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1.
Sorghum [Sorghum bicolor (L.) Moench] and sunflower (Helianthus annuus L.) were grown in a greenhouse with roots divided between sand irrigated with nutrient solution (–0.097 MPa) or nutrient solution containing polyethylene glycol (PEG) (–0.570 MPa) to compare the effect of unequal root zone stress on plant water relations of a C4 (sorghum) and a C3 (sunflower) plant. Roots also were divided between two pots of sand irrigated only with nutrient solution (controls) or only with PEG in nutrient solution. In addition to plant water-status measurements, photosynthetic rate, growth (height, root, and shoot dry weights), and evolution of ethylene (a gaseous hormone indicative of stress) were measured. Under all three split-root treatments, sunflower had a lower leaf water potential and produced more ethylene than sorghum. Sunflower was able to survive the PEG stress if half of its root system was under nonstressed conditions. Sunflower with half its root system irrigated with PEG usually had values of leaf water potential, osmotic potential, stomatal resistance, transpiration rate, photosynthetic rate, ethylene evolution, height, and dry weights that were close to those of the control plants. Sunflower with all roots exposed to PEG was wilted severely. Sorghum was little affected by PEG stress applied either to half or all the root system. Growth of sorghum was the same under all treatments. Apparently because stomata of sorghum were more closed in the partial stress test than those of sunflower, sorghum conserved water and had a higher leaf water potential, which might have permitted growth with stress. 相似文献
2.
Hanna Bandurska 《Acta Physiologiae Plantarum》1998,20(4):375-381
The aim of this work was to examine the ability of ABA and proline to counteract the deleterious effect of water deficit stress
on cell membrane injuries.
Six-day-old seedlings of two barley genotypes (cv. Aramir, line R567) were treated with ABA (2·10−4 M) or proline (0.1 M) for 24 h, and then subjected to osmotic stress for 24h, by immersing their roots in polyethylene glycol
(PEG 6000) solution of osmotic potential of −1.0 MPa and −1.5 MPa or by submerging the leaf pieces in PEG solution of osmotic
potential of −1.6 MPa.
Pretreatment of plants with ABA and proline caused an increase of free proline level in the leaves. Plants treated with ABA
exhibited a lower membrane injury index under water stress conditions than those untreated even when no effect of this hormone
on RWC in the leaves of stressed plants was observed. Pretreatment of plants with proline prevented to some extent membrane
damage in leaves of the stressed seedlings, but only in the case when stress was imposed to roots. Improvement in water status
of leaves was also observed in seedlings pretreatment with proline. The protective effect of both ABA and proline was more
pronounced in line R567 that exhibited higher membrane injury under water deficit stress conditions. 相似文献
3.
Kapilan Ranganathan Janice E. K. Cooke Walid El Kayal Maria A. Equiza Maryamsadat Vaziriyeganeh Janusz J. Zwiazek 《Acta Physiologiae Plantarum》2017,39(8):187
The effects of mild osmotic stress conditions on aquaporin-mediated water transport are not well understood. In the present study, mild osmotic stress treatments with 20 and 50 g L?1 polyethylene glycol 6000 (PEG) in Hoagland’s mineral solution were applied for 3 weeks under controlled environmental conditions to transgenic Populus tremula × Populus alba plants constitutively over-expressing a Populus PIP2;5 aquaporin and compared with the wild-type plants. The PEG treatments resulted in growth reductions and triggered changes in net photosynthesis, transpiration, stomatal conductance and root hydraulic conductivity in the wild-type plants. However, height growth, leaf area, gas exchange, and root hydraulic conductivity were less affected by the PEG treatments in PIP2;5-over-expressing poplar lines. These results suggest that water transport across the PIP2;5 aquaporin is an important process contributing to tolerance of mild osmotic stress in poplar. Greater membrane abundance of PIP2;5 was most likely the factor that was responsible for higher root hydraulic conductivity leading to improved plant water flux and, consequently, greater gas exchange and growth rates under mild osmotic stress conditions. The results also provide evidence for the functional significance of PIP2;5 aquaporin in water transport and its strong link to growth processes in poplar. 相似文献
4.
Physiological and Biochemical Responses Reveal the Drought Tolerance Efficacy of the Halophyte Salicornia brachiata 总被引:1,自引:0,他引:1
The drought tolerance of Salicornia brachiata seedlings was assessed by monitoring growth, nutrient uptake, electrolyte leakage, lipid peroxidation, and biochemical responses under drought conditions simulated with 0, 10, 20, and 30 % polyethylene glycol (PEG 6000). After 7 days of drought induction, plants were harvested for measurement of various parameters. The biomass decreased and the plant height remained unchanged with PEG treatment. The total plant water content (TWC%) decreased by 11 % at the highest concentration of PEG (30 %). The electrolyte leakage and lipid peroxidation of shoots increased by 17 and 5 %, respectively, in 30 % PEG-treated plants. K+ and Ca2+ contents of shoots increased in a dose-dependent manner. However, in roots K+ content decreased and Ca2+ content remained unaffected by PEG treatment. Mg2+ content increased at high concentrations of PEG (20–30 %) in shoots and decreased at the highest concentration of PEG (30 %) in roots. Total free amino acids, proline, and polyphenol contents increased progressively with increase in severity of the drought stress. Total sugar content and reducing sugar content increased in 10 and 20 % PEG-treated plants and decreased in 30 % PEG-treated plants. Our results suggest that proline and other free amino acids, sugars, and polyphenols are the main compatible solutes in S. brachiata for maintenance of osmotic balance, protection of cellular macromolecules, detoxification of the cells, and scavenging of free radicals under drought stress. A greater accumulation of compatible solutes also facilitates the maintenance of nutrient uptake and adequate tissue water status and protection of membranes under drought conditions in S. brachiata. The results from the present study suggest that S. brachiata can be used for restoration of arid and semiarid lands of coastal ecosystems. 相似文献
5.
Brassinosteroids (BRs) have been proposed to increase the resistance of plants to drought stress. The effect of foliar application
of 0.1 μM 24-epibrassinolide (EBR) on chlorophyll (Chl) content, photosystem 2 (PS 2) photochemistry, membrane permeability,
lipid peroxidation, relative water content (RWC), proline content, and the antioxidant system in drought-stressed Chorispora bungeana plants was investigated. The results showed that polyethylene glycol (PEG) induced water stress decreased RWC, Chl content
and variable to maximum Chl fluorescence ratio (Fv/Fm) less in plants pretreated with EBR than in non-pretreated plants. In addition, lipid peroxidation, measured in terms of
malondialdehyde content, membrane permeability and proline content in drought-stressed plants were less increased in EBR pretreated
plants, while antioxidative enzyme activities and reduced ascorbate and glutathione contents were more increased in EBR pretreated
than in non-pretreated plants. These results suggested that EBR could improve plant growth under drought stress 相似文献
6.
The objective of this study was to investigate the behaviour of different legumes against salinity and water stress, thus trying to discover simultaneous adaptations to both stresses. The nitrogen fixation, transpiration, predawn leaf water potential, and stomatal response of Medicago sativa L. (cvs. Tierra de Campos and Aragon), Trifolium repens L. (cv. Aberystwyth S-184) and T. brachycalycinum Katzn. et Morley (= T. subterraneum L. cv. Clare) were compared at three levels of stress (0.05, 0.3 and 0.5 MPa of either NaCl or polyethylene glycol 6000) in nutrient solution. The plants were stressed for three days and then returned to control nutrient solution. The changes in the parameters analyzed were dependent on the proportion of stress treatments and the nature of the species, always being greater in plants from PEG than from NaCl solutions. Transfer of lucerne and subclover plants from NaCl at 0.05 MPa to a non-saline medium resulted in an increase of nitrogen fixation above the level of the non-salinized control plants, especially significant in lucerne. Analysis of possible inorganic impurities in commercial PEG suggest that such type of impurities are not responsible for the toxic effects reported. Plant damage resulting from PEG treatment was apparently due to penetrations of PEG (as determined qualitatively by using the tetraiodinebismuthic acid technique) or low-molecular organic impurities into the plant. – The results are discussed as part of the adaptation of the different species to salinity and water stress. The best performance was given by "Tierra de Campos". 相似文献
7.
Fourteen days-old bean plants, grown on sand with Knop's nutrient solution were subjected to water stress (three days without
irrigation). The stress led to a decrease in almost all lipid classes except phospholipids in the primary leaves. The content
of palmitic acid increased, and that of the linolenic acid decreased. An increase of hexadecenoic acid in phospholipids was
also observed. Rewatering for 24 h led to the recovery of the stressed plants including that of the photosynthetic apparatus,
but the changes in the lipid composition were insignificant. The spraying of the plants before and after the water stress
with 5 × 10-6 M solution of the phenylurea cytokinin 4-PU-30 alleviated negative effect of water stress on the lipid membrane
composition permitting the plants to resist the harmful environment.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
The present study was carried out to determine interactive and comparative effects of salinity and water stress on growth,
proline accumulation, chlorophyll, carotenoid and macro nutrient content and antioxidative enzymes such as superoxide dismutase
(SOD), guaiacol peroxidase (POX), and polyphenol oxidase (PPO) in hydroponically grown maize (Zea mays L.cv DKC647) plants. Plants were treated two salt (NaCl) concentrations and polyethylene glycol 6000 (PEG 6000) to create
water stress. The results obtained from this experiment show that high salinity reduced growth through decreasing shoot and
root dry and fresh weight, chlorophyll, and carotenoid content, but PEG treatment had no significant effect on this parameters.
Under NaCl and PEG 6000 treatment, uptake and translocation of mineral nutrients changed drastically. The high presence of
Na+ in nutrient solution affected considerably the plant nutritional requirement, especially influencing the uptake of Ca2+ and K+, which were restricted for competition. Proline accumulation, and SOD, POX and PPO activities were increased with the increasing
intensity of NaCl stress, but PEG 6000 treatment in addition to NaCl had more significant effect on this enzyme activities.
These results suggest that maize plants may be increased proline content to maintain osmotic adjustment and increased the
activity of antioxidant enzymes to have a better protection against active oxygen species (AOS) under salt and water stress. 相似文献
9.
Iron-Deficiency Stress Responses in Cucumber (Cucumis sativus L.) Roots (A Possible Role for Ethylene?) 总被引:3,自引:2,他引:1
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Most dicotyledonous species respond to Fe deficiency by developing several mechanisms known as Fe-deficiency stress responses. To study the regulation of these responses, young cucumber plants (Cucumis sativus L. cv Ashley) were grown in nutrient solution for 11 d, being deprived of Fe during the last 4 or 5 d. Inhibitors of ethylene synthesis (2 or 10 [mu]M aminoethoxyvinylglycine; 10 or 20 [mu]M aminooxyacetic acid; 1, 2, 5, or 10 [mu]M Co2+ as CoCl2) or action (50, 200, or 800 [mu]M Ag+ as silver thiosulfate) were added to the nutrient solution at different times during this period of growth with no Fe. After this period, the reduction of Fe3+ ethylenedi-aminetetraacetate by the roots of entire plants was measured with ferrozine by reading the absorbance at 562 nm after 2 h. The presence of the ethylene inhibitors in the nutrient solution inhibited the Fe-deficiency stress responses ferric-reducing capacity and subapical root swelling. In another experiment, the addition of 1 [mu]M 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene synthesis, to the nutrient solution of plants having low ferric-reducing activity increased notably the ferric-reducing capacity and subapical root swelling. Here we show evidence that ethylene plays a role in the development of Fe-deficiency stress responses, since when ethylene synthesis or action was inhibited, the responses were also inhibited, and when a precursor of ethylene (ACC) was added, the responses were increased. 相似文献
10.
Sorghum (Sorghum bicolor L. Moench) plants were grown in solution culture and stressed at three rates of decreasing leaf water potential (−0.123,
−0.068 and −0.029 MPa day−1) achieved by the incremental addition of an osmoticum, polyethylene glycol (PEG) 6000 to the solutions. Plants were also
grown in soil and given different amounts of water which resulted in rates of decreasing leaf water potentials of −0.130 and
−0.073 MPa day−1.
The rate of stress and the culture system influenced the accumulation of solutes in the cell, but not cell volume. A rapid
stress (−0.123 and −0.130 MPa day−1) to approximately −1.6 MPa leaf water potential resulted in 0.75 and 0.16 MPa of osmotic adjustment in the PEG and soil culture
respectively. At moderate stress (−0.068 and −0.073 MPa day−1) respective values were 1.68 and 0.58 MPa. There were some visual symptoms in the solution grown plants characteristic of
uptake of high molecular weight PEG. However the relative growth rates of these plants were equal to or greater than those
of the soil grown plants.
In view of the differences in plant water status of soil and PEG solution cultured plants it was concluded that the use of
the latter system would not be entirely suitable for some studies of drought resistance in sorghum, as related to crop performance
in the field. 相似文献
11.
Hanna Bandurska 《Acta Physiologiae Plantarum》2000,22(4):409-415
The aim of this work was to examine the relationship between proline accumulation and membrane injury in barley leaves suffering
from the effects of water deficit. Water deficit stress was induced by water withholding or by immersing the roots in polyethylene
glycol (PEG 6000) solution of osmotic potential −1.5 MPa. The effect of water stress on proline accumulation and on membrane
injury was evaluated in leaf blades of several barley genotypes. Substantial differences in proline accumulation and membrane
injury indices among most of the genotypes investigated were observed. It was found that in drought stressed plants a higher
ability to accumulate proline positively correlates with lower membrane injury. Whereas, in osmotically stressed plants the
highest proline accumulation in the leaves was noticed in genotype with the largest membrane injury. The possible role of
proline in membrane protection under conditions of slow-acting drought or shock-acting osmotic stress is discussed. 相似文献
12.
Seedlings of two barley genotypes (‘Maresi’ and wild form of Hordeum spontaneum) were treated with jasmonic acid (JA 5 μM and 15 μM) for 24 h, and then subjected to water stress (PEG 6000 solution of −
1.5 MPa). JA caused an increase in the content of ABA but not in that of proline and spermidine in the two studied genotypes.
The effect of the treatment did not depend on the applied JA concentration. The pre-stress treatment with JA changed plant
response to water deficit with regard to membrane injury. Treatment with a lower JA concentration (5 μM) caused a substantial
reduction of the stress-induced membrane damage in the both genotypes. A higher JA concentration (15 μM) caused the reduction
of membrane injury only in H. spontaneum and was ineffective in ‘Maresi’. JA had no influence on the leaf water status in water-stressed plants. A possible role of
JA in leaf ABA accumulation and alleviation of cell membrane injury under water deficit is discussed.
The work was partly supported by the Polish Committee For Scientific Research, grant No 5 PO6A 036 18 相似文献
13.
Mirza Hasanuzzaman Kamrun Nahar Md. Shahadat Hossain Taufika Islam Anee Khursheda Parvin Masayuki Fujita 《Journal of Plant Interactions》2017,12(1):323-331
Nitric oxide (NO) is dynamic molecule implicated in diverse biological functions demonstrating its protective effect against damages provoked by abiotic stresses. The present study investigated that exogenous NO pretreatment (500?µM sodium nitroprusside, 24?h) prevented the adverse effect of drought stress [induced by 10% and 20% polyethylene glycol (PEG), 48?h] on rapeseed seedlings. Drought stress resulted in reduced relative water content with increased proline (Pro) level. Drought stress insisted high H2O2 generation and consequently increased membrane lipid peroxidation which are clear indications of oxidative damage. Drought stress disrupted the glyoxalase system too. Exogenous NO successfully alleviated oxidative damage effects on rapeseed seedlings through improving the levels of nonenzymatic antioxidant pool and upregulating antioxidant enzymes’ activities. Improvement of glyoxalase system (glyoxalase I and glyoxalase II activities) by exogenous NO was significant to improve plants’ tolerance. Nonetheless, regulation of Pro level and improvement of plant–water status were vital to confer drought stress tolerance. 相似文献
14.
This investigation was carried on to find out the changes occurred in Stevia rebaudiana in response to paclobutrazol (PBZ; 0–4 mg L?1) treatment and drought stress. Polyethylene glycol (PEG; 0–6 % w/v) was used to stimulate drought stress. Drought stress reduced fresh and dry weight, water content, chlorophylls, carotenoids, anthocyanins, water soluble carbohydrates, reducing sugar and proline amounts. Electrolyte leakage, MDA, α-tocopherol and glycine betaine contents increased in drought-stressed plants. The activity of P5CS and PDH enzymes and protein content showed no significant changes under drought stress. PBZ (with or without PEG) treatments decreased fresh and dry weight and water content. In PBZ-treated plants, less pigments was damaged by drought stress. PBZ treatment reduced the negative effect of drought stress on lipid peroxidation which resulted in lower electrolyte leakage and MDA content, compared to the same PEG level without PBZ. PBZ (with or without PEG) treatments increased glycine betaine, α-tocopherol, proline and protein contents. The amount of water soluble carbohydrates, reducing sugar and activity of P5CS and PDH were not affected by PBZ treatments. SDS-PAGE analysis revealed that drought stress increased a 25 kD protein with a critical function in plant development under stresses. According to the results, PEG provoked a severe drought stress in S. rebaudiana that could partly be restored by PBZ treatment. 相似文献
15.
The effect of arbuscular mycorrhizal (AM) colonisation by Glomus clarum on fruit yield and water use efficiency (WUE) was evaluated in watermelon (Citrullus lanatus) cv. Crimson Sweet F1 under field conditions. Treatments were: (1) well-watered plants without mycorrhizae (WW-M), (2) well-watered plants with mycorrhizae (WW+M), (3) water- stressed plants without mycorrhizae (WS-M) and (4) water-stressed plants with mycorrhizae (WS+M). When soil water tension readings reached –20 and –50 kPa for well-watered (WW) and water-stressed (WS) treatments, respectively, irrigation was initiated to restore the top soil to near field capacity. Water stress reduced watermelon shoot and root dry matter, fruit yield, water use efficiency but not total soluble solids (TSS) in the fruit, compared with the non-stressed treatments. Mycorrhizal plants had significantly higher biomass and fruit yield compared to nonmycorrhizal plants, whether plants were water stressed or not. AM colonisation increased WUE in both WW and WS plants. Macro- (N, P, K, Ca and Mg) and micro- (Zn, Fe and Mn) nutrient concentrations in the leaves were significantly reduced by water stress. Mycorrhizal colonisation of WS plants restored leaf nutrient concentrations to levels in WW plants in most cases. This is the first report of the mitigation of the adverse effect of water stress on yield and quality of a fruit crop. 相似文献
16.
Silicon Improves the Tolerance to Water-Deficit Stress Induced by Polyethylene Glycol in Wheat (Triticum aestivum L.) Seedlings 总被引:3,自引:0,他引:3
Z. F. Pei D. F. Ming D. Liu G. L. Wan X. X. Geng H. J. Gong W. J. Zhou 《Journal of Plant Growth Regulation》2010,29(1):106-115
Drought stress usually causes a serious yield reduction in wheat production. Silicon (Si) has been reported to be able to
alleviate drought stress damage; however, the mechanism is still poorly understood. In this article, the effects of Si (as
sodium silicate) on some parameters related to oxidative damage, proline, soluble sugar, and inorganic ions in the leaves
of wheat under 20% (w/v) polyethylene glycol (PEG-6000) simulative drought stress are investigated. PEG stress depressed the
growth of shoot and root and decreased leaf water potential and chlorophyll concentration. Addition of 1.0 mM Si could partially
improve the growth of shoot (but not root) and increase the leaf chlorophyll concentrations of stressed plants. Inclusion
of Si in culture solution also maintained leaf water potential of stressed plants at the same level as that of the control
plants. PEG stress induced significant accumulation of leaf hydrogen peroxide (H2O2) and malondialdehyde (MDA) as well as an increase in electrolyte leakage, which were all decreased by added silicon. These
results suggest that stress-induced membrane lipid peroxidation could be partly alleviated by added silicon. Moreover, the
results were also supported by the observation that PEG stress-induced decrease in glutathione concentration in the leaves
was reversed by added silicon. The proline concentration in the leaves was markedly increased under PEG stress, whereas added
silicon partially reversed this. PEG stress decreased the leaf soluble sugar concentration. There were significant negative
regressions between proline concentration and both shoot dry weight and leaf chlorophyll concentrations, whereas there were
positive regressions between the proline concentration and both H2O2 and MDA concentrations in the leaves, supporting the view that proline accumulation is a symptom of stress damage rather
than stress tolerance. Addition of Si obviously increased Si accumulation in the shoot. Analyses of Na, Mg, K, and Ca showed
no accumulation of these ions in the shoot (on the basis of per tissue dry weight) under water stress, and added Si even decreased
their concentrations. These results suggest that under short-term PEG-induced water stress conditions (1 week), antioxidant
defense, rather than osmotic adjustment, contributed to the improved wheat growth by Si. 相似文献
17.
Maria Filek Stanisław Walas Halina Mrowiec Elżbieta Rudolphy-Skórska Apolonia Sieprawska Jolanta Biesaga-Kościelniak 《Acta Physiologiae Plantarum》2012,34(3):985-995
The comparative responses of ten spring wheat cultivars to water stress were investigated. Wheat plants were cultured under
hydroponics conditions (Hoagland nutrient) to the stage of three-leaf seedlings. Then, the water medium was supplemented with
PEG (drought) or NaCl (salinity) to obtain a water status equal to −1.5 MPa. After a 2-day treatment, the changes in the following
parameters were determined: fresh and dry weight, macro- and microelement accumulation, membrane injury (electrolyte leakage,
lipid peroxidation) and fatty acid content of the phospholipid fraction of plasmalemma (in comparison to plants not stressed,
taken as a control). Generally, the plants were more significantly influenced by water stress stimulated by PEG than by NaCl
treatment, as compared to the plants cultivated in the control media. The results of the decrease in water content in leaves
and electrolyte leakage from cells corresponded well with the intensity of lipid peroxidation (determined by malondialdehyde—MDA-content)
and were chosen for the selection of investigated genotypes for tolerance to both stresses. The more tolerant genotypes exhibited
the opposite changes in phospholipid fatty acid unsaturation for two applied stresses i.e. NaCl treatment caused a decrease
in unsaturation whereas in PEG-treated plants an increase in unsaturation was observed. These changes were reversed for less
tolerant plants, i.e. NaCl treatment influenced an increase in fatty acid unsaturation whereas in PEG-treated plants a decrease
in unsaturation was measured. The ratio of U/S (unsaturated to saturated fatty acids) correlated with the total amount of
accumulated macroelements. The content of Mg, Ca and S in leaves of plants undergoing both stress factors (NaCl and PEG) dropped
whereas the K and P content increased in leaves of wheat seedlings cultured on media containing NaCl only. For microelements,
a decrease in the accumulation of these nutrients was detected in all investigated seedlings. However, a greater reduction
in the level of these elements occurred in seedlings grown on media with PEG in comparison to those grown on NaCl containing
media. 相似文献
18.
Water-extractable humic substances enhance iron deficiency responses by Fe-deficient cucumber plants 总被引:1,自引:1,他引:0
The ability of Fe-deficient cucumber plants to use iron complexed to a water-extractable humic substances fraction (WEHS),
was investigated. Seven-day-old Fe-deficient plants were transferred to a nutrient solution supplemented daily for 5 days
with 0.2 μM Fe as Fe-WEHS (5 μg org. C mL-1), Fe-EDTA, Fe-citrate or FeCl3. These treatments all allowed re-greening of the leaf tissue, and partial recovery of dry matter accumulation, chlorophyll
and iron contents. However, the recovery was faster in plants supplied with Fe-WEHS and was already evident 48 h after Fe
supply. The addition of 0.2 μM Fe to the nutrient solution caused also a partial recovery of the dry matter and iron accumulation
in roots of Fe-deficient cucumber plants, particularly in those supplied with Fe-WEHS. The addition of WEHS alone (5 μg org.
C mL-1, 0.04 μM Fe) to the nutrient solution slightly but significantly increased iron and chlorophyll contents in leaves of Fe-deficient
plants; in these plants, dry matter accumulation in leaves and roots was comparable or even higher than that measured in plants
treated with Fe-citrate or FeCl3. After addition of the different iron sources for 5 days to Fe-deficient roots, morphological modifications (proliferation
of lateral roots, increase in the diameter of the sub-apical zones and amplified root-hair formation) and physiological responses
(enhanced Fe(III)-chelate reductase and acidification of the nutrient solution) induced by Fe deficiency, were still evident,
particularly in plants treated with the humic molecules. The presence of WEHS caused also a further acidification of the nutrient
medium by Fe-deficient plants. The Fe-WEHS complex (1 μM Fe) could be reduced by intact cucumber roots, at rates of reduction
higher than those measured for Fe-EDTA at equimolar iron concentration. Plasma membrane vesicles, purified by two-phase partition
from root microsomes of Fe-deficient plants, were also able to reduce Fe-WEHS. Results show that Fe-deficient cucumber plants
can use iron complexed to water soluble humic substances, at least in part via reduction of complexed Fe(III) by the plasma
membrane Fe(III)-chelate reductase of root cells. In addition, the stimulating effect of humic substances on H+ release might be of relevance for the overall response of the plants to iron shortage.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
19.
20.
Hanna Bandurska 《Acta Physiologiae Plantarum》2001,23(4):483-490
The purpose of this research was to examine whether proline accumulation in leaves of barley under conditions of mild water
deficit (PEG — 0.75 MPa imposed on roots) may modify membrane injuries caused by subsequent severe osmotic stress (PEG — 1.6
MPa imposed on leaves). Six-day-old seedlings of four barley genotypes were used in the experiments. Substantial and different
proline accumulation was found in the leaves of mild water deficit-stressed plants of the most investigated genotypes. This
stress factor caused rather a small decrease in RWC and did not lead to membrane injuries. Severe osmotic stress imposed on
leaves caused considerable membrane injuries in all the genotypes investigated. Leaves of plants pre-stressed with mild water
deficit and then subjected to severe osmotic stress exhibited about a 50% lower membrane injury than those of not pre-stressed
plants. A possible role of proline accumulated in the leaves of pre-stressed plants in the process of alleviating cell membrane
injuries in the leaves subsequently exposed to severe water deficit is discussed. 相似文献