, showing that profilin is present in most if not all parts of the tomato plant.We gratefully acknowledge the help provided by Dr. A.T. Jagendorf and the donation of tomato seeds and maize pollen by N. Eanetta and Dr. M. Smith, respectively. The use of Dr. R. Wayne's SZH ILLD dissecting microscope is gratefully acknowledged. This work was aided by helpful discussions with C.S. Combs, Dr. C.A. Conley, and Dr. J. Andersland. This work was supported by a Hatch grant and NRI Competitive Grants Program/USDA 94-37304-1046 to MVP. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship to DWD. 相似文献
6.
Dong-Hee Lee 《Journal of Plant Biology》1998,41(2):86-92
An anthocyanin-free tomato plant, H957, and its parental wild type, H883, were hydroponically grown to test for tolerance
to a low phosphorus (P) in H957. The tolerance was evaluated by comparing growth and metabolism of H957 vs. H883 at different
P concentrations ranging 25–400 μM. Fresh weights were measured weekly. Dry weight, mineral contents, photosynthetic rate,
and P utilization ratios of the plants were measured after five weeks of growth in the hydroponic culture. Although the growth
of both varieties was severely impaired at 25 μM P, H957 showed a greater fresh weight and dry weight at 50–400 μM P. H957
showed a higher net photosynthetic rate on older leaves while both varieties showed similar photosynthetic rate on young leaves.
H957 tissue contains an overall lower P concentration in its tissue than H883. These observations together indicate that the
anthocyaninless mutant H957 tolerate to lower P concentration. It does so by utilizing internal P with better efficiency rather
than by absorbing external P better. 相似文献
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8.
Characterization of the subtilase gene family in tomato (Lycopersicon esculentum Mill.) 总被引:2,自引:0,他引:2
The gene family of subtilisin-like serine proteases (subtilases, SBTs) in tomato (Lycopersicon esculentum Mill.) comprises at least 15 members, 12 of which have been characterized in this study. Sequence comparison revealed that tomato subtilases fall into 5 distinct subfamilies. Single genes were shown to exist for LeSBT1, LeSBT2 and tmp, while 5 and 6 genes were found in the LeSBT3/4 and P69 subfamilies, respectively. With the exception of tmp, tomato subtilase genes were found to lack introns. Expression of subtilase genes was confirmed at the mRNA level by northern blot analysis and/or by primer extension experiments. For each of the 5 subtilase subfamilies, a distinctive pattern of expression was observed in tomato organs. At least one of the subtilases was found to be expressed in each organ analysed. Structural features evident from deduced amino acid sequences are discussed with reference to the related mammalian proprotein convertases. 相似文献
9.
Diurnal nitrate uptake in young tomato (Lycopersicon esculentum Mill.) plants: test of a feedback-based model 总被引:3,自引:0,他引:3
A simple model is proposed to describe diurnal net nitrate uptake rate
patterns observed experimentally on young plants grown under constant
non-limiting nutrition. It rests on two hypotheses: net uptake rate is
under negative feedback control by internal plant nitrate content, and
nitrogen metabolism occurs only during the light period. The model
parameters were determined from the results of three independent
experiments performed under non-disturbing conditions in a growth room at
constant air and solution temperatures. Net hourly nitrate uptake rate was
measured through a diurnal cycle and after an extended 28 h period of
darkness. It increased continuously during the light period and decreased
during the dark period. Under prolonged darkness, net uptake declined to an
asymptotic positive uptake rate of about 10-5 mol
h-1 g-1 total plant dry
weight. The measured hourly nitrate uptake rate values were consistent with
independent determinations of long-term nitrate and total N accumulations
in the plant. Realistic simulations of experimental data are achieved with
the proposed model. Furthermore, the maintenance of a positive net uptake
rate, measured in non-growing plants subjected to prolonged darkness, is
explained in the model by the continuous increase of plant water content.
The importance of the diurnal variations of plant water content for nitrate
uptake rate is emphasized and gives consistency to the homeostasis
hypothesis of the model. The diurnal changes in nitrate uptake predicted by
the model are strongly dependent on the assumption made for diurnal changes
in nitrate assimilation. While the purely photosynthetic assumption is
convenient, a more realistic metabolism sub-model is
needed. 相似文献
10.
Summary A histological study ofin vitro cultured cotyledonary expiants of tomato (Lycopersicon esculentum) was performed in order to determine the site (differentiated tissue or developing callus) and the mode of plant regeneration.Results have shown that callus develops at the excision sites of cotyledonary expiants and that shoots are formed exclusively within the unorganized callus: excision areas are the only morphogenetic sites and the proximal excision is the preferred site for plant regeneration.Shoots differentiate by organogenesis within the superficial region of the callus. Few neocambial cells cooperate in the neoformation. Origin from a single cell is highly unlikely since rarely observed single activated cells never developed into shoots.Regenerated plants may be chimeras if invitro culture induces genetic diversity in the initial cells.Abbreviations IAA
Indole-3-acetic acid
- c
callus
- d
vegetative dome
- s
shoot
- ad
adaxial
- ab
abaxial
- t
tracheid
- p
parenchyma
- S
sieve tube 相似文献
11.
Role of extensin peroxidase in tomato (Lycopersicon esculentum Mill.) seedling growth 总被引:3,自引:0,他引:3
It is proposed that inhibition of extensin peroxidase activity leads to a less rigid cell wall and thus promotes cell expansion
and plant growth. A low-molecular-weight inhibitor derived from the cell walls of suspension-cultured tomato cells was found
to completely inhibit extensin peroxidase-mediated extensin cross-linking in vitro at a concentration of 260 μg/ml. The inhibitor
had no effect upon guaiacol oxidation catalyzed by extensin peroxidase or horseradish peroxidase. We have demonstrated that
the light-irradiated inhibition of plant growth may be partially offset by inhibition of endogenous extensin peroxidase activity.
Overall plant growth was enhanced by up to 15% in the presence of inhibitor relative to control plants. Inhibitor-treated
and illuminated tomato hypocotyls grew up to 15% taller than untreated controls. The inhibitor had no effect upon etiolated
plants over a 15-d period, suggesting that only low levels of peroxidase-mediated cross-linking can be found in the cell walls
of etiolated plants. SDS-PAGE/Western blots of ionically bound protein from both etiolated and illuminated hypocotyls identified
a doublet at 57/58.5 kDa which is immuno-reactive with antibodies raised to tomato extensin peroxidase. Levels of the 58.5-kDa
protein, determined by SDS-PAGE, were at least threefold higher in illuminated tomato hypocotyls than in etiolated hypocotyls.
Three fold higher levels of extensin peroxidase, elevated in-vitro extensin cross-linking activity and 15% higher levels of
cross-linked, non-extractable extensin were observed in illuminated tomato hypocotyls compared with etiolated tomato hypocotyls.
This suggests that white-light inhibition of tomato hypocotyl growth appears to be mediated, at least partially, by deposition
of cell wall extensin, a process regulated by Mr-58,500 extensin peroxidase. Our results indicate that the contribution of peroxidase-mediated extensin deposition to plant
cell wall architecture may have an important role in plant growth.
Received: 22 July 1999 / Accepted: 11 October 1999 相似文献
12.
13.
In order to investigate the effects of homogeneous and localized supply of different nitrogen forms (nitrate, NO3 ? vs ammonium, NH4 +) on the growth of tomato seedlings, root morphology and six cytokinin (CTK) fractions in xylem sap were analyzed. Whole roots were supplied with different ratios of NO3 ? to NH4 + (100:0, as 100-0NA; 75:25, as 75-25NA; 50:50, as 50-50NA) under homogeneous supply. In split-root experiments, three treatments were compared: a sole NO3 ? supply (N|N), a spatially separated supply of NO3 ? and NH4 + (N|A), and a spatially separated supply of NO3 ? and a mixture of NO3 ? and NH4 + nutrition at a ratio of 75:25 (N|AN). All concentrations of total N were set at 5 mM. The results showed that (1) homogeneous 75% NO3 ? plus 25% NH4 + supply to the whole root zone led to maximum shoot and root dry matter (DM), root surface area (RS) and root volume (RV). The spatially separated supply of NO3 ? and NH4 + (N|A) resulted in a contrasting effect on root morphology: in comparison to N|N, root DM in the NO3 ?-containing pot was increased by 50% whereas it was depressed by 50% in the NH4 +-containing pot. The 75% NO3 ? plus 25% NH4 + supply in the split-root experiment led to no significant effects either on shoot DM and root DM, or on RS and RV when compared to N|N. (2) The presence of NH4 + in the external medium led to a significantly reduced total xylem-CTK concentration, and a close negative correlation was found between xylem NH4 + and total CTK concentration irrespective of culture mode. A relatively high level of zeatin riboside (ZR) was maintained both in 75-25NA and N|A treatments. It was concluded that, in addition to the percentage of NH4 + to NO3 ? in the nutrient solution, whether NH4 + was supplied to the whole root system or to only part of the root system was also an important factor affecting plant growth. The fact that the 75-25NA and N|A treatments resulted in optimal growth of tomato seedlings might be attributed to the higher ZR concentration in xylem. 相似文献
14.
The internal distribution processes of cadmium (115mCd) in the stems of tomato plants have been investigated using in vivo -spectrometric measurements with semiconductor detectors. The initial penetration into the xylem after root uptake and the subsequent lateral redistribution in the surrounding tissues were monitored continuously in each individual plant. The kinetics of the lateral migration toward the epidermis can be described by a diffusion process, characterized by an apparent diffusion coefficient of about 10-8 cm2 s-1. After two days of cadmium supply this heavy metal is accumulated in relatively large amounts in the epidermal and cortical layers, from which it can be released only very slowly. On the contrary, the exchange processes with other divalent cations cause in the xylem a quick release, its rate being dependent on the duration of the preceding cadmium treatment. 相似文献
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In flooded soils, the rapid effects of decreasing oxygen availability on root metabolic activity are likely to generate many potential chemical signals that may impact on stomatal apertures. Detached leaf transpiration tests showed that filtered xylem sap, collected at realistic flow rates from plants flooded for 2 h and 4 h, contained one or more factors that reduced stomatal apertures. The closure could not be attributed to increased root output of the glucose ester of abscisic acid (ABA-GE), since concentrations and deliveries of ABA conjugates were unaffected by soil flooding. Although xylem sap collected from the shoot base of detopped flooded plants became more alkaline within 2 h of flooding, this rapid pH change of 0.5 units did not alter partitioning of root-sourced ABA sufficiently to prompt a transient increase in xylem ABA delivery. More shoot-sourced ABA was detected in the xylem when excised petiole sections were perfused with pH 7 buffer, compared with pH 6 buffer. Sap collected from the fifth oldest leaf of "intact" well-drained plants and plants flooded for 3 h was more alkaline, by approximately 0.4 pH units, than sap collected from the shoot base. Accordingly, xylem [ABA] was increased 2-fold in sap collected from the fifth oldest petiole compared with the shoot base of flooded plants. However, water loss from transpiring, detached leaves was not reduced when the pH of the feeding solution containing 3-h-flooded [ABA] was increased from 6.7 to 7.1 Thus, the extent of the pH-mediated, shoot-sourced ABA redistribution was not sufficient to raise xylem [ABA] to physiologically active levels. Using a detached epidermis bioassay, significant non-ABA anti-transpirant activity was also detected in xylem sap collected at intervals during the first 24 h of soil flooding. 相似文献
18.
A procedure is described which allows the purification of fructokinase (EC 2.7.1.4) from young tomato fruit. The procedure yielded a 400-fold purification and two isoenzymes designated fructokinase I and II (FKI and FKII) were separated by anion-exchange chromatography. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) the molecular mass was estimated to be 35 kDa. Gel filtration on Sepharose-12 indicated that for both fructokinases the functional form is a dimer. Two dimensional isoelectric focusing/SDS-PAGE combined with immunoblotting showed that FKI has two components with isoelectric points (pIs) of 6.42 and 6.55, while four components with pIs from 6.07 to 6.55 were detected for FKII. A mixture of both fructokinases showed that the components of FKI match the more alkaline components of FKII. The activity of both fructokinases increased with increasing pH to around 8.0 and equal activity was observed from 8.0 to 9.5. Both fructokinases were specific for fructose with K m values for fructose of 0.131 and 0.201 mM for FKI and FKII, respectively. At high concentrations (> 0.5 mM), fructose was also a strong inhibitor with inhibition constants (K i) of 1.82 and 1.39 mM for FKI and FKII, respectively. The preferred phosphate donor for both isoforms was ATP, and K m values of 0.11 and 0.15 mM were observed for FKI and FKII. At low concentrations (0.05–0.2 mM), fructose exhibited noncompetitive inhibition with respect to ATP for both fructokinases. This inhibition pattern changed to uncompetitive when higher fructose concentrations (0.5–10 mM) were used. These data indicated that substrate addition is ordered, with ATP adding first. Inhibition by ADP was also affected by the fructose concentrations. At 0.5 mM fructose, FKI showed non-competitive inhibition by ADP with respect to ATP and this inhibition changed to uncompetitive when 3 mM fructose was used. The isoform FKII showed a competitive inhibition pattern for ADP at 0.5 mM fructose which also changed to uncompetitive when 3 mM fructose was used. The features of the regulation of both fructokinases suggest that this enzyme might have a relevant role in carbon metabolism during tomato fruit development. 相似文献
19.
R. Ecochard 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1972,42(5):189-195
Summary The genetic behaviour of three chlorophyll variegated F1 tomato plants, derived from irradiated gametophytes, was analyzed over several generations of selfing and backcrossing. The results suggest that irradiation has put genes, different in all three mutants, into a labile state, n*, remaining so after fertilization. This state had the power of converting the associated wild allele N into a deficient form.Somatic conversion was soon followed, in Plant C11 always and nearly always in Plant C12, by stabilization of both alleles in a conversion-inactive recessive state, genetically similar, and stable except in special conditions.In the other type, found seldom in C12, always in C6, the n* state was permanent and transmissible. Conversion occurred with a certain frequency determined by developmental and genotypic influences, and the converted allele also acquired conversion power, so that gametes from an N n* plant were of three kinds: N, n* and n*. This process corresponds to paramutation (Brink 1958).Results were compared and contrasted with other published data.Contribution nr. 748 of the Biology Division of Euratom. 相似文献