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1.
Influence of external zinc and phosphorus supply on Cd uptake by rice (Oryza sativa L.) seedlings with root surface iron plaque 总被引:1,自引:0,他引:1
Rice seedlings were grown in hydroponic culture to determine the effects of external Zn and P supply on plant uptake of Cd
in the presence or absence of iron plaque on the root surfaces. Iron plaque was induced by supplying 50 mg l−1 Fe2+ in the nutrient solution for 2 day. Then 43-day-old seedlings were exposed to 10 μmol l−1 Cd together with 10 μmol l−1 Zn or without Zn (Zn–Cd experiment), or to 10 μmol l−1 Cd with 1.0 mmol l−1 P or without P (P–Cd experiment) for another 2 day. The seedlings were then harvested and the concentrations of Fe, Zn, P
and Cd in dithionite–citrate–bicarbonate (DCB) extracts and in roots and shoots were determined. The dry weights of roots
and shoots of seedlings treated with 50 mg l−1 Fe were significantly lower than when no Fe was supplied. Adsorption of Cd, Zn and P on the iron plaque increased when Fe
was supplied but Cd concentrations in DCB extracts were unaffected by external Zn or P supply levels. Cd concentrations in
shoots and roots were lower when Fe was supplied. Zn additions decreased Cd concentrations in roots but increased Cd concentrations
in shoots, whereas P additions significantly increased shoot and root Cd concentrations and this effect diminished when Fe
was supplied. The percentage of Cd in DCB extracts was significantly lower than in roots or shoots, accounting for up to 1.8–3.8%
of the plant total Cd, while root and shoot Cd were within the ranges 57–76% and 21–40% respectively in the two experiments.
Thus, the main barrier to Cd uptake seemed to be the root tissue and the contribution of iron plaque on root surfaces to plant
Cd uptake was minor. The changes in plant Cd uptake were not due to Zn or P additions altering Cd adsorption on iron plaque,
but more likely because Zn or P interfered with Cd uptake by the roots and translocation to the shoots. 相似文献
2.
The effects of low concentrations of aluminium on the growth and uptake of nitrate-N by white clover 总被引:1,自引:0,他引:1
Summary The effects of aluminium (Al3+) at concentrations of 0, 25, 50 and 100 μM on the growth of white clover, dependent upon N supplied as NO
3
−
, were examined in flowing solution culture. Plants were established with a normal nutrient supply for 7 weeks and then grown
with carefully controlled pH (at 4.5) and P concentrations, and with 0, 25, 50 or 100 μM Al3+ for a further three weeks. There were rapid visual effects (i.e. symptoms of P deficiency and reduction in root extension) and the dry weights of shoots and roots were reduced at 50 and
100 μM. Less than 10% of Al absorbed from solution was transported to the shoots. The uptake of P, and its transport between roots
and shoots, were reduced in plants grown with Al. The uptake of NO
3
−
stopped immediately after the introduction of 50 or 100 μM Al, and was significantly reduced at 25 μM after three weeks.
During a second phase of the experiment, plants previously grown at 0, 25, 50 and 100 μM Al, were grown for a further 2 weeks either with NO
3
−
(with and without 50 μM Al3+) or without NO
3
−
but with inoculation by Rhizobia (and with or without 50 μM Al3+). The effects of the previous treatments with Al on N uptake were small during the second phase, but uptake by all plants
was restricted when Al was present. Inoculation did not result in nodulation in the second phase when Al3+ was present in the solution, but Al already in the plant from the first phase did not prevent nodulation in the absence of
Al during the second phase. 相似文献
3.
Dynamics of zinc uptake and accumulation in the hyperaccumulating and non-hyperaccumulating ecotypes of Sedum alfredii Hance 总被引:2,自引:0,他引:2
X. E. Yang T. Q Li X. X. Long Y. H. Xiong Z. L. He P. J. Stoffella 《Plant and Soil》2006,284(1-2):109-119
Sedum alfredii Hance has been identified as a Zn-hyperaccumulating plant species native to China. The characteristics of Zn uptake and accumulation
in the hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of S. alfredii were investigated under nutrient solution and soil culture conditions. The growth of HE was normal up to 1000 μM Zn in nutrient solution, and 1600 mg Zn kg−1 soil in a Zn-amended soil. Growth of the NHE was inhibited at Zn levels ≥250 μM in nutrient solution. Zinc concentrations in the leaves and stems increased with increasing Zn supply levels, peaking at
500 and 250 μM Zn in nutrient solution for the HE and the NHE, respectively, and then gradually decreased or leveled off with further increase
in solution Zn. Minimal increases in root Zn were noted at Zn levels up to 50 μM; root Zn sharply increased at higher Zn supply. The maximum Zn concentration in the shoots of the HE reached 20,000 and
29,000 mg kg−1 in the nutrient solution and soil experiments, respectively, approximately 20 times greater than those of the NHE. Root Zn
concentrations were higher in the NHE than in the HE when plants were grown at Zn levels ≥50 μM. The time-course of Zn uptake and accumulation exhibited a hyperbolic saturation curve: a rapid linear increase during the
first 6 days in the long-term and 60 min in the short-term studies; followed by a slower increase or leveling off with time.
More than 80% of Zn accumulated in the shoots of the HE at half time (day 16) of the long-term uptake in 500 μM Zn, and also at half time (120 min) of the short-term uptake in 10 μM 65Zn2+. These results indicate that Zn uptake and accumulation in the shoots of S. alfredii exhibited a down-regulation by internal Zn accumulated in roots or leaves under both nutrient solution and soil conditions.
An altered Zn transport system and increased metal sequestration capacity in the shoot tissues, especially in the stems, may
be the factors that allow increased Zn accumulation in the hyperaccumulating ecotype of S. alfredii.
Section Editor: F. J. Zhao 相似文献
4.
There is ample experimental evidence that, Na, if supplied in separate fertiliser granules or crystals to N, i.e., in blended
fertiliser form, can improve both the yield and the recovery of fertiliser N by grassland swards in situations of limited
K supply, but not in situations of K abundance. There is some evidence, though, that in K-replete situations, Na, if supplied
in the same fertiliser granule as N, i.e. in concentrated complex fertiliser (CCF) form, also improves dry matter production
and N recovery by swards whilst lowering the risk of grass tetany in grazing animals. However, the mechanism for the latter
effect of Na on N uptake has never been elucidated, nor has it been clarified whether Na stimulates NH
4
+
and NO
3
−
uptake by plants or simply NO
3
−
uptake alone. The aim of the present study was to see if supplying Na in the same fertiliser pellets (NNa-CCF) as NH4NO3 (differentially labelled with15N), or in separate pellets (NNa-blend), had any effect on the recovery of15N-labelled NH
4
+
and NO
3
−
-N by perennial ryegrass plants growing in a glasshouse under K-replete conditions. The results of the experiment confirmed
that using an NNa-CCF was more beneficial to shoot production than using an NNa-blend. However, the differential in shoot
production occurred without any corresponding difference in total N (i.e. NH
4
+
plus NO
3
−
-N) recovery in shoot tissue. Instead, Na, in the CCF appears to have stimulated NO
3
−
uptake at the expense of NH
4
+
absorption, thereby altering the balance between NH
4
+
and NO
3
−
-nutrition in favour of NO
3
−
-nutrition, and stimulating shoot production as a consequence. It was concluded that if grassland is already well supplied
with K it would be more beneficial in terms of sward production to apply a Na and N-containing CCF than a blend of separate
Na and N-containing granules or crystals. 相似文献
5.
Renata Matraszek 《Acta Physiologiae Plantarum》2008,30(3):361-370
The author studied the effect of different nickel concentrations (0, 0.4, 40 and 80 μM Ni) on the nitrate reductase (NR) activity
of New Zealand spinach (Tetragonia expansa Murr.) and lettuce (Lactuca sativa L. cv. Justyna) plants supplied with different nitrogen forms (NO3
−–N, NH4
+–N, NH4NO3). A low concentration of Ni (0.4 μM) did not cause statistically significant changes of the nitrate reductase activity in
lettuce plants supplied with nitrate nitrogen (NO3
−–N) or mixed (NH4NO3) nitrogen form, but in New Zealand spinach leaves the enzyme activity decreased and increased, respectively. The introduction
of 0.4 μM Ni in the medium containing ammonium ions as a sole source of nitrogen resulted in significantly increased NR activity
in lettuce roots, and did not cause statistically significant changes of the enzyme activity in New Zealand spinach plants.
At a high nickel level (Ni 40 or 80 μM), a significant decrease in the NR activity was observed in New Zealand spinach plants
treated with nitrate or mixed nitrogen form, but it was much more marked in leaves than in roots. An exception was lack of
significant changes of the enzyme activity in spinach leaves when plants were treated with 40 μM Ni and supplied with mixed
nitrogen form, which resulted in the stronger reduction of the enzyme activity in roots than in leaves. The statistically
significant drop in the NR activity was recorded in the aboveground parts of nickel-stressed lettuce plants supplied with
NO3
−–N or NH4NO3. At the same time, there were no statistically significant changes recorded in lettuce roots, except for the drop of the
enzyme activity in the roots of NO3
−-fed plants grown in the nutrient solution containing 80 μM Ni. An addition of high nickel doses to the nutrient solution
contained ammonium nitrogen (NH4
+–N) did not affect the NR activity in New Zealand spinach plants and caused a high increase of this enzyme in lettuce organs,
especially in roots. It should be stressed that, independently of nickel dose in New Zealand spinach plants supplied with
ammonium form, NR activity in roots was dramatically higher than that in leaves. Moreover, in New Zealand spinach plants treated
with NH4
+–N the enzyme activity in roots was even higher than in those supplied with NO3
−–N. 相似文献
6.
Vengadesan G Amutha S Muruganantham M Anand RP Ganapathi A 《Plant cell reports》2006,25(11):1174-1180
Transgenic herbicide tolerant Acacia sinuata plants were produced by transformation with the bar gene conferring phosphinothricin resistance. Precultured hypocotyl explants were infected with Agrobacterium tumefaciens strain EHA105 in the presence of 100 μM acetosyringone and shoots regenerated on MS (Murashige and Skoog, 1962, Physiol Plant 15:473–497) medium with 13.3 μM benzylaminopurine, 2.6 μM indole-3-acetic acid, 1 g l−1 activated charcoal, 1.5 mg l−1 phosphinothricin, and 300 mg l−1 cefotaxime. Phosphinothricin at 1.5 mg l−1 was used for the selection. Shoots surviving selection on medium with phosphinothricin expressed GUS. Following Southern hybridization, eight independent shoots regenerated of 500 cocultivated explants were demonstrated to be transgenic, which represented transformation frequency of 1.6%. The transgenics carried one to four copies of the transgene. Transgenic shoots were propagated as microcuttings in MS medium with 6.6 μM 6-benzylaminopurine and 1.5 mg l−1 phosphinothricin. Shoots elongated and rooted in MS medium with gibberellic acid and indole-3-butyric acid, respectively both supplemented with 1.5 mg l−1 phosphinothricin. Micropropagation of transgenic plants by microcuttings proved to be a simple means to bulk up the material. Several transgenic plants were found to be resistant to leaf painting with the herbicide Basta. 相似文献
7.
The toxicity of cadmium to barley plants as affected by complex formation with humic acid 总被引:3,自引:0,他引:3
An ‘alternating solution’ culture method was used to study the effects of chloride ions and humic acid (HA) on the uptake
of cadmium by barley plants. The plants were transferred periodically between a nutrient solution and a test solution containing
one of four levels of HA (0, 190, 569 or 1710 μg cm−3) and one of five levels of Cd (0, 0.5, 1.0, 2.5 or 5.0 μg cm−3) in either a 0.006M NaNO3 or 0.006M NaCl medium. Harvest and analysis of shoots and roots was after nineteen days. The distribution of Cd in the test solutions
between Cd2+, CdCl+ and HA-Cd was determined in a separate experiment by dialysis equilibrium.
In the nitrate test solutions Cd uptake was clearly controlled by Cd2+ concentration and was therefore reduced by HA complex formation. In the absence of HA, chloride suppressed Cd uptake indicating
that Cd2+ was the preferred species. However complex formation with Cl− enhanced uptake when HA was present because of an increase in the concentration of inorganic Cd species relative to the nitrate
system.
The ratio root-Cd/shoot-Cd remained at about 10 across a wide range of shoot-Cd concentrations, from about 3 μg g−1 (sub-toxic) up to 85 μg g−1 (80% yield reduction). The ability of the barley plants to accumulate ‘non-toxic’ Cd in their roots was thus very limited.
Humic acid also had no effect on Cd translocation within the plant and the root/shoot weight ratio did not vary with any treatment.
At shoot-Cd concentrations in excess of 50 μg g−1, K, Ca, Cu and Zn uptake was reduced, probably the result of root damage rather than a specific ion antagonism. The highest
concentration of HA also lowered Fe and Zn uptake and there was a toxic effect with increasing HA concentration at Cd=0. However
the lowest HA level, comparable with concentrations found in mineral soil solutions, only reduced yield (in the absence of
Cd) by <5% while lowering Cd uptake across the range of Cd concentrations by 66%–25%. 相似文献
8.
The effect of the fungicide, chlorothalonil, on vesicular-arbuscular mycorrhizal (VAM) symbiosis was studied in a greenhouse
using Leucaena leucocephala as test plant. Chlorothalonil was applied to soil at 0, 50, 100 and 200 μg g−1. The initial soil solution P levels were 0.003 μg mL−1 (sub-optimal) and 0.026 μg mL−1 (optimal). After 4 weeks, the sub-optimal P level was raised to 0.6 μg mL−1 (high). The soil was either uninoculated or inoculated with the VAM fungus, Glomus aggregatum. The fungicide reduced mycorrhizal colonization of roots, development of mycorrhizal effectiveness, shoot P concentration
and uptake and dry matter yields at all concentrations tested, although the highest inhibitory effect was noted as the concentration
of the fungicide was increased from 50 to 100 μg g−1. Phosphorus applied after four weeks tended to partially offset the deleterious effects of chlorothalonil in plants grown
in the inoculated and uninoculated soil which suggests that the fungicide was interfering with plant P uptake. The results
suggest that the use of chlorothalonil should be restricted to levels below 50 μg g−1 if the benefits of mycorrhizal symbiosis are to be expected.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464. 相似文献
9.
Summary This is the first communication of direct shoot regeneration from fully developed leaves of potted mature Echinacea purpurea plants. Shoot buds were induced directly on the adaxial surface of mature leaf tissues of E. purpurea 30 d after culture initiation on Woody Plant Medium (WPM) supplemented with various levels of 6-benzyladenine (BA). Maximum
shoot organogenesis, with 12–20 shoots per leaf segment, was obtained with 5% coconut milk and 2.5 mg l−1 (6μM) BA in 30 d. Callus was induced using 0.5 mgl−1 (1μM) α-naphthaleneacetic acid and 2.5 mgl−1 (6μM) BA. The regenerated shoots were rooted on WPM supplemented with 1.5 mgl−1 (3μM) of indole-3-butyric acid, 3% sucrose, and 0.85% agarose. Rooted plants were successfully transferred to soil in pots and
appeared morphologically normal and flowered in a growth chamber. 相似文献
10.
Summary Axillary and terminal buds from suckers of Ananas comosus cv. Phuket were established on Murashige and Tucker-based (MT) medium with 2.0 mgl−1 (9.8 μM) indolebutyric acid, 2.0 mgl−1 (10.74 μM) naphthaleneacetic acid, and 2.0 mgl−1 (9.29 μM) kinetin, followed by multiplication on Murashige and Skoog-based (MS) medium containing 2.0 mgl−1 (8.87 μM) benzyladenine (BA) to provide a continuous supply of axenic shoots. Leaves, excised from such cultured shoots, produced
adventitious shoots from their bases when these explants were cultured on MS medium containing 0.5 mgl−1 (2.26 μM) 2,4-dichlorophenoxyacetic acid (2,4-D) and 2.0 mgl−1 (8.87 μM) BA. Embryogenic callus was produced when leaf explants were cultured on MS medium with 3.0 mgl−1 (12.42 μM) 4-amino-3,5,6-trichloropicolinic acid (picloram). Somatic embryos developed into shoots following transfer of embryogenic
tissues to MS medium with 1.0 mgl−1 (4.44 μM) BA. Cell suspensions, initiated by transfer of embryogenic callus to liquid MS medium with 1.0 mgl−1 (4.14 μM) picloram or 1.0 mgl−1 (4.52 μM) 2,4-D, also regenerated shoots by somatic embryogenesis, on transfer of cells to semisolid MS medium with 1.0 mgl−1 (4.44 μM) BA. All regenerated shoots rooted on growth regulator-free MS medium, prior to ex vitro acclimation and transfer to the glasshouse. These studies provide a baseline for propagation, conservation, and genetic manipulation
of elite pineapple germplasms. 相似文献
11.
Summary
Leptadenia reticulata (Retz.) Wight. & Arn., an important herbal medicinal plant, belongs to the family Asclepiadaceae. This plant has been known
for its medicinal uses since 4500 BC. Presently this is an endangered species. There is a need for applying non-conventional
methods of propagation for conservation and sustainable utilization of biodiversity of Leptadenia reticulata. We developed a micropropagation method for mass multiplication of L. reticulata. Explants harvested from greenhouse-maintained and field-grown plants were used to establish cultures of L. reticulata. The nodal shoot segments were surface-sterilized and cultured on Murashige and Skoog (MS) medium along with additives (25
mg l−1 each of adenine sulfate, arginine, and citric acid, and 50 mg l−1 ascorbic acid) containing 0.6 μM indole-3-acetic acid (IAA) and 9 μM N6-benzyladenine (BA). Three to four shoots differentiated from each node within 25–30 d at 26±2°C and 36 μmol m−2 s−1 spectral flux photon (SFP) for 12 hd−1. Shoots were further multiplied by (1) repeated transfer of mother explant on fresh medium containing 0.6 μM IAA and 2.2 μM BA, and (2) subculture of in vitro-differentiated shoots on MS medium with 6.6 μM BA and 0.6 μM IAA. After three or four subcultures, the basal clump with shoot bases was divided into three or four subclumps and multiplied
on the fresh medium. From each clump 15–20 shoots regenerated within 25 d. Ninety percent of the in vitro-produced shoots rooted ex vitro if these were pulse-treated with 123 μM each of indole-3-butyric acid and β-naphthoxyacefic acid. The plantlets were transferred to bottles containing sterile ‘soilrite’
(soilless compost and soil conditioner) moistened with half-strength MS macrosalts. Ninety-five percent of the plantlets were
hardened in the bottles within 15 d. The hardened plants were then transferred to black polybags in the nursery. Field transferred
plants are growing normally and have flowered. The protocol developed is reproducible. From a single nodal segment about 1700
hardened plants could be regenerated within 174 d. 相似文献
12.
Summary An efficient in vitro propagation system was developed for Arnebia euchroma, an important Chinese traditional medicinal plant. The present study utilized thidiazuron (TDZ) for the induction of shoot
organogenesis on cotyledon and hypocotyl explants. The maximal number of shoots was obtained on the modified Linsmaier and
Skoog (LS) medium supplemented with 1.0 mgl−1 (4.5 μM) TDZ for 12d on cotyledon explants (8.6 shoots per cotyledon explant). Other cytokinins (kinetin and 6-benzyladenine) and
auxin (α-naphthaleneacetic acid) were not efficient in inducing regeneration on cotyledon explants. Browning of the basal
portion of the subcultured shoots could be significantly reduced when they were cultured on the modified LS medium supplemented
with 100 mgl−1 (33.3 μM) polyvinylpyrrolidone. Well-developed shoots formed roots on the same medium containing 1.0 mgl−1 (4.9 μM) indole-3-butyric acid. The efficient regeneration protocol reported here provides an important means of micropropagation
of this plant. Furthermore, this protocol is essential to future genetic improvement of plants via transformation protocols. 相似文献
13.
Summary Cadmium and zinc uptake parameters were determined for intact corn (Zea mays L.) seedlings grown for 15 and 22 in nutrient solutions containing levels of Cd and Zn that were similar to those found in
soil solutions. Uptake of both elements was assumed to follow Michaelis-Menten kinetics. Calculations were based on the concentrations
of free ionic Cd (Cd2+) and Zn (Zn2+) rather than the total solution concentration. Rates of Zn uptake were measured by determining depletion of Zn for periods
of up to 30 h from solutions containing initial concentrations of 1.5 and 10μmol Zn 1−1. Depletion curves suggested that Zn uptake characteristics were similar at both levels of Zn in solution. The Imax for Zn
uptake decreased from 550 to 400 pmol m−2 root surface s−1 between 16 and 22 d of growth while Km decreased from 2.2 to 1.5 μmol Zn2+ 1−1. Cadmium uptake parameters were measured by controlling Cd2+ activities in nutrient solution betwen 6.3 to 164 nmol l−1 by continuous circulation of nutrient solution through a mixed-resin system. Imax for Cd uptake was 400 pmol m−2 root surface s−1 at 15 and 22 d of growth. The magnitude of Km increased from 30 to 100 nmol Cd2+ 1−1 during this time period. The Km value suggests that corn is efficient for Cd uptake. The results of these uptake studies
are consistent with the observed uptake of Zn and Cd by corn seedlings in soils. 相似文献
14.
The effects of temperature (20, 24 and 28 °C) and irradiance (15 and 40 μmol photon m−2 s−1) on the nitrate and ammonium uptake rates of the subtropical red alga, Laurencia brongniartii, were investigated to prepare for tank cultivation. Nitrate uptake followed saturation kinetics and was faster at higher
irradiances and temperatures. In contrast, ammonium uptake was linear over the experimental range and was not affected by
an increase in temperature. A parameter, β, was calculated to compare substrate uptake rates of nitrate along the linear portion
of the uptake curve with that of ammonium. For nitrate, β was lower at low irradiance and higher at high irradiance (β = 0.007
± 0.003 and 0.030 ± 0.002 [μmol N L−1 (μmol N gww−1 d−)−1], respectively). However, β was 0.023 ± 0.002 and 0.034 ± 0.002 [μmol N L−1 (μmol N gww−1 d−1)−1] for ammonium, suggesting a preference for ammonium over nitrate. 相似文献
15.
Adam M. Dimech Rob Cross Rebecca Ford Paul W. J. Taylor 《Plant Cell, Tissue and Organ Culture》2007,88(2):157-165
The physiological effects of three auxins [indole-3-butyric acid (IBA), α-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic
acid (2,4-d)] and two cytokinins [thidiazuron (TDZ) and N6-benzylaminopurine (NAA)] on in vitro morphogenesis of Doryanthes excelsa were measured. Longitudinal bud sections derived from immature inflorescences were used as a source of explants. Callus regeneration
was observed at the highest frequencies (46.2%) when grown on media containing 50 μmol L-1 NAA and 0.5 μmol L−1 TDZ. Adventitious shoot organogenesis was observed at the highest frequency (56.8%) when grown on media containing 0.5 μmol L−1 NAA and 50 μmol L−1 TDZ. Regenerated shoots were rooted ex vitro after 6 weeks when dipped in a solution of 50 μmol L−1 NAA or no plant growth regulators were applied. 相似文献
16.
Summary
In vitro banana (Musa spp.) shoots were cultured under photomixotrophic (30 gl−1 sucrose and 0.2 h−1 number of air exchanges of culture vessels) and photoautotrophic (0 gl−1 sucrose and 3.9 h−1 number of air exchanges) conditions for 28 d in 370 cm3 Magenta boxes (GA7-type) containing 70 ml of half-strength Murashige and Skoog (MS) medium with 22.2 μM N6-benzyladenine (BA). The effects of varying CO2 concentration (475 or 1340 μmol mol−1) and light intensity (photosynthetic photon flux (PPF) of 100 or 200 μmol m−2 s−1) were investigated. Fresh and dry weights of banana shoots grown photomixotrophically were significantly greater on day 28
than those grown photoautotrophically. Photoautorophic shoots had a larger number of unfolded leaves and greater leaf area
than photomixotrophic plants by days 14 and 28, regardless of CO2 concentration. The shoot fresh and dry weights on day 14 in photoautotrophic conditions were significantly greater at PPF
of 200 μmol m−2 s−1 than at 100 μmol m−2 s−1. The increase in net photosynthetic rate of photoautotrophic banana shoots was significant compared with photomixotrophic
shoots. The multiplication ratio of in vitro banana shoots grown photoautotrophically in a 28-d culture period was the greatest at 100 μmol m−2 s−1 PPF and 475 μmol mol−1 CO2. 相似文献
17.
NADH specific glutamate dehydrogenase (GDH) activity was examined in roots and shoots of maize seedlings grown in half-strength
Hoagland’s solution containing NH4NO3 as sole nitrogen source under irradiance of 60 W m−2 and temperature of 25±2°C. When 5,5′-dithio-bis (2-nitrobenzoic acid) (DTNB) was supplied to the assay mixture, it inhibited
NADH-GDH activity in both roots and shoots, irrespective of whether the enzymes were extracted from light- or dark-treated
roots and shoots. In each case the inhibition increased with the increase in DTNB concentration. At the maximum concentration
of DTNB used (20 μM) the inhibition of shoot NADH-GDH was more pronounced than inhibition of root enzyme. This indicated differences
in shoot and root NADH-GDH. 相似文献
18.
A pot experiment was conducted to examine the effect of arbuscular mycorrhizal fungus, Glomus fasciculatum, and salinity on the growth of Acacia nilotica. Plants were grown in soil under different salinity levels (1.2, 4.0, 6.5, and 9.5 dS m−1). In saline soil, mycorrhizal colonization was higher at 1.2, 4.0, and 6.5 dS m−1 salinity levels in AM-inoculated plants, which decreased as salinity levels further increased (9.5 dS m−1). Mycorrhizal plants maintained greater root and shoot biomass at all salinity levels compared to nonmycorrhizal plants.
AM-inoculated plants had higher P, Zn, and Cu concentrations than uninoculated plants. In mycorrhizal plants, nutrient concentrations
decreased with the increasing levels of salinity, but were higher than those of the nonmycorrhizal plants. Mycorrhizal plants
had greater Na concentration at low salinity levels (1.2, 4.0 dS m−1), which lowered as salinity levels increased (6.5, 9.5 dS m−1), whereas Na concentration increased in control plants. Mycorrhizal plants accumulated a higher concentration of K at all
salinity levels. Unlike Na, the uptake of K increased in shoot tissues of mycorrhizal plants with the increasing levels of
salinity. Our results indicate that mycorrhizal fungus alleviates deleterious effects of saline soils on plant growth that
could be primarily related to improved P nutrition. The improved K/Na ratios in root and shoot tissues of mycorrhizal plants
may help in protecting disruption of K-mediated enzymatic processes under salt stress conditions. 相似文献
19.
Summary An efficient in vitro plant regeneration system from cotyledons was established in tetraploid Isatis indigotica Fort. Factors influencing shoot regeneration from cotyledons, including culture medium type, combinations of plant growth
regulators, and sucrose concentrations in the medium, as well as illumination were investigated. Murashige and Skoog's (MS)
medium was found to be best for promoting shoot regeneration, followed by Gamborg's B5 and White's medium. The highest shoot regeneration frequency was achieved from cotyledons cultured on MS medium supplemented
with 2.0 mgl−1 (8.9 μM) 6-benzyladenine and 1.0 mgl−1 (5.4 μM) α-naphthaleneacetic acid (NAA), with 97.9% regeneration, associated with a high number of multiple shoots developed per
explant (8.6 shoots per explant). A sucrose concentration of 3% present in the medium and light conditions were beneficial
for shoot regeneration. The shoots developed were rooted in a half-strength MS medium supplemented with 1.0 mgl−1 (5.4 μM) NAA and successfully transplanted in soil in pots with over 85% survival. The establishment of an efficient plant regeneration
procedure from cotyledons provides a basis for the rapid in vitro multiplication of tetraploid Isatis indigotica Fort., one of the most extensively used medicinal plants in China currently under great shortage. 相似文献
20.
Sufficient supply of potassium (K) can alleviate the adverse effects of excess sodium (Na) on plant growth. However, it remains
unclear if such a beneficial function is related to regulation of root growth and/or expression of K/Na transporters. Herein
we report the responses of a rice cultivar, which was pretreated with normal nutrient solution for 1 month, to three levels
of Na (0, 25, and 100 mM) without or with supply of K for 9 days. High Na (100 mM) significantly decreased plant growth, root
activity, and total K uptake, and increased biomass ratio of roots to shoots. Short-term removal of K supply (9 days) did
not affect root morphology and biomass ratio of roots to shoots, but decreased root activity of seedlings grown in high Na
solution. K deficiency increased uptake of Na and transport of K from roots to shoots. Moreover, expression of OsHAK1, a putative K transporter gene, was upregulated by low Na (25 mM) and downregulated by high Na (100 mM) in roots. In leaves,
its expression was suppressed by the Na treatments when K supply was maintained. Expression of OsHKT2;1, which encodes a protein that acts mainly as a Na transporter, was downregulated by high Na, but was enhanced by K deficiency
both in roots and leaves. Expression of five other putative K/Na transporter or Na+/H+ genes, OsHKT1;1, OsHKT1;2, OsHKT2;3, OsNHX1, and OsSOS1, was not affected by the treatments. The results suggest that OsHAK1 and OsHKT2;1 were involved in the interactive effects of K and Na on their uptake and distribution in rice.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献